Onychophoran-like musculature in a phosphatized Cambrian lobopodian

Zhang, Xi-guang; Smith, Martin R.; Yang, Jie; Hou, Jin-bo

doi:10.1098/rsbl.2016.0492

Cited by 24 publications

(32 citation statements)

References 22 publications

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“…Although they may be rare, there is no shortage of preserved internal soft-tissue structures reported from the fossil record. Fossilized internal soft tissues in the Ediacaran are limited to one possible occurrence of a muscular cnidarian 39 ; on the other hand, Cambrian examples are much more numerous and diverse, including cardiovasculature 40 , nervous and neurological tissues 41 , musculature 42 , and copious reports of digestive tracts 43 . In Cambrian lagerstätten, guts are the most frequently preserved internal structures 44 .…”

Section: Resultsmentioning

confidence: 99%

“…In Cambrian lagerstätten, guts are the most frequently preserved internal structures 44 . Whereas fossil vasculature or nervous tissues are preserved as compressed or flattened features 40,41 and musculature as bundled fibrous structures 42 , fossil guts can reveal a broadly tubular nature where three-dimensionally preserved, and sometimes occur with the presence of associated digestive glands 43,44 . Cambrian guts are typically preserved either as carbonaceous films 45 , sediment infillings 46 , or via phosphatization 44 , the latter of which is potentially reflective of the organism's digestive physiology.…”

Section: Resultsmentioning

confidence: 99%

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Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period

et al. 2020

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The fossil record of the terminal Ediacaran Period is typified by the iconic index fossil Cloudina and its relatives. These tube-dwellers are presumed to be primitive metazoans, but resolving their phylogenetic identity has remained a point of contention. The root of the problem is a lack of diagnostic features; that is, phylogenetic interpretations have largely centered on the only available source of information-their external tubes. Here, using tomographic analyses of fossils from the Wood Canyon Formation (Nevada, USA), we report evidence of recognizable soft tissues within their external tubes. Although alternative interpretations are plausible, these internal cylindrical structures may be most appropriately interpreted as digestive tracts, which would be, to date, the earliest-known occurrence of such features in the fossil record. If this interpretation is correct, their nature as one-way through-guts not only provides evidence for establishing these fossils as definitive bilaterians but also has implications for the long-debated phylogenetic position of the broader cloudinomorphs.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period

et al. 2020

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“…The Cambrian lobopodian Tritonychus phanerosarkus preserved in Orsten fashion shows extensive phosphatisation of muscle tissue while the claws are lost (Zhang et al . ). In such cases, it appears the musculature was subject to microbially‐induced mineralization soon after decay commenced, resulting in a relatively high fidelity replication of these tissues.…”

Section: Discussionmentioning

confidence: 97%

“…The Cambrian stem‐group onychophoran T. phaneroskarkus shows an exceptionally preserved, complex trunk musculature composed of three distinct layers (Zhang et al . ). The outermost layer is composed of longitudinal fibres.…”

Section: Discussionmentioning

confidence: 97%

Onychophoran‐like myoanatomy of the Cambrian gilled lobopodian Pambdelurion whittingtoni

Young

Vinther²

2016

Palaeontology

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Arthropods are characterized by a rigid, articulating, exoskeleton operated by a lever‐like system of segmentally arranged, antagonistic muscles. This skeletomuscular system evolved from an unsegmented body wall musculature acting on a hydrostatic skeleton, similar to that of the arthropods’ close relatives, the soft‐bodied onychophorans. Unfortunately, fossil evidence documenting this transition is scarce. Exceptionally‐preserved panarthropods from the Cambrian Lagerstätte of Sirius Passet, Greenland, including the soft‐bodied stem‐arthropod Pambdelurion whittingtoni and the hard‐bodied arthropods Kiisortoqia soperi and Campanamuta mantonae, are unique in preserving extensive musculature. Here we show that Pambdelurion's myoanatomy conforms closely to that of extant onychophorans, with unsegmented dorsal, ventral and longitudinal muscle groups in the trunk, and extrinsic and intrinsic muscles controlling the legs. Pambdelurion also possesses oblique musculature, which has previously been interpreted as an arthropodan characteristic. However, this oblique musculature appears to be confined to the cephalic region and first few body segments, and does not represent a shift towards arthropodan myoanatomy. The Sirius Passet arthropods, Kiisortoqia and Campanamuta, also possess large longitudinal muscles in the trunk, although, unlike Pambdelurion, they are segmentally divided at the tergal boundaries. Thus, the transition towards an arthropodan myoanatomy from a lobopodian ancestor probably involved the division of the peripheral longitudinal muscle into segmented units.

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“…Despite their relevance, there are still many gaps in our knowledge of these animals. A recent discussion regarding the evolution of their locomotory system, for example, has brought them back into the scientific spotlight (18). In particular, researchers try to understand the evolution of the limb musculature from their ancestors-marine Cambrian animals called lobopodiansto exclusively terrestrial modern onychophorans (18).…”

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confidence: 99%

Myoanatomy of the velvet worm leg revealed by laboratory-based nanofocus X-ray source tomography

Müller

Oliveira

Allner

et al. 2017

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

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X-ray computed tomography (CT) is a powerful noninvasive technique for investigating the inner structure of objects and organisms. However, the resolution of laboratory CT systems is typically limited to the micrometer range. In this paper, we present a table-top nanoCT system in conjunction with standard processing tools that is able to routinely reach resolutions down to 100 nm without using X-ray optics. We demonstrate its potential for biological investigations by imaging a walking appendage of , a representative of Onychophora-an invertebrate group pivotal for understanding animal evolution. Comparative analyses proved that the nanoCT can depict the external morphology of the limb with an image quality similar to scanning electron microscopy, while simultaneously visualizing internal muscular structures at higher resolutions than confocal laser scanning microscopy. The obtained nanoCT data revealed hitherto unknown aspects of the onychophoran limb musculature, enabling the 3D reconstruction of individual muscle fibers, which was previously impossible using any laboratory-based imaging technique.

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Onychophoran-like musculature in a phosphatized Cambrian lobopodian

Abstract: These authors contributed equally to this study.Electronic supplementary material is available online at https://dx.doi.org/10.6084/m9.figshare.c.3464565.

Cited by 24 publications

References 22 publications

Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period

Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period

Onychophoran‐like myoanatomy of the Cambrian gilled lobopodian Pambdelurion whittingtoni

Myoanatomy of the velvet worm leg revealed by laboratory-based nanofocus X-ray source tomography

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