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Briggs DEG, Mongiardino Koch N. A Silurian pseudocolonial pterobranch. Curr Biol 2023; 33:5225-5232.e3. [PMID: 37935193 DOI: 10.1016/j.cub.2023.10.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 07/07/2023] [Accepted: 10/16/2023] [Indexed: 11/09/2023]
Abstract
Pterobranchs, a major group of the phylum Hemichordata, first appear in the fossil record during the Cambrian,1 and there are more than 600 fossil genera dominated by the mainly planktic graptolites of the Paleozoic, which are widely used as zone fossils for correlating sedimentary rock sequences.2 Pterobranchs are rare today; they are sessile marine forms represented by Rhabdopleura, which is considered the only living graptolite, and Cephalodiscus. Unlike their sister taxon, the colonial graptolites, cephalodiscids are pseudocolonial.3,4 Here, we describe a problematic fossil from the Silurian (Pridoli) Bertie Group of Ontario (420 mya), a sequence of near-shore sediments well known for its remarkably preserved diversity of eurypterids (sea scorpions).5 The fossil, Rotaciurca superbus, a new genus and species, was familiarly known as Ezekiel's Wheel,5 with reference to the unusual circular arrangement of the tubes that compose it. The structure and arrangement of the tubes identify Rotaciurca as a pterobranch, and phylogenetic analysis groups it with the cephalodiscids. We place it in a new family Rotaciurcidae to distinguish it from Cephalodiscidae. A large structure associated with the tubes is interpreted as a float, which would distinguish Rotaciurca as the only known planktic cephalodiscid-thus cephalodiscids, like the graptolites, invaded the water column. This mode of life reflects the rarity of pseudocolonial macroinvertebrates in planktic ocean communities, a role occupied by the tunicates (Chordata) known as salps today. Our estimates of divergence times, the first using relaxed total-evidence clocks, date the origins of both hemichordates and pterobranchs to the earliest Cambrian (Fortunian).
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Affiliation(s)
- Derek E G Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06520, USA; Yale Peabody Museum, New Haven, CT 06520, USA.
| | - Nicolás Mongiardino Koch
- Marine Biology Research Division, Scripps Institution of Oceanography, UC San Diego, 9500 Gilman Drive #0202, La Jolla, CA 92093, USA.
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2
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Briggs DEG, Mongiardino Koch N. A Silurian pseudocolonial pterobranch. Curr Biol 2023; 33:5273. [PMID: 38052164 DOI: 10.1016/j.cub.2023.11.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
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3
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Anderson RP, Woltz CR, Tosca NJ, Porter SM, Briggs DEG. Fossilisation processes and our reading of animal antiquity. Trends Ecol Evol 2023; 38:1060-1071. [PMID: 37385847 DOI: 10.1016/j.tree.2023.05.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 05/19/2023] [Accepted: 05/22/2023] [Indexed: 07/01/2023]
Abstract
Estimates for animal antiquity exhibit a significant disconnect between those from molecular clocks, which indicate crown animals evolved ∼800 million years ago (Ma), and those from the fossil record, which extends only ∼574 Ma. Taphonomy is often held culpable: early animals were too small/soft/fragile to fossilise, or the circumstances that preserve them were uncommon in the early Neoproterozoic. We assess this idea by comparing Neoproterozoic fossilisation processes with those of the Cambrian and its abundant animal fossils. Cambrian Burgess Shale-type (BST) preservation captures animals in mudstones showing a narrow range of mineralogies; yet, fossiliferous Neoproterozoic mudstones rarely share the same mineralogy. Animal fossils are absent where BST preservation occurs in deposits ≥789 Ma, suggesting a soft maximum constraint on animal antiquity.
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Affiliation(s)
- Ross P Anderson
- Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, UK; All Souls College, University of Oxford, Oxford, OX1 4AL, UK.
| | - Christina R Woltz
- Department of Earth Science, University of California at Santa Barbara, Santa Barbara, CA 93106, USA; Department of Earth and Planetary Sciences, Stanford University, Stanford, CA, 94305, USA
| | - Nicholas J Tosca
- Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK
| | - Susannah M Porter
- Department of Earth Science, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Derek E G Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06511, USA; Yale Peabody Museum, Yale University, New Haven, CT 06520, USA
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4
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Wiemann J, Menéndez I, Crawford JM, Fabbri M, Gauthier JA, Hull PM, Norell MA, Briggs DEG. Reply to: Amniote metabolism and the evolution of endothermy. Nature 2023; 621:E4-E6. [PMID: 37673991 DOI: 10.1038/s41586-023-06412-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Affiliation(s)
- Jasmina Wiemann
- Earth Science Section, Field Museum of Natural History, Chicago, IL, USA.
- Geophysical Sciences, University of Chicago, Chicago, IL, USA.
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA.
| | - Iris Menéndez
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany.
| | | | - Matteo Fabbri
- Earth Science Section, Field Museum of Natural History, Chicago, IL, USA
| | - Jacques A Gauthier
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Yale Peabody Museum, Yale University, New Haven, CT, USA
| | - Pincelli M Hull
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Yale Peabody Museum, Yale University, New Haven, CT, USA
| | - Mark A Norell
- Division of Paleontology, American Museum of Natural History, New York, NY, USA
| | - Derek E G Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Yale Peabody Museum, Yale University, New Haven, CT, USA
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Briggs DEG, Siveter DJ, Siveter DJ, Sutton MD, Legg D, Lamsdell JC. A vicissicaudatan arthropod from the Silurian Herefordshire Lagerstätte, UK. R Soc Open Sci 2023; 10:230661. [PMID: 37538743 PMCID: PMC10394423 DOI: 10.1098/rsos.230661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 07/17/2023] [Indexed: 08/05/2023]
Abstract
A new arthropod, Carimersa neptuni gen. et sp. nov., is described from the Silurian (Wenlock Series) Herefordshire Konservat-Lagerstätte, UK. The head bears pedunculate eyes and five pairs of appendages. Triflagellate antennae are followed by two pairs of uniramous limbs each with an endopod bearing a pronounced gnathobasic basipod. The posterior two pairs of head limbs and all trunk limbs bear an endopod, exopod and filamentous exite. The trunk consists of 10 appendage-bearing segments followed by an apodous abdomen of four segments. The arthropod resolves as sister taxon to Kodymirus and Eozetetes + Aglaspidida. It is the first representative of Vicissicaudata reported from the Herefordshire Lagerstätte and the first Silurian example with well-preserved appendages. The preservation of a cluster of radiolarians apparently captured by the trunk appendages is the first direct association of predator and prey discovered in the Herefordshire fauna, and suggests that Carimersa was a nektobenthic form that used its gnathobasic basipods in microdurophagy.
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Affiliation(s)
- Derek E. G. Briggs
- Department of Earth and Planetary Sciences, and Yale Peabody Museum, Yale University, New Haven, CT 06520-8109, USA
| | - David J. Siveter
- School of Geography, Geology and the Environment, University of Leicester, Leicester LE1 7RH, UK
| | - Derek J. Siveter
- Earth Collections, University Museum of Natural History, Oxford OX1 3PW, UK
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
| | - Mark D. Sutton
- Department of Earth Sciences and Engineering, Imperial College London, London SW7 2BP, UK
| | - David Legg
- Department of Earth and Environmental Sciences, University of Manchester, Manchester M13 9PL, UK
| | - James C. Lamsdell
- Department of Geology and Geography, West Virginia University, 98 Beechurst Avenue, Brooks Hall, Morgantown, WV 26506, USA
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Briggs DEG, Parry LA. Putting heads together. Science 2022; 378:831-832. [DOI: 10.1126/science.add7372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Cambrian fossils reveal ancestry of the segmented brain in arthropods
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Affiliation(s)
- Derek E. G. Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT, USA
| | - Luke A. Parry
- Department of Earth Sciences, University of Oxford, Oxford, UK
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Wiemann J, Menéndez I, Crawford JM, Fabbri M, Gauthier JA, Hull PM, Norell MA, Briggs DEG. Fossil biomolecules reveal an avian metabolism in the ancestral dinosaur. Nature 2022; 606:522-526. [PMID: 35614213 DOI: 10.1038/s41586-022-04770-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 04/19/2022] [Indexed: 11/09/2022]
Abstract
Birds and mammals independently evolved the highest metabolic rates among living animals1. Their metabolism generates heat that enables active thermoregulation1, shaping the ecological niches they can occupy and their adaptability to environmental change2. The metabolic performance of birds, which exceeds that of mammals, is thought to have evolved along their stem lineage3-10. However, there is no proxy that enables the direct reconstruction of metabolic rates from fossils. Here we use in situ Raman and Fourier-transform infrared spectroscopy to quantify the in vivo accumulation of metabolic lipoxidation signals in modern and fossil amniote bones. We observe no correlation between atmospheric oxygen concentrations11 and metabolic rates. Inferred ancestral states reveal that the metabolic rates consistent with endothermy evolved independently in mammals and plesiosaurs, and are ancestral to ornithodirans, with increasing rates along the avian lineage. High metabolic rates were acquired in pterosaurs, ornithischians, sauropods and theropods well before the advent of energetically costly adaptations, such as flight in birds. Although they had higher metabolic rates ancestrally, ornithischians reduced their metabolic abilities towards ectothermy. The physiological activities of such ectotherms were dependent on environmental and behavioural thermoregulation12, in contrast to the active lifestyles of endotherms1. Giant sauropods and theropods were not gigantothermic9,10, but true endotherms. Endothermy in many Late Cretaceous taxa, in addition to crown mammals and birds, suggests that attributes other than metabolism determined their fate during the terminal Cretaceous mass extinction.
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Affiliation(s)
- Jasmina Wiemann
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA.
