Dotted lines hypothesizing where groups split on a cladogram for which there is no fossil evidence.
-lower carboniferous of w. Virginia
-long bodied, 40 vertebrae, broad tail, short limbs
-lateral lines indicate aquatic lifestyle
Eucritta that fed on arthropods and lived in the midland valley of Scotland.
megalocephalus, early Carboniferous, lateral line canals, adductor muscles are reconstructed to close the jaws, marginal and palatial teeth, first evidence of depressor mandibulae muscle
Why did vertebrates move to land?
They were probably trying to stay in the water! Lungfishes and other "walking catfishes" today, can survive out of water long enough to leave a drying pond in search of a better water source.
We're a group in the Linnaean classification scheme but were polyphyletic. No longer describes a single related group but reflects the complex enamel of teeth of several amphibian lineages.
Eusthenopteron and pandericthyes (Devonian)
proximal limbs similar to other tetrapods but more fingers and toes.
more obviously a swimmer with weak front arms
more robust possibly could have lifted itself
six toes, ? Fingers
Animals with more than five fingers or toes.
five is not set in stone.
Allow for repetition of body parts or elements.
Period when the continents were joining and most areas of amphibian evolution were tropical
coal forests developing at this time
large fauna identified from scotland including Balenerpeton and Eucritta
Lower Carboniferous (Scotland)
otic notch probably really a spiracle (gill opening to get more oxygen for the brain like in sharks)
itsy bitty forelimbs
Main amphibian group
abundant in Triassic lived into cretaceous
broad skulls adapted for sucking in prey underwater
breathed using buccal pumping by broad mouths and short straight ribs
example of extant amphibian suction feeding
40 families, 170 genera
Upper Carboniferous of nova scotia
broad mid palatial open space (= interptertyoid vacuity)
narrow process anterior from braincase running across vacuity
paired, broad flat anterior vomers
stout arms and legs-strong hip/shoulder girdles
Succeeded rhinesuchids world wide
Skulls may be a meter long
largest among the temnospondyls
0.5-1 meter long
broad skulls with lateral line groves
Erupts and edops
1-2 meters long
a top preditor
Ex. Cacops, most terrestrial amphibians
probably fully terrestrial
Pineal/parietal "eye" opening
lower triassic, long thin snouts-marine
lower permain, long snouted.
possibly gave rise to trematosaurus-gharial-like fish eaters
first with small enough stapes for impedance matching ear which amplifies force of sounds transmitted through air to match to fluid-filled inner ear - force magnified proportional to area of tympanum and stapes footplate
Upper Permian-lower Triassic
medium to large
evolved from eryopoids
Small, poorly ossified external gills
Describes vertebral anatomy but is not A Unified group
no supratemporal bone
no stapedial foramen
cylindrical vertebrae of pleurocentra only
neural arches and centra fuse indistinguishably early in ontogeny
no atlantal intercentrum
largest group of lepospondyls
both aquatic and terrestrial; mainly terrestrial
carboniferous and Permian
ex: panthylus and pelodosotus
newt like with long laterally compressed tails
relatively small, paired limbs
early species have cranial kinesis (lost in diplocaulis)
funky shaped head may have been used to support a longer lateral line system.
appear cloaest to labyrinthodonts
no cranial kinesics and dorsoventrally flattened skulls
palatal fused to braincase
N. Africa, N. America and Europe
Most snakelike and specialized
Up to 230 vertebrae- lack limbs and limb girdles
Mid Jurassic-Miocene of europe
salamander like and confused with them
triangular fused trontals
cervical vertebrae reduced to two fused
(some of the first animals that had differentiated teeth, some of the earliest known herbivores)
jointed skull that allowed flexion during jaw opening
short neck, large vertebrae, flat sided tail-aquatic
600 mm long
active terrestrial animal
midwestern united states and Germany
ex: Kotlassia-russian, broad skulls; piscivorous, terrestrial and aquatic forms both, Permian
Heavy, massive limb girdles, short limbs, heavy vertebrae and ribs
late Carboniferous and early Permina
Herbivore-short, blunt teeth for chopping
Modern amphibians-4000 species-4 clades
albanerpetontids-extinct-basal outgroup for amphibia
anurans-salientia (frogs and toads)
urodeles (newts and salamanders)
Gymniophonians (limbless caecilians)
All have bicuspid pedicellate teeth
arose from temnospondyls
frogs and salamders=sister group (Batrachia)
Most components of vertebrae evolved separately and fused in different patterns among different vertebrate groups.
vertebral structure varies in accordance with need to resist forces.
differential directional forces depend on movements and postures of individual species.
Evolution of differences in pectoral girdles
Pectoral girdles evolved to simpler forms, loss of bones and fusions.
reorientation for different limb functions
pelvic girdles mirror this
Basic organization of manus and pes
early ability to identify bones of limbs
homologous to those of later tetrapods
Locomotion changes on land
Locomotion in early transition onto land used lateral undulation
limbs strengthen to push animal forward
Balance must be maintained once body is lifted from ground
Limb reorientation for quadrupedal walking in early tetrapods
Rotation of limbs, especially distal elements, for increased efficiency with limb reoriented to be