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Theriosuchus (atoposaurid crocodylomorph) from Middle Jurassic of Scotland (free pdf)



Ben Creisler
bcreisler@gmail.com


A new paper in open access:


Mark T. Young, Jonathan P. Tennant, Stephen L. Brusatte, Thomas J.
Challands, Nicholas C. Fraser, Neil D. L. Clark and Dugald A. Ross
(2015)
The first definitive Middle Jurassic atoposaurid (Crocodylomorpha,
Neosuchia), and a discussion on the genus Theriosuchus.
Zoological Journal of the Linnean Society (advance online publication)
DOI: 10.1111/zoj.12315
http://onlinelibrary.wiley.com/doi/10.1111/zoj.12315/abstract

Free pdf:
http://onlinelibrary.wiley.com/doi/10.1111/zoj.12315/pdf


Atoposaurids were a clade of semiaquatic crocodyliforms known from the
Late Jurassic to the latest Cretaceous. Tentative remains from Europe,
Morocco, and Madagascar may extend their range into the Middle
Jurassic. Here we report the first unambiguous Middle Jurassic (late
Bajocian–Bathonian) atoposaurid: an anterior dentary from the Isle of
Skye, Scotland, UK. A comprehensive review of atoposaurid specimens
demonstrates that this dentary can be referred to Theriosuchus based
on several derived characters, and differs from the five previously
recognized species within this genus. Despite several diagnostic
features, we conservatively refer it to Theriosuchus sp., pending the
discovery of more complete material. As the oldest known definitively
diagnostic atoposaurid, this discovery indicates that the oldest
members of this group were small-bodied, had heterodont dentition, and
were most likely widespread components of European faunas. Our review
of mandibular and dental features in atoposaurids not only allows us
to present a revised diagnosis of Theriosuchus, but also reveals a
great amount of variability within this genus, and indicates that
there are currently five valid species that can be differentiated by
unique combinations of dental characteristics. This variability can be
included in future broad-scale cladistics analyses of atoposaurids and
closely related crocodyliforms, which promise to help untangle the
complicated taxonomy and evolutionary history of Atoposauridae.