Data from: 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 due 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.