A superarmored lobopodian from the Cambrian of China and early disparity in the evolution of Onychophora

Yang, Jie; Ortega‐Hernández, Javier; Gerber, Sylvain; Butterfield, Nicholas J.; Hou, Jin-bo; Lan, Tian; Zhang, Xiguang

doi:10.1073/pnas.1505596112

Cited by 82 publications

(126 citation statements)

References 44 publications

(57 reference statements)

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“…The trunk of the EBS lobopodian bears three long, robust spines arranged across the dorsal side of each body segment. These characters are shared with the Chinese early Cambrian luolishaniids Luolishania (Chengjiang biota) and Collinsium (Xiaoshiba biota); the latter strengthens the hypothesis that these armoured lobopodians are stem-group onychophorans (Yang et al 2015).…”

Section: Box 2 Acute Vision In the Early Cambriansupporting

confidence: 65%

The Emu Bay Shale Konservat-Lagerstätte: a view of Cambrian life from East Gondwana

Paterson

García‐Bellido

Jago

et al. 2015

JGS

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Recent fossil discoveries from the lower Cambrian Emu Bay Shale (EBS) on Kangaroo Island, South Australia, have provided critical insights into the tempo of the Cambrian explosion of animals, such as the origin and seemingly rapid evolution of arthropod compound eyes, as well as extending the geographical ranges of several groups to the East Gondwanan margin, supporting close faunal affinities with South China. The EBS also holds great potential for broadening knowledge on taphonomic pathways involved in the exceptional preservation of fossils in Cambrian Konservat-Lagerstätten. EBS fossils display a range of taphonomic modes for a variety of soft tissues, especially phosphatization and pyritization, in some cases recording a level of anatomical detail that is absent from most Cambrian Konservat-Lagerstätten.

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Section: Box 2 Acute Vision In the Early Cambriansupporting

confidence: 65%

The Emu Bay Shale Konservat-Lagerstätte: a view of Cambrian life from East Gondwana

Paterson

García‐Bellido

Jago

et al. 2015

JGS

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“…S6A); subsequent repetitions with variable concavity values (k) were used to explore the effect of different degrees of homoplasy penalization to test the robustness of the dataset (Fig. S6 B-D) (36).…”

Section: Methodsmentioning

confidence: 99%

Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda

Yang

Ortega‐Hernández

Butterfield

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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142

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Panarthropods are typified by disparate grades of neurological organization reflecting a complex evolutionary history. The fossil record offers a unique opportunity to reconstruct early character evolution of the nervous system via exceptional preservation in extinct representatives. Here we describe the neurological architecture of the ventral nerve cord (VNC) in the upper-stem group euarthropod Chengjiangocaris kunmingensis from the early Cambrian Xiaoshiba Lagerstätte (South China). The VNC of C. kunmingensis comprises a homonymous series of condensed ganglia that extend throughout the body, each associated with a pair of biramous limbs. Submillimetric preservation reveals numerous segmental and intersegmental nerve roots emerging from both sides of the VNC, which correspond topologically to the peripheral nerves of extant Priapulida and Onychophora. The fuxianhuiid VNC indicates that ancestral neurological features of Ecdysozoa persisted into derived members of stem-group Euarthropoda but were later lost in crown-group representatives. These findings illuminate the VNC ground pattern in Panarthropoda and suggest the independent secondary loss of cycloneuralian-like neurological characters in Tardigrada and Euarthropoda.stem-group Euarthropoda | Onychophora | phylogeny | Cambrian Explosion | Xiaoshiba Lagerstätte T he nervous system represents a critical source of phylogenetic information and has been used extensively for exploring the evolutionary relationships of extant Panarthropoda (i.e., Onychophora, Tardigrada, Euarthropoda) (1-7). Identification of fossilized nervous tissues has provided a unique perspective on early euarthropod brain neuroanatomy and suggests that broad patterns of extant neurological diversity were already in place by the Cambrian (8-11). The ventral nerve cord (VNC) reflects fundamental aspects of panarthropod body organization that complement the organization of the brain and together illuminate the evolution of the CNS (1-3, 5, 7, 12-16). The early evolutionary history of the panarthropod postcephalic CNS, however, remains obscure due to the exclusive preservation of brains in most available fossils (8,10,11). Moreover, the unresolved phylogenetic relationships within Panarthropoda complicate accurate reconstruction of the CNS ground pattern (16)(17)(18)(19)(20)(21)(22). In this study, we demonstrate the exceptional preservation of postcephalic neurological features in the early Cambrian fuxianhuiid Chengjiangocaris kunmingensis, an upper stem-group euarthropod (17) from the Xiaoshiba Lagerstätte, South China (23). These fossils clarify the neurological organization of the VNC in early euarthropod ancestors, thereby polarizing the evolution of the panarthropod CNS.

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“…1 To pick but one example, the famously bizarre Hallucigenia has been identified as a stem onychophoran (velvet worm), a group closely related to arthropods [3]. 2 Our general focus on eukaryotic evolution is partially due to historical interest (this was Gould's focus), and partly due to the fact that prokaryotic evolution may be overwhelmed by lateral gene transfer [22], making convergent evolution hard to assess in the prokaryotic history of life [23].…”

Section: Endnotesmentioning

confidence: 99%

“…2 Our general focus on eukaryotic evolution is partially due to historical interest (this was Gould's focus), and partly due to the fact that prokaryotic evolution may be overwhelmed by lateral gene transfer [22], making convergent evolution hard to assess in the prokaryotic history of life [23]. 3 Although most discussions of convergent evolution focus on morphology, the concept is broad enough to encompass similarities in molecular and developmental structure, as well as functional and relational resemblances, irrespective of their particular structural realization. 4 In his last and most comprehensive monograph, Gould contends that 'homologous developmental pathways can also be employed .…”

Section: Endnotesmentioning

confidence: 99%

Convergent evolution as natural experiment: the tape of life reconsidered

Powell

Mariscal

2015

Interface Focus.

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Stephen Jay Gould argued that replaying the ‘tape of life’ would result in radically different evolutionary outcomes. Recently, biologists and philosophers of science have paid increasing attention to the theoretical importance of convergent evolution—the independent origination of similar biological forms and functions—which many interpret as evidence against Gould's thesis. In this paper, we examine the evidentiary relevance of convergent evolution for the radical contingency debate. We show that under the right conditions, episodes of convergent evolution can constitute valid natural experiments that support inferences regarding the deep counterfactual stability of macroevolutionary outcomes. However, we argue that proponents of convergence have problematically lumped causally heterogeneous phenomena into a single evidentiary basket, in effect treating all convergent events as if they are of equivalent theoretical import. As a result, the ‘critique from convergent evolution’ fails to engage with key claims of the radical contingency thesis. To remedy this, we develop ways to break down the heterogeneous set of convergent events based on the nature of the generalizations they support. Adopting this more nuanced approach to convergent evolution allows us to differentiate iterated evolutionary outcomes that are probably common among alternative evolutionary histories and subject to law-like generalizations, from those that do little to undermine and may even support, the Gouldian view of life.

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A superarmored lobopodian from the Cambrian of China and early disparity in the evolution of Onychophora

Cited by 82 publications

References 44 publications

The Emu Bay Shale Konservat-Lagerstätte: a view of Cambrian life from East Gondwana

The Emu Bay Shale Konservat-Lagerstätte: a view of Cambrian life from East Gondwana

Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda

Convergent evolution as natural experiment: the tape of life reconsidered

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