Lesson 9 Flashcards
crown tetropods
- classified as the nearest living ancestor of all living tetropods
- have fewer than or equal to 5 digits
- have the presence of an occipital condyle
- originally – all tetrapods were thought to be carniverous
if you look at exant lissamphibia –> no adults eat plants
what is the purpose of an occipital condyle
like the ball and socket – it enables up and down motion
- aquatic fish do not have this and can’t move their heads up and down
amniotes
- we share a more recent common ancestor with a lizard than has to a salamander
(amniotic eggs sac) - having this amniotic egg stopped the dependance of water for reproduction
- have waterproof skin
- find at least 2 sacral divisions for fossil amniotes
- lateral phalanges of pterigoids
- an astralagus
key derivations of amniotes
- having an astralagus (ankle joint)
- having an amniotic sac
roamers gap
- gap in the carboniferous period (gap in tetrapod fossil record)
- very few terrestial rock outcrops
- as a result - early tetrapods are not really known
temnospondyli
- range broadly in size from cm to the size of aligators
- have aquatic larvae
^^^ and most were semiaquartic
early stereosponduli
- presence of sturdy zygapopheses
- interpterygoid vacuity
- lived in lowland swamps – compared to crocodiles
importance of sturdy zygapopheses
greatly resist torsion and other forms of vending
interpteryoid vacuity
- big opening in skull
- 2 occipital condyles
disaurophoydia
- includes batracia (frogs and salamanders)
basal amniote skull
paired dermal bones in skull
- gonna really form the basics for formation of phenestrae
^^^^ which is the hole inside the skull through which muscles pass
hylonomus
- extinct
- early amniote
- reveals the 4 regions of vertebral column quite well
basic amniote character
- lateral flange of pterygoid
- the second vertebra forms a unique vertebra (axis) first one is the atlas
- ankle mesotarsal joint
- separation of axial musculator and appendicular musculature
- at least 2 sacral vertebrae
- lateral flange of pterygoid
- important origin for muscle
- for a greater body size – it helps to have a good jaw action for catching prey
- the second vertebra forms a unique vertebra (axis) first one is the atlas
process that articulates (dens) enables site of side to side movement
ankle mesotarsal joint
thought to be associated with the new skill of feet and to be used for locomotion
– ^^^ prior — feet and hands were more like holdfass
albumen (amniotic egg)
- water in the sac
- provides shock absorption