BIOL 2003 Lecture Notes - Lecture 21: Marine Iguana, Squamata, Lepidosauria
Lepidosauria
November 23, 2015
Lepidosauria: tuataras and squamates (lizards and snakes) ***Squamates and Sphenodon
• Tuatara: outgroup to squamates **endangered
• Not specialized but earliest offshoot
Typical Lizard: small, mostly insectivorous
• Anolis lizard (new world)
• Like Lacerta (old world)
• Skull is modified, long tails
• Radiated on continental masses
Squamate Subgroups:
• Geckos – large group of insectivorous lizards
o Many have specialized foot pads *can stick upside down
o Gecko feet: dry adhesion
▪ Never wears off *no mucous
▪ Pads stick via a series of ridges that conform to surface irregularities to create
effective VDW forces over atomic distances
o Uses arrays of seate, and spatulae
• Skinks: 1200 species
o No visible neck
o Smooth, shiny scales
o Small legs are sometimes lost
o Similar to snake with very different skull – useful for swimming (sand swimmer are
legless)
• Chameleons
o Tongue projection
o Eyes move is opposite directions
o Grasp branches with mitten hands and feet
• Marine Iguana: only marine lizard!
o Found in Galapagos islands
o Eat macroalgae off of rocks
• Carnivorous Snakes (no vegetarians)
o Constrict or strike and transmit venom to eat prey
o Limited range in body form
o Relatively similar skulls
o Tree Snakes: long and thin
o 1001 uses for ribs
▪ hood of cobra: supported by ribs
▪ spread ribs, flattened body is shaped like aerofoil to glide
o Amphisibaenid – legless lizard; not a snake!; function=burrowing, skull pushed into soil
*horizontal segmentation instead of vertical
• Monitor Lizards: ancestral group?
o Forked tongue
Key to Snake Success: Single largest group of lizards
• Kinetic skull – can eat things larger than it’s head
o Special muscles move upper jaw out to the sides and down
o Can reposition jaw to get a better grip on prey
o Jaw is connected by elasic ligament so it can spread far apart
o Jaw has various joints that move it out to the side
o Many bones are mobile
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