Onychophoran-like musculature in a phosphatized Cambrian lobopodian.
The restricted, exclusively terrestrial distribution of modern Onychophora contrasts strikingly with the rich diversity of onychophoran-like fossils preserved in marine Cambrian Lagerstätten The transition from these early forebears to the modern onychophoran body plan is poorly constrained, in part owing to the absence of fossils preserving details of the soft anatomy. Here, we report muscle tissue in a new early Cambrian (Stage 3) lobopodian, Tritonychus phanerosarkus gen. et sp. nov., preserved in the Orsten fashion by three-dimensional replication in phosphate. This first report of Palaeozoic onychophoran musculature establishes peripheral musculature as a characteristic of the ancestral panarthropod, but documents an unexpected muscular configuration. Phylogenetic analysis reconstructs T. phanerosarkus as one of a few members of the main onychophoran lineage-which was as rare and as cryptic in the Cambrian period as it is today.
Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, People's Republic of China xgzhang@ynu.edu.cn.
Xi-Guang
http://orcid.org/0000-0003-4697-0531
XG
Zhang
Department of Earth Sciences, Durham University, Durham, DH1 3LE, UK.
Martin R
http://orcid.org/0000-0001-5660-1727
MR
Smith
Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, People's Republic of China.
Jie
J
Yang
Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, People's Republic of China.
Jin-Bo
JB
Hou
Cambrian Stage 3; evolution; lobopodians; muscle; phylogenetics; taphonomy
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