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Mángano MG, Buatois LA. The rise and early evolution of animals: where do we stand from a trace-fossil perspective? Interface Focus 2020; 10:20190103. [PMID: 32642049 DOI: 10.1098/rsfs.2019.0103] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2020] [Indexed: 01/10/2023] Open
Abstract
The trace-fossil record provides a wealth of information to track the rise and early evolution of animals. It comprises the activity of both hard- and soft-bodied organisms, is continuous through the Ediacaran (635-539 Ma)- Cambrian (539-485 Ma) transition, yields insights into animal behaviour and their role as ecosystem engineers, and allows for a more refined characterization of palaeoenvironmental context. In order to unravel macroevolutionary signals from the trace-fossil record, a variety of approaches is available, including not only estimation of degree of bioturbation, but also analysis of ichnodiversity and ichnodisparity trajectories, and evaluation of the occupation of infaunal ecospace and styles of ecosystem engineering. Analysis of the trace-fossil record demonstrates the presence of motile benthic bilaterians in the Ediacaran, mostly feeding from biofilms. Although Ediacaran trace fossils are simple and emplaced at or immediately below the sediment surface, an increase in ichnofossil complexity, predation pressure, sediment disturbance and penetration depth is apparent during the terminal Ediacaran. Regardless of this increase, a dramatic rise in trace fossil diversity and disparity took place during the earliest Cambrian, underscoring that the novelty of the Fortunian (539-529 Ma) cannot be underestimated. The Fortunian still shows the persistence of an Ediacaran-style matground ecology, but is fundamentally characterized by the appearance of new trace-fossil architectural plans reflecting novel ways of interacting with the substrate. The appearance of Phanerozoic-style benthic ecosystems attests to an increased length and connectivity of the food web and improved efficiency in organic carbon transfer and nutrient recycling. A profound reorganization of the infaunal ecospace is recorded in both high-energy sand-dominated nearshore areas and low-energy mud-dominated offshore environments, during the early Cambrian, starting approximately during Cambrian Age 2 (529-521 Ma), but continuing during the rest of the early Cambrian. A model comprising four evolutionary phases is proposed to synthetize information from the Ediacaran-Cambrian trace-fossil record. The use of a rich ichnological toolbox; critical, systematic and comprehensive evaluation of the Ediacaran-Cambrian trace-fossil record; and high-resolution integration of the ichnological dataset and sedimentological information show that the advent of biogenic mixing was an important factor in fully marine environments at the dawn of the Phanerozoic.
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Affiliation(s)
- M Gabriela Mángano
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, Canada S7N 5E2
| | - Luis A Buatois
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, Canada S7N 5E2
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Zachos LG, Platt BF. Actuopaleoichnology of a modern Bay of Fundy macro-tidal flat: analogy with a Mississippian tidal flat deposit (Hartselle Sandstone) from Alabama. PeerJ 2019; 7:e6975. [PMID: 31149409 PMCID: PMC6534113 DOI: 10.7717/peerj.6975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 04/17/2019] [Indexed: 11/20/2022] Open
Abstract
Trace fossil zonation in the Hartselle Sandstone of Mississippian age (Chesterian: Visean-Serpukhovian) exposed on Fielder Ridge, Alabama is compared with modern macro-tidal flat ichnocoenoses on the Bay of Fundy at Lubec, Maine, and demonstrated to be analogous by sedimentologic and ichnotaxonomic criteria. The modern flat has minimal influence from either waves or freshwater influx, and can be divided into five distinct ichnocoenoses, characterized by surface traces (epichnia) and four sedimentologic facies defined by gross grain texture or hydrodynamic characteristics, but lacking significant surface traces. Several characteristics of tidal flat deposits in a fetch-limited, marine (i.e., non-estuarine), meso- to macro-tidal regime can be used to recognize similar environments as old as the late Paleozoic. These criteria include (1) limited influence of wind and waves on the depositional environment, (2) lack of significant freshwater influence and therefore any persistent brackish environments, (3) a distinct spatial distribution of microenvironments defined by substrate and exposure period, (4) high diversity of epichnial traces directly associated with microenvironments across the tidal flat, (5) generally low degree of reworking of traces by bioturbation but high degree of reworking by tidal currents, and (6) preservation of traces of predation and scavenging behavior on an exposed surface. These features, together with the regional depositional pattern of the Hartselle Sandstone interpreted as tide-influenced bars and shoals, support a meso- to macro-tidal interpretation of the depositional environment.
