FORS2355 Vertebrate Natural History
Lab 4 -- Squamates
September 20, 2021
Class Reptilia
Scales present o Folded areas of the epidermis Functions Resistance to abrasion Defense (e.g., spines) Water loss is not tied to presence of scales. o Lipids in skin
Epiderm
Dermis
Osteoderm Melanophores Flexible hinge
Scale Types
Keeled -- rougher to the touch; overlapping Smooth -- tend to not be overlapping; no raised keel in the center of each scale.
Scale Types Keeled Smooth
Osteoderms - raised layers of bone that develop within the dermis and provide rigidity to the skin. Bone tissue. Example: crocodilians
Squamates
Snakes
3,700+ species Lack eyelids Lack ears
Lizards
More than 6500+ species Have eyelids Have ears
Lepidosauria -- Squamata -- Lizards and Snakes
Squamata Lizards (including amphisbaenians) and snakes Transverse cloacal opening Full body ecdysis (shedding of skin) Tail autotomy (have the ability to drop the tail as a defense mechanism and can regrow). Some lizards have brightly covered tails to deter predators from the major parts of the body.
o Paired hemipenes -- organs that are tucked within the tail and are used for mating. Diagnostic characteristic to compare different species.
Males vs Females
NO MORE THAN 1-3 SUBCAUDALS
FEMALE
CLOACA SEXING PROBE
SEXING PROBE
CLOACA
MALE AT LEAST 9-15 SUBCAUDALS
ENGTH OF
HEMIPENIS POCKE
Cloacal Plate -
Divided or Undivided
Dentition in Snakes
Opisthogylph -- "rear-fanged" o Enlarged, grooved fangs on posterior portion of maxilla (colubrids) Proterogylph o Each maxilla bears a single hollow fang that remains erect (elapids) Solenogylph o Reduced maxilla but hollow fang is erected by rotation of the maxilla
Reproductive Modes
Oviparity -- egg laying (ancestral condi