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Liu C, Fu D, Wu Y, Zhang X. Cambrian euarthropod Urokodia aequalis sheds light on the origin of Artiopoda body plan. iScience 2024; 27:110443. [PMID: 39148713 PMCID: PMC11325232 DOI: 10.1016/j.isci.2024.110443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 05/22/2024] [Accepted: 07/01/2024] [Indexed: 08/17/2024] Open
Abstract
The origin and evolution of trilobated body plan of the Artiopoda, a group of epibenthic euarthropods from Cambrian Lagerstätten, remain unclear. Here we examine old and new specimens of Urokodia aequalis, one of euarthropods from the Chengjiang biota, revealing new morphological details and revising its taxonomy. Urokodia possesses an elongate body with a five-segmented head, a thorax with 13-15 tergites, and a three-segmented pygidium with well-defined axial region. The ventral morphology includes paired stalked eyes, one fleshy antenna pair, the following homogeneous head and thoracic appendages, each with an annular proximal-element, an articulated stenopodous branch and a lamellar flap, and the pygidial appendages solely consisting of lamellar flaps. Cladistic analyses resolved Urokodia as the basal-most member of the Artiopoda, offering a hypothesis of the initial origin of trilobation in the pygidium. The new data, in conjunction with the presence of the elongated body plan across major lineages of euarthropods, suggest a convergent evolution of this trait.
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Affiliation(s)
- Cong Liu
- State Key Laboratory of the Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi'an 710069, China
| | - Dongjing Fu
- State Key Laboratory of the Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi'an 710069, China
| | - Yu Wu
- State Key Laboratory of the Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi'an 710069, China
| | - Xingliang Zhang
- State Key Laboratory of the Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi'an 710069, China
- Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing 210008, China
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2
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Jin C, Chen H, Mai H, Hou X, Yang X, Zhai D. Discovery of diverse Pectocaris species at the Cambrian series 2 Hongjingshao formation Xiazhuang section (Kunming, SW China) and its ecological, taphonomic, and biostratigraphic implications. PeerJ 2024; 12:e17230. [PMID: 38638159 PMCID: PMC11025544 DOI: 10.7717/peerj.17230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/21/2024] [Indexed: 04/20/2024] Open
Abstract
Pectocaris species are intermediate- to large-sized Cambrian bivalved arthropods. Previous studies have documented Pectocaris exclusively from the Cambrian Series 2 Stage 3 Chengjiang biota in Yu'anshan Formation, Chiungchussu Stage in SW China. In this study, we report Pectocaris paraspatiosa sp. nov., and three other previously known Pectocaris from the Xiazhuang section in Kunming, which belongs to the Hongjingshao Formation and is a later phase within Cambrian Stage 3 than the Yu'anshan Formation. The new species can be distinguished from its congeners by the sparsely arranged endopodal endites and the morphologies of the abdomen, telson, and telson processes. We interpret P. paraspatiosa sp. nov. as a filter-feeder and a powerful swimmer adapted to shallow, agitated environments. Comparison among the Pectocaris species reinforces previous views that niche differentiation had been established among the congeneric species based on morphological differentiation. Our study shows the comprehensive occurrences of Pectocaris species outside the Chengjiang biota for the first time. With a review of the shared fossil taxa of Chengjiang and Xiaoshiba biotas, we identify a strong biological connection between the Yu'anshan and Hongjingshao Formations.
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Affiliation(s)
- Changfei Jin
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
| | - Hong Chen
- School of Biological Sciences and Technology, Liupanshui Normal University, Liupanshui, China
| | - Huijuan Mai
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
| | - Xianguang Hou
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
| | - Xianfeng Yang
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
| | - Dayou Zhai
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
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3
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Zhang C, Liu Y, Ortega-Hernández J, Wolfe JM, Jin C, Mai H, Hou X, Guo J, Zhai D. Three-dimensional morphology of the biramous appendages in Isoxys from the early Cambrian of South China, and its implications for early euarthropod evolution. Proc Biol Sci 2023; 290:20230335. [PMID: 37072042 PMCID: PMC10113025 DOI: 10.1098/rspb.2023.0335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023] Open
Abstract
Early euarthropod evolution involved a major transition from lobopodian-like taxa to organisms featuring a segmented, well-sclerotized trunk (arthrodization) and limbs (arthropodization). However, the precise origin of a completely arthrodized trunk and arthropodized ventral biramous appendages remain controversial, as well as the early onset of anterior-posterior limb differentiation in stem-group euarthropods. New fossil material and micro-computed tomography inform the detailed morphology of the arthropodized biramous appendages in the carapace-bearing euarthropod Isoxys curvirostratus from the early Cambrian Chengjiang biota. In addition to well-developed grasping frontal appendages, I. curvirostratus possesses two batches of morphologically and functionally distinct biramous limbs. The first batch consists of four pairs of short cephalic appendages with robust endites with a feeding function, whereas the second batch has more elongate trunk appendages for locomotion. Critically, our new material shows that the trunk of I. curvirostratus was not arthrodized. The results of our phylogenetic analyses recover isoxyids as some of the earliest branching sclerotized euarthropods, and strengthens the hypothesis that arthropodized biramous appendages evolved before full body arthrodization.
