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Middle Triassic Chañares Formation tetrapod community

From: Ben Creisler

A new paper:

Adriana C. Mancuso, Leandro C. Gaetano, Juan M. Leardi, Fernando
Abdala & Andrea B. Arcucci (2014)
The Chañares Formation: a window to a Middle Triassic tetrapod community.
Lethaia 47(2): 244-265
DOI: 10.1111/let.12055

The Chañares Formation is known worldwide for its diverse and
well-preserved Ladinian non-marine tetrapod assemblage, including a
wide variety of archosauriform reptiles (proterochampsids, early
offshoots of the crocodilian line and dinosaurian precursors) and
synapsids represented by dicynodonts and cynodonts. This tetrapod
record offers an opportunity to evaluate, within a taphonomic context,
the palaeoecology of this Middle Triassic fauna. The taphonomic
analysis of the Chañares assemblage, under precise stratigraphical
control, indicates that it is a good representation of the original
faunal composition allowing us to address the palaeoecological
interactions between its components. Mass estimations and
morphology-based palaeobiological inferences of Chañares tetrapods are
used to reconstruct the trophic structure of the community. Chañares
tetrapod fauna was numerically dominated by middle-sized herbivorous
and small faunivorous cynodonts, whereas middle-sized faunivorous
cynodonts and large dicynodonts were less common. In contrast to the
therapsids, which show a low species-richness and high abundance, the
archosauriforms are less abundant, but are the most taxonomically
diverse group. The large paracrocodylomorphs (estimated body masses
between 350 and 500 kg) are identified as the top predators of the
community, and the traversodontid cynodonts and dicynodonts (estimated
body masses reaching approximately 43 and 360 kg, respectively) are
indentified as the base herbivores of the trophic pyramid. We conclude
that the worldwide faunal composition in the Ladinian reveals two
continental assemblages: an eastern Laurasian assemblage dominated by
temnospondyl amphibians; and a western Gondwanan assemblage dominated
by therapsids but including a wide diversity of archosauriforms.