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Theropod cranial diversity



From: Ben Creisler
bcreisler@gmail.com


A new online paper in Acta Palaeontologica Polonica:

Christian Foth and Oliver W.M. Rauhut (2012)
Macroevolutionary and morphofunctional patterns in theropod skulls: a
morphometric approach.
Acta Palaeontologica Polonica (advance online publication)
http://dx.doi.org/10.4202/app.2011.0145
http://app.pan.pl/article/item/app20110145.html

Theropod dinosaurs are one of the most remarkable lineages of
terrestrial vertebrates in the Mesozoic, showing high taxonomic and
ecological diversity. We investigate the cranial diversity of
non-avian theropods and some basal birds, using geometric
morphometrics to obtain insights into the evolutionary modifications
of the skull. Theropod skulls mostly vary in the shape of the snout
and length of the postorbital region (PC 1), with further variation in
orbit shape, depth of the postorbital region, and position of the jaw
joint (PC 2 and PC 3). These results indicate that the cranial shape
of theropods is closely correlated with phylogeny and dietary
preference. Skull shapes of non-carnivorous taxa differ significantly
from carnivorous taxa, suggesting that dietary preference affects
skull shape. Furthermore, we found a significant correlation between
the first three PC axes and functional proxies (average maximum stress
and an indicator of skull strength). Interestingly, basal birds occupy
a large area within the morphospace, indicating a high cranial, and
thus also ecological, diversity. However, we could include only a
small number of basal avialan species, because their skulls are
fragile and there are few good skull reconstructions. Taking the known
diversity of basal birds from the Jehol biota into account, the
present result might even underestimate the morphological diversity of
basal avialans.