A Norian lagerpetid dinosauromorph from the Quebrada del Barro Formation, Argentina
Publicado por Leonardo Filippi en 13:34
Ricardo
N. Martínez, Cecilia Apaldetti, Gustavo A. Correa, And Diego Abelín
The early evolution of
Ornithodira the clade including 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 the poor fossil record
restricted to specimens known from the Ladinian Chañares Formation in
Argentina. Over 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 survived at least well
into the Norian. Although Norian non-dinosaurian dinosauromorphs have been
reported from several regions around the world, the only known Norian non-dinosauriform
dinosauromorphs Dromomeron romeri Irmis, Nesbitt, Padian, Smith, Turner, Woody,
and Downs and Dromomeron gregorii Nesbitt, Irmis, Parker, Smith, Turner, and
Rowe 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 new information on the basal radiation of
Dinosauromorpha constituting the first record of a Norian association of
dinosaurs with non-dinosauriform dinosauromorphs outside North America.
Ricardo N. Martínez,
Cecilia Apaldetti, Gustavo A. Correa, Diego Abelín (2016). A Norian lagerpetid
dinosauromorph from the Quebrada del Barro Formation, northwestern Argentina.
Ameghiniana 53: 1–13.
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