New Conchoraptor paper

[Guy Leahy <xrciseguy@sbcglobal.net>]

Naturwissenschaften. 2007 May 25; [Epub ahead of
print]
Cranial pneumatization and auditory perceptions of the
oviraptorid dinosaur Conchoraptor gracilis (Theropoda,
Maniraptora) from the Late Cretaceous of Mongolia.

Kundrát M, Janáèek J.
Redpath Museum-Biology Department, McGill University,
859 Sherbrooke Street West, Montreal, Quebec, H3A 2K6,
Canada, martin@martinkundrat.sk.

The distribution of air-filled structures in the
craniofacial and neurocranial bones of the oviraptorid
ZPAL MgD-I/95, discovered at the Hermiin Tsav
locality, Mongolia, is restored. Based on the complete
obliteration of most of the cranial sutures, the
specimen is identified as an adult individual of
Conchoraptor gracilis Barsbold 1986. Except for the
orbitosphenoids and epipterygoids, the preserved bones
of the neurocranium are hollow. Three types of
tympanic recess are present in Conchoraptor, a
characteristic shared with troodontids,
dromaeosaurids, and avian theropods. The contralateral
middle ear cavities are interconnected by the
supraencephalic pathway that passes through the dorsal
tympanic recesses, the posterodorsal prootic sinuses
and the parietal sinus. The spatial arrangements of
the middle ear cavity and a derived neurocranial
pneumatic system in Conchoraptor indicate enhancements
of acoustic perception in the lower-frequency
registers and of auditory directionality. We further
speculate that this improvement of binaural hearing
could be explained as an adaptation required for
accurate detection of prey and/or predators under
conditions of low illumination. The other potentially
pneumatic structures of the Conchoraptor cranium
include (1) recessus-like irregularities on the dorsal
surface of the nasal and frontal bones (a putative
oviraptorid synapomorphy; pos); (2) a subotic recess;
(3) a sub-condylar recess; and (4) a posterior
condylar recess (pos).