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Schoenemann B, Clarkson ENK. The median eyes of trilobites. Sci Rep 2023; 13:3917. [PMID: 36890176 PMCID: PMC9995485 DOI: 10.1038/s41598-023-31089-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 03/06/2023] [Indexed: 03/10/2023] Open
Abstract
Arthropods typically possess two types of eyes-compound eyes, and the ocellar, so called 'median eyes'. Only trilobites, an important group of arthropods during the Palaeozoic, seem not to possess median eyes. While compound eyes are in focus of many investigations, median eyes are not as well considered. Here we give an overview of the occurence of median eyes in the arthropod realm and their phylogenetic relationship to other ocellar eye-systems among invertebrates. We discuss median eyes as represented in the fossil record e.g. in arthropods of the Cambrian fauna, and document median eyes in trilobites the first time. We make clear that ocellar systems, homologue to median eyes and possibly their predecessors are the primordial visual system, and that the compound eyes evolved later. Furthermore, the original number of median eyes is two, as retained in chelicerates. Four, probably the consequence of a gene-dublication, can be found for example in basal crustaceans, three is a derived number by fusion of the central median eyes and characterises Mandibulata. Median eyes are present in larval trilobites, but lying below a probably thin, translucent cuticle, as described here, which explains why they have hitherto escaped detection. So this article gives a review about the complexity of representation and evolution of median eyes among arthropods, and fills the gap of missing median eyes in trilobites. Thus now the number of median eyes represented in an arthropod is an important tool to find its position in the phylogenetic tree.
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Affiliation(s)
- Brigitte Schoenemann
- Department of Biology, Institute of Zoology (Neurobiology, Animal Physiology), University of Cologne, 50674, Cologne, Germany.
| | - Euan N K Clarkson
- Grant Institute, School of Geosciences, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JW, UK
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2
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Saleh F, Ma X, Guenser P, Mángano MG, Buatois LA, Antcliffe JB. Probability-based preservational variations within the early Cambrian Chengjiang biota (China). PeerJ 2022; 10:e13869. [PMID: 36032952 PMCID: PMC9415357 DOI: 10.7717/peerj.13869] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/19/2022] [Indexed: 01/18/2023] Open
Abstract
The Chengjiang biota (Yunnan Province, China) is a treasure trove of soft-bodied animal fossils from the earliest stages of the Cambrian explosion. The mechanisms contributing to its unique preservation, known as the Burgess Shale-type preservation, are well understood. However, little is known about the preservation differences between various animal groups within this biota. This study compares tissue-occurrence data of 11 major animal groups in the Chengjiang biota using a probabilistic methodology. The fossil-based data from this study is compared to previous decay experiments. This shows that all groups are not equally preserved with some higher taxa more likely to preserve soft tissues than others. These differences in fossil preservation between taxa can be explained by the interaction of biological and environmental characteristics. A bias also results from differential taxonomic recognition, as some taxa are easily recognized from even poorly preserved fragments while other specimens are difficult to assign to higher taxa even with exquisite preservation.
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Affiliation(s)
- Farid Saleh
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China,Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming, China
| | - Xiaoya Ma
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China,Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming, China,Centre for Ecology and Conservation, University of Exeter, Penryn, United Kingdom
| | - Pauline Guenser
- University Bordeaux, CNRS, Bordeaux INP, EPOC, UMR5805, Pessac, France
| | - M. Gabriela Mángano
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada
| | - Luis A. Buatois
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada
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3
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Introduction. Vision (Basel) 2021. [DOI: 10.1017/9781108946339.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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4
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Index. Vision (Basel) 2021. [DOI: 10.1017/9781108946339.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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5
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6
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Visions. Vision (Basel) 2021. [DOI: 10.1017/9781108946339.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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7
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Visions of a Digital Future. Vision (Basel) 2021. [DOI: 10.1017/9781108946339.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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8
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Science, Vision, Perspective. Vision (Basel) 2021. [DOI: 10.1017/9781108946339.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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9
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The Evolution of Eyes. Vision (Basel) 2021. [DOI: 10.1017/9781108946339.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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10
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Computer Vision. Vision (Basel) 2021. [DOI: 10.1017/9781108946339.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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11
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Vision of the Cosmos. Vision (Basel) 2021. [DOI: 10.1017/9781108946339.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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12
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Paterson JR, Edgecombe GD, García-Bellido DC. Disparate compound eyes of Cambrian radiodonts reveal their developmental growth mode and diverse visual ecology. SCIENCE ADVANCES 2020; 6:6/49/eabc6721. [PMID: 33268353 PMCID: PMC7821881 DOI: 10.1126/sciadv.abc6721] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 10/20/2020] [Indexed: 05/28/2023]
Abstract
Radiodonts are nektonic stem-group euarthropods that played various trophic roles in Paleozoic marine ecosystems, but information on their vision is limited. Optical details exist only in one species from the Cambrian Emu Bay Shale of Australia, here assigned to Anomalocaris aff. canadensis We identify another type of radiodont compound eye from this deposit, belonging to 'Anomalocaris' briggsi This ≤4-cm sessile eye has >13,000 lenses and a dorsally oriented acute zone. In both taxa, lenses were added marginally and increased in size and number throughout development, as in many crown-group euarthropods. Both species' eyes conform to their inferred lifestyles: The macrophagous predator A. aff. canadensis has acute stalked eyes (>24,000 lenses each) adapted for hunting in well-lit waters, whereas the suspension-feeding 'A.' briggsi could detect plankton in dim down-welling light. Radiodont eyes further demonstrate the group's anatomical and ecological diversity and reinforce the crucial role of vision in early animal ecosystems.
