Regionalization of the vertebral column and its correlation with heart position in snakes: Implications for evolutionary pathways and morphological diversification.

Spinal regionalization has important implications for the evolution of vertebrate body plans. We determined the variation in the number and morphology of vertebrae across the vertebral column (i.e.

Macroevolution in axial morphospace: innovations accompanying the transition to marine environments in elapid snakes.

Sea snakes in the clade (Elapidae) show exceptional body shape variation along a continuum from similar forebody and hindbody girths, to dramatically reduced girths of the forebody relative to hindbody. The latter is associated with specializations on burrowing prey. This variation underpins high sympatric diversity and species richness and is not shared by other marine (or terrestrial) snakes.

Ontogenetic prey size selection in snakes: predator size and functional limitations to handling minimum prey sizes.

As body size increases, some predators eliminate small prey from their diet exhibiting an ontogenetic shift toward larger prey. In contrast, some predators show a telescoping pattern of prey size in which both large and small prey are consumed with increasing predator size. To explore a functional explanation for the two feeding patterns, I examined feeding effort as both handling time and number of upper jaw movements during ingestion of fish of consistent size.

Allometry of skull morphology, gape size and ingestion performance in the banded watersnake (Nerodia fasciata) feeding on two types of prey.

Small body size imposes limitations on the feeding capabilities of juveniles, particularly in species that consume their prey whole. It has been hypothesized that juveniles exhibit exceptional performance measures to compensate for their small size. However, few studies have examined whether juveniles have better feeding performance relative to adults and investigations of snake feeding ontogeny have not shown enhanced performance in smaller snakes.

Gape size, its morphological basis, and the validity of gape indices in western diamond-backed rattlesnakes (Crotalus atrox).

Maximum gape is important to the ecology and evolution of many vertebrates, particularly gape-limited predators, because it can restrict the sizes and shapes of prey that can be eaten. Although many cranial elements probably contribute to gape, it is typically estimated from jaw length or jaw width, or occasionally from a combination of these two measures. We measured maximum gape directly for 18 individuals of the western diamond-backed rattlesnake, Crotalus atrox.

Comparison of cranial form and function in association with diet in natricine snakes.

The skull of squamates has many functions, with food acquisition and ingestion being paramount. Snakes vary interspecifically in the frequency, size, and types of prey that are consumed. Natural selection should favor phenotypes that minimize the costs of energy acquisition; therefore, trophic morphology should reflect a snake's primary prey type to enhance some aspect of feeding performance.