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Affiliation(s)
- Caixia Zhang
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming 650091, People's Republic of China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Waihuan South Road, Chenggong District, Kunming 650500, People's Republic of China
| | - Yu Liu
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming 650091, People's Republic of China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Waihuan South Road, Chenggong District, Kunming 650500, People's Republic of China
- Management Committee of the Chengjiang Fossil Site World Heritage, Chengjiang 652599, People's Republic of China
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Joanna M Wolfe
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Changfei Jin
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming 650091, People's Republic of China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Waihuan South Road, Chenggong District, Kunming 650500, People's Republic of China
| | - Huijuan Mai
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming 650091, People's Republic of China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Waihuan South Road, Chenggong District, Kunming 650500, People's Republic of China
| | - Xianguang Hou
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming 650091, People's Republic of China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Waihuan South Road, Chenggong District, Kunming 650500, People's Republic of China
| | - Jin Guo
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming 650091, People's Republic of China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Waihuan South Road, Chenggong District, Kunming 650500, People's Republic of China
- Management Committee of the Chengjiang Fossil Site World Heritage, Chengjiang 652599, People's Republic of China
| | - Dayou Zhai
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming 650091, People's Republic of China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Waihuan South Road, Chenggong District, Kunming 650500, People's Republic of China
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Izquierdo-López A, Caron JB. The problematic Cambrian arthropod Tuzoia and the origin of mandibulates revisited. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220933. [PMID: 36483757 PMCID: PMC9727825 DOI: 10.1098/rsos.220933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Accepted: 11/10/2022] [Indexed: 06/17/2023]
Abstract
The origin of mandibulates, the hyperdiverse arthropod group that includes pancrustaceans and myriapods, dates back to the Cambrian. Bivalved arthropod groups such as hymenocarines have been argued to be early mandibulates, but many species are still poorly known, and their affinities remain uncertain. One of the most common and globally distributed Cambrian bivalved arthropods is Tuzoia. Originally described in 1912 from the Burgess Shale based on isolated carapaces, its full anatomy has remained largely unknown. Here, we describe new specimens of Tuzoia from the Canadian Burgess Shale (Wuliuan, Cambrian) showcasing exceptionally preserved soft tissues, allowing for the first comprehensive reconstruction of its anatomy, ecology and evolutionary affinities. The head bears antennae and differentiated cephalic appendages. The body is divided into a cephalothorax, a homonomous trunk bearing ca 10 pairs of legs with heptopodomerous endopods and enlarged basipods, and a tail fan with two pairs of caudal rami. These traits suggest that Tuzoia swam along the seafloor and used its spinose legs for predation or scavenging. Tuzoia is retrieved by a Bayesian phylogenetic analysis as an early mandibulate hymenocarine lineage, exemplifying the rapid diversification of this group in open marine environments during the Cambrian Explosion.
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Affiliation(s)
- Alejandro Izquierdo-López
- Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
- Royal Ontario Museum, Toronto, Ontario, Canada, M5S 2C6
| | - Jean-Bernard Caron
- Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
- Earth Sciences, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
- Royal Ontario Museum, Toronto, Ontario, Canada, M5S 2C6
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5
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Holmes JD, Budd GE. Reassessing a cryptic history of early trilobite evolution. Commun Biol 2022; 5:1177. [PMCID: PMC9636250 DOI: 10.1038/s42003-022-04146-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022] Open
Abstract
Trilobites are an iconic Paleozoic group of biomineralizing marine euarthropods that appear abruptly in the fossil record (c. 521 million years ago) during the Cambrian ‘explosion’. This sudden appearance has proven controversial ever since Darwin puzzled over the lack of pre-trilobitic fossils in the Origin of Species, and it has generally been assumed that trilobites must have an unobserved cryptic evolutionary history reaching back into the Precambrian. Here we review the assumptions behind this model, and suggest that a cryptic history creates significant difficulties, including the invocation of rampant convergent evolution of biomineralized structures and the abandonment of the synapomorphies uniting the clade. We show that a vicariance explanation for early Cambrian trilobite palaeobiogeographic patterns is inconsistent with factors controlling extant marine invertebrate distributions, including the increasingly-recognized importance of long-distance dispersal. We suggest that survivorship bias may explain the initial rapid diversification of trilobites, and conclude that the group’s appearance at c. 521 Ma closely reflects their evolutionary origins. A reassessment of early trilobite phylogenetic relationships and palaeobiogeographic patterns suggests that a cryptic evolutionary history is unlikely for this group. The abrupt appearance of trilobites is likely to closely reflect their evolutionary origins, and may be explained by survivorship biases inherent in the fossil record.