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
- Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA.
| | - Iris Menéndez
- Departamento de Geodinámica, Estratigrafía y Paleontología, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, Madrid, Spain
- Departamento de Cambio Medioambiental, Instituto de Geociencias (UCM, CSIC), Madrid, Spain
| | | | - Matteo Fabbri
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
| | - Jacques A Gauthier
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT, USA
| | - Pincelli M Hull
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT, USA
| | - Mark A Norell
- Division of Paleontology, American Museum of Natural History, New York, NY, USA
| | - Derek E G Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT, USA
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8
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Wiemann J, Briggs DEG. Raman spectroscopy is a powerful tool in molecular paleobiology: An analytical response to Alleon et al. (https://doi.org/10.1002/bies.202000295). Bioessays 2022; 44:e2100070. [PMID: 34993976 DOI: 10.1002/bies.202100070] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 12/03/2021] [Accepted: 12/07/2021] [Indexed: 01/08/2023]
Abstract
A recent article argued that signals from conventional Raman spectroscopy of organic materials are overwhelmed by edge filter and fluorescence artefacts. The article targeted a subset of Raman spectroscopic investigations of fossil and modern organisms and has implications for the utility of conventional Raman spectroscopy in comparative tissue analytics. The inferences were based on circular reasoning centered around the unconventional analysis of spectra from just two samples, one modern, and one fossil. We validated the disputed signals with in situ Fourier-Transform Infrared (FT-IR) Spectroscopy and through replication with different lasers, filters, and operators in independent laboratories. Our Raman system employs a holographic notch filter which is not affected by edge filter or other artefacts. Multiple lines of evidence confirm that conventional Raman spectra of fossils contain biologically and geologically meaningful information. Statistical analyses of large Raman and FT-IR spectral data sets reveal patterns in fossil composition and yield valuable insights into the history of life.
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Affiliation(s)
- Jasmina Wiemann
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA.,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA.,Dinosaur Institute, Natural History Museum of LA County, Los Angeles, California, USA
| | - Derek E G Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA.,Yale Peabody Museum of Natural History, New Haven, Connecticut, USA
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9
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Luque J, Xing L, Briggs DEG, Clark EG, Duque A, Hui J, Mai H, McKellar RC. Crab in amber reveals an early colonization of nonmarine environments during the Cretaceous. Sci Adv 2021; 7:eabj5689. [PMID: 34669480 PMCID: PMC8528423 DOI: 10.1126/sciadv.abj5689] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/26/2021] [Indexed: 06/13/2023]
Abstract
Amber fossils provide snapshots of the anatomy, biology, and ecology of extinct organisms that are otherwise inaccessible. The best-known fossils in amber are terrestrial arthropods—principally insects—whereas aquatic organisms are rarely represented. Here, we present the first record of true crabs (Brachyura) in amber—from the Cretaceous of Myanmar [~100 to 99 million years (Ma)]. The new fossil preserves large compound eyes, delicate mouthparts, and even gills. This modern-looking crab is nested within crown Eubrachyura, or “higher” true crabs, which includes the majority of brachyuran species living today. The fossil appears to have been trapped in a brackish or freshwater setting near a coastal to fluvio-estuarine environment, bridging the gap between the predicted molecular divergence of nonmarine crabs (~130 Ma) and their younger fossil record (latest Cretaceous and Paleogene, ~75 to 50 Ma) while providing a reliable calibration point for molecular divergence time estimates for higher crown eubrachyurans.
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Affiliation(s)
- Javier Luque
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06520-8109, USA
- Smithsonian Tropical Research Institute, Balboa–Ancón, 0843-03092 Panamá, Panamá
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Lida Xing
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China
- School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
| | - Derek E. G. Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06520-8109, USA
| | - Elizabeth G. Clark
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06520-8109, USA
- Biology Department, Duke University, Durham, NC 27708, USA
| | - Alex Duque
- Computer Animation and Visual Effects, College of Communication and Design, Lynn University, 2601 North Military Trail, Boca Raton, FL 33431, USA
| | - Junbo Hui
- Longyin Amber Museum, Xishan District, Kunming 650228, Yunnan, China
| | - Huijuan Mai
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, Yunnan, China
- MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming 650091, Yunnan, China
| | - Ryan C. McKellar
- Royal Saskatchewan Museum, Regina, SK S4P 4W7, Canada
- Biology Department, University of Regina, Regina, SK S4S 0A2, Canada
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Ruebenstahl A, Ciurca SJ, Briggs DEG. A Giant Eurypterus from the Silurian (Pridoli) Bertie Group of North America. Bulletin of the Peabody Museum of Natural History 2021. [DOI: 10.3374/014.062.0101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Alexander Ruebenstahl
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06520-8109 USA
| | | | - Derek E. G. Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06520-8109; and Yale Peabody Museum of Natural History, Yale University, New Haven, CT 06520-8118 USA —
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11
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Anderson RP, McCoy VE, McNamara ME, Briggs DEG. Correction to 'What big eyes you have: the ecological role of giant pterygotid eurypterids'. Biol Lett 2020; 16:20200753. [PMID: 33232653 DOI: 10.1098/rsbl.2020.0753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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12
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Whalen CD, Hull PM, Briggs DEG. Paleozoic ammonoid ecomorphometrics test ecospace availability as a driver of morphological diversification. Sci Adv 2020; 6:6/37/eabc2365. [PMID: 32917688 DOI: 10.1126/sciadv.abc2365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/21/2020] [Indexed: 06/11/2023]
Abstract
The early burst model suggests that disparity rises rapidly to fill empty ecospace following clade origination or in the aftermath of a mass extinction. Early bursts are considered common features of fossil data, but neontological studies have struggled to identify them. Furthermore, tests have proven difficult because factors besides ecology can drive changes in morphology. Here, we document the ecomorphometric evolution of the extinct Ammonoidea at 1-million-year resolution, from their origination in the Early Devonian (Emsian) to the Early Triassic (Induan), over ~156 million years. This time interval encompasses six global extinction events, including two of the Big Five, and incorporates multiple ammonoid radiations. However, we find no evidence for early bursts of ecomorphological disparity. This contradicts arguments that the temporal scope, or traits measured in genomic data, conceal evidence of early bursts. Rather, early bursts may be less prevalent in fossil data than is often assumed.
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Affiliation(s)
- Christopher D Whalen
- Department of Earth and Planetary Sciences, Yale University, 210 Whitney Ave., New Haven, CT 06511, USA.
| | - Pincelli M Hull
- Department of Earth and Planetary Sciences, Yale University, 210 Whitney Ave., New Haven, CT 06511, USA
- Peabody Museum of Natural History, Yale University, 170 Whitney Ave., New Haven, CT 06511, USA
| | - Derek E G Briggs
- Department of Earth and Planetary Sciences, Yale University, 210 Whitney Ave., New Haven, CT 06511, USA
- Peabody Museum of Natural History, Yale University, 170 Whitney Ave., New Haven, CT 06511, USA
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13
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McCoy VE, Wiemann J, Lamsdell JC, Whalen CD, Lidgard S, Mayer P, Petermann H, Briggs DEG. Chemical signatures of soft tissues distinguish between vertebrates and invertebrates from the Carboniferous Mazon Creek Lagerstätte of Illinois. Geobiology 2020; 18:560-565. [PMID: 32347003 DOI: 10.1111/gbi.12397] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/17/2020] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Abstract
The chemical composition of fossil soft tissues is a potentially powerful and yet underutilized tool for elucidating the affinity of problematic fossil organisms. In some cases, it has proven difficult to assign a problematic fossil even to the invertebrates or vertebrates (more generally chordates) based on often incompletely preserved morphology alone, and chemical composition may help to resolve such questions. Here, we use in situ Raman microspectroscopy to investigate the chemistry of a diverse array of invertebrate and vertebrate fossils from the Pennsylvanian Mazon Creek Lagerstätte of Illinois, and we generate a ChemoSpace through principal component analysis (PCA) of the in situ Raman spectra. Invertebrate soft tissues characterized by chitin (polysaccharide) fossilization products and vertebrate soft tissues characterized by protein fossilization products plot in completely separate, non-overlapping regions of the ChemoSpace, demonstrating the utility of certain soft tissue molecular signatures as biomarkers for the original soft tissue composition of fossil organisms. The controversial problematicum Tullimonstrum, known as the Tully Monster, groups with the vertebrates, providing strong evidence of a vertebrate rather than invertebrate affinity.
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Affiliation(s)
- Victoria E McCoy
- Department of Geosciences, University of Wisconsin, Milwaukee, Milwaukee, WI, USA
- Institute of Geosciences, University of Bonn, Bonn, Germany
| | - Jasmina Wiemann
- Department of Geology and Geophysics, Yale University, New Haven, CT, USA
| | - James C Lamsdell
- Department of Geology and Geography, West Virginia University, Morgantown, WV, USA
| | | | | | - Paul Mayer
- Field Museum of Natural History, Chicago, IL, USA
| | - Holger Petermann
- Department of Earth Sciences, Denver Museum of Nature and Science, Colorado Boulevard, Denver, CO, USA
| | - Derek E G Briggs
- Department of Geology and Geophysics, Yale University, New Haven, CT, USA
- Yale Peabody Museum of Natural History, New Haven, CT, USA
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Anderson RP, Tosca NJ, Cinque G, Frogley MD, Lekkas I, Akey A, Hughes GM, Bergmann KD, Knoll AH, Briggs DEG. Aluminosilicate haloes preserve complex life approximately 800 million years ago. Interface Focus 2020; 10:20200011. [PMID: 32642055 PMCID: PMC7333908 DOI: 10.1098/rsfs.2020.0011] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2020] [Indexed: 02/07/2023] Open
Abstract
Mudstone-hosted microfossils are a major component of the Proterozoic fossil record, particularly dominating the record of early eukaryotic life. Early organisms possessed no biomineralized parts to resist decay and controls on their fossilization in mudstones are poorly understood. Consequently, the Proterozoic fossil record is compromised-we do not know whether changing temporal/spatial patterns of microfossil occurrences reflect evolution or the distribution of favourable fossilization conditions. We investigated fossilization within the approximately 1000 Ma Lakhanda Group (Russia) and the approximately 800 Ma Svanbergfjellet and Wynniatt formations (Svalbard and Arctic Canada). Vertical sections of microfossils and surrounding matrices were extracted from thin sections by focused ion beam milling. Elemental mapping and synchrotron-based infrared microspectroscopy revealed that microfossils are surrounded by haloes rich in aluminium, probably hosted in kaolinite. Kaolinite has been implicated in Cambrian Burgess Shale-type (BST) fossilization and is known to slow the growth of degraders. The Neoproterozoic mudstone microfossil record may be biased to tropical settings conducive to kaolinite formation. These deposits lack metazoan fossils even though they share fossilization conditions with younger BST deposits that are capable of preserving non-mineralizing metazoans. Thus metazoans, at least those typically preserved in BST deposits, were probably absent from sedimentary environments before approximately 800 Ma.
