New opabiniid diversifies the weirdest wonders of the euarthropod stem
group.
Abstract
Once considered 'weird wonders' of the Cambrian, the emblematic
Burgess Shale animals Anomalocaris and Opabinia are now recognized as
lower stem-group euarthropods and have provided crucial data for
constraining the polarity of key morphological characters in the
group. Anomalocaris and its relatives (radiodonts) had worldwide
distribution and survived until at least the Devonian. However,
despite intense study, Opabinia remains the only formally described
opabiniid to date. Here we reinterpret a fossil from the Wheeler
Formation of Utah as a new opabiniid, Utaurora comosa nov. gen. et sp.
By visualizing the sample of phylogenetic topologies in treespace, our
results fortify support for the position of U. comosa beyond the nodal
support traditionally applied. Our phylogenetic evidence expands
opabiniids to multiple Cambrian stages. Our results underscore the
power of treespace visualization for resolving imperfectly preserved
fossils and expanding the known diversity and spatio-temporal ranges
within the euarthropod lower stem group.
Open access:
https://royalsocietypublishing.org/doi/10.1098/rspb.2021.2093
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