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Affiliation(s)
- James D. Holmes
- grid.8993.b0000 0004 1936 9457Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, Uppsala, 752 36 Sweden
| | - Graham E. Budd
- grid.8993.b0000 0004 1936 9457Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, Uppsala, 752 36 Sweden
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6
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Functional importance of the mandibular skeleto-muscular system in the bivalved arthropod Heterocypris incongruens (Crustacea, Ostracoda, Cyprididae). Naturwissenschaften 2022; 109:37. [DOI: 10.1007/s00114-022-01806-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/09/2022] [Accepted: 06/20/2022] [Indexed: 11/27/2022]
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7
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Aria C. The origin and early evolution of arthropods. Biol Rev Camb Philos Soc 2022; 97:1786-1809. [PMID: 35475316 DOI: 10.1111/brv.12864] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 04/12/2022] [Accepted: 04/14/2022] [Indexed: 12/18/2022]
Abstract
The rise of arthropods is a decisive event in the history of life. Likely the first animals to have established themselves on land and in the air, arthropods have pervaded nearly all ecosystems and have become pillars of the planet's ecological networks. Forerunners of this saga, exceptionally well-preserved Palaeozoic fossils recently discovered or re-discovered using new approaches and techniques have elucidated the precocious appearance of extant lineages at the onset of the Cambrian explosion, and pointed to the critical role of the plankton and hard integuments in early arthropod diversification. The notion put forward at the beginning of the century that the acquisition of extant arthropod characters was stepwise and represented by the majority of Cambrian fossil taxa is being rewritten. Although some key traits leading to Euarthropoda are indeed well documented along a diversified phylogenetic stem, this stem led to several speciose and ecologically diverse radiations leaving descendants late into the Palaeozoic, and a large part, if not all of the Cambrian euarthropods can now be placed on either of the two extant lineages: Mandibulata and Chelicerata. These new observations and discoveries have altered our view on the nature and timing of the Cambrian explosion and clarified diagnostic characters at the origin of extant arthropods, but also raised new questions, especially with respect to cephalic plasticity. There is now strong evidence that early arthropods shared a homologous frontalmost appendage, coined here the cheira, which likely evolved into antennules and chelicerae, but other aspects, such as brain and labrum evolution, are still subject to active debate. The early evolution of panarthropods was generally driven by increased mastication and predation efficiency and sophistication, but a wealth of recent studies have also highlighted the prevalent role of suspension-feeding, for which early panarthropods developed their own adaptive feedback through both specialized appendages and the diversification of small, morphologically differentiated larvae. In a context of general integumental differentiation and hardening across Cambrian metazoans, arthrodization of body and limbs notably prompted two diverging strategies of basipod differentiation, which arguably became founding criteria in the divergence of total-groups Mandibulata and Chelicerata. The kinship of trilobites and their relatives remains a source of disagreement, but a recent topological solution, termed the 'deep split', could embed Artiopoda as sister taxa to chelicerates and constitute definitive support for Arachnomorpha. Although Cambrian fossils have been critical to all these findings, data of exceptional quality have also been accumulating from other Palaeozoic Konservat-Lagerstätten, and a better integration of this information promises a much more complete and elaborate picture of early arthropod evolution in the near future. From the broader perspective of a total-evidence approach to the understanding of life's history, and despite persisting systematic debates and new interpretative challenges, various advances based on palaeontological evidence open the prospect of finally using the full potential of the most diverse animal phylum to investigate macroevolutionary patterns and processes.
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Affiliation(s)
- Cédric Aria
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing, 210008, P. R. China.,Shaanxi Key Laboratory of Early Life and Environments, Northwest University, Xi'an, 710069, P.R. China
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8
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Fu D, Legg DA, Daley AC, Budd GE, Wu Y, Zhang X. The evolution of biramous appendages revealed by a carapace-bearing Cambrian arthropod. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210034. [PMID: 35125000 PMCID: PMC8819368 DOI: 10.1098/rstb.2021.0034] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Biramous appendages are a common feature among modern marine arthropods that evolved deep in arthropod phylogeny. The branched appendage of Cambrian arthropods has long been considered as the ancient biramous limb, sparking numerous investigations on its origin and evolution. Here, we report a new arthropod, Erratus sperare gen. et sp. nov., from the Lower Cambrian (Stage 3, 520 Ma) Chengjiang biota of Yunnan, China, with unique trunk appendages formed of lateral anomalocaridid-type flaps and ventral subconical endopods. These appendages represent an intermediate stage of biramous limb evolution, i.e. from 'two pairs of flap appendages' in radiodonts to 'flap + endopod' in Erratus, to 'exopod + endopod' in the rest of carapace-bearing arthropods that populate the basal region of the upper-stem lineage arthropods (deuteropods). The new species occupies a phylogenetic position at the first node closer to deuteropods than to radiodonts, and therefore pinpoints the earliest occurrence of the endopod within Deuteropoda. The primitive endopod is weakly sclerotized, and has unspecialized segments without endites or claw. The findings might support previous claims that the outer branch of the biramous limb of fossil marine arthropods, such as trilobites, is not a true exopod, but is instead a modified exite. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.