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Affiliation(s)
- Ross P. Anderson
- All Souls College, University of Oxford, Oxford OX1 4AL, UK
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
| | - Nicholas J. Tosca
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
| | - Gianfelice Cinque
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 ODE, UK
| | - Mark D. Frogley
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 ODE, UK
| | - Ioannis Lekkas
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 ODE, UK
| | - Austin Akey
- Center for Nanoscale Systems, Harvard University, Cambridge, MA 02138, USA
| | - Gareth M. Hughes
- Department of Materials, University of Oxford, Oxford OX1 3PH, UK
| | - Kristin D. Bergmann
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Andrew H. Knoll
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Derek E. G. Briggs
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
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Wiemann J, Crawford JM, Briggs DEG. Phylogenetic and physiological signals in metazoan fossil biomolecules. Sci Adv 2020; 6:eaba6883. [PMID: 32832604 PMCID: PMC7439315 DOI: 10.1126/sciadv.aba6883] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 06/01/2020] [Indexed: 06/11/2023]
Abstract
Proteins, lipids, and sugars establish animal form and function. However, the preservation of biological signals in fossil organic matter is poorly understood. Here, we used high-resolution in situ Raman microspectroscopy to analyze the molecular compositions of 113 Phanerozoic metazoan fossils and sediments. Proteins, lipids, and sugars converge in composition during fossilization through lipoxidation and glycoxidation to form endogenous N-, O-, and S-heterocyclic polymers. Nonetheless, multivariate spectral analysis reveals molecular heterogeneities: The relative abundance of glycoxidation and lipoxidation products distinguishes different tissue types. Preserved chelating ligands are diagnostic of different modes of biomineralization. Amino acid-specific fossilization products retain phylogenetic information and capture higher-rank metazoan relationships. Molecular signals survive in deep time and provide a powerful tool for reconstructing the evolutionary history of animals.
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Affiliation(s)
- Jasmina Wiemann
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06511, USA
| | - Jason M. Crawford
- Department of Chemistry, Yale University, New Haven, CT 06520, USA
- Department of Microbial Pathogenesis, Yale University, New Haven, CT 06536, USA
- Chemical Biology Institute, Yale University, West Haven, CT 06516, USA
| | - Derek E. G. Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06511, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT 06511, USA
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16
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Clark EG, Hutchinson JR, Bishop PJ, Briggs DEG. Arm waving in stylophoran echinoderms: three-dimensional mobility analysis illuminates cornute locomotion. R Soc Open Sci 2020; 7:200191. [PMID: 32742688 PMCID: PMC7353985 DOI: 10.1098/rsos.200191] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 05/12/2020] [Indexed: 05/16/2023]
Abstract
The locomotion strategies of fossil invertebrates are typically interpreted on the basis of morphological descriptions. However, it has been shown that homologous structures with disparate morphologies in extant invertebrates do not necessarily correlate with differences in their locomotory capability. Here, we present a new methodology for analysing locomotion in fossil invertebrates with a rigid skeleton through an investigation of a cornute stylophoran, an extinct fossil echinoderm with enigmatic morphology that has made its mode of locomotion difficult to reconstruct. We determined the range of motion of a stylophoran arm based on digitized three-dimensional morphology of an early Ordovician form, Phyllocystis crassimarginata. Our analysis showed that efficient arm-forward epifaunal locomotion based on dorsoventral movements, as previously hypothesized for cornute stylophorans, was not possible for this taxon; locomotion driven primarily by lateral movement of the proximal aulacophore was more likely. Three-dimensional digital modelling provides an objective and rigorous methodology for illuminating the movement capabilities and locomotion strategies of fossil invertebrates.
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Affiliation(s)
- Elizabeth G. Clark
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
| | - John R. Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield AL9 7TA, UK
| | - Peter J. Bishop
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield AL9 7TA, UK
- Geosciences Program, Queensland Museum, Brisbane, Australia
| | - Derek E. G. Briggs
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT 06511, USA
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17
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Nadhira A, Sutton MD, Botting JP, Muir LA, Gueriau P, King A, Briggs DEG, Siveter DJ, Siveter DJ. Three-dimensionally preserved soft tissues and calcareous hexactins in a Silurian sponge: implications for early sponge evolution. R Soc Open Sci 2019; 6:190911. [PMID: 31417767 PMCID: PMC6689616 DOI: 10.1098/rsos.190911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 07/09/2019] [Indexed: 06/10/2023]
Abstract
Sponges (Porifera), as one of the earliest-branching animal phyla, are crucial for understanding early metazoan phylogeny. Recent studies of Lower Palaeozoic sponges have revealed a variety of character states and combinations unknown in extant taxa, challenging our views of early sponge morphology. The Herefordshire Konservat-Lagerstätte yields an abundant, diverse sponge fauna with three-dimensional preservation of spicules and soft tissue. Carduispongia pedicula gen. et sp. nov. possesses a single layer of hexactine spicules arranged in a regular orthogonal network. This spicule type and arrangement is characteristic of the reticulosans, which have traditionally been interpreted as early members of the extant siliceous Class Hexactinellida. However, the unusual preservation of the spicules of C. pedicula reveals an originally calcareous composition, which would be diagnostic of the living Class Calcarea. The soft tissue architecture closely resembles the complex sylleibid or leuconid structure seen in some modern calcareans and homoscleromorphs. This combination of features strongly supports a skeletal continuum between primitive calcareans and hexactinellid siliceans, indicating that the last common ancestor of Porifera was a spiculate, solitary, vasiform animal with a thin skeletal wall.
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Affiliation(s)
- Ardianty Nadhira
- Department of Earth Sciences and Engineering, Imperial College London, London SW7 2BP, UK
| | - Mark D. Sutton
- Department of Earth Sciences and Engineering, Imperial College London, London SW7 2BP, UK
| | - Joseph P. Botting
- Nanjing Institute of Geology and Palaeontology, 39 East Beijing Road, Nanjing 210008, People's Republic of China
- Department of Natural Sciences, Amgueddfa Cymru—National Museum Wales, Cathays Park, Cardiff CF10 3NP, UK
| | - Lucy A. Muir
- Department of Natural Sciences, Amgueddfa Cymru—National Museum Wales, Cathays Park, Cardiff CF10 3NP, UK
| | - Pierre Gueriau
- IPANEMA, CNRS, Ministère de la Culture, UVSQ, USR 3461, Université Paris-Saclay, 91192 Gif-sur-Yvette, France
- Institute of Earth Sciences, University of Lausanne, Géopolis, CH-1015 Lausanne, Switzerland
| | - Andrew King
- SOLEIL synchrotron, 91192 Gif-sur-Yvette, France
| | - Derek E. G. Briggs
- Department of Geology & Geophysics, and Yale Peabody Museum of Natural History, Yale University, PO Box 208109, New Haven, CT 06520-8109, USA
| | - David J. Siveter
- School of Geography, Geology and the Environment, University of Leicester, Leicester LE1 7RH, UK
| | - Derek J. Siveter
- Earth Collections, University Museum of Natural History, Oxford OX1 3PW, UK
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
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18
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Rahman IA, Thompson JR, Briggs DEG, Siveter DJ, Siveter DJ, Sutton MD. A new ophiocistioid with soft-tissue preservation from the Silurian Herefordshire Lagerstätte, and the evolution of the holothurian body plan. Proc Biol Sci 2019; 286:20182792. [PMID: 30966985 DOI: 10.1098/rspb.2018.2792] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Reconstructing the evolutionary assembly of animal body plans is challenging when there are large morphological gaps between extant sister taxa, as in the case of echinozoans (echinoids and holothurians). However, the inclusion of extinct taxa can help bridge these gaps. Here we describe a new species of echinozoan, Sollasina cthulhu, from the Silurian Herefordshire Lagerstätte, UK. Sollasina cthulhu belongs to the ophiocistioids, an extinct group that shares characters with both echinoids and holothurians. Using physical-optical tomography and computer reconstruction, we visualize the internal anatomy of S. cthulhu in three dimensions, revealing inner soft tissues that we interpret as the ring canal, a key part of the water vascular system that was previously unknown in fossil echinozoans. Phylogenetic analyses strongly suggest that Sollasina and other ophiocistioids represent a paraphyletic group of stem holothurians, as previously hypothesized. This allows us to reconstruct the stepwise reduction of the skeleton during the assembly of the holothurian body plan, which may have been controlled by changes in the expression of biomineralization genes.
