Reptiles Flashcards
What set of traits allowed the evolution of a tetrapod without the dependence on water? What are these vertebrates called?
- egg with a shell impermeable to water
These reduced water loss: - skin that is impermeable to water
- kidneys that could excrete concentrated urine
These are called amniotes (after the egg they produce)
What are amniotes eggs like?
Leathery or have calcium shell
This prevents evaporation, but allows O2 and CO2 to diffuse
Contain a lot of yolk allowing the embryo to become relatively advanced before hatching
What are the 4 extra embryonic membranes in amniote eggs?
Amnion - surrounds embryo itself
Yolk sac - surrounds yolk
Chorion -surrounds embryo and yolk sac
Allantois - evolved to store nitrogenous waste and aid gas exchange between embryo and egg surface
What are the main groups of the reptilia?
- Synapsids (mammal like, including ancestors of mammals)
- sauropsids (lizard like)
What are the 2 types of sauropsids?
Anapsids - testudines Dispsids - archosaurs (dinosaurs, crocodiles, birds) - lepidosaurs (lizards, snakes)
What is anapsid synapsid or diapsid?
Relates to number of temporal fenestra
- anapsid (no holes) testudines
- synapsid (one hole) mammals
- diapsid (two holes) dinosaurs, lizards snakes crocs birds
What is the early amniote lineage that diversified 360-290mya?
Reptiles (not actually a class, a paraphyletic group)
What is ovo-viviparity?
When the egg doesn’t have a shell and is kept inside the females body until they hatch, some reptiles
What is reptiles skin covered in?
Ketatinised scales that reduce water loss
What is the new finding about the origins of mammals and reptiles?
They are sister groups, rather than mammals being derived from reptiles
What are the 2 subdivision of dinosauria?
Saurischians
-diplodocus
- velociraptor, trex birds
Ornithischians
Why are ornithischians called that?
Because their pelvis is bird like, but DID NOT give rise to the birds
What lineage of the saurischians did birds evolve from?
Therapods
What are the archosaurs?
‘Old lizards’
Only extant group are crocodiles
Tropical and warm temperate environments
Most of time in water but build nests on land
What are the testudines?
Turtles, tortoises and terrapins
Shell - carapace (dorsal) and plastron (ventral)
What are the 2 groups of testudines?
Cryptodires - tortoises turtles and terrapins - retract head vertically Pleurodires - matamata - retract head horizontally
What is different about testudines vertebral column and ribs?
Fused to carapace
Do testudines have diaphragm ventilation
Yes
Where are testudines limb girdles
Inside shell
What determines sex?
Temperature of brood, cool for males, warm for females
What marine lineages of diapsid reptiles are there? (All extinct)
Plesiosaurs - ribbon reptiles
Ichthyosaurs - fish reptiles
What are the terrestrial lineages?
Lepidosaurs (all living diapsid reptiles in this lineage)
- squamata (lizards and snakes)
- tuatara
What are tuataras?
Sister group of lizards, 2 species, endemic to new Zealand
What are included in the Squamata?
Lizards
Snakes
Amphisbaenians
What do snakes specialise in?
Locomotion
Prey capture
Swallowing
What ecological types of snakes are there?
Fossorial (burrowing)
Epigean (soils surface)
Aquatic
What are the consequences of diameter reduction
- left lung reduced or absent
- gall bladder posterior to liver
- right kidney anterior to left
- gonads offset
What locomotory types in snakes are there?
- lateral undulation: S movement of body pushing against ground
- rectilinear: movement of scales, only in straight line
- concertina: S shape moves through body
- side winding: allows snake to have little contact with hot sand
In what ways are snakes specialised for eating?
- skull with 8 flexible links
- each side can move independent of the other
- constriction
- venom (all snakes)
What are the 4 morphologies of snake teeth
- aglyphous: ancestral, no specialisation, sharp backward pointing teeth
- opisthotlyphous: bAck fanged, one or two enlarged teeth near rear of maxilla
- proteroglyphous: hollow fangs on front of maxilla, permanently erect (so limit to length), short teeth behind
- solenoglyphous: only teeth on maxilla are long hollow fangs, maxilla rotates to allow jaw closure