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Affiliation(s)
- Dongjing Fu
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xian 710069, People's Republic of China
| | - David A Legg
- Department of Earth, Atmospheric, and Environmental Sciences, University of Manchester, Manchester, UK
| | - Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Geopolis, Lausanne 1015, Switzerland
| | - Graham E Budd
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, Uppsala 752 36, Sweden
| | - Yu Wu
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xian 710069, People's Republic of China
| | - Xingliang Zhang
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xian 710069, People's Republic of China
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9
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Jiao DG, Pates S, Lerosey-Aubril R, Ortega-Hernández J, Yang J, Lan T, Zhang XG. New multipodomerous appendages of stem-group euarthropods from the Cambrian (Stage 4) Guanshan Konservat-Lagerstätte. ROYAL SOCIETY OPEN SCIENCE 2021; 8:211134. [PMID: 34804574 PMCID: PMC8580442 DOI: 10.1098/rsos.211134] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 10/04/2021] [Indexed: 05/13/2023]
Abstract
Stem-group euarthropods are important for understanding the early evolutionary and ecological history of the most species-rich animal phylum on Earth. Of particular interest are fossil taxa that occupy a phylogenetic position immediately crownwards of radiodonts, for this part of the euarthropod tree is associated with the appearance of several morphological features that characterize extant members of the group. Here, we report two new euarthropods from the Cambrian Stage 4 Guanshan Biota of South China. The fuxianhuiid Alacaris? sp. is represented by isolated appendages composed of a gnathobasic protopodite and an endite-bearing endopod of at least 20 podomeres. This material represents the youngest occurrence of the family Chengjiangocarididae, and its first record outside the Chengjiang and Xiaoshiba biotas. We also describe Lihuacaris ferox gen. et sp. nov. based on well-preserved and robust isolated appendages. Lihuacaris ferox exhibits an atypical combination of characters including an enlarged rectangular base, 11 endite-bearing podomeres and a hypertrophied distal element bearing 8-10 curved spines. Alacaris? sp. appendages display adaptations for macrophagy. Lihuacaris ferox appendages resemble the frontal appendages of radiodonts, as well as the post-oral endopods of chengjiangocaridid fuxianhuids and other deuteropods with well-documented raptorial/predatory habits. Lihuacaris ferox contributes towards the record of endemic biodiversity in the Guanshan Biota.
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Affiliation(s)
- De-guang Jiao
- Yuxi Normal University, Kunming, 134 Phoenix Road, Yuxi, Yunnan 653100, People's Republic of China
- Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, People's Republic of China
| | - Stephen Pates
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Rudy Lerosey-Aubril
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Jie Yang
- Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, People's Republic of China
| | - Tian Lan
- College of Resources and Environmental Engineering, Guizhou University, Guiyang 550003, People's Republic of China
| | - Xi-guang Zhang
- Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, People's Republic of China
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10
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Strausfeld NJ, Olea-Rowe B. Convergent evolution of optic lobe neuropil in Pancrustacea. ARTHROPOD STRUCTURE & DEVELOPMENT 2021; 61:101040. [PMID: 33706077 DOI: 10.1016/j.asd.2021.101040] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 06/12/2023]
Abstract
A prevailing opinion since 1926 has been that optic lobe organization in malacostracan crustaceans and insects reflects a corresponding organization in their common ancestor. Support for this refers to malacostracans and insects both possessing three, in some instances four, nested retinotopic neuropils beneath their compound eyes. Historically, the rationale for claiming homology of malacostracan and insect optic lobes referred to those commonalities, and to comparable arrangements of neurons. However, recent molecular phylogenetics has firmly established that Malacostraca belong to Multicrustacea, whereas Hexapoda and its related taxa Cephalocarida, Branchiopoda, and Remipedia belong to the phyletically distinct clade Allotriocarida. Insects are more closely related to remipedes than are either to malacostracans. Reconciling neuroanatomy with molecular phylogenies has been complicated by studies showing that the midbrains of remipedes share many attributes with the midbrains of malacostracans. Here we review the organization of the optic lobes in Malacostraca and Insecta to inquire which of their characters correspond genealogically across Pancrustacea and which characters do not. We demonstrate that neuroanatomical characters pertaining to the third optic lobe neuropil, called the lobula complex, may indicate convergent evolution. Distinctions of the malacostracan and insect lobula complexes are sufficient to align neuroanatomical descriptions of the pancrustacean optic lobes within the constraints of molecular-based phylogenies.
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11
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Bicknell RDC, Holmes JD, Edgecombe GD, Losso SR, Ortega-Hernández J, Wroe S, Paterson JR. Biomechanical analyses of Cambrian euarthropod limbs reveal their effectiveness in mastication and durophagy. Proc Biol Sci 2021; 288:20202075. [PMID: 33499790 DOI: 10.1098/rspb.2020.2075] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Durophagy arose in the Cambrian and greatly influenced the diversification of biomineralized defensive structures throughout the Phanerozoic. Spinose gnathobases on protopodites of Cambrian euarthropod limbs are considered key innovations for shell-crushing, yet few studies have demonstrated their effectiveness with biomechanical models. Here we present finite-element analysis models of two Cambrian trilobites with prominent gnathobases-Redlichia rex and Olenoides serratus-and compare these to the protopodites of the Cambrian euarthropod Sidneyia inexpectans and the modern American horseshoe crab, Limulus polyphemus. Results show that L. polyphemus, S. inexpectans and R. rex have broadly similar microstrain patterns, reflecting effective durophagous abilities. Conversely, low microstrain values across the O. serratus protopodite suggest that the elongate gnathobasic spines transferred minimal strain, implying that this species was less well-adapted to masticate hard prey. These results confirm that Cambrian euarthropods with transversely elongate protopodites bearing short, robust gnathobasic spines were likely durophages. Comparatively, taxa with shorter protopodites armed with long spines, such as O. serratus, were more likely restricted to a soft food diet. The prevalence of Cambrian gnathobase-bearing euarthropods and their various feeding specializations may have accelerated the development of complex trophic relationships within early animal ecosystems, especially the 'arms race' between predators and biomineralized prey.