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Affiliation(s)
- Louis G Zachos
- Institut für Evolutionsbiologie und Ökologie, Rheinische Friedrich-Wilhelms Universität Bonn, Bonn, Germany.,Department of Geology & Geological Engineering, University of Mississippi, University, MS, USA.,Center for Biodiversity & Conservation Research, University of Mississippi, University, MS, USA
| | - Brian F Platt
- Department of Geology & Geological Engineering, University of Mississippi, University, MS, USA.,Center for Biodiversity & Conservation Research, University of Mississippi, University, MS, USA
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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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Mángano MG, Hawkes CD, Caron JB. Trace fossils associated with Burgess Shale non-biomineralized carapaces: bringing taphonomic and ecological controls into focus. ROYAL SOCIETY OPEN SCIENCE 2019; 6:172074. [PMID: 30800334 PMCID: PMC6366168 DOI: 10.1098/rsos.172074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 12/17/2018] [Indexed: 06/09/2023]
Abstract
The association of trace fossils and non-biomineralized carapaces has been reported from Cambrian Lagerstätten worldwide, but the abundance, ichnodiversity, taphonomy and ecological significance of such associations have yet to be fully investigated. Two main end-member hypotheses are explored based on the study of a relatively wide variety of trace fossils preserved associated to Tuzoia carapaces from the middle Cambrian Burgess Shale in British Columbia. In the ecological Tuzoia garden hypothesis, the bacterially enriched surface of carapaces provides opportunities for intricate ecologic interactions among trophic levels. In the taphonomic shielding hypothesis, the trace fossil-carapace association results from preferential preservation of traces as controlled by compaction independent of any association in life. In an attempt to better understand the role of the carapace as a medium for preservation of trace fossils and to evaluate the effects of mechanical stress related to burial, a numerical model was developed. Results indicate that the carapace can shield underlying sediment from mechanical stress for a finite time, differentially protecting trace fossils during the initial phase of burial and compaction. However, this taphonomic model alone fails to fully explain relatively high-density assemblages displaying a diversity of structures spatially confined within the perimeter of carapaces or branching patterns recording re-visitation.
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Affiliation(s)
- M. Gabriela Mángano
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Christopher David Hawkes
- Department of Civil, Geological and Environmental Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9, Canada
| | - Jean-Bernard Caron
- Department of Natural History-Palaeobiology, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada
- Department of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1, Canada
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Haug JT, Caron JB, Haug C. Demecology in the Cambrian: synchronized molting in arthropods from the Burgess Shale. BMC Biol 2013; 11:64. [PMID: 23721223 PMCID: PMC3685569 DOI: 10.1186/1741-7007-11-64] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 05/10/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Burgess Shale is well known for its preservation of a diverse soft-bodied biota dating from the Cambrian period (Series 3, Stage 5). While previous paleoecological studies have focused on particular species (autecology) or entire paleocommunities (synecology), studies on the ecology of populations (demecology) of Burgess Shale organisms have remained mainly anecdotal. RESULTS Here, we present evidence for mass molting events in two unrelated arthropods from the Burgess Shale Walcott Quarry, Canadaspis perfecta and a megacheiran referred to as Alalcomenaeus sp. CONCLUSIONS These findings suggest that the triggers for such supposed synchronized molting appeared early on during the Cambrian radiation, and synchronized molting in the Cambrian may have had similar functions in the past as it does today. In addition, the finding of numerous juvenile Alalcomenaeus sp. molts associated with the putative alga Dictyophycus suggests a possible nursery habitat. In this nursery habitat a population of this animal might have found a more protected environment in which to spend critical developmental phases, as do many modern species today.
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Affiliation(s)
- Joachim T Haug
- Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, Soldmannstrasse 23, 17487 Greifswald, Germany.
