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Alioramus (Theropoda) braincase anatomy
From: Ben Creisler
A new monograph available in BioOne.
The AMNH site has not listed the open access version yet.
Gabe S. Bever, Stephen L. Brusatte, Thomas D. Carr, Xing Xu, Amy M.
Balanoff, Mark A. Norell (2013)
The Braincase Anatomy of the Late Cretaceous Dinosaur Alioramus
Bulletin of the American Museum of Natural History 376 :1-72
The late Cretaceous tyrannosaurid Alioramus altai is known from a
single specimen whose articulated braincase exhibits a nearly unique
combination of preservational quality, subadult stage of growth, and
morphological complexity. We use a detailed physical preparation
combined with high-resolution computed tomography to provide an
expanded description of this braincase that includes details of the
neurocranium and its dermal roof, pneumatic recesses and sinuses,
cranial endocast, and inner ear cavities. A few notable features
include a highly developed rostral tympanic recess marked by three
pneumatic fenestrae, a highly pneumatic paroccipital process with both
rostral and caudal pneumatic foramina, a prootic fossa housing
external foramina for the trigeminal and facial nerves, a
well-developed superficial lamina of the prootic, an expanded
vestibular cavity, and an osseous labyrinth that is plesiomorphic in
appearance. These observations, set within the currently available
comparative context, elucidate numerous neuroanatomical
transformations within Tyrannosauroidea and clarify where more data
and work are needed. We expand the discussion for the 21 characters
from the neurocranium utilized in a recent revision of tyrannosauroid
phylogeny, including a listing of which tyrannosauroid taxa can be
scored for the primitive and derived states of each character.