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Affiliation(s)
- Russell D C Bicknell
- Palaeoscience Research Centre, School of Environmental & Rural Science University of New England, Armidale, NSW 2351, Australia.,Function, Evolution and Anatomy Research Lab, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| | - James D Holmes
- School of Biological Sciences, University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
| | - Gregory D Edgecombe
- Department of Earth Sciences, The Natural History Museum, London SW7 5BD, UK
| | - Sarah R Losso
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Stephen Wroe
- Palaeoscience Research Centre, School of Environmental & Rural Science University of New England, Armidale, NSW 2351, Australia.,Function, Evolution and Anatomy Research Lab, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| | - John R Paterson
- Palaeoscience Research Centre, School of Environmental & Rural Science University of New England, Armidale, NSW 2351, Australia
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12
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Edgecombe GD. Arthropod Origins: Integrating Paleontological and Molecular Evidence. ANNUAL REVIEW OF ECOLOGY, EVOLUTION, AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-011720-124437] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Phylogenomics underpins a stable and mostly well-resolved hypothesis for the interrelationships of extant arthropods. Exceptionally preserved fossils are integrated into this framework by coding their morphological characters, as exemplified by total-evidence dating approaches that treat fossils as dated tips in analyses numerically dominated by molecular data. Cambrian fossils inform on the sequence of character acquisition in the arthropod stem group and in the stems of its main extant clades. The arthropod head problem incorporates unique appendage combinations and remains of the nervous system in fossils into a scheme mostly based on neuroanatomy and Hox expression domains for extant forms. Molecular estimates of arthropod origins in the Cryogenian or Ediacaran predate a coherent picture from the arthropod fossil record, which commences as trace fossils in the earliest Cambrian. Probabilistic morphological clock analysis of trilobites, which exemplify the earliest arthropod body fossils, supports a Cambrian origin, without the need to posit an unfossilized Ediacaran history.
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Affiliation(s)
- Gregory D. Edgecombe
- Department of Earth Sciences, The Natural History Museum, London SW7 5BD, United Kingdom
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13
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Liu Y, Ortega-Hernández J, Chen H, Mai H, Zhai D, Hou X. Computed tomography sheds new light on the affinities of the enigmatic euarthropod Jianshania furcatus from the early Cambrian Chengjiang biota. BMC Evol Biol 2020; 20:62. [PMID: 32487135 PMCID: PMC7268425 DOI: 10.1186/s12862-020-01625-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 05/11/2020] [Indexed: 11/16/2022] Open
Abstract
Background The Chengjiang biota is one of the most species-rich Cambrian Konservat-Lagerstätten, and preserves a community dominated by non-biomineralized euarthropods. However, several Chengjiang euarthropods have an unfamiliar morphology, are extremely rare, or incompletely preserved. Results We employed micro-computed tomography to restudy the enigmatic euarthropod Jianshania furcatus. We reveal new morphological details, and demonstrate that the specimens assigned to this species represent two different taxa. The holotype of J. furcatus features a head shield with paired anterolateral notches, stalked lateral eyes, and an articulated tailspine with a bifurcate termination. The other specimen is formally redescribed as Xiaocaris luoi gen. et sp. nov., and is characterized by stalked eyes connected to an anterior sclerite, a subtrapezoidal head shield covering three small segments with reduced tergites, a trunk with 15 overlapping tergites with a well-developed dorsal keel, and paired tail flukes. Conclusions The presence of antennae, biramous appendages with endopods composed of 15 articles, and multiple appendage pairs associated with the trunk tergites identify X. luoi nov. as a representative of Fuxianhuiida, an early branching group of stem-group euarthropods endemic to the early Cambrian of Southwest China. X. luoi nov. represents the fifth fuxianhuiid species described from the Chengjiang biota, and its functional morphology illuminates the ecological diversity of this important clade for understanding the early evolutionary history of euarthropods.
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Affiliation(s)
- Yu Liu
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, 650500, China. .,MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650500, China.
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA.
| | - Hong Chen
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, 650500, China.,MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650500, China
| | - Huijuan Mai
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, 650500, China.,MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650500, China
| | - Dayou Zhai
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, 650500, China.,MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650500, China
| | - Xianguang Hou
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, 650500, China.,MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650500, China
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14
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Abstract
Ortega-Hernández et al. introduce fuxianhuiids, Cambrian arthropods that are important for our understaindg how the largest animal phylum evolved.
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Affiliation(s)
- Javier Ortega-Hernández
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK; Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA.
| | - Jie Yang
- Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China
| | - Xi-Guang Zhang
- Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China.