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Affiliation(s)
- Imran A Rahman
- 1 Oxford University Museum of Natural History , Oxford OX1 3PW , UK
| | - Jeffrey R Thompson
- 2 Department of Earth Sciences, University of Southern California , Los Angeles, CA 90089-0740 , USA
| | - Derek E G Briggs
- 3 Department of Geology and Geophysics and Yale Peabody Museum of Natural History, Yale University , New Haven, CT 06520-8109 , USA
| | - David J Siveter
- 4 School of Geography, Geology and the Environment, University of Leicester , Leicester LE1 7RH , UK
| | - Derek J Siveter
- 1 Oxford University Museum of Natural History , Oxford OX1 3PW , UK.,5 Department of Earth Sciences, University of Oxford , South Parks Road, Oxford OX1 3AN , UK
| | - Mark D Sutton
- 6 Department of Earth Sciences and Engineering, Imperial College London , London SW7 2BP , UK
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19
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Mongiardino Koch N, Coppard SE, Lessios HA, Briggs DEG, Mooi R, Rouse GW. A phylogenomic resolution of the sea urchin tree of life. BMC Evol Biol 2018; 18:189. [PMID: 30545284 PMCID: PMC6293586 DOI: 10.1186/s12862-018-1300-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 11/19/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Echinoidea is a clade of marine animals including sea urchins, heart urchins, sand dollars and sea biscuits. Found in benthic habitats across all latitudes, echinoids are key components of marine communities such as coral reefs and kelp forests. A little over 1000 species inhabit the oceans today, a diversity that traces its roots back at least to the Permian. Although much effort has been devoted to elucidating the echinoid tree of life using a variety of morphological data, molecular attempts have relied on only a handful of genes. Both of these approaches have had limited success at resolving the deepest nodes of the tree, and their disagreement over the positions of a number of clades remains unresolved. RESULTS We performed de novo sequencing and assembly of 17 transcriptomes to complement available genomic resources of sea urchins and produce the first phylogenomic analysis of the clade. Multiple methods of probabilistic inference recovered identical topologies, with virtually all nodes showing maximum support. In contrast, the coalescent-based method ASTRAL-II resolved one node differently, a result apparently driven by gene tree error induced by evolutionary rate heterogeneity. Regardless of the method employed, our phylogenetic structure deviates from the currently accepted classification of echinoids, with neither Acroechinoidea (all euechinoids except echinothurioids), nor Clypeasteroida (sand dollars and sea biscuits) being monophyletic as currently defined. We show that phylogenetic signal for novel resolutions of these lineages is strong and distributed throughout the genome, and fail to recover systematic biases as drivers of our results. CONCLUSIONS Our investigation substantially augments the molecular resources available for sea urchins, providing the first transcriptomes for many of its main lineages. Using this expanded genomic dataset, we resolve the position of several clades in agreement with early molecular analyses but in disagreement with morphological data. Our efforts settle multiple phylogenetic uncertainties, including the position of the enigmatic deep-sea echinothurioids and the identity of the sister clade to sand dollars. We offer a detailed assessment of evolutionary scenarios that could reconcile our findings with morphological evidence, opening up new lines of research into the development and evolutionary history of this ancient clade.
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Affiliation(s)
| | - Simon E. Coppard
- Department of Biology, Hamilton College, Clinton, NY USA
- Smithsonian Tropical Research Institute, Balboa, Panama
| | | | - Derek E. G. Briggs
- Department of Geology and Geophysics, Yale University, New Haven, CT USA
- Peabody Museum of Natural History, Yale University, New Haven, CT USA
| | - Rich Mooi
- Department of Invertebrate Zoology and Geology, California Academy of Sciences, San Francisco, CA USA
| | - Greg W. Rouse
- Scripps Institution of Oceanography, UC San Diego, La Jolla, CA USA
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20
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Clark EG, Hutchinson JR, Darroch SAF, Mongiardino Koch N, Brady TR, Smith SA, Briggs DEG. Integrating morphology and in vivo skeletal mobility with digital models to infer function in brittle star arms. J Anat 2018; 233:696-714. [PMID: 30353539 PMCID: PMC6231174 DOI: 10.1111/joa.12887] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2018] [Indexed: 12/15/2022] Open
Abstract
Brittle stars (Phylum Echinodermata, Class Ophiuroidea) have evolved rapid locomotion employing muscle and skeletal elements within their (usually) five arms to apply forces in a manner analogous to that of vertebrates. Inferring the inner workings of the arm has been difficult as the skeleton is internal and many of the ossicles are sub-millimeter in size. Advances in 3D visualization and technology have made the study of movement in ophiuroids possible. We developed six virtual 3D skeletal models to demonstrate the potential range of motion of the main arm ossicles, known as vertebrae, and six virtual 3D skeletal models of non-vertebral ossicles. These models revealed the joint center and relative position of the arm ossicles during near-maximal range of motion. The models also provide a platform for the comparative evaluation of functional capabilities between disparate ophiuroid arm morphologies. We made observations on specimens of Ophioderma brevispina and Ophiothrix angulata. As these two taxa exemplify two major morphological categories of ophiuroid vertebrae, they provide a basis for an initial assessment of the functional consequences of these disparate vertebral morphologies. These models suggest potential differences in the structure of the intervertebral articulations in these two species, implying disparities in arm flexion mechanics. We also evaluated the differences in the range of motion between segments in the proximal and distal halves of the arm length in a specimen of O. brevispina, and found that the morphology of vertebrae in the distal portion of the arm allows for higher mobility than in the proximal portion. Our models of non-vertebral ossicles show that they rotate further in the direction of movement than the vertebrae themselves in order to accommodate arm flexion. These findings raise doubts over previous hypotheses regarding the functional consequences of ophiuroid arm disparity. Our study demonstrates the value of integrating experimental data and visualization of articulated structures when making functional interpretations instead of relying on observations of vertebral or segmental morphology alone. This methodological framework can be applied to other ophiuroid taxa to enable comparative functional analyses. It will also facilitate biomechanical analyses of other invertebrate groups to illuminate how appendage or locomotor function evolved.
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Affiliation(s)
| | - John R. Hutchinson
- Structure and Motion LaboratoryDepartment of Comparative Biomedical SciencesThe Royal Veterinary CollegeHertfordshireUK
| | - Simon A. F. Darroch
- Department of Earth and Environmental ScienceVanderbilt UniversityNashvilleTNUSA
| | | | - Travis R. Brady
- Department of Biomedical EngineeringYale UniversityNew HavenCTUSA
| | - Sloane A. Smith
- Department of Biomedical EngineeringYale UniversityNew HavenCTUSA
| | - Derek E. G. Briggs
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
- Yale Peabody Museum of Natural HistoryYale UniversityNew HavenCTUSA
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21
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Wiemann J, Fabbri M, Yang TR, Stein K, Sander PM, Norell MA, Briggs DEG. Fossilization transforms vertebrate hard tissue proteins into N-heterocyclic polymers. Nat Commun 2018; 9:4741. [PMID: 30413693 PMCID: PMC6226439 DOI: 10.1038/s41467-018-07013-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 10/10/2018] [Indexed: 02/06/2023] Open
Abstract
Vertebrate hard tissues consist of mineral crystallites within a proteinaceous scaffold that normally degrades post-mortem. Here we show, however, that decalcification of Mesozoic hard tissues preserved in oxidative settings releases brownish stained extracellular matrix, cells, blood vessels, and nerve projections. Raman Microspectroscopy shows that these fossil soft tissues are a product of diagenetic transformation to Advanced Glycoxidation and Lipoxidation End Products, a class of N-heterocyclic polymers generated via oxidative crosslinking of proteinaceous scaffolds. Hard tissues in reducing environments, in contrast, lack soft tissue preservation. Comparison of fossil soft tissues with modern and experimentally matured samples reveals how proteinaceous tissues undergo diagenesis and explains biases in their preservation in the rock record. This provides a target, focused on oxidative depositional environments, for finding cellular-to-subcellular soft tissue morphology in fossils and validates its use in phylogenetic and other evolutionary studies.
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Affiliation(s)
- Jasmina Wiemann
- Department of Geology & Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT, 06511, USA.
| | - Matteo Fabbri
- Department of Geology & Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT, 06511, USA
| | - Tzu-Ruei Yang
- Steinmann Institute for Geology, Mineralogy, and Paleontology, University of Bonn, Nussallee 8, 53115, Bonn, Germany
| | - Koen Stein
- Earth System Sciences AMGC, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - P Martin Sander
- Steinmann Institute for Geology, Mineralogy, and Paleontology, University of Bonn, Nussallee 8, 53115, Bonn, Germany
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA, 90007, USA
| | - Mark A Norell
- Division of Vertebrate Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY, 10024-5192, USA
| | - Derek E G Briggs
- Department of Geology & Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT, 06511, USA
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22
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Siveter DJ, Briggs DEG, Siveter DJ, Sutton MD. A well-preserved respiratory system in a Silurian ostracod. Biol Lett 2018; 14:rsbl.2018.0464. [PMID: 30404865 PMCID: PMC6283931 DOI: 10.1098/rsbl.2018.0464] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/12/2018] [Indexed: 11/13/2022] Open
Abstract
Ostracod crustaceans are diverse and ubiquitous in aqueous environments today but relatively few known species have gills. Ostracods are the most abundant fossil arthropods but examples of soft-part preservation, especially of gills, are exceptionally rare. A new ostracod, Spiricopia aurita (Myodocopa), from the marine Silurian Herefordshire Lagerstätte (430 Mya), UK, preserves appendages, lateral eyes and gills. The respiratory system includes five pairs of gill lamellae with hypobranchial and epibranchial canals that conveyed haemolymph. A heart and associated vessels had likely evolved in ostracods by the Mid-Silurian.
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Affiliation(s)
- David J Siveter
- School of Geography, Geology and the Environment, University of Leicester, Leicester LE1 7RH, UK
| | - Derek E G Briggs
- Department of Geology and Geophysics, and Yale Peabody Museum of Natural History, Yale University, PO Box 208109, New Haven, CT 06520-8109, USA
| | - Derek J Siveter
- Earth Collections, University Museum of Natural History, Oxford OX1 3PW, UK.,Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - Mark D Sutton
- Department of Earth Sciences and Engineering, Imperial College London, London SW7 2BP, UK
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23
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Siveter DJ, Briggs DEG, Siveter DJ, Sutton MD, Legg D. A three-dimensionally preserved lobopodian from the Herefordshire (Silurian) Lagerstätte, UK. R Soc Open Sci 2018; 5:172101. [PMID: 30224988 PMCID: PMC6124121 DOI: 10.1098/rsos.172101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 07/06/2018] [Indexed: 06/08/2023]
Abstract
The Herefordshire (Silurian) Lagerstätte (approx. 430 Myr BP) has yielded, among many exceptionally preserved invertebrates, a wide range of new genera belonging to crown-group Panarthropoda. Here, we increase this panarthropod diversity with the lobopodian Thanahita distos, a new total-group panarthropod genus and species. This new lobopodian preserves at least nine paired, long, slender appendages, the anterior two in the head region and the posterior seven representing trunk lobopods. The body ends in a short post-appendicular extension. Some of the trunk lobopods bear two claws, others a single claw. The body is covered by paired, tuft-like papillae. Thanahita distos joins only seven other known three-dimensionally preserved lobopodian or onychophoran (velvet worm) fossil specimens and is the first lobopodian to be formally described from the Silurian. Phylogenetic analysis recovered it, together with all described Hallucigenia species, in a sister-clade to crown-group panarthropods. Its placement in a redefined Hallucigeniidae, an iconic Cambrian clade, indicates the survival of this clade to Silurian times.
