In this paper, we address the problem of recovering the camera radial distortion coefficients from one image. The approach that we propose uses a special kind of snakes called radial distortion snakes. Radial distortion snakes behave like conventional deformable contours, except that their behavior are globally connected via a consistent model of image radial distortion. Experiments show that r...

Relationships between the major lineages of snakes are assessed based on a phylogenetic analysis of the most extensive phenotypic data set to date (212 osteological, 48 soft anatomical, and three ecological characters). The marine, limbed Cretaceous snakes Pachyrhachis and Haasiophis emerge as the most primitive snakes: characters proposed to unite them with advanced snakes (macrostomatans) are...

TRPA1 is a calcium ion channel protein recently identified as the infrared receptor in pit organ-containing snakes. Therefore, understanding the molecular evolution of TRPA1 may help to illuminate the origin of "heat vision" in snakes and reveal the molecular mechanism of infrared sensitivity for TRPA1. To this end, we sequenced the infrared sensory gene TRPA1 in 24 snake species, representing ...

22 Traditional explanations for the evolution of high orbital convergence and stereoscopic vision in 23 primates have focused on how stereopsis might have aided early primates in foraging or 24 locomoting in an arboreal environment. It has recently been suggested that predation risk by 25 constricting snakes was the selective force which favored the evolution of orbital convergence in 26 early ...

We performed field experiments to examine brown tree snake (Boiga irregularis) attraction to carrion. These snakes were attracted to carrion and entered traps baited with dead mice as readily as traps baited with live mice. Using the cues arising from both live and dead prey, we examined the relative importance of visual and chemical cues to brown tree snakes. With carrion lures, chemical cues ...

Hormonal and behavioral responses to a stressor depend on many factors, including the influence of other hormones. We examined the role of melatonin in modulating hormonal responses to capture stress in two populations of male garter snakes, Thamnophis sirtalis. Studies of red-sided (T. sirtalis parietalis) and red-spotted (T. sirtalis concinnus) garter snakes were conducted in the field with f...

Arboreal environments pose many functional challenges for animal locomotion including fitting within narrow spaces, balancing on cylindrical surfaces, moving on inclines, and moving around branches that obstruct a straight path. Many species of snakes are arboreal and their elongate, flexible bodies appear well-suited to meet many of these demands, but the effects of arboreal habitat structure ...

The renal sexual segment (RSS) of immature Northern and Diamondback Water Snakes and Red-Sided Garter Snakes exhibited varying responses to testosterone or 17beta-estradiol. In both male and female water snakes, kidney mass was not a reliable indicator of hormone treatment, whereas tubule diameter, epithelial height and number of sexual granules responded to hormone treatment. In male water sna...

—We describe a new technique for tracking snakes that is an alternative to radio-transmitters and thread trails. We coated the bodies of three species of garter snakes (Thamnophis) in fluorescent powder, then followed and marked the trails with a UV light at night. The use of a UV light allowed us to see very detailed paths left by the snakes. This technique was effective for snakes > 10 g and ...

Elapid coral snakes of the Neotropics and Nearctic are highly venomous and frequently brightly coloured, with rings of red, yellow (or white), and black encircling the body (Roze 1996). Predators typically avoid tricolour ringed patterns (Brodie 1993; Brodie & Janzen 1995; Hinman et al. 1997; Pfennig et al. 2001; Harper & Pfennig 2007; Pfennig et al. 2007; Harper & Pfennig 2008; Kikuchi & Pfenn...