Redescription of the Skull of Coloradisaurus brevis, (Dinosauria, Sauropodomorpha) from the Late Triassic of Argentina
Publicado por Leonardo Filippi en 6:51
Cecilia
Apaldetti, Ricardo N. Martinez, Diego Pol and Thibaud Souter
The cranial anatomy of
the basal sauropodomorph Coloradisaurus brevis from the upper
levels of the Norian Los Colorados
Formation is here redescribed and comparisons made based on the holotype
skull and mandible. Coloradisaurus brevis is diagnosed by most of the features
proposed in the original description and an additional set of autapomorphies,
such as presence of circular upper temporal fenestrae, laminae on the
ventrolateral margins of a ventral fossa of the basisphenoid and on the ventral
region of the parasphenoid, and tab-like medial process at the posteromedial
end of the mandible. Coloradisaurus is placed within Massospondylidae, as in recent analyses.
This position is supported primarily by postcranial characters, but some
cranial features identified in this study provide additional evidence
supporting this position (e.g., jugal contribution to the antorbital fenestra,
frontal proportionately longer than nasals). However, the cranial anatomy of
Coloradisaurus also bears several characters that are shared with plateosaurids
(e.g., low mandibular articulation, broad maxillary wall on the anterior margin
of antorbital fossa, broad prefrontals, projection of infratemporal fenestra behind
the orbit, stepped braincase, robust septum between basipterygoid processes).
Thus, Coloradisaurus is interpreted as a massospondylid that has
convergently acquired characters that are otherwise only known in
plateosaurids, highlighting the conflicting pattern of character distribution
among basal sauropodomorphs.
Cecilia Apaldetti,
Ricardo N. Martinez, Diego Pol & Thibaud Souter (2014) Redescription of the
Skull of Coloradisaurus brevis
(Dinosauria, Sauropodomorpha) from the Late Triassic Los Colorados Formation of
the Ischigualasto-Villa Union Basin, northwestern Argentina, Journal of
Vertebrate Paleontology, 34:5, 1113-1132.
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