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Affiliation(s)
- John R Paterson
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia.
| | - Gregory D Edgecombe
- Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Diego C García-Bellido
- School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
- South Australian Museum, North Terrace, Adelaide, SA 5000, Australia
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13
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Scholtz G, Staude A, Dunlop JA. Trilobite compound eyes with crystalline cones and rhabdoms show mandibulate affinities. Nat Commun 2019; 10:2503. [PMID: 31175282 PMCID: PMC6555793 DOI: 10.1038/s41467-019-10459-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 05/14/2019] [Indexed: 01/23/2023] Open
Abstract
Most knowledge about the structure, function, and evolution of early compound eyes is based on investigations in trilobites. However, these studies dealt mainly with the cuticular lenses and little was known about internal anatomy. Only recently some data on crystalline cones and retinula cells were reported for a Cambrian trilobite species. Here, we describe internal eye structures of two other trilobite genera. The Ordovician Asaphus sp. reveals preserved crystalline cones situated underneath the cuticular lenses. The same is true for the Devonian species Archegonus (Waribole) warsteinensis, which in addition shows the fine structure of the rhabdom in the retinula cells. These results suggest that an apposition eye with a crystalline cone is ancestral for Trilobita. The overall similarity of trilobite eyes to those of myriapods, crustaceans, and hexapods corroborates views of a phylogenetic position of trilobites in the stem lineage of Mandibulata. Little is known about the internal anatomy of early eyes. Here, Scholtz and colleagues show the internal eye structures from fossils of two genera of trilobites, which support an ancestral apposition eye with crystalline cones in Trilobita and a close affinity with Mandibulata.
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Affiliation(s)
- Gerhard Scholtz
- Humboldt-Universität zu Berlin, Institut für Biologie/Vergleichende Zoologie, Philippstr. 13, 10115, Berlin, Germany.
| | - Andreas Staude
- Fachbereich 8.5 "Mikro-ZfP", BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, 12205, Berlin, Germany.,Thermo Fisher Scientific, c/o Zuse Institut Berlin (ZIB), Takustr. 7, 14195, Berlin, Germany
| | - Jason A Dunlop
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, 10115, Berlin, Germany
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14
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Du KS, Ortega-Hernández J, Yang J, Zhang XG. A soft-bodied euarthropod from the early Cambrian Xiaoshiba Lagerstätte of China supports a new clade of basal artiopodans with dorsal ecdysial sutures. Cladistics 2019; 35:269-281. [PMID: 34622993 DOI: 10.1111/cla.12344] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2018] [Indexed: 11/28/2022] Open
Abstract
We describe the exceptionally well-preserved non-trilobite artiopodan Zhiwenia coronata gen. et sp. nov. from the Cambrian Stage 3 Xiaoshiba Lagerstätte in Yunnan, China. The exoskeleton consists of a cephalic shield with dorsal sutures expressed as lateral notches that accommodate stalked lateral eyes, an elongate trunk composed of 20 tergites-the first of which is reduced-and a short tailspine with marginal spines. Appendicular data include a pair of multi-segmented antennae, and homonomous biramous trunk limbs consisting of an endopod with at least seven podomeres and a flattened exopod with lamellae. Although the presence of cephalic notches and a reduced first trunk tergite invites comparisons with the petalopleurans Xandarella, Luohiniella and Cindarella, the proportions and exoskeletal tagmosis of Zhiwenia do not closely resemble those of any major group within Trilobitomorpha. Parsimony and Bayesian phylogenetic analyses consistently support Zhiwenia as sister-taxon to the Emu Bay Shale artiopodan Australimicola spriggi, and both of them as closely related to Acanthomeridion from the Chengjiang. This new monophyletic clade, Protosutura nov., occupies a basal phylogenetic position within Artiopoda as sister-group to Trilobitomorpha and Vicissicaudata, illuminates the ancestral organization of these successful euarthropods, and leads to a re-evaluation of the evolution of ecdysial dorsal sutures within the group.
