Article

A Carboniferous Non-Onychophoran Lobopodian Reveals Long-Term Survival of a Cambrian Morphotype

Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, University of Greifswald, Soldmannstrasse 23, 17487 Greifswald, Germany. Electronic address: .
Current Biology (Impact Factor: 9.57). 08/2012; 22(18):1673-5. DOI: 10.1016/j.cub.2012.06.066
Source: PubMed

ABSTRACT

Lobopodians, a nonmonophyletic assemblage of worm-shaped soft-bodied animals most closely related to arthropods, show two major morphotypes: long-legged and short-legged forms. The morphotype with stubby, conical legs has a long evolutionary history, from the early Cambrian [1] through the Carboniferous [2, 3], including the living onychophorans and tardigrades [4-6]. Species with tubular lobopods exceeding the body diameter have been reported exclusively from the Cambrian [7-12]; the three-dimensionally preserved Orstenotubulus evamuellerae from the uppermost middle Cambrian "Orsten" (Sweden) is the youngest long-legged lobopodian reported thus far [8]. Here we describe a new long-legged lobopodian, Carbotubulus waloszeki gen. et sp. nov., from Mazon Creek, Illinois, USA (∼296 million years ago) [13]. This first post-Cambrian long-legged lobopodian extends the range of this morphotype by about 200 million years. The three-dimensionally preserved specimen differs significantly from the associated short-legged form Ilyodes inopinata [2], of which we also present new head details. The discovery of a Carboniferous long-legged lobopodian provides a more striking example of the long-term survival of Cambrian morphotypes than, for example, the occurrence of a Burgess Shale-type biota in the Ordovician of Morocco [14] and dampens the effect of any major extinction of taxa at the end of the middle Cambrian [15, 16].

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    • "Alongside the material described by Thompson and Jones[8]as Helenodora inopinata (FMNH PE 29049 & 29050; Figs. 2 and 3 respectively), seven subsequently discovered specimens were examined, FMNH PE 13966, 33380, 33822, 45049, 49784 (Fig. 4) and ROM 45565 & 47513, alongside illustrations of ROM 47978 presented in Haug et al.[10]. Specimens are housed at the Field Museum, Chicago (FMNH) and the Royal Ontario Museum , Toronto (ROM), and examined while on loan in Leicester with permission from the respective museums. "
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    • "Within the Ecdysozoa, Onychophora is commonly united with Tardigrada and Arthropoda in the clade Panarthropoda, although the exact relationship among these three animal groups remains unresolved (Mayer and Whitington 2009a; Rota-Stabelli et al. 2010; Campbell et al. 2011; Nielsen 2012; Mayer et al. 2013a, 2013b). In contrast to their relatives, the arthropods and tardigrades, the overall anatomy of the onychophoran body has remained largely unchanged since the Early Cambrian and extant onychophorans strikingly resemble the habitus of fossil lobopodians, a non-monophyletic assemblage of stem-group representatives of Panarthropoda, Onychophora, Tardigrada, and/or Arthropoda (e.g., Maas et al. 2007; Ma et al. 2009; Liu et al. 2011; Haug et al. 2012; Ou et al. 2012; Smith and Ortega-Hernández 2014). Herein we provide an outline of our current knowledge about the feeding mechanisms, functional morphology, and elementary composition of the jaws in Onychophora. "
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