An early Cambrian euarthropod with radiodont-like raptorial appendages

Zeng, Han; Zhao, Fangchen; Niu, Kecheng; Zhu, Maoyan; Huang, Diying

doi:10.1038/s41586-020-2883-7

Cited by 53 publications

(106 citation statements)

References 34 publications

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“…Furthermore, in some putative stem-group chelicerates such as Offacolus, the chelicera appears to be long and slender with no "elbow" joint (Sutton et al 2002;Budd and Legg 2012;Legg 2014). It is clear that no GA exactly resembles a chelicera or chelicere; furthermore, the GA also resembles the frontal appendage of radiodontids, a point recognised by Haug et al (2012; see also Zeng et al 2020). Haug et al (2012) tentatively propose to solve this problem by placing the radiodontids in the stem group of the chelicerates and thus separate them from the more lobopodan taxa such as Kerygmachela and Pambdelurion.…”

Section: Similaritymentioning

confidence: 97%

“…It is doubtful, however, whether this is a reasonable solution, because Kerygmachela and Pambdelurion clearly share several important (plesiomorphic) features with radiodontids (Budd 1998(Budd , 1999. Zeng et al (2020) wish to accept the protocerebral affinity of the FA of radiodontids; the deutocerebral affinity of the GA; and homology between the two, by reference to homeotic mutation (see their supplementary information for discussion).…”

Section: Similaritymentioning

confidence: 99%

“…Although some authors have accepted the homology between radiodontid and megacheiran great appendages (Chen et al 2004;Aria and Caron 2020;Aria et al 2020;Zeng et al 2020), this suggestion has been otherwise rejected. Partly, this rejection has rested on a distinction that has been made between "short" great appendages such as those of the megacheirans, and "long" great appendages such as those of the radiodontids.…”

Section: Parapeytoiamentioning

confidence: 99%

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The origin and evolution of the euarthropod labrum

Budd¹

2020

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A widely (although not universally) accepted model of arthropod head evolution postulates that the problematic labrum, a structure seen in almost all living euarthropods, evolved from an anterior pair of appendages homologous to the frontal appendages of onychophorans. However, the implications of this model for the interpretation of fossil arthropods have not been fully integrated into reconstructions of the euarthropod stem group, which remains in a state of some disorder. Here I review the evidence for the evolution of the labrum from living taxa, and reconsider how fossils should be interpreted in the light of this. Identification of the segmental identity of head appendage in fossil arthropods remains problematic, and often rests ultimately on unproven assertions. New evidence from Parapeytoia is presented to suggest that the labral appendage persisted well up into the upper stem-group of the euarthropods, which prompts a re-evaluation of widely-accepted segmental homologies and the interpretation of fossil central nervous systems. Only a protocerebral brain was present in large part of the euarthropod stem group, and the modern deutocerebrum must have been a relatively late addition.

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Section: Similaritymentioning

confidence: 97%

Section: Similaritymentioning

confidence: 99%

Section: Parapeytoiamentioning

confidence: 99%

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The origin and evolution of the euarthropod labrum

Budd¹

2020

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“…Our results have implications for larger scale questions, such as the relative phylogenetic positions of opabiniids and radiodonts along the euarthropod stem group, and detailed consideration of conflicting topologies. We replicate the dichotomy of recent publications, where matrices analyzed using MP find opabiniids as the sister group to deuteropods (Yang et al , 2016, 2018; Howard et al , 2020) and those analyzed using BI or maximum likelihood instead resolve radiodonts in that position (Fleming et al , 2018; Moysiuk and Caron, 2019; Howard et al , 2020; Zeng et al , 2020). The branching order of these three clades has ramifications for the sequence of acquisition, and evolutionary reversals or convergences, of key crown group euarthropod characters (Ortega-Hernández, 2016), such as the posterior mouth and arthropodized appendages, as well as the dorsal expression of trunk segmentation ( Supplementary Fig.…”

Section: Discussionmentioning

confidence: 69%

“…Little weight should be placed on this particular result from this study, as the support for radiodont monophyly is poor and not enhanced by additional bipartitions (as in opabiniids), and as other matrices consistently resolve radiodonts as a monophyletic group when analysed with both MP and BI (e.g. Lerosey-Aubril and Pates, 2018; Moysiuk and Caron, 2019; Zeng et al , 2020).…”

Section: Extended Systematic Palaeontologymentioning

confidence: 88%

New opabiniid diversifies the weirdest wonders of the euarthropod lower stem group

Pates

Wolfe

Lerosey‐Aubril

et al. 2021

Preprint

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Once considered "weird wonders" of the Cambrian, the emblematic Burgess Shale animals Anomalocaris and Opabinia are now recognized as lower stem-group euarthropods. Anomalocaris and its relatives (radiodonts) had a worldwide distribution and survived until at least the Devonian, whereas - despite intense study - Opabinia remains the only formally described opabiniid to date. Here we reinterpret a fossil from the Wheeler Formation of Utah as a new opabiniid, KUMIP 314087. By visualizing the sample of phylogenetic topologies in treespace, our results fortify support for the position of KUMIP 314087 beyond the nodal support traditionally applied. Our phylogenetic evidence expands opabiniids to multiple Cambrian Stages spanning approximately five million years. Our results underscore the power of treespace visualization for resolving imperfectly preserved fossils and expanding the known diversity and spatiotemporal ranges within the euarthropod lower stem group.

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Interpreting fossilized nervous tissues

et al. 2023

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Paleoneuranatomy is an emerging subfield of paleontological research with great potential for the study of evolution. However, the interpretation of fossilized nervous tissues is a difficult task and presently lacks a rigorous methodology. We critically review here cases of neural tissue preservation reported in Cambrian arthropods, following a set of fundamental paleontological criteria for their recognition. These criteria are based on a variety of taphonomic parameters and account for morphoanatomical complexity. Application of these criteria shows that firm evidence for fossilized nervous tissues is less abundant and detailed than previously reported, and we synthesize here evidence that has stronger support. We argue that the vascular system, and in particular its lacunae, may be central to the understanding of many of the fossilized peri‐intestinal features known across Cambrian arthropods. In conclusion, our results suggest the need for caution in the interpretation of evidence for fossilized neural tissue, which will increase the accuracy of evolutionary scenarios. Also see the video abstract here: https://youtu.be/2_JlQepRTb0

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An early Cambrian euarthropod with radiodont-like raptorial appendages

Cited by 53 publications

References 34 publications

The origin and evolution of the euarthropod labrum

The origin and evolution of the euarthropod labrum

New opabiniid diversifies the weirdest wonders of the euarthropod lower stem group

Interpreting fossilized nervous tissues

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