Lecture 13 - 2.0 Flashcards
Sauropsids: Archosaurs (4):
- Crocodilians
- Pterosaurs
- Dinosaurs
- Ornithischinas
- Saurischians - Birds
Archosaurs: Crocodilians (3):
- Aquatic and predatory lifestyle
- Ability to regulate body temp by lying with its mouth open
- Four chambered heart
- Temp of nest determines offspring sex (seen in other vertebrates)
Archosaurs: Crocodilians (Aquatic and Predatory Lifestyle) (3):
- Nostrils, eyes and ears on top of head
- Eyelid is transparent
- Bony flaps in throat
Archosaurs: Pterosaurs (4):
- First vertebrate group to evolve powered flight
- Used membranous wings supported by elongated forelimb
- Early forms had long tails and elongated forelimb
- Later forms lost tail and teeth; had projection at back of head
Archosaurs: Dinosaurs (2 Groups):
- Distinguished by the structue of the pelvic girdle
1. Saurischia = girdle bones radiate outward from the centre (Omnivours)
2. Ornithischia = ischium and part of the pubis are parallel and project backwards (herbivores)
Archosaurs: Birds (Aves) (4):
- Likely evolved from theropod dinosurs
- Basic avian design is highly adaptable and their distinguished characteristic is feathers
- Flyers gain access to flying prey, escape from non-flying predators and have unrivaled migratory abilities
- Locomotion is Varied - wings exclusively to swim or not used
Origin of Flight (Classical Idea: Arboreal Hypothesis)
Gliding from tree to tree
Origin of Flight (Classical Idea: Cursorial Hypothesis)
Running start and lifted off the ground for insect foraging
Origin of Flight (Modern Flight: Pouncing Proavis Model)
Specialized in ambush from elevated sites, used hindlimb in leaping attacks
Origin of Flight (Modern Flight: Wing-Assisted Incline Running):
Use wings to scale inclined objects and trees
Can the Modern Species be Synthesized for the Modern Hypothesis? (Y/N)
Yes
Skeletal Adaptations in Birds (4):
- Skull
- Neck
- Backbone
- Pelvic girdle fused with synsacrum
Skeletal Adaptations in Birds (Skull):
Reduced number of bones, thinner bones; no teeth (beak) to reduce weight
Skeletal Adaptations in Birds (Neck (2)):
- Exceptionally flexible, compensate for the ‘loss’ of forelimbs
- Heterocoelous cervical vertebrae
Skeletal Adaptations in Birds (Backbone)
Very rigid to minimize the number of muscles needed to maintain streamlined body during flight; thereby reducing energy consumption
Skeletal Adaptations in Birds (Pelvic Girdle Fused with Synsacrum):
Bipedal; no symphysis (pelvic bones not fused) so large outlet for massive eggs
Synsacrum Modifications:
Fusion of sacral vertebrae to pelvic girdle allows for rigidity and support of hindlimbs
Sternum Modifications:
Ossified and well pronounced keel (carina) to provide attachment for flight muscles
Integument of Sauropsids
(Reptiles) (3):
- Relatively few glands - dry integument
- Gland produce poisons, pheromones as signals for sex, identity, navigation
- Well developed epidermal keratinized (horny) scales (scutes)
Well developed epidermal keratinized (horny) scales (scutes) Aspects (reptiles) (4):
- Continuous folds of epidermis
- SHed regularly in lizards and snakes
- Protection and desiccation
- Locomotion (snakes)
Integument of Sauropsids (Birds) (2):
- Single large gland (uropygial gland) produces oily secretion for transfer of feathers (waterproofing)
- Have numerous epidermal derivatives
Have numerous epidermal derivatives (In Birds) (4):
- Scales in places without feathers (legs)
- Claws at the ends of digits
- Beaks often include tooth-like protuberances (not ‘true’ dermal teeth)
- Feathers for thermoregulation, locomotion, and attraction of mates