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Affiliation(s)
- Kun-Sheng Du
- Key Laboratory for Palaeobiology, Yunnan University, Kunming, 650091, China.,MEC International Joint Laboratory for Palaeoenvironment, Yunnan University, Kunming, 650091, China
| | - Javier Ortega-Hernández
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.,Museum of Comparative Zoology and, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
| | - Jie Yang
- Key Laboratory for Palaeobiology, Yunnan University, Kunming, 650091, China.,MEC International Joint Laboratory for Palaeoenvironment, Yunnan University, Kunming, 650091, China
| | - Xi-Guang Zhang
- Key Laboratory for Palaeobiology, Yunnan University, Kunming, 650091, China.,MEC International Joint Laboratory for Palaeoenvironment, Yunnan University, Kunming, 650091, China
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15
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Isotopic evidence for temperate oceans during the Cambrian Explosion. Sci Rep 2019; 9:6330. [PMID: 31004083 PMCID: PMC6474879 DOI: 10.1038/s41598-019-42719-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 04/02/2019] [Indexed: 11/08/2022] Open
Abstract
The Cambrian Explosion was a key event in the evolution of life on Earth. This event took place at a time when sea surface temperatures have been proposed to reach about 60 °C. Such high temperatures are clearly above the upper thermal limit of 38 °C for modern marine invertebrates and preclude a major biological revolution. To address this dichotomy, we performed in situ δ18O analyses of Cambrian phosphatic brachiopods via secondary ion mass spectrometry (SIMS). The δ18Ophosphate data, which are considered to represent the most primary δ18Oseawater signature, were identified by evaluating the diagenetic alteration of the analyzed shells. Assuming ice-free conditions for the Cambrian ocean and no change in δ18Oseawater (-1.4‰ to -1‰; V-SMOW) through time, our temperatures vary between 35 °C ± 12 °C and 41 °C ± 12 °C. They are thus clearly above (1) recent subequatorial sea surface temperatures of 27 °C-35 °C and (2) the upper lethal limit of 38 °C of marine organisms. Our new data can therefore be used to infer a minimal depletion in early Cambrian δ18Oseawater relative to today of about -3‰. With this presumption, our most pristine δ18Ophosphate values translate into sea surface temperatures of about 30 °C indicating habitable temperatures for subequatorial oceans during the Cambrian Explosion.
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16
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Abstract
Until now, the fossil record has not been capable of revealing any details of the mechanisms of complex vision at the beginning of metazoan evolution. Here, we describe functional units, at a cellular level, of a compound eye from the base of the Cambrian, more than half a billion years old. Remains of early Cambrian arthropods showed the external lattices of enormous compound eyes, but not the internal structures or anything about how those compound eyes may have functioned. In a phosphatized trilobite eye from the lower Cambrian of the Baltic, we found lithified remnants of cellular systems, typical of a modern focal apposition eye, similar to those of a bee or dragonfly. This shows that sophisticated eyes already existed at the beginning of the fossil record of higher organisms, while the differences between the ancient system and the internal structures of a modern apposition compound eye open important insights into the evolution of vision.
