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Endocranial anatomy of Therizinosauria
From: Ben Creisler
New in PLoS ONE:
Stephan Lautenschlager, Emily J. Rayfield, Perle Altangerel, Lindsay
E. Zanno & Lawrence M. Witmer (2012)
The Endocranial Anatomy of Therizinosauria and Its Implications for
Sensory and Cognitive Function.
PLoS ONE 7(12): e52289.
Therizinosauria is one of the most enigmatic and peculiar clades among
theropod dinosaurs, exhibiting an unusual suite of characters, such as
lanceolate teeth, a rostral rhamphotheca, long manual claws, and a
wide, opisthopubic pelvis. This specialized anatomy has been
associated with a shift in dietary preferences and an adaptation to
herbivory. Despite a large number of discoveries in recent years, the
fossil record for Therizinosauria is still relatively poor, and
cranial remains are particularly rare.
Based on computed tomographic (CT) scanning of the nearly complete and
articulated skull of Erlikosaurus andrewsi, as well as partial
braincases of two other therizinosaurian taxa, the endocranial anatomy
is reconstructed and described. The wider phylogenetic range of the
described specimens permits the evaluation of sensory and cognitive
capabilities of Therizinosauria in an evolutionary context. The
endocranial anatomy reveals a mosaic of plesiomorphic and derived
characters in therizinosaurians. The anatomy of the olfactory
apparatus and the endosseous labyrinth suggests that olfaction,
hearing, and equilibrium were well-developed in therizinosaurians and
might have affected or benefited from an enlarged telencephalon.
This study presents the first appraisal of the evolution of
endocranial anatomy and sensory adaptations in Therizinosauria.
Despite their phylogenetically basal position among maniraptoran
dinosaurs, therizinosaurians had developed the neural pathways for a
well developed sensory repertoire. In particular olfaction and hearing
may have played an important role in foraging, predator evasion,
and/or social complexity.