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15
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Chipman AD, Edgecombe GD. Developing an integrated understanding of the evolution of arthropod segmentation using fossils and evo-devo. Proc Biol Sci 2019; 286:20191881. [PMID: 31575373 DOI: 10.1098/rspb.2019.1881] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Segmentation is fundamental to the arthropod body plan. Understanding the evolutionary steps by which arthropods became segmented is being transformed by the integration of data from evolutionary developmental biology (evo-devo), Cambrian fossils that allow the stepwise acquisition of segmental characters to be traced in the arthropod stem-group, and the incorporation of fossils into an increasingly well-supported phylogenetic framework for extant arthropods based on genomic-scale datasets. Both evo-devo and palaeontology make novel predictions about the evolution of segmentation that serve as testable hypotheses for the other, complementary data source. Fossils underpin such hypotheses as arthropodization originating in a frontal appendage and then being co-opted into other segments, and segmentation of the endodermal midgut in the arthropod stem-group. Insights from development, such as tagmatization being associated with different modes of segment generation in different body regions, and a distinct patterning of the anterior head segments, are complemented by palaeontological evidence for the pattern of tagmatization during ontogeny of exceptionally preserved fossils. Fossil and developmental data together provide evidence for a short head in stem-group arthropods and the mechanism of its formation and retention. Future breakthroughs are expected from identification of molecular signatures of developmental innovations within a phylogenetic framework, and from a focus on later developmental stages to identify the differentiation of repeated units of different systems within segmental precursors.
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Affiliation(s)
- Ariel D Chipman
- Department of Ecology, Evolution and Behavior, The Silberman Institute of Life Sciences, Edmond J. Safra Campus - Givat Ram, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Gregory D Edgecombe
- Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
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16
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Chen X, Ortega-Hernández J, Wolfe JM, Zhai D, Hou X, Chen A, Mai H, Liu Y. The appendicular morphology of Sinoburius lunaris and the evolution of the artiopodan clade Xandarellida (Euarthropoda, early Cambrian) from South China. BMC Evol Biol 2019; 19:165. [PMID: 31387545 PMCID: PMC6685191 DOI: 10.1186/s12862-019-1491-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/29/2019] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Artiopodan euarthropods represent common and abundant faunal components in sites with exceptional preservation during the Cambrian. The Chengjiang biota in South China contains numerous taxa that are exclusively known from this deposit, and thus offer a unique perspective on euarthropod diversity during the early Cambrian. One such endemic taxon is the non-trilobite artiopodan Sinoburius lunaris, which has been known for approximately three decades, but few details of its anatomy are well understood due to its rarity within the Chengjiang, as well as technical limitations for the study of these fossils. Furthermore, the available material does not provide clear information on the ventral organization of this animal, obscuring our understanding of phylogenetically significant details such as the appendages. RESULTS We employed X-ray computed tomography to study the non-biomineralized morphology of Sinoburius lunaris. Due to the replacement of the delicate anatomy with pyrite typical of Chengjiang fossils, computed tomography reveals substantial details of the ventral anatomy of Sinoburius lunaris, and allow us to observe in detail the three-dimensionally preserved appendicular organization of this taxon for the first time. The dorsal exoskeleton consists of a crescent-shaped head shield with well-developed genal spines, a thorax with seven freely articulating tergites, and a fused pygidium with lateral and median spines. The head bears a pair of ventral stalked eyes that are accommodated by dorsal exoskeletal bulges, and an oval elongate ventral hypostome. The appendicular organization of the head is unique among Artiopoda. The deutocerebral antennae are reduced, consisting of only five podomeres, and bear an antennal scale on the second podomere that most likely represents an exite rather than a true ramus. The head includes four post-antennal biramous limb pairs. The first two biramous appendages are differentiated from the rest. The first appendage pair consists of a greatly reduced endopod coupled with a greatly elongated exopod with a potentially sensorial function. The second appendage pair carries a more conventionally sized endopod, but also has an enlarged exopod. The remaining biramous appendages are homonomous in their construction, but decrease in size towards the posterior end of the body. They consist of a basipodite with ridge-like crescentic endites, an endopod with seven podomeres and a terminal claw, and a lamellae-bearing exopod with a slender shaft. Contrary to previous reports, we confirm the presence of segmental mismatch in Sinoburius lunaris, expressed as diplotergites in the thorax. Maximum parsimony and Bayesian phylogenetic analyses support the monophyly of Xandarellida within Artiopoda, and illuminate the internal relationships within this enigmatic clade. Our results allow us to propose a transformation series explaining the origin of archetypical xandarellid characters, such as the evolution of eye slits in Xandarella spectaculum and Phytophilaspis pergamena as derivates from the anterolateral notches in the head shield observed in Cindarella eucalla and Luohuilinella species. In this context, Sinoburius lunaris is found to feature several derived characters within the group, such as the secondary loss of eye slits and a high degree of appendicular tagmosis. Contrary to previous findings, our analyses strongly support close affinities between Sinoburius lunaris, Xandarella spectaculum and Phytophilaspis pergamena, although the precise relationships between these taxa are sensitive to different methodologies. CONCLUSIONS The revised morphology of Sinoburius lunaris, made possible through the use of computed tomography to resolve details of its three-dimensionally preserved appendicular anatomy, contributes towards an improved understanding of the morphology of this taxon and the evolution of Xandarellida more broadly. Our results indicate that Sinoburius lunaris possesses an unprecedented degree of appendicular tagmosis otherwise unknown within Artiopoda, with the implication that this iconic group of Palaeozoic euarthropods likely had a more complex ecology and functional morphology than previously considered. The application of computer tomographic techniques to the study of Chengjiang euarthropods holds exceptional promise for understanding the morphological diversity of these organisms, and also better reconstructing their phylogenetic relationships and evolutionary history.
