Variation in the shape and mechanical performance of the lower jaws in ceratopsid dinosaurs (Ornithischia, Ceratopsia).

Ceratopsidae represents a group of quadrupedal herbivorous dinosaurs that inhabited western North America and eastern Asia during the Late Cretaceous. Although horns and frills of the cranium are highly variable across species, the lower jaw historically has been considered to be relatively conservative in morphology. Here, the lower jaws from 58 specimens representing 21 ceratopsoid taxa were sampled, using geometric morphometrics and 2D finite element analysis (FEA) to explore differences in morphology and mechanical performance across Ceratopsoidea (the clade including Ceratopsidae, Turanoceratops and Zuniceratops).

Digging adaptation in insectivorous subterranean eutherians. The enigma of Mesoscalops montanensis unveiled by geometric morphometrics and finite element analysis.

The enigmatic Early Miocene fossorial mammal Mesoscalops montanensis shows one of the most modified humeri among terrestrial mammals. It has been suggested, on qualitative considerations, that this species has no extant homologues for humerus kinematics and that, functionally, the closest extant group is represented by Chrysochloridae. We combine here three dimensional geometric morphometrics, finite element analysis and phylogenetic comparative methods to explore the shape and mechanical stress states of Mesoscalops montanensis as well as of extant and extinct Talpidae and Chrysochloridae under realistic digging simulations.

Males Resemble Females: Re-Evaluating Sexual Dimorphism in Protoceratops andrewsi (Neoceratopsia, Protoceratopsidae).

Background: Protoceratops andrewsi (Neoceratopsia, Protoceratopsidae) is a well-known dinosaur from the Upper Cretaceous of Mongolia. Some previous workers hypothesized sexual dimorphism in the cranial shape of this taxon, using qualitative and quantitative observations. In particular, width and height of the frill as well as the development of a nasal horn have been hypothesized as potentially sexually dimorphic.

Morphological integration and functional modularity in the crocodilian skull.

We explored the morphological organization of the skull within Crocodylidae, analyzing functional and phylogenetic interactions between its 2 constituent functional modules: the rostrum and the postrostrum. We used geometric morphometrics to identify localized shape changes, focusing on the differences between the major clades of the crown-group Crocodylia: Alligatoridae and Crocodylidae. We used published bite performance data to correlate rostral function with postrostral morphology.

Is torosaurus triceratops? Geometric morphometric evidence of late maastrichtian ceratopsid dinosaurs.

Background: Recent assessments of morphological changes in the frill during ontogeny hypothesized that the late Maastrichtian horned dinosaur Torosaurus represents the "old adult" of Triceratops, although acceptance of this finding has been disputed on several lines of evidence.

Methodology/principal Findings: Examining the cranial morphology of 28 skulls in lateral view and 36 squamosals of Nedoceratops hatcheri, Triceratops spp. and Torosaurus spp.

Bite of the cats: relationships between functional integration and mechanical performance as revealed by mandible geometry.

Cat-like carnivorous mammals represent a relatively homogeneous group of species whose morphology appears constrained by exclusive adaptations for meat eating. We present the most comprehensive data set of extant and extinct cat-like species to test for evolutionary transformations in size, shape and mechanical performance, that is, von Mises stress and surface traction, of the mandible. Size and shape were both quantified by means of geometric morphometrics, whereas mechanical performance was assessed applying finite element models to 2D geometry of the mandible.

The Gavialis-Tomistoma debate: the contribution of skull ontogenetic allometry and growth trajectories to the study of crocodylian relationships.

The phylogenetic placement of Tomistoma and Gavialis crocodiles depends largely upon whether molecular or morphological data are utilized. Molecular analyses consider them as sister taxa, whereas morphological/paleontological analyses set Gavialis apart from Tomistoma and other crocodylian species. Here skull allometric trajectories of Tomistoma and Gavialis were contrasted with those of two longirostral crocodylian taxa, Crocodylus acutus and Mecistops cataphractus, to examine similarities in growth trajectories in light of this phylogenetic controversy.