Lab Exam Flashcards
Turtle shell composition
Carapace (50 bony plates mostly ribs), plastron, bridge. Carpace and plastron are covered in horny keratin. Adds to strength of shell etc.
Lepidosauria
Scaly. Tuatara, snakes, lizards. United by Caudal Anatomy.
Rhynchocephalia: tuatara
Sphenodon lives on 18 islands. 2 premaxillary enlarged teeth (autapomorphy). Males are bigger. Can switch between male and female. 3rd eye, different skull.
Squamata
Hemipenes. Spiny penises. Ones on snakes are covered.
Chameleon
Laterally compresed, great vision. Fused toes.
Anoles
Native to Americas, flappy chins, good toe pads, almost all change color.
Geckos
Lost temporal arches, can move heads freely. Mostly nocturnal. Light sensitive. Well developed subdigital lamellae (also called scansors), which allow them to climb smooth surfaces. Tubercles.
Toxicofera: Serpentes
Wide ventral scales.
Sensing heat: Loreal pits
Between eyes and nose. Have temperature sensitive cells to detect changes as small as 0.03.
Pits in boas vs pit vipers
pitvipers possess one large pit organ on either side of the head, between the eye and the nostril (loreal pits), while boas and pythons have three or more comparatively smaller pits lining the upper and sometimes the lower lip, in or between the scales (labial pits). Those of the pitvipers are the more advanced, having a suspended sensory membrane as opposed to a simple pit structure.
External ears
Lizards, amphisbaenian
Holes in skull
number of holes (temporal fenestrae) present on either side of the skull, behind the
eye. The diapsids (two temporal fenestrae on each side of the skull) have traditionally
included the lepidosaurs and archosaurs. Turtles (Testudines) are now thought to have
secondarily closed their temporal fenestrae, and have been reclassified as diapsids, though
their position relative to archosaurs and lepidosaurs remains controversial. The function of
temporal fenestrae is to allow for the expansion of jaw muscles. The function of other
fenestrae (such as antorbital fenestrae in archosaurs) is more debated.
Anapsid
Dont have temporal opening
Crocs
migration of the internal nares to the back of the mouth
behind the large fleshy flap from the back of the tongue and the secondary palate (palatal
valve: autapomorphy) that allows an individual to completely close off its mouth from its
throat and a complete secondary palate
Alligatoridae
lower teeth fit into pits in the upper jaw so you
can’t see the lower teeth when the mouth is closed (you do see the upper teeth); snout
relatively broad
Gavialidae
– long thin snout with lots of teeth; fish eater. Consists of only
two extant species, the “true” gharial (Gavialis gangeticus) and “false” gharial (Tomistoma
schlegelii).
Crocodylidae
–The pair of 4th teeth in the lower jaw lie in notches outside the
upper jaw so you can see them when the mouth is closed. Snout narrower than
Alligatoridae, but broader than Gavialidae
Croc head
keratinized epidermal scales and a dermal layer in
which osteoderms (bony plates) are embedded (around the forelegs and along the back,
although some species also have belly osteoderms). The osteoderms are interconnected
like joints, adding to the strength of the armour while allowing for some mobility. The
crocodylian head, however, is a completely different story. It is not covered by scales, but
rather by a layer of extremely thick epidermis fortified with twice the normal amount of b
keratin that cracks extensively during development. In essence the embryo’s face/jaws
grow faster than its skin, which causes the skin to crack. Each
dot is called a dome pressure receptor