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Affiliation(s)
- Xiaohan Chen
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, North Cuihu Road 2, Kunming, 650091, China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650091, China
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA.
| | - Joanna M Wolfe
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
| | - Dayou Zhai
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, North Cuihu Road 2, Kunming, 650091, China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650091, China
| | - Xianguang Hou
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, North Cuihu Road 2, Kunming, 650091, China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650091, China
| | - Ailin Chen
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650091, China
- Research Center of Paleobiology, Yuxi Normal University, Yuxi, 653100, Yunnan, China
| | - Huijuan Mai
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, North Cuihu Road 2, Kunming, 650091, China
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650091, China
| | - Yu Liu
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, North Cuihu Road 2, Kunming, 650091, China.
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650091, China.
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18
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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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19
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Yang J, Ortega-Hernández J, Drage HB, Du KS, Zhang XG. Ecdysis in a stem-group euarthropod from the early Cambrian of China. Sci Rep 2019; 9:5709. [PMID: 30952888 PMCID: PMC6450865 DOI: 10.1038/s41598-019-41911-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 03/20/2019] [Indexed: 11/26/2022] Open
Abstract
Moulting is a fundamental component of the ecdysozoan life cycle, but the fossil record of this strategy is susceptible to preservation biases, making evidence of ecdysis in soft-bodied organisms extremely rare. Here, we report an exceptional specimen of the fuxianhuiid Alacaris mirabilis preserved in the act of moulting from the Cambrian (Stage 3) Xiaoshiba Lagerstätte, South China. The specimen displays a flattened and wrinkled head shield, inverted overlap of the trunk tergites over the head shield, and duplication of exoskeletal elements including the posterior body margins and telson. We interpret this fossil as a discarded exoskeleton overlying the carcass of an emerging individual. The moulting behaviour of A. mirabilis evokes that of decapods, in which the carapace is separated posteriorly and rotated forward from the body, forming a wide gape for the emerging individual. A. mirabilis illuminates the moult strategy of stem-group Euarthropoda, offers the stratigraphically and phylogenetically earliest direct evidence of ecdysis within total-group Euarthropoda, and represents one of the oldest examples of this growth strategy in the evolution of Ecdysozoa.
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Affiliation(s)
- Jie Yang
- Key Laboratory for Palaeobiology, Yunnan University, Kunming, 650091, China
- MEC International Joint Laboratory for Palaeoenvironment, Yunnan University, Kunming, 650091, China
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Harriet B Drage
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK
- Institute of Earth Sciences, University of Lausanne, Géopolis, CH-1015, Lausanne, Switzerland
| | - Kun-Sheng Du
- 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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20
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Zhai D, Ortega-Hernández J, Wolfe JM, Hou X, Cao C, Liu Y. Three-Dimensionally Preserved Appendages in an Early Cambrian Stem-Group Pancrustacean. Curr Biol 2019; 29:171-177.e1. [DOI: 10.1016/j.cub.2018.11.060] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 09/06/2018] [Accepted: 11/28/2018] [Indexed: 10/27/2022]
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Bicknell RDC, Ledogar JA, Wroe S, Gutzler BC, Watson WH, Paterson JR. Computational biomechanical analyses demonstrate similar shell-crushing abilities in modern and ancient arthropods. Proc Biol Sci 2018; 285:rspb.2018.1935. [PMID: 30355715 DOI: 10.1098/rspb.2018.1935] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 10/05/2018] [Indexed: 12/28/2022] Open
Abstract
The biology of the American horseshoe crab, Limulus polyphemus, is well documented-including its dietary habits, particularly the ability to crush shell with gnathobasic walking appendages-but virtually nothing is known about the feeding biomechanics of this iconic arthropod. Limulus polyphemus is also considered the archetypal functional analogue of various extinct groups with serial gnathobasic appendages, including eurypterids, trilobites and other early arthropods, especially Sidneyia inexpectans from the mid-Cambrian (508 Myr) Burgess Shale of Canada. Exceptionally preserved specimens of S. inexpectans show evidence suggestive of durophagous (shell-crushing) tendencies-including thick gnathobasic spine cuticle and shelly gut contents-but the masticatory capabilities of this fossil species have yet to be compared with modern durophagous arthropods. Here, we use advanced computational techniques, specifically a unique application of 3D finite-element analysis (FEA), to model the feeding mechanics of L. polyphemus and S. inexpectans: the first such analyses of a modern horseshoe crab and a fossil arthropod. Results show that mechanical performance of the feeding appendages in both arthropods is remarkably similar, suggesting that S. inexpectans had similar shell-crushing capabilities to L. polyphemus This biomechanical solution to processing shelly food therefore has a history extending over 500 Myr, arising soon after the first shell-bearing animals. Arrival of durophagous predators during the early phase of animal evolution undoubtedly fuelled the Cambrian 'arms race' that involved a rapid increase in diversity, disparity and abundance of biomineralized prey species.