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17
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Gorzelak P, Rahman IA, Zamora S, Gąsiński A, Trzciński J, Brachaniec T, Salamon MA. Towards a Better Understanding of the Origins of Microlens Arrays in Mesozoic Ophiuroids and Asteroids. Evol Biol 2017. [DOI: 10.1007/s11692-017-9411-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Rust J, Bergmann A, Bartels C, Schoenemann B, Sedlmeier S, Kühl G. The Hunsrück biota: A unique window into the ecology of Lower Devonian arthropods. ARTHROPOD STRUCTURE & DEVELOPMENT 2016; 45:140-151. [PMID: 26826500 DOI: 10.1016/j.asd.2016.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 01/11/2016] [Indexed: 06/05/2023]
Abstract
The approximately 400-million-year old Hunsrück biota provides a unique window into Devonian marine life. Fossil evidence suggests that this biota was dominated by echinoderms and various classes of arthropods, including Trilobita, stem lineage representatives of Euarthropoda, Chelicerata and Eucrustacea, as well as several crown group Chelicerata and Eucrustacea. The Hunsrück biota's exceptional preservation allows detailed reconstructions and description of key-aspects of its fauna's functional morphologies thereby revealing modes of locomotion, sensory perception, and feeding strategies. Morphological and stratigraphic data are used for a critical interpretation of the likely habitats, mode of life and nutritional characteristics of this diverse fauna. Potential predators include pycnogonids and other chelicerates, as well as the now extinct stem arthropods Schinderhannes bartelsi, Cambronatus brasseli and Wingertshellicus backesi. Mainly the deposit feeding Trilobita, Marrellomorpha and Megacheira, such as Bundenbachiellus giganteus, represents scavengers. Possibly, opportunistic scavenging was also performed by the afore-mentioned predators. Most of the studied arthropods appear to have been adapted to living in relatively well-illuminated conditions within the photic zone. Fossil evidence for associations amongst arthropods and other classes of metazoans is reported. These associations provide evidence of likely community structures.
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Affiliation(s)
- Jes Rust
- Steinmann Institute for Geology, Mineralogy and Palaeontology, Division of Palaeontology, Nussallee 8, 53639 Bonn, Germany.
| | - Alexandra Bergmann
- Steinmann Institute for Geology, Mineralogy and Palaeontology, Division of Palaeontology, Nussallee 8, 53639 Bonn, Germany.
| | | | | | - Stephanie Sedlmeier
- Steinmann Institute for Geology, Mineralogy and Palaeontology, Division of Palaeontology, Nussallee 8, 53639 Bonn, Germany
| | - Gabriele Kühl
- Steinmann Institute for Geology, Mineralogy and Palaeontology, Division of Palaeontology, Nussallee 8, 53639 Bonn, Germany.
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Strausfeld NJ, Ma X, Edgecombe GD, Fortey RA, Land MF, Liu Y, Cong P, Hou X. Arthropod eyes: The early Cambrian fossil record and divergent evolution of visual systems. ARTHROPOD STRUCTURE & DEVELOPMENT 2016; 45:152-172. [PMID: 26276096 DOI: 10.1016/j.asd.2015.07.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 07/28/2015] [Accepted: 07/31/2015] [Indexed: 05/14/2023]
Abstract
Four types of eyes serve the visual neuropils of extant arthropods: compound retinas composed of adjacent facets; a visual surface populated by spaced eyelets; a smooth transparent cuticle providing inwardly directed lens cylinders; and single-lens eyes. The first type is a characteristic of pancrustaceans, the eyes of which comprise lenses arranged as hexagonal or rectilinear arrays, each lens crowning 8-9 photoreceptor neurons. Except for Scutigeromorpha, the second type typifies Myriapoda whose relatively large eyelets surmount numerous photoreceptive rhabdoms stacked together as tiers. Scutigeromorph eyes are facetted, each lens crowning some dozen photoreceptor neurons of a modified apposition-type eye. Extant chelicerate eyes are single-lensed except in xiphosurans, whose lateral eyes comprise a cuticle with a smooth outer surface and an inner one providing regular arrays of lens cylinders. This account discusses whether these disparate eye types speak for or against divergence from one ancestral eye type. Previous considerations of eye evolution, focusing on the eyes of trilobites and on facet proliferation in xiphosurans and myriapods, have proposed that the mode of development of eyes in those taxa is distinct from that of pancrustaceans and is the plesiomorphic condition from which facetted eyes have evolved. But the recent discovery of enormous regularly facetted compound eyes belonging to early Cambrian radiodontans suggests that high-resolution facetted eyes with superior optics may be the ground pattern organization for arthropods, predating the evolution of arthrodization and jointed post-protocerebral appendages. Here we provide evidence that compound eye organization in stem-group euarthropods of the Cambrian can be understood in terms of eye morphologies diverging from this ancestral radiodontan-type ground pattern. We show that in certain Cambrian groups apposition eyes relate to fixed or mobile eyestalks, whereas other groups reveal concomitant evolution of sessile eyes equipped with optics typical of extant xiphosurans. Observations of fossil material, including that of trilobites and eurypterids, support the proposition that the ancestral compound eye was the apposition type. Cambrian arthropods include possible precursors of mandibulate eyes. The latter are the modified compound eyes, now sessile, and their underlying optic lobes exemplified by scutigeromorph chilopods, and the mobile stalked compound eyes and more elaborate optic lobes typifying Pancrustacea. Radical divergence from an ancestral apposition type is demonstrated by the evolution of chelicerate eyes, from doublet sessile-eyed stem-group taxa to special apposition eyes of xiphosurans, the compound eyes of eurypterids, and single-lens eyes of arachnids. Different eye types are discussed with respect to possible modes of life of the extinct species that possessed them, comparing these to extant counterparts and the types of visual centers the eyes might have served.
