Sauropsid Amniotes Flashcards
What two major components are important to look at when examining the evolution of the turtle’s body plan?
- shell: vertebrae, ribs, osteoderms; scutes: keratin
- position of scapula inside rib cage
What are the two hypotheses about how the turtle’s body plan evolved?
- gradual transformation
- rapid evolution via changes in developmental regulation
Which organisms make up lepidosaurs within the sauropsids?
- tuatara: single extant species
- lizards and snakes
What are the skull adaptations is lizards and snakes?
- loss of temporal bars around fenestrae (lower in lizards, upper and lower in snakes)
- opening of skull transcranial joints across top of skull (front orbit in snakes, rear orbit and back of skull in lizards)
- rotation of quadrate bone about dorsal connection with braincase
Briefly describe the cranial kinesis in lizards. What joints are used?
- equal perpendicular force of jaws on food, less chance of prey escaping
- mesokinetic joint
- streptostylic joint
Briefly describe the cranial kinesis in snakes.
- lower jaw loosely hinged
- sides of mandible come apart, connected only by skin, allows for large prey
- skull and upper jaws moveable
T or F: The loss of limbs is not a successful adaptation
False: this trait has evolved several times, many amniote species are limbless
What is lateral undulation?
- form of limbless locomotion
- moving waves push sideways against contact points
- generates rxn force with fwd component because lateral components cancel
What is concertina movement?
- form of limbless locomotion
- requires energy, used in narrow spaces
- stationary coils wedge animal into place while free body parts move forward
What is sidewinding?
- form of limbless locomotion
- used on sandy soil
- body in contact with 2-3 straight tracts at a time with different segments in succession
- only segments between tracts are moving
What is rectilinear movement?
- form of limbless locomotion
- slow but discreet
- requires specialized muscles progressively lifting and bringing ventral scutes fwd to peg to ground
- body not in contact with ground is moved fwd within distensible skin
What are some features of crocs in the group archosaurs?
- aquatic predators
- sense organs on head, transparent eyelid
- bony flaps in throat allows for eating and breathing simultaneously
- thermoregulate by lying with mouth open
- 4 chambered heart
- nest temp determines offspring sex
What are some features of the pterosaurs within the archosaurs?
- first vert group to evolve powered flight
- membranous wings with elongated forelimb
- some had long tails, while others lost tails and teeth
- later evolved birds and bats
T or F: the two groups of dinosaurs, saurishia & ornithischia, are distinguished by the structure of their pelvic girdle
True
- saurischia: girdle bones radiate outward from centre
- ornithiscia: ischium and pubis parallel and project backwards
Ornithischians, including stegosaurs, triceratops, duck-bills, etc. are ____ (herbivorous/carnivorous)
all herbivorous
What are some adaptations of the big dinosaurs?
- shortened pillar-like limbs for supporting weight
- reduced/shortened wrists/fingers and ankles/toes
- elongated necks, with lighter, longer, and more cervical vertebrae
What are some of the hypotheses for the origin of flight?
Arboreal hyp: gliding between trees
Cursorial hyp: running start and lifted off ground for insect foraging
-new: used wings to scale inclined objects and trees
What are some skeletal adaptations within the birds?
- reduced # and thinner bones within skull-no teeth
- flexible neck, compensate for loss of forelimbs
- rigid backbone minimizes # of muscles for maintaining streamlined body
- pelvic girdle fused with synsacrum
Briefly explain the features of the integument in the reptiles
- few glands, dry
- glands produce poison, pheromones
- epidermal keratinized scales and scutes
Briefly explain the features of the integument of the birds
- single gland: uropygial gland that produces oily secretion to coat feathers
- have some epidermal derivatives: scales where feathers aren’t, claws, beaks, feathers
