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Arenysuchus, new Cretaceous crocodylian from Spain



From: Ben Creisler
bh480@scn.org

Also new in PLoS ONE:

Puértolas E, Canudo JI, Cruzado-Caballero P (2011).
A New Crocodylian from the Late Maastrichtian of Spain: Implications for
the Initial Radiation of Crocodyloids. 
PLoS ONE 6(6): e20011. 
doi:10.1371/journal.pone.0020011
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0020011

Background
The earliest crocodylians are known primarily from the Late Cretaceous of
North America and Europe. The representatives of Gavialoidea and
Alligatoroidea are known in the Late Cretaceous of both continents, yet the
biogeographic origins of Crocodyloidea are poorly understood. Up to now,
only one representative of this clade has been known from the Late
Cretaceous, the basal crocodyloid Prodiplocynodon from the Maastrichtian of
North America.

Methodology/Principal Findings
The fossil studied is a skull collected from sandstones in the lower part
of the Tremp Formation, in Chron C30n, dated at −67.6 to 65.5 Ma
(late Maastrichtian), in Arén (Huesca, Spain). It is located in a
continuous section that contains the K/P boundary, in which the dinosaur
faunas closest to the K/P boundary in Europe have been described, including
Arenysaurus ardevoli and Blasisaurus canudoi. Phylogenetic analysis places
the new taxon, Arenysuchus gascabadiolorum, at the base of Crocodyloidea.

Conclusions/Significance
The new taxon is the oldest crocodyloid representative in Eurasia.
Crocodyloidea had previously only been known from the Palaeogene onwards in
this part of Laurasia. Phylogenetically, Arenysuchus gascabadiolorum is
situated at the base of the first radiation of crocodyloids that occurred
in the late Maastrichtian, shedding light on this part of the cladogram.
The presence of basal crocodyloids at the end of the Cretaceous both in
North America and Europe provides new evidence of the faunal exchange via
the Thulean Land Bridge during the Maastrichtian.





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