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Affiliation(s)
- Nicholas J Strausfeld
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China; Department of Neuroscience and Center for Insect Science, University of Arizona, Tucson, AZ 85721, USA.
| | - Xiaoya Ma
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China; Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK.
| | - Gregory D Edgecombe
- Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Richard A Fortey
- Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Michael F Land
- School of Life Science, University of Sussex, John Maynard Smith Building, Falmer, Brighton BN1 9QG, UK
| | - Yu Liu
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China; Developmental Neurobiology, Biozentrum der LMU, Munich, Germany
| | - Peiyun Cong
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China
| | - Xianguang Hou
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China.
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20
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Abstract
The fossil record offers unique insights into the environmental and geographic partitioning of biodiversity during global diversifications. We explored biodiversity patterns during the Cambrian radiation, the most dramatic radiation in Earth history. We assessed how the overall increase in global diversity was partitioned between within-community (alpha) and between-community (beta) components and how beta diversity was partitioned among environments and geographic regions. Changes in gamma diversity in the Cambrian were chiefly driven by changes in beta diversity. The combined trajectories of alpha and beta diversity during the initial diversification suggest low competition and high predation within communities. Beta diversity has similar trajectories both among environments and geographic regions, but turnover between adjacent paleocontinents was probably the main driver of diversification. Our study elucidates that global biodiversity during the Cambrian radiation was driven by niche contraction at local scales and vicariance at continental scales. The latter supports previous arguments for the importance of plate tectonics in the Cambrian radiation, namely the breakup of Pannotia.
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21
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Gorzelak P, Salamon MA, Lach R, Loba M, Ferré B. Microlens arrays in the complex visual system of Cretaceous echinoderms. Nat Commun 2014; 5:3576. [PMID: 24691465 DOI: 10.1038/ncomms4576] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 03/06/2014] [Indexed: 11/09/2022] Open
Abstract
It has long been assumed that photosensitivity in echinoderms is mainly related to diffuse photoreception mediated by photosensitive regions embedded within the dermis. Recent studies, however, have shown that some extant echinoderms may also display modified ossicles with microlenses acting as sophisticated photosensory organs. Thanks to their remarkable properties, these calcitic microlenses serve as an inspiration for scientists across various disciplines among which bio-inspired engineering. However, the evolutionary origins of these microlenses remain obscure. Here we provide microstructural evidence showing that analogous spherical calcitic lenses had been acquired in some brittle stars and starfish of Poland by the Late Cretaceous (Campanian, ~79 Ma). Specimens from Poland described here had a highly developed visual system similar to that of modern forms. We suggest that such an optimization of echinoderm skeletons for both mechanical and optical purposes reflects escalation-related adaptation to increased predation pressure during the so-called Mesozoic Marine Revolution.
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Affiliation(s)
- Przemysław Gorzelak
- Department of Biogeology, Institute of Paleobiology, Polish Academy of Sciences, Twarda Street 51/55, 00-818 Warsaw, Poland
| | - Mariusz A Salamon
- Department of Palaeontology and Biostratigraphy, Faculty of Earth Sciences, University of Silesia, Będzińska Street 60, 41-200 Sosnowiec, Poland
| | - Rafał Lach
- Department of Palaeontology and Biostratigraphy, Faculty of Earth Sciences, University of Silesia, Będzińska Street 60, 41-200 Sosnowiec, Poland
| | - Michał Loba
- Faculty of Geology, University of Warsaw, Żwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Bruno Ferré
- Dame du Lac 213, 3 rue Henri Barbusse, F-76300 Sotteville-lès-Rouen, France
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