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Stein M, Budd GE, Peel JS, Harper DAT. Arthroaspis n. gen., a common element of the Sirius Passet Lagerstätte (Cambrian, North Greenland), sheds light on trilobite ancestry. BMC Evol Biol 2013; 13:99. [PMID: 23663519 PMCID: PMC3662621 DOI: 10.1186/1471-2148-13-99] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 04/29/2013] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Exceptionally preserved Palaeozoic faunas have yielded a plethora of trilobite-like arthropods, often referred to as lamellipedians. Among these, Artiopoda is supposed to contain taxa united by a distinctive appendage structure. This includes several well supported groups, Helmetiida, Nektaspida, and Trilobita, as well as a number of problematic taxa. Interrelationships remain unclear, and the position of the lamellipedian arthropods as a whole also remains the subject of debate. RESULTS Arthroaspis bergstroemi n. gen. n. sp., a new arthropod from the early Cambrian Sirius Passet Lagerstätte of North Greenland shows a striking combination of both dorsal and ventral characters of Helmetiida, Nektaspida, and Trilobita. Cladistic analysis with a broad taxon sampling of predominantly early Palaeozoic arthropods yields a monophyletic Lamellipedia as sister taxon to the Crustacea or Tetraconata. Artiopoda is resolved as paraphyletic, giving rise to the Marrellomorpha. Within Lamellipedia, a clade of pygidium bearing taxa is resolved that can be shown to have a broadly helmetiid-like tergite morphology in its ground pattern. This morphology is plesiomorphically retained in Helmetiida and in Arthroaspis, which falls basally into a clade containing Trilobita. The trilobite appendages, though similar to those of other lamellipedians in gross morphology, have a unique outward rotation of the anterior trunk appendages, resulting in a 'hard wired' lateral splay, different to that observed in other Lamellipedia. CONCLUSIONS The combination of helmetiid, trilobite, and nektaspid characters in Arthroaspis gives important hints concerning character polarisation within the trilobite-like arthropods. The distinctive tergite morphology of trilobites, with its sophisticated articulating devices, is derived from flanged edge-to-edge articulating tergites forming a shield similar to the helmetiids, previously considered autapomorphic for that group. The stereotypical lateral splay of the appendages of lamellipedians is a homoplastic character shown to be achieved by several groups independently.
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Affiliation(s)
- Martin Stein
- Natural History Museum of Denmark, Universitetsparken 15, DK-2100 Copenhagen, Denmark
| | - Graham E Budd
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, SE 752 36 Uppsala, Sweden
| | - John S Peel
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, SE 752 36 Uppsala, Sweden
| | - David AT Harper
- Department of Earth Sciences, Durham University, Science Labs, Durham DH1 3LE, UK
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Vannier J. Gut contents as direct indicators for trophic relationships in the Cambrian marine ecosystem. PLoS One 2012; 7:e52200. [PMID: 23300612 PMCID: PMC3530608 DOI: 10.1371/journal.pone.0052200] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Accepted: 11/12/2012] [Indexed: 11/30/2022] Open
Abstract
Present-day ecosystems host a huge variety of organisms that interact and transfer mass and energy via a cascade of trophic levels. When and how this complex machinery was established remains largely unknown. Although exceptionally preserved biotas clearly show that Early Cambrian animals had already acquired functionalities that enabled them to exploit a wide range of food resources, there is scant direct evidence concerning their diet and exact trophic relationships. Here I describe the gut contents of Ottoia prolifica, an abundant priapulid worm from the middle Cambrian (Stage 5) Burgess Shale biota. I identify the undigested exoskeletal remains of a wide range of small invertebrates that lived at or near the water sediment interface such as hyolithids, brachiopods, different types of arthropods, polychaetes and wiwaxiids. This set of direct fossil evidence allows the first detailed reconstruction of the diet of a 505-million-year-old animal. Ottoia was a dietary generalist and had no strict feeding regime. It fed on both living individuals and decaying organic matter present in its habitat. The feeding behavior of Ottoia was remarkably simple, reduced to the transit of food through an eversible pharynx and a tubular gut with limited physical breakdown and no storage. The recognition of generalist feeding strategies, exemplified by Ottoia, reveals key-aspects of modern-style trophic complexity in the immediate aftermath of the Cambrian explosion. It also shows that the middle Cambrian ecosystem was already too complex to be understood in terms of simple linear dynamics and unique pathways.
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Affiliation(s)
- Jean Vannier
- Laboratoire de géologie de Lyon, Terre, Planètes, Environnement, Université de Lyon, Université Lyon 1, Villeurbanne, France.
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