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Affiliation(s)
- Russell D C Bicknell
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia .,Function, Evolution and Anatomy Research Lab, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
| | - Justin A Ledogar
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia.,Function, Evolution and Anatomy Research Lab, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia.,Department of Evolutionary Biology, Duke University, Durham, NC 27708, USA
| | - Stephen Wroe
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia.,Function, Evolution and Anatomy Research Lab, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
| | - Benjamin C Gutzler
- Department of Biological Sciences and School of Marine Science and Ocean Engineering, University of New Hampshire, Durham, NH 03824, USA
| | - Winsor H Watson
- Department of Biological Sciences and School of Marine Science and Ocean Engineering, University of New Hampshire, Durham, NH 03824, USA
| | - John R Paterson
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
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22
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Anamorphic development and extended parental care in a 520 million-year-old stem-group euarthropod from China. BMC Evol Biol 2018; 18:147. [PMID: 30268090 PMCID: PMC6162911 DOI: 10.1186/s12862-018-1262-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 09/20/2018] [Indexed: 11/28/2022] Open
Abstract
Background Extended parental care is a complex reproductive strategy in which progenitors actively look after their offspring up to – or beyond – the first juvenile stage in order to maximize their fitness. Although the euarthropod fossil record has produced several examples of brood-care, the appearance of extended parental care within this phylum remains poorly constrained given the scarcity of developmental data for Palaeozoic stem-group representatives that would link juvenile and adult forms in an ontogenetic sequence. Results Here, we describe the post-embryonic growth of Fuxianhuia protensa from the early Cambrian Chengjiang Lagerstätte in South China. Our data demonstrate anamorphic post-embryonic development for F. protensa, in which new tergites were sequentially added from a posterior growth zone, the number of tergites varies from eight to 30. The growth of F. protensa is typified by the alternation between segment addition, followed by the depletion of the anteriormost abdominal segment into the thoracic region. The transformation of abdominal into thoracic tergite is demarcated by the development of laterally tergopleurae, and biramous walking legs. The new ontogeny data leads to the recognition of the rare Chengjiang euarthropod Pisinnocaris subconigera as a junior synonym of Fuxianhuia. Comparisons between different species of Fuxianhuia and with other genera within Fuxianhuiida suggest that heterochrony played a prominent role in the morphological diversification of fuxianhuiids. Functional analogy with the flexible trunk ontogeny of Cambrian and Silurian olenimorphic trilobites suggests an adaptation to sporadic low oxygen conditions in Chengjiang deposits for F. protensa. Finally, understanding the growth of F. protensa allows for the interpretation of an exceptional life assemblage consisting of a sexually mature adult alongside four ontogenetically coeval juveniles, which constitutes the oldest occurrence of extended parental care by prolonged cohabitation in the panarthropod fossil record. Conclusions Our findings constitute the most detailed characterization of the post-embryonic development in a soft-bodied upper stem-group euarthropod available to date. The new ontogeny data illuminates the systematics, trunk segmentation and palaeoecology of F. protensa, offers insights on the macroevolutionary processes involved in the diversification of this clade, and contributes towards an improved understanding of complex post-embryonic reproductive ecology in Cambrian euarthropods. Electronic supplementary material The online version of this article (10.1186/s12862-018-1262-6) contains supplementary material, which is available to authorized users.
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23
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Chen A, Chen H, Legg DA, Liu Y, Hou XG. A redescription of Liangwangshania biloba Chen, 2005, from the Chengjiang biota (Cambrian, China), with a discussion of possible sexual dimorphism in fuxianhuiid arthropods. ARTHROPOD STRUCTURE & DEVELOPMENT 2018; 47:552-561. [PMID: 30125735 DOI: 10.1016/j.asd.2018.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 06/13/2018] [Accepted: 08/11/2018] [Indexed: 06/08/2023]
Abstract
Material attributed to Liangwangshania biloba, a fuxianhuiid arthropod from the lower Cambrian (Series 2, Stage 3) of southwest China, is redescribed, with many specimens illustrated for the first time. Newly recognized features include, potential optical neuropils, a stout posterolateral carapace spine, serrated tergal pleurae, two rows of mediolateral carinae, an abdomen composed of seven segments, the last possessing a tripartite lateral flap, and a triangular telson. The presence of tergal carinae, a prothorax composed of six segments, and a trunk composed of 43 segments tipped with a flap-like terminal segment, increase similarities with the previously described Shankouia zhenghei, thus prompting a reevaluation of the potential synonymy of these taxa. These previously recognized species also show considerable overlap in body size, and the ratios of selected body features, such as the carapace. This, combined with their co-occurrence over a temporally and geographically limited range, further support their synonymy. L. biloba is considered the senior synonym in accordance with ICZN rulings, with morphological differences, specifically the presence of posterolateral spines on the carapace, serrated tergopleurae, and spines on the terminal abdominal segment, attributed to sexual variation. An evaluation of potential sexual dimorphism in other fuxianhuiids, and a reassessment of terminology applied to this group is also provided.
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Affiliation(s)
- Ailin Chen
- Research Center of Paleobiology, Yuxi Normal University, Yuxi, Yunnan 653100, China.
| | - Hong Chen
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming, Yunnan 650091, China; MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, Yunnan 650091, China; School of Biological Sciences and Technology, Liupanshui Normal University, Liupanshui, Guizhou 553004, China
| | - David A Legg
- Department of Earth, Atmospheric, and Environmental Sciences, University of Manchester, Manchester M13 9PL, UK.
| | - Yu Liu
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming, Yunnan 650091, China; MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, Yunnan 650091, China
| | - Xian-Guang Hou
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming, Yunnan 650091, China; MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, Yunnan 650091, China
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