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Dromomeron gigas, new lagerpetid dinosauromorph from Late Triassic of Argentina



Ben Creisler
bcreisler@gmail.com

A new online paper:

Ricardo N. Martínez, Cecilia Apaldetti, Gustavo A. Correa & Diego Abelín (2015)
A Norian lagerpetid dinosauromorph from the Quebrada del Barro
Formation, northwestern Argentina.
Ameghiniana (advance online publication)
doi:10.5710/AMGH.21.06.2015.2894
http://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/1036

The early evolution of Ornithodira, the clade that includes pterosaurs
and dinosaurs, is poorly known. Until a decade ago, the basal
radiation of Dinosauromorpha, the clade including dinosaurs and birds,
was poorly understood because of a scarce of fossil record, which was
restricted to specimens known of the Ladinian Chañares Formation from
Argentina. In the last years the discovery of several non-dinosaurian
dinosauromorphs dramatically expanded this record and also
demonstrated that this group—previously restricted to de Middle
Triassic—persisted at least well into the Norian. Although Norian
non-dinosaurian dinosauromorphs have been reported from several places
around the world, the only known Norian non-dinosauriform
dinosauromorphs—Dromomeron romeri and Dromomeron gregorii—come from
North America. We report here the first record from the Southern
Hemisphere of a non-dinosauriform dinosauromorph, Dromomeron gigas sp.
nov., from the Norian Quebrada del Barro Formation, northwestern
Argentina. A phylogenetic analysis recovers Dromomeron gigas nested
into the monophyletic group Lagerpetidae, and as the sister taxon to
Dromomeron romeri. The inclusion of D. gigas within Lagerpetidae
suggests that body size increased in this lineage over time, as was
previously demonstrated for Dinosauriformes as a whole, and that
lagerpetids reached a larger size than previously thought. Finally,
the new finding provides novel information on the basal radiation of
Dinosauromorpha constituting the first record of a Norian association
of dinosaurs with non-dinosauriform dinosauromorphs outside North
America.