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Affiliation(s)
- Derek J. Siveter
- Earth Collections, University Museum of Natural History, Oxford OX1 3PW, UK
- Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3AN, UK
| | - Derek E. G. Briggs
- Department of Geology and Geophysics and Yale Peabody Museum of Natural History, Yale University, PO Box 208109, New Haven, CT 06520-8109, USA
| | - David J. Siveter
- School of Geography, Geology and the Environment, University of Leicester, Leicester LE1 7RH, UK
| | - Mark D. Sutton
- Department of Earth Sciences and Engineering, Imperial College London, London SW7 2BP, UK
| | - David Legg
- School of Earth and Environmental Sciences, University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK
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24
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Whalen CD, Briggs DEG. The Palaeozoic colonization of the water column and the rise of global nekton. Proc Biol Sci 2018; 285:20180883. [PMID: 30051837 PMCID: PMC6083262 DOI: 10.1098/rspb.2018.0883] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 06/21/2018] [Indexed: 11/12/2022] Open
Abstract
The colonization of the water column is among the most important transformations in the evolution of animal life and global ecosystems. The Devonian nekton revolution has been identified as a major macroevolutionary event signifying the rapid occupation of the water column by independent radiations of swimming animals. Using new data, an expanded taxonomic coverage, sample standardization and increased ecological resolution, we analysed patterns of nektonization during the Palaeozoic. We find that nekton and eunekton were well established prior to the Devonian and did not diversify dramatically during any Palaeozoic interval. Relative nektic diversity and occurrences decreased rather than increased during the Devonian. Eunektic diversity and occurrences increased throughout the Palaeozoic, but this rise was protracted and cannot be attributed to any single interval. Our new data indicate that the metazoan colonization of the water column was considerably more complex and gradual than previously understood.
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Affiliation(s)
- Christopher D Whalen
- Department of Geology and Geophysics, Yale University, 170 Whitney Ave., New Haven, CT 06511, USA
| | - Derek E G Briggs
- Department of Geology and Geophysics, Yale University, 170 Whitney Ave., New Haven, CT 06511, USA
- Peabody Museum of Natural History, Yale University, 170 Whitney Ave., New Haven, CT 06511, USA
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25
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Lamsdell JC, Marshall DJ, Briggs DEG. Hit and Miss: (A Comment on Persons and Acorn, “A Sea Scorpion’s Strike: New Evidence of Extreme Lateral Flexibility in the Opisthosoma of Eurypterids”). Am Nat 2018. [DOI: 10.1086/695955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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26
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Clark EG, Kanauchi D, Kano T, Aonuma H, Briggs DEG, Ishiguro A. The function of the ophiuroid nerve ring: how a decentralized nervous system controls coordinated locomotion. J Exp Biol 2018; 222:jeb.192104. [DOI: 10.1242/jeb.192104] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/15/2018] [Indexed: 12/25/2022]
Abstract
Echinoderms lack a centralized nervous control system yet each extant echinoderm class has evolved unique and effective strategies for locomotion. Brittle stars (Ophiuroidea) stride swiftly over the seafloor by coordinating motions of their five muscular arms. Their arms consist of many repeating segments, requiring them to use a complex control system to coordinate motions among segments and between arms. We conducted in vivo experiments with brittle stars to analyze the functional role of the nerve ring, which connects the nerves in each arm. These experiments were designed to determine how the ophiuroid nervous system performs complex decision-making and locomotory actions under decentralized control. Our results show that brittle star arms must be connected by the nerve ring for coordinated locomotion, but information can travel bidirectionally around the nerve ring so that it circumvents the severance. Evidence presented indicates that ophiuroids rely on adjacent nerve ring connections for sustained periodic movements. The number of arms connected via the nerve ring is correlated positively with the likelihood that the animal will show coordinated locomotion, indicating that integrated nerve ring tissue is critical for control. The results of the experiments should provide a basis for the advancement of complex artificial decentralized systems.
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Affiliation(s)
- Elizabeth G. Clark
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
| | - Daichi Kanauchi
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-Ward, Sendai 980-8577, Japan
| | - Takeshi Kano
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-Ward, Sendai 980-8577, Japan
| | - Hitoshi Aonuma
- Research Center of Mathematics for Social Creativity, Research Institute for Electronic Science, Hokkaido University, N12W7, Kita-Ward, Sapporo, Hokkaido 060-0812, Japan
| | - Derek E. G. Briggs
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT 06511, USA
| | - Akio Ishiguro
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-Ward, Sendai 980-8577, Japan
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27
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Clark EG, Bhullar BAS, Darroch SAF, Briggs DEG. Water vascular system architecture in an Ordovician ophiuroid. Biol Lett 2017; 13:20170635. [PMID: 29212753 PMCID: PMC5746540 DOI: 10.1098/rsbl.2017.0635] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/07/2017] [Indexed: 11/12/2022] Open
Abstract
Understanding the water vascular system (WVS) in early fossil echinoderms is critical to elucidating the evolution of this system in extant forms. Here we present the first report of the internal morphology of the water vascular system of a stem ophiuroid. The radial canals are internal to the arm, but protected dorsally by a plate separate to the ambulacrals. The canals zig-zag with no evidence of constrictions, corresponding to sphincters, which control pairs of tube feet in extant ophiuroids. The morphology suggests that the unpaired tube feet must have operated individually, and relied on the elasticity of the radial canals, lateral valves and tube foot musculature alone for extension and retraction. This arrangement differs radically from that in extant ophiuroids, revealing a previously unknown Palaeozoic configuration.
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Affiliation(s)
- Elizabeth G Clark
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
| | - Bhart-Anjan S Bhullar
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT 06511, USA
| | - Simon A F Darroch
- Department of Earth and Environmental Science, Vanderbilt University, 5726 Stevenson Center, Nashville, TN 37240, USA
| | - Derek E G Briggs
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT 06511, USA
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Parry LA, Smithwick F, Nordén KK, Saitta ET, Lozano-Fernandez J, Tanner AR, Caron JB, Edgecombe GD, Briggs DEG, Vinther J. Soft-Bodied Fossils Are Not Simply Rotten Carcasses - Toward a Holistic Understanding of Exceptional Fossil Preservation. Bioessays 2017; 40. [DOI: 10.1002/bies.201700167] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/21/2017] [Indexed: 12/31/2022]
Affiliation(s)
- Luke A. Parry
- School of Earth Sciences, University of Bristol, Wills Memorial Building; Queen's Road Bristol BS8 1RJ UK
- Royal Ontario Museum; 100 Queen's Park Toronto ON M5S 2C6 Canada
- Department of Earth Sciences, The Natural History Museum; Cromwell Road London SW7 5BD UK
| | - Fiann Smithwick
- Royal Ontario Museum; 100 Queen's Park Toronto ON M5S 2C6 Canada
| | - Klara K. Nordén
- Royal Ontario Museum; 100 Queen's Park Toronto ON M5S 2C6 Canada
| | - Evan T. Saitta
- Royal Ontario Museum; 100 Queen's Park Toronto ON M5S 2C6 Canada
| | - Jesus Lozano-Fernandez
- School of Biological Sciences, University of Bristol; Life Sciences Building, 24 Tyndall Avenue Bristol BS8 1TQ UK
| | - Alastair R. Tanner
- School of Biological Sciences, University of Bristol; Life Sciences Building, 24 Tyndall Avenue Bristol BS8 1TQ UK
| | - Jean-Bernard Caron
- School of Earth Sciences, University of Bristol, Wills Memorial Building; Queen's Road Bristol BS8 1RJ UK
| | - Gregory D. Edgecombe
- Department of Earth Sciences, The Natural History Museum; Cromwell Road London SW7 5BD UK
| | - Derek E. G. Briggs
- Department of Geology and Geophysics, Yale University; 210 Whitney Avenue New Haven CT 06511 USA
- Yale Peabody Museum of Natural History; 170 Whitney Avenue New Haven CT 06520 USA
- Departments of Ecology and Evolutionary Biology and Earth Sciences, University of Toronto; Toronto ON M5S 3B2 Canada
| | - Jakob Vinther
- School of Earth Sciences, University of Bristol, Wills Memorial Building; Queen's Road Bristol BS8 1RJ UK
- Royal Ontario Museum; 100 Queen's Park Toronto ON M5S 2C6 Canada
- School of Biological Sciences, University of Bristol; Life Sciences Building, 24 Tyndall Avenue Bristol BS8 1TQ UK
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Briggs DEG, Siveter DJ, Siveter DJ, Sutton MD, Rahman IA. An edrioasteroid from the Silurian Herefordshire Lagerstätte of England reveals the nature of the water vascular system in an extinct echinoderm. Proc Biol Sci 2017; 284:rspb.2017.1189. [PMID: 28904139 DOI: 10.1098/rspb.2017.1189] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 08/01/2017] [Indexed: 11/12/2022] Open
Abstract
Echinoderms are unique in having a water vascular system with tube feet, which perform a variety of functions in living forms. Here, we report the first example of preserved tube feet in an extinct group of echinoderms. The material, from the Silurian Herefordshire Lagerstätte, UK, is assigned to a new genus and species of rhenopyrgid edrioasteroid, Heropyrgus disterminus The tube feet attach to the inner surface of compound interradial plates and form two sets, an upper and a lower, an arrangement never reported previously in an extant or extinct echinoderm. Cover plates are absent and floor plates are separated creating a large permanent entrance to the interior of the oral area. The tube feet may have captured food particles that entered the oral area and/or enhanced respiration. The pentameral symmetry of the oral surface transitions to eight columns in which the plates are vertically offset resulting in a spiral appearance. This change in symmetry may reflect flexibility in the evolutionary development of the axial and extraxial zones in early echinoderm evolution.
