Maotianshan-Shale nemathelminths — Morphology, biology, and the phylogeny of Nemathelminthes

Maas, Andreas; Huang, Diying; Chen, Jun-Yuan; Waloszek, Dieter; Braun, Andreas

doi:10.1016/j.palaeo.2007.03.019

Cited by 86 publications

(106 citation statements)

References 43 publications

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“…Much the same position was adopted by Maas et al (2007). In addition, some recent molec− ular data appear to support the latter view.…”

Section: Comparisonssupporting

confidence: 59%

“…We would suggest that the palaeoscolecidans and related forms are equi− valent to this stage of ecdysozoan evolution (Fig. 7), so that the characteristic priapulan introvert (Conway Morris 1977) is in fact plesiomorphic to the cycloneuralians (see e.g., Maas et al 2007), if not the ecdysozoans. This explains why so far as the Cambrian taxa are concerned it is routine to refer to them as priapulids, priapulimorphs, etc.…”

Section: Comparisonsmentioning

confidence: 97%

“…Palaeoscolecidans are usually reconstructed as infaunal, al− though at least some taxa may have engaged in epifaunal ex− cursions (e.g., Huang 2005;Han et al 2007a-c;Maas et al 2007). Note that the claim by the latter authors (Maas et al 2007: 301) (Fig.…”

Section: Modes Of Lifementioning

confidence: 99%

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Evidence of Priapulid Scavenging From the Early Cambrian Chengjiang Deposits, Southern China

Han¹,

Zhang²,

Liu³

et al. 2007

PALAIOS

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“…Much the same position was adopted by Maas et al (2007). In addition, some recent molec− ular data appear to support the latter view.…”

Section: Comparisonssupporting

confidence: 59%

Section: Comparisonsmentioning

confidence: 97%

See 1 more Smart Citation

Evidence of Priapulid Scavenging From the Early Cambrian Chengjiang Deposits, Southern China

Han¹,

Zhang²,

Liu³

et al. 2007

PALAIOS

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“…The arthropods are now largely accepted to have arisen via a rather heterogeneous group of lobopods, although the exact root is far from being agreed on (Budd 1996;Zhang & Briggs 2007). In addition to the arthropods, the cycloneuralians have come under some scrutiny, especially since the description of stem-group scalidophoran embryos from the Lower Cambrian (Budd 2001a;Dong et al 2004;Donoghue et al 2006;Maas et al 2007). Nevertheless, the intriguing question of what sort of animal the last common ancestor of the ecdysozoans was like (Budd 2001b) remains currently unanswered at least from the fossil record, although the suspicion that the earliest lobopods such as Aysheaia (Whittington 1978) are more or less priapulids on legs is not one that is easily shaken off (Dzik & Krumbiegel 1989).…”

Section: Fossil Evidence For the Origin Of Animals: The State Of Playmentioning

confidence: 99%

The earliest fossil record of the animals and its significance

Budd

2008

Phil. Trans. R. Soc. B

108

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The fossil record of the earliest animals has been enlivened in recent years by a series of spectacular discoveries, including embryos, from the Ediacaran to the Cambrian, but many issues, not least of dating and interpretation, remain controversial. In particular, aspects of taphonomy of the earliest fossils require careful consideration before pronouncements about their affinities. Nevertheless, a reasonable case can now be made for the extension of the fossil record of at least basal animals (sponges and perhaps cnidarians) to a period of time significantly before the beginning of the Cambrian. The Cambrian explosion itself still seems to represent the arrival of the bilaterians, and many new fossils in recent years have added significant data on the origin of the three major bilaterian clades. Why animals appear so late in the fossil record is still unclear, but the recent trend to embrace rising oxygen levels as being the proximate cause remains unproven and may even involve a degree of circularity.

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“…1D), exclusively of marine animals living in sand and soft mud (Ruppert et al, 2004). They first appeared in the Early Cambrian and were dominant animals in the endobenthic community both in the Lower Cambrian Maotianshan Shale Huang, 2004a,b;Maas et al, 2007;Dornbos and Chen, 2008) and Middle Cambrian Burgess Shale fauna (Conway Morris, 1977), and are comprised of at least 11 species in Maotianshan Shale (Huang, 2006) and 3 species in Burgess Shale (Conway Morris, 1979). The body plan as exemplified by Cambrian adult priapulids is characterized by having an elongated body that is divided into a large trunk with an anterior introvert, and one or two caudal appendages ( Fig.…”

mentioning

confidence: 99%

The sudden appearance of diverse animal body plansduring the Cambrian explosion

Chen¹

2009

Int. J. Dev. Biol.

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Beautifully preserved organisms from the Lower Cambrian Maotianshan Shale in central Yunnan, southern China, document the sudden appearance of diverse metazoan body plans at phylum or subphylum levels, which were either short-lived or have continued to the present day. These 530 million year old fossil representatives of living animal groups provide us with unique insight into the foundations of living animal groups at their evolutionary roots. Among these diverse animal groups, many are conservative, changing very little since the Early Cambrian. Others, especially Panarthropoda (superphylum), however, evolved rapidly, with origination of novel body plans representing different evolutionary stages one after another in a very short geological period of Early Cambrian time. These nested body plans portray a novel big picture of pararthropod evolution as a progression of step-wise changes both in the head and the appendages. The evolution of the pararthropods displays how the head/trunk boundary progressively shifted to the posterior, and how the simple annulated soft uniramous appendages progressively changed into stalked eyes in the first head appendages, into whip-like sensorial and grasping organs in the second appendage, and into jointed and biramous bipartite limbs in the post-antennal appendages. Haikouella is one of most remarkable fossils representing the origin body plan of Cristozoa, or «crest animals» (procraniates+craniates). The anatomy of Early Cambrian crest animals, including Haikouella and Yunnanozoon, contributes to novel understanding and discussion for the origins of the vertebrate brain, neural crest cells, branchial system and vertebrae. KEY WORDS: body plan, head segmentation, evolution, appendage, brain, Cambrian explosionThe incredible 580 million year old Weng'an biota from Precambrian Doushantuo phosphate deposits reveals the presence of diverse metazoans including sponges (Li et la., 1998), cnidarians 2002;Xiao et al., 2000 and and bilateral animals and related embryos Chen et al., 2006). Animal body organization patterns, especially in bilaterian animals, were diverse until the Early Cambrian . However, early animals were mostly soft-bodied, and never left their mark on the fossil record except for the rare deposits of exceptional preservation, which preserve both soft tissues and the articulated complete skeletons.The exceptionally preserved Cambrian fossils, especially the beautifully preserved fossils from the Lower Cambrian Maotianshan Shale deposits in areas (Chengjiang, and Haikou and Anning) adjacent to Kunming, China, document a sudden appearance of a diversity of metazoans that were not only Int. J. Dev. Biol. 53: 733-751 (2009) doi: 10.1387/ijdb.072513cj diverse at the species level, consisting of over 100 species, but that show morphological disparity among them that provides the first manifest evidence for the appearance of the diversity of metaozoan body plans, which were either short-lived or have continued to the present day (Hou et al., 2004;.Body plan (or...

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Maotianshan-Shale nemathelminths — Morphology, biology, and the phylogeny of Nemathelminthes

Cited by 86 publications

References 43 publications

Evidence of Priapulid Scavenging From the Early Cambrian Chengjiang Deposits, Southern China

Evidence of Priapulid Scavenging From the Early Cambrian Chengjiang Deposits, Southern China

The earliest fossil record of the animals and its significance

The sudden appearance of diverse animal body plansduring the Cambrian explosion

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