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Oviraptorosaur tail forms and functions
From: Ben Creisler
A new online paper:
W. Scott Persons, IV, Philip J. Currie, and Mark A. Norell
Oviraptorosaur tail forms and functions.
Acta Palaeontologica Polonica (in press)
Oviraptorosaur caudal osteology is unique among theropods and is
characterized by posteriorly persistent and exceptionally wide
transverse processes, anteroposteriorly short centra, and a high
degree of flexibility across the pre-pygostyle vertebral series.
Three-dimensional digital muscle reconstructions reveal that, while
oviraptorosaur tails were reduced in length relative to the tails of
other theropods, they were muscularly robust. Despite overall caudal
length reduction, the relative size of the M. caudofemoralis in most
oviraptorosaurs was comparable with those of other non-avian
theropods. The discovery of a second Nomingia specimen with a
pygostyle confirms that the fused terminal vertebrae of the type
specimen were not an abnormality. New evidence shows that pygostyles
were also present in the oviraptorosaurs Citipati and Conchoraptor.
Based on the observed osteological morphology and inferred muscle
morphology, along with the recognition that many members of the group
probably sported broad tail-feather fans, it is postulated that
oviraptorosaur tails were uniquely adapted to serve as dynamic
intraspecific display structures. Similarities, including a reduced
vertebral series and a terminal pygostyle, between the tails of
oviraptorosaurs and the tails of theropods widely accepted as basal
members of the Avialae, appear to be convergences.