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New Temnodontosaurus (Ichthyosauria) species from France



From: Ben Creisler
bcreisler@gmail.com


In the new issue of Palaeontology:


JEREMY E. MARTIN, VALENTIN FISCHER, PEGGY VINCENT & GUILLAUME SUAN (2012)
A longirostrine Temnodontosaurus (Ichthyosauria) with comments on
Early Jurassic ichthyosaur niche partitioning and disparity.
Palaeontology 55 (5): 995–1005
DOI: 10.1111/j.1475-4983.2012.01159.x
http://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2012.01159.x/abstract


We describe an almost complete ichthyosaur skeleton from the middle
Toarcian (Lower Jurassic) of the Beaujolais foothills near Lyon,
France, and assign it to Temnodontosaurus azerguensis sp. nov. This
new species exhibits cranial peculiarities such as a thin, elongated
and possibly edentulous rostrum, as well as a reduced quadrate. These
characters indicate dietary preferences that markedly differ from
other species referred to Temnodontosaurus, a genus previously
considered as the top predator of the Early Jurassic seas. Despite a
conservative postcranial skeleton, we propose that Temnodontosaurus is
one of the most ecologically disparate genera of ichthyosaurs,
including apex predators and now a soft prey longirostrine hunter.
Ammonites collected from the same stratigraphic level as the described
specimen indicate that the new species is somewhat younger (bifrons
ammonite zone) than the most known Toarcian ichthyosaurs and therefore
slightly postdates the interval of severe environmental changes and
marine invertebrate extinctions known as the Toarcian Oceanic Anoxic
Event. The present study therefore raises the question of whether
postcrisis recovery of vertebrate faunas, including the radiation of
Temnodontosaurus into a new ecological niche, may have been a
consequence of marine ecosystem reorganization across this event.