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Affiliation(s)
- Derek E G Briggs
- Department of Geology and Geophysics, and Yale Peabody Museum of Natural History, Yale University, PO Box 208109, New Haven, CT 06520-8109, USA
| | - Derek J Siveter
- Oxford University Museum of Natural History, Oxford OX1 3PW, UK.,Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - David J Siveter
- Department of Geology, University of Leicester, Leicester LE1 7RH, UK
| | - Mark D Sutton
- Department of Earth Sciences and Engineering, Imperial College London, London SW7 2BP, UK
| | - Imran A Rahman
- Oxford University Museum of Natural History, Oxford OX1 3PW, UK
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Siveter DJ, Briggs DEG, Siveter DJ, Sutton MD, Legg D. A new crustacean from the Herefordshire (Silurian) Lagerstätte, UK, and its significance in malacostracan evolution. Proc Biol Sci 2017; 284:20170279. [PMID: 28330926 PMCID: PMC5378094 DOI: 10.1098/rspb.2017.0279] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 03/07/2017] [Indexed: 12/25/2022] Open
Abstract
Cascolus ravitis gen. et sp. nov. is a three-dimensionally preserved fossil crustacean with soft parts from the Herefordshire (Silurian) Lagerstätte, UK. It is characterized by a head with a head shield and five limb pairs, and a thorax (pereon) with nine appendage-bearing segments followed by an apodous abdomen (pleon). All the appendages except the first are biramous and have a gnathobase. The post-mandibular appendages are similar one to another, and bear petal-shaped epipods that probably functioned as a part of the respiratory-circulatory system. Cladistic analysis resolves the new taxon as a stem-group leptostracan (Malacostraca). This well-preserved arthropod provides novel insights into the evolution of appendage morphology, tagmosis and the possible respiratory-circulatory physiology of a basal malacostracan.
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Affiliation(s)
- David J Siveter
- Department of Geology, University of Leicester, Leicester LE1 7RH, UK
| | - Derek E G Briggs
- Department of Geology and Geophysics, and Yale Peabody Museum of Natural History, Yale University, PO Box 208109, New Haven, CT 06520-8109, USA
| | - Derek J Siveter
- Earth Collections, University Museum of Natural History, Oxford OX1 3PW, UK
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - Mark D Sutton
- Department of Earth Sciences and Engineering, Imperial College London, London SW7 2BP, UK
| | - David Legg
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
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McNamara ME, Briggs DEG, Orr PJ, Field DJ, Wang Z. Correction to 'Experimental maturation of feathers: implications for reconstructions of fossil feather colour'. Biol Lett 2017; 13:rsbl.2017.0128. [PMID: 28330977 DOI: 10.1098/rsbl.2017.0128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Briggs DEG. Seilacher, Konstruktions-Morphologie, Morphodynamics, and the Evolution of form. J Exp Zool B Mol Dev Evol 2017; 328:197-206. [PMID: 28111907 DOI: 10.1002/jez.b.22725] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 11/28/2016] [Accepted: 12/09/2016] [Indexed: 01/28/2023]
Abstract
Adolf Seilacher (1925-2014) was a German paleontologist who made the concept of Konstruktions-Morphologie (constructional morphology) his own, recognizing that organism morphology is not simply an adaptive response to selection pressure but incorporates phylogenetic and structural influences as well. He was particularly interested in "fabricational noise," nonadaptive features that are a consequence of available materials and modes of growth, but he also elucidated the nature of adaptive radiations-in bivalves and sand dollars, for example. His interpretations relied on detailed study of specimens, and during a long international career he investigated examples from almost every invertebrate fossil group resulting in his 2015 book Morphodynamics, a compilation of his observations and iconic drawings that was published after his death. Seilacher's insights and observations on fossils have the potential to generate hypotheses about evolutionary development that may eventually be tested experimentally.
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Affiliation(s)
- Derek E G Briggs
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut
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Gold DA, O'Reilly SS, Luo G, Briggs DEG, Summons RE. Prospects for Sterane Preservation in Sponge Fossils from Museum Collections and the Utility of Sponge Biomarkers for Molecular Clocks. Bulletin of the Peabody Museum of Natural History 2016. [DOI: 10.3374/014.057.0208] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Abstract
The sudden appearance of fossils that marks the so-called 'Cambrian explosion' has intrigued and exercised biologists since Darwin's time. In On the Origin of Species, Darwin made it clear that he believed that ancestral forms 'lived long before' their first fossil representatives. While he considered such an invisible record necessary to explain the level of complexity already seen in the fossils of early trilobites, Darwin was at a loss to explain why there were no corresponding fossils of these earlier forms. In chapter 9 of the Origin, entitled 'On the imperfection of the geological record', he emphasized the 'poorness of our palaeontological collections' and stated categorically that 'no organism wholly soft can be preserved'. Fortunately much has been discovered in the last 150 years, not least multiple examples of Cambrian and Precambrian soft-bodied fossils. We now know that the sudden appearance of fossils in the Cambrian (541-485 million years ago) is real and not an artefact of an imperfect fossil record: rapid diversification of animals coincided with the evolution of biomineralized shells. And although fossils in earlier rocks are rare, they are not absent: their rarity reflects the low diversity of life at this time, as well as the low preservation potential of Precambrian organisms (see Primer by Butterfield, in this issue).
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Affiliation(s)
- Derek E G Briggs
- Department of Geology and Geophysics and Yale Peabody Museum of Natural History, Yale University, PO Box 208109, New Haven, CT 06511, USA.
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35
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McCoy VE, Lamsdell JC, Poschmann M, Anderson RP, Briggs DEG. All the better to see you with: eyes and claws reveal the evolution of divergent ecological roles in giant pterygotid eurypterids. Biol Lett 2016; 11:rsbl.2015.0564. [PMID: 26289442 DOI: 10.1098/rsbl.2015.0564] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pterygotid eurypterids have traditionally been interpreted as active, high-level, visual predators; however, recent studies of the visual system and cheliceral morphology of the pterygotid Acutiramus contradict this interpretation. Here, we report similar analyses of the pterygotids Erettopterus, Jaekelopterus and Pterygotus, and the pterygotid sister taxon Slimonia. Representative species of all these genera have more acute vision than A. cummingsi. The visual systems of Jaekelopterus rhenaniae and Pterygotus anglicus are comparable to that of modern predatory arthropods. All species of Jaekelopterus and Pterygotus have robust crushing chelicerae, morphologically distinct from the weaker slicing chelicerae of Acutiramus. Vision in Erettopterus osiliensis and Slimonia acuminata is more acute than in Acutiramus cummingsi, but not to the same degree as in modern active predators, and the morphology of the chelicerae in these genera suggests a grasping function. The pterygotids evolved with a shift in ecology from generalized feeder to specialized predator. Pterygotid eurypterids share a characteristic morphology but, although some were top predators, their ecology differs radically between genera.
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Affiliation(s)
- Victoria E McCoy
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
| | - James C Lamsdell
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
| | - Markus Poschmann
- Referat Erdgeschichte, Direktion Landesarchäologie, Generaldirektion Kulturelles Erbe RLP, Große Langgasse 29, 55116 Mainz, Germany
| | - Ross P Anderson
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
| | - Derek E G Briggs
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA Yale Peabody Museum of Natural History, 170 Whitney Avenue, New Haven, CT 06520, USA
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Briggs DEG, Siveter DJ, Siveter DJ, Sutton MD, Legg D. Tiny individuals attached to a new Silurian arthropod suggest a unique mode of brood care. Proc Natl Acad Sci U S A 2016; 113:4410-5. [PMID: 27044103 PMCID: PMC4843443 DOI: 10.1073/pnas.1600489113] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The ∼430-My-old Herefordshire, United Kingdom, Lagerstätte has yielded a diversity of remarkably preserved invertebrates, many of which provide fundamental insights into the evolutionary history and ecology of particular taxa. Here we report a new arthropod with 10 tiny arthropods tethered to its tergites by long individual threads. The head of the host, which is covered by a shield that projects anteriorly, bears a long stout uniramous antenna and a chelate limb followed by two biramous appendages. The trunk comprises 11 segments, all bearing limbs and covered by tergites with long slender lateral spines. A short telson bears long parallel cerci. Our phylogenetic analysis resolves the new arthropod as a stem-group mandibulate. The evidence suggests that the tethered individuals are juveniles and the association represents a complex brooding behavior. Alternative possibilities-that the tethered individuals represent a different epizoic or parasitic arthropod-appear less likely.
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Affiliation(s)
- Derek E G Briggs
- Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109; Yale Peabody Museum of Natural History, Yale University, New Haven, CT 06520-8109;
| | - Derek J Siveter
- Oxford University Museum of Natural History, Oxford OX1 3PW, United Kingdom; Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, United Kingdom
| | - David J Siveter
- Department of Geology, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Mark D Sutton
- Department of Earth Sciences and Engineering, Imperial College London, London SW7 2BP, United Kingdom
| | - David Legg
- Oxford University Museum of Natural History, Oxford OX1 3PW, United Kingdom
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McCoy VE, Saupe EE, Lamsdell JC, Tarhan LG, McMahon S, Lidgard S, Mayer P, Whalen CD, Soriano C, Finney L, Vogt S, Clark EG, Anderson RP, Petermann H, Locatelli ER, Briggs DEG. The 'Tully monster' is a vertebrate. Nature 2016; 532:496-9. [PMID: 26982721 DOI: 10.1038/nature16992] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 01/12/2016] [Indexed: 11/09/2022]
Abstract
Problematic fossils, extinct taxa of enigmatic morphology that cannot be assigned to a known major group, were once a major issue in palaeontology. A long-favoured solution to the 'problem of the problematica', particularly the 'weird wonders' of the Cambrian Burgess Shale, was to consider them representatives of extinct phyla. A combination of new evidence and modern approaches to phylogenetic analysis has now resolved the affinities of most of these forms. Perhaps the most notable exception is Tullimonstrum gregarium, popularly known as the Tully monster, a large soft-bodied organism from the late Carboniferous Mazon Creek biota (approximately 309-307 million years ago) of Illinois, USA, which was designated the official state fossil of Illinois in 1989. Its phylogenetic position has remained uncertain and it has been compared with nemerteans, polychaetes, gastropods, conodonts, and the stem arthropod Opabinia. Here we review the morphology of Tullimonstrum based on an analysis of more than 1,200 specimens. We find that the anterior proboscis ends in a buccal apparatus containing teeth, the eyes project laterally on a long rigid bar, and the elongate segmented body bears a caudal fin with dorsal and ventral lobes. We describe new evidence for a notochord, cartilaginous arcualia, gill pouches, articulations within the proboscis, and multiple tooth rows adjacent to the mouth. This combination of characters, supported by phylogenetic analysis, identifies Tullimonstrum as a vertebrate, and places it on the stem lineage to lampreys (Petromyzontida). In addition to increasing the known morphological disparity of extinct lampreys, a chordate affinity for T. gregarium resolves the nature of a soft-bodied fossil which has been debated for more than 50 years.
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Affiliation(s)
- Victoria E McCoy
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA
| | - Erin E Saupe
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA
| | - James C Lamsdell
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA.,American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024, USA
| | - Lidya G Tarhan
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA
| | - Sean McMahon
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA
| | - Scott Lidgard
- Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, Illinois 60605, USA
| | - Paul Mayer
- Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, Illinois 60605, USA
| | - Christopher D Whalen
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA
| | - Carmen Soriano
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Lydia Finney
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Stefan Vogt
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Elizabeth G Clark
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA
| | - Ross P Anderson
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA
| | - Holger Petermann
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA
| | - Emma R Locatelli
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA
| | - Derek E G Briggs
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA.,Yale Peabody Museum of Natural History, 170 Whitney Avenue, New Haven, Connecticut 06511, USA
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Briggs DEG. Extraordinary fossils reveal the nature of Cambrian life: a commentary on Whittington (1975) 'The enigmatic animal Opabinia regalis, Middle Cambrian, Burgess Shale, British Columbia'. Philos Trans R Soc Lond B Biol Sci 2015; 370:rstb.2014.0313. [PMID: 25750235 PMCID: PMC4360120 DOI: 10.1098/rstb.2014.0313] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Harry Whittington's 1975 monograph on Opabinia was the first to highlight how some of the Burgess Shale animals differ markedly from those that populate today's oceans. Categorized by Stephen J. Gould as a 'weird wonder' (Wonderful life, 1989) Opabinia, together with other unusual Burgess Shale fossils, stimulated ongoing debates about the early evolution of the major animal groups and the nature of the Cambrian explosion. The subsequent discovery of a number of other exceptionally preserved fossil faunas of Cambrian and early Ordovician age has significantly augmented the information available on this critical interval in the history of life. Although Opabinia initially defied assignment to any group of modern animals, it is now interpreted as lying below anomalocaridids on the stem leading to the living arthropods. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society.
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Affiliation(s)
- Derek E G Briggs
- Department of Geology and Geophysics and Yale Peabody Museum of Natural History, Yale University, PO Box 208109, New Haven, CT 06520-8109, USA
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Abstract
Eurypterids are a group of extinct chelicerates that ranged for over 200 Myr from the Ordovician to the Permian. Gigantism is common in the group; about 50% of families include taxa over 0.8 m in length. Among these were the pterygotids (Pterygotidae), which reached lengths of over 2 m and were the largest arthropods that ever lived. They have been interpreted as highly mobile visual predators on the basis of their large size, enlarged, robust chelicerae and forward-facing compound eyes. Here, we test this interpretation by reconstructing the visual capability of Acutiramus cummingsi (Pterygotidae) and comparing it with that of the smaller Eurypterus sp. (Eurypteridae), which lacked enlarged chelicerae, and other arthropods of similar geologic age. In A. cummingsi, there is no area of lenses differentiated to provide increased visual acuity, and the interommatidial angles (IOA) do not fall within the range of high-level modern arthropod predators. Our results show that the visual acuity of A. cummingsi is poor compared with that of co-occurring Eurypterus sp. The ecological role of pterygotids may have been as predators on thin-shelled and soft-bodied prey, perhaps in low-light conditions or at night.
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Affiliation(s)
- Ross P Anderson
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
| | - Victoria E McCoy
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
| | - Maria E McNamara
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Republic of Ireland
| | - Derek E G Briggs
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA Yale Peabody Museum of Natural History, New Haven, CT 06520, USA
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Lamsdell JC, Briggs DEG, Liu HP, Witzke BJ, McKay RM. A new Ordovician arthropod from the Winneshiek Lagerstätte of Iowa (USA) reveals the ground plan of eurypterids and chasmataspidids. Naturwissenschaften 2015; 102:63. [DOI: 10.1007/s00114-015-1312-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 09/01/2015] [Accepted: 09/04/2015] [Indexed: 11/24/2022]
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Lamsdell JC, Briggs DEG, Liu HP, Witzke BJ, McKay RM. The oldest described eurypterid: a giant Middle Ordovician (Darriwilian) megalograptid from the Winneshiek Lagerstätte of Iowa. BMC Evol Biol 2015; 15:169. [PMID: 26324341 PMCID: PMC4556007 DOI: 10.1186/s12862-015-0443-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 07/30/2015] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Eurypterids are a diverse group of chelicerates known from ~250 species with a sparse Ordovician record currently comprising 11 species; the oldest fully documented example is from the Sandbian of Avalonia. The Middle Ordovician (Darriwilian) fauna of the Winneshiek Lagerstätte includes a new eurypterid species represented by more than 150 specimens, including some juveniles, preserved as carbonaceous cuticular remains. This taxon represents the oldest described eurypterid, extending the documented range of the group back some 9 million years. RESULTS The new eurypterid species is described as Pentecopterus decorahensis gen. et sp. nov.. Phylogenetic analysis places Pentecopterus at the base of the Megalograptidae, united with the two genera previously assigned to this family by the shared possession of two or more pairs of spines per podomere on prosomal appendage IV, a reduction of all spines except the pair on the penultimate podomere of appendage V, and an ornamentation of guttalate scales, including angular scales along the posterior margin of the dorsal tergites and in longitudinal rows along the tergites. The morphology of Pentecopterus reveals that the Megalograptidae are representatives of the derived carcinosomatoid clade and not basal eurypterids as previously interpreted. CONCLUSIONS The relatively derived position of megalograptids within the eurypterids indicates that most eurypterid clades were present by the Middle Ordovician. Eurypterids either underwent an explosive radiation soon after their origination, or earlier representatives, perhaps Cambrian in age, remain to be discovered. The available instars of Pentecopterus decorahensis suggest that eurypterids underwent extreme appendage differentiation during development, a potentially unique condition among chelicerates. The high degree of appendage specialization in eurypterids is only matched by arachnids within chelicerates, supporting a sister taxon relationship between them.
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Affiliation(s)
- James C Lamsdell
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT, 06511, USA.
| | - Derek E G Briggs
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT, 06511, USA.
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT, 06511, USA.
| | - Huaibao P Liu
- Iowa Geological Survey, IIHR-Hydroscience & Engineering, University of Iowa, 340 Trowbridge Hall, Iowa City, IA, 52242, USA.
| | - Brian J Witzke
- Department of Earth and Environmental Sciences, University of Iowa, 121 Trowbridge Hall, Iowa City, IA, 52242, USA.
| | - Robert M McKay
- Iowa Geological Survey, IIHR-Hydroscience & Engineering, University of Iowa, 340 Trowbridge Hall, Iowa City, IA, 52242, USA.
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McNamara ME, Saranathan V, Locatelli ER, Noh H, Briggs DEG, Orr PJ, Cao H. Cryptic iridescence in a fossil weevil generated by single diamond photonic crystals. J R Soc Interface 2015; 11:20140736. [PMID: 25185581 DOI: 10.1098/rsif.2014.0736] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Nature's most spectacular colours originate in integumentary tissue architectures that scatter light via nanoscale modulations of the refractive index. The most intricate biophotonic nanostructures are three-dimensional crystals with opal, single diamond or single gyroid lattices. Despite intense interest in their optical and structural properties, the evolution of such nanostructures is poorly understood, due in part to a lack of data from the fossil record. Here, we report preservation of single diamond (Fd-3m) three-dimensional photonic crystals in scales of a 735,000 year old specimen of the brown Nearctic weevil Hypera diversipunctata from Gold Run, Canada, and in extant conspecifics. The preserved red to green structural colours exhibit near-field brilliancy yet are inconspicuous from afar; they most likely had cryptic functions in substrate matching. The discovery of pristine fossil examples indicates that the fossil record is likely to yield further data on the evolution of three-dimensional photonic nanostructures and their biological functions.
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Affiliation(s)
- Maria E McNamara
- Department of Geology and Geophysics, Kline Geology Laboratory, Yale University, 210 Whitney Avenue, New Haven, CT 06520, USA UCD School of Geological Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | - Vinod Saranathan
- Edward Grey Institute, Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK
| | - Emma R Locatelli
- Department of Geology and Geophysics, Kline Geology Laboratory, Yale University, 210 Whitney Avenue, New Haven, CT 06520, USA
| | - Heeso Noh
- Department of Nano and Electronic Physics, Kookmin University, 77 Jeong-neong Ro, Seongbuk-gu, Seoul, Korea Department of Applied Physics, Yale University, Becton Centre, 15 Prospect St., New Haven, CT 06520, USA
| | - Derek E G Briggs
- Department of Geology and Geophysics, Kline Geology Laboratory, Yale University, 210 Whitney Avenue, New Haven, CT 06520, USA Yale Peabody Museum of Natural History, 170 Whitney Avenue, New Haven, CT 06520, USA
| | - Patrick J Orr
- UCD School of Geological Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | - Hui Cao
- Department of Applied Physics, Yale University, Becton Centre, 15 Prospect St., New Haven, CT 06520, USA
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Van Roy P, Daley AC, Briggs DEG. Anomalocaridid trunk limb homology revealed by a giant filter-feeder with paired flaps. Nature 2015; 522:77-80. [DOI: 10.1038/nature14256] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/23/2015] [Indexed: 12/12/2022]
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Haug C, Briggs DEG, Mikulic DG, Kluessendorf J, Haug JT. The implications of a Silurian and other thylacocephalan crustaceans for the functional morphology and systematic affinities of the group. BMC Evol Biol 2014; 14:159. [PMID: 25927449 PMCID: PMC4448278 DOI: 10.1186/s12862-014-0159-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 07/11/2014] [Indexed: 11/17/2022] Open
Abstract
Background Thylacocephala is a group of enigmatic extinct arthropods. Here we provide a full description of the oldest unequivocal thylacocephalan, a new genus and species Thylacares brandonensis, which is present in the Silurian Waukesha fauna from Wisconsin, USA. We also present details of younger, Jurassic specimens, from the Solnhofen lithographic limestones, which are crucial to our interpretation of the systematic position of Thylacocephala. In the past, Thylacocephala has been interpreted as a crustacean ingroup and as closely related to various groups such as cirripeds, decapods or remipeds. Results The Waukesha thylacocephalan, Thylacares brandonensis n. gen. n. sp., bears compound eyes and raptorial appendages that are relatively small compared to those of other representatives of the group. As in other thylacocephalans the large bivalved shield encloses much of the entire body. The shield lacks a marked optical notch. The eyes, which project just beyond the shield margin, appear to be stalked. Head appendages, which may represent antennulae, antennae and mandibles, appear to be present. The trunk is comprised of up to 22 segments. New details observed on thylacocephalans from the Jurassic Solnhofen lithographic limestones include antennulae and antennae of Mayrocaris bucculata, and endites on the raptorial appendages and an elongate last trunk appendage in Clausocaris lithographica. Preserved features of the internal morphology in C. lithographica include the muscles of the raptorial appendage and trunk. Conclusions Our results indicate that some ‘typical’ thylacocephalan characters are unique to the group; these autapomorphies contribute to the difficulty of determining thylacocephalan affinities. While the new features reported here are consistent with a eucrustacean affinity, most previous hypotheses for the position of Thylacocephala within Eucrustacea (as Stomatopoda, Thecostraca or Decapoda) are shown to be unlikely. A sister group relationship to Remipedia appears compatible with the observed features of Thylacocephala but more fossil evidence is required to test this assertion. The raptorial appendages of Thylacocephala most likely projected 45 degrees abaxially instead of directly forward as previously reconstructed. The overall morphology of thylacocephalans supports a predatory mode of life.
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Affiliation(s)
- Carolin Haug
- Department of Biology II and GeoBio-Center, LMU Munich, Großhaderner Str. 2, 82152, Martinsried-Planegg, Germany.
| | - Derek E G Briggs
- Department of Geology and Geophysics, Yale University, PO Box 208109-06511, New Haven, CT, USA. .,Yale Peabody Museum of Natural History, Yale University, 06520, New Haven, CT, USA.
| | | | - Joanne Kluessendorf
- Weis Earth Science Museum, University of Wisconsin - Fox Valley, 54952, Menasha, WI, USA.
| | - Joachim T Haug
- Department of Biology II and GeoBio-Center, LMU Munich, Großhaderner Str. 2, 82152, Martinsried-Planegg, Germany.
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Abstract
An important survival strategy for animal species is the so-called niche differentiation between larva and adult. Different developmental stages of the same animal occupy different ecological niches to avoid competing for food or other essential resources. Here, we describe an exceptionally preserved larval stage of the short great appendage (SGA) arthropod (megacheiran) Leanchoilia illecebrosa from the early Cambrian Chengjiang biota of China. The larval specimen preserves fine details of the main feeding limb, the SGA, which are unknown in the adult of the same species. This discovery demonstrates that niche differentiation during ontogeny was developed in this species of megacheiran--a group of fossil arthropods that has been considered to be early representatives of Chelicerata, which includes horseshoe crabs and arachnids. Hence, this type of niche differentiation, which is common today, originated from the early Cambrian.
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Affiliation(s)
- Yu Liu
- 1] Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China [2] Developmental Neurobiology Group, Biocenter, Ludwig-Maximilians-Universität München, Großhaderner Street 2, 82152 Planegg-Martinsried, Germany
| | - Joachim T Haug
- Department of Biology II, GeoBio-Center, Ludwig-Maximilians-Universität München, Großhaderner Street 2, 82152 Planegg-Martinsried, Germany
| | - Carolin Haug
- Department of Biology II, GeoBio-Center, Ludwig-Maximilians-Universität München, Großhaderner Street 2, 82152 Planegg-Martinsried, Germany
| | - Derek E G Briggs
- Department of Geology and Geophysics, and Peabody Museum of Natural History, Yale University, PO Box 208109, New Haven, Connecticut 06520-8109, USA
| | - Xianguang Hou
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China
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Affiliation(s)
- Derek E. G. Briggs
- Department of Geology and Geophysics; Yale University; New Haven CT USA
- Yale Peabody Museum of Natural History; New Haven CT USA
| | - Roger E. Summons
- Department of Earth, Atmospheric and Planetary Sciences; Massachusetts Institute of Technology; Cambridge MA USA
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Abstract
A new arthropod, Enalikter aphson gen. et sp. nov., is described from the Silurian (Wenlock Series) Herefordshire Lagerstätte of the UK. It belongs to the Megacheira (=short-great-appendage group), which is recognized here, for the first time, in strata younger than mid-Cambrian age. Discovery of this new Silurian taxon allows us to identify a Devonian megacheiran representative, Bundenbachiellus giganteus from the Hunsrück Slate of Germany. The phylogenetic position of megacheirans is controversial: they have been interpreted as stem chelicerates, or stem euarthropods, but when Enalikter and Bundenbachiellus are added to the most comprehensive morphological database available, a stem euarthropod position is supported. Enalikter represents the only fully three-dimensionally preserved stem-group euarthropod, it falls in the sister clade to the crown-group euarthropods, and it provides new insights surrounding the origin and early evolution of the euarthropods. Recognition of Enalikter and Bundenbachiellus as megacheirans indicates that this major arthropod group survived for nearly 100 Myr beyond the mid-Cambrian.
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Affiliation(s)
- Derek J Siveter
- Earth Collections, University Museum of Natural History, , Parks Road, Oxford OX1 3PW, UK, Department of Earth Sciences, University of Oxford, , South Parks Road, Oxford OX1 3PR, UK, Department of Geology and Geophysics and Yale Peabody Museum of Natural History, Yale University, , PO Box 208109, New Haven, CT 06520-8109, USA, Department of Geology, University of Leicester, , Leicester LE1 7RH, UK, Department of Earth Sciences and Engineering, Imperial College London, , London SW7 2BP, UK
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McNamara ME, Briggs DEG, Orr PJ, Field DJ, Wang Z. Experimental maturation of feathers: implications for reconstructions of fossil feather colour. Biol Lett 2013; 9:20130184. [PMID: 23536445 DOI: 10.1098/rsbl.2013.0184] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Fossil feathers often preserve evidence of melanosomes-micrometre-scale melanin-bearing organelles that have been used to infer original colours and patterns of the plumage of dinosaurs. Such reconstructions acknowledge that evidence from other colour-producing mechanisms is presently elusive and assume that melanosome geometry is not altered during fossilization. Here, we provide the first test of this assumption, using high pressure-high temperature autoclave experiments on modern feathers to simulate the effects of burial on feather colour. Our experiments show that melanosomes are retained despite loss of visual evidence of colour and complete degradation of other colour-producing structures (e.g. quasi-ordered arrays in barbs and the keratin cortex in barbules). Significantly, however, melanosome geometry and spatial distribution are altered by the effects of pressure and temperature. These results demonstrate that reconstructions of original plumage coloration in fossils where preserved features of melanosomes are affected by diagenesis should be treated with caution. Reconstructions of fossil feather colour require assessment of the extent of preservation of various colour-producing mechanisms, and, critically, the extent of alteration of melanosome geometry.
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Affiliation(s)
- Maria E McNamara
- Department of Geology and Geophysics, Yale University, New Haven, CT 06520, USA.
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Siveter DJ, Briggs DEG, Siveter DJ, Sutton MD, Joomun SC. A Silurian myodocope with preserved soft-parts: cautioning the interpretation of the shell-based ostracod record. Proc Biol Sci 2012; 280:20122664. [PMID: 23235709 DOI: 10.1098/rspb.2012.2664] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Ostracod crustaceans are the most abundant fossil arthropods. The Silurian Pauline avibella gen. et sp. nov., from the Herefordshire Lagerstätte, UK, is an extremely rare Palaeozoic example with soft-part preservation. Based on its soft-part morphology, especially the exceptionally preserved limbs and presence of lateral eyes, it is assigned to the myodocopid myodocopes. The ostracod is very large, with an epipod on the fifth limb pair, as well as gills implying the presence of a heart and an integrated respiratory-circulatory system as in living cylindroleberidid myodocopids. Features of its shell morphology, however, recall halocyprid myodocopes and palaeocopes, encouraging caution in classifying ostracods based on the carapace alone and querying the interpretation of their shell-based fossil record, especially for the Palaeozoic, where some 500 genera are presently assigned to the Palaeocopida.
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Affiliation(s)
- David J Siveter
- Department of Geology, University of Leicester, Leicester LE1 7RH, UK.
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