Deuterostomes part 3 Flashcards
amniotes
- monophyletic clade within the tetrapod clade
- no larval stage (direct development)
key adaptations to live a fully terrestrial life..
- amniotic egg
- tough,dry skin
amniotic egg
- embryo surrounded by 4 tissue membranes
- covered by a shell that slows water loss, but allows gas exchange
- amniote embryos develop in a self contained aqueous environment
- can be fully terrestrial
amniotic egg have 4 extraembryonic membranes
- amniotic protects embryo from sudden movement
- yolk sac encloses nutrients for developing embryo
- chorion and allantois changes gas exchange and excretion of wastes
tough, dry skin
- skin cells filled with keratin, lipids- mostly impermeable to water
- decreased vulnerability of dehydration/ desiccation
reptilian synapomorphy
-outer layer of skin forms scales or feathers made of keratin
function of feathers/scales
- to reduce desiccation
- to protect against abrasion
- in locomotion in some
reptiles
- all reptiles have internal fertilization
- most deposit amniotic egg on land (oviparous)
- females retains eggs, gives birth to juveniles (ovoviviparous)
thermoregulation
- reptiles are ectothermic
- cant regulate body temperature
- maintain body temperature by absorbing heat from the environment
- behavioral thermoregulation
extinct groups of reptiles in both marine and terrestrial habitats
- plesiosaurs: marine predators
- pterosaurs: flying predators
- parareptiles: large herbivores
- Ichthyosaurs: marine predators
three clades of extant reptiles
- turtles
- archosaurs
- lepidosaurs
turtles
- inhabit freshwater, marine and terrestrial habitats
- all lay eggs on land
- body plan changed little in 200 my
- bony, box like shell
- shell of dorsal and ventral plates fused to vertebrae (dorsally) and ribs (ventrally)
Lepidosaurs
- tuatarans
- squamates
- snakes and lizards
tuatarans
- lizard like in appearance
- only 2 extant species
- both found only on islands off the coast of New Zealand
Squamates
- snakes and lizards
- both have overlapping scales that protect against desiccation and abrasion
- scales are a reptilian synapomorphy
lizards
- most with limbs, some legless species
- most are small
- mostly insectivores, some herbivores, some larger predators such as the komodo dragon
snakes
- limbless squamates (some with vestigial limbs)
- streamlined body for efficient burrowing, climbing, swimming
- all carnivorous, some with toxin glands that immobilize, kill, partially digest prey, many others are constrictors
Archosaurs
-crocodilians and birds
relationship between crocodiles and birds
- gene sequences
- circulation and respiration
- both have 4 chambered heart, unidirectional air flow through lungs
- degreee of parental care
crocodilians
- 20 species including crocodiles, alligators, caimans
- all semi aquatic, but lay eggs on land, or in floating piles of vegetation
- all pare predatory archosaurs
dinosaurs
- very diverse groups of archosaurs
- carnivores and herbivores, quadrupeds and bipeds,tiny and enormous
therapod dinosaurs
- all bipedal, with 3 fingered feet and hands
- some therapods made feather like structures out of keratin
archaeopteryx
- an extinct bird like therapod dinosaur
- fossils show traits of both feathered dinosaurs and birds
therapods that are still alive
- birds!
- only surviving clades of dinosaurs
- all have feathers, provide substantial insulation, used for locomotion, camouflage, and in courtship displays
- feathers also increase surface area to forelimbs, generate lift for flight
features of birds important for flight
- hollow bones, with internal struts
- reduces weight, while maintaining strength
- sternum forms broad surface area for pectoral (flight) muscles to attach
- furcula (wishbone) strengthens the thoraic skeleton
- flight metabolically expensive and bird lungs are complex in forms
- air pumped through lungs unidirectional (not in and out)
- maximize input of oxygen
- air pumped through lungs unidirectional (not in and out)
birds lack teeth
- teeth lost over evolutionary time
- inferred from presence of teeth in other archosaurs
- birds eat a diversity of plants/ animals including seeds, fruits, insects, other vertebrates, and carrion
paleognaths
- flightless or weak flying birds
- emu, kiwis, ostrich, cassowary
neognaths
much more diverse clade, which includes the rest of the living birds
synapsid
one distinct opening in skull behind the eye
