Glossary of Herpetological Terms

Anterior:
Towards the front, or towards the head of the animal.
Carapace:
The carapace is the top part of the shell.
A smooth posterior margin of the carapace.
(Photo by J. Andrews)
A toothed posterior margin of the carapace.
(Photo by J. Andrews)
Cranial kinesis:
The movement of skull bones relative to each other. The upper jaw in snakes and some lizards can move away from the brain case to allow ingestion of large prey. See also mandibular liberation.
Dorsolateral ridges:
The presence or absence of a dorsolateral ridge can be very helpful in the identification of a frog. The ridge is a fold of skin beginning behind the eye and extending part or all of the way to the rear legs on both sides.
(Photo by E. Talmage)
Ectotherm:
Doesn’t generate its own body heat; receiving its heat from external sources. Snakes, turtles, lizards, frogs and salamanders are ectotherms.
Herptile:
a reptile or amphibian.
Mandibular liberation:
The state of having the two lower mandibles not fused together at the front of the mouth; a feature of snakes. This allows the mandibles to stretch apart, allowing the snake to swallow prey larger than than its head. See also cranial kinesis.
Ophiophagus:
Snake-eater. Few snakes specialize in eating other snakes.
Plastron:
The plastron is the underside of the shell.
(Photo by C. Fichtel)
Posterior:
Towards the back, or towards the tail of the animal.
Scales:
keeled or smooth
Keeled scales have a ridge along the centerline of the scale.
Smooth scales do not have a ridge.
(Photo by J. Andrews)
Scute:
A single plate or scale on a turtle’s shell.
Tympanum:
The tympanum is the eardrum of a frog and in some species it can be seen very clearly. In the green-faced frogs (American Bullfrog, Green Frog, and Mink Frog) the size of the tympanum relative to the eye can be used to determine the sex of the animal. The males have tympana that are noticeably larger than their eyes. The female’s tympana are about the same size as their eyes.
Male tympanum
Female tympanum
(Photo of male frog by E. Talmage; photo of female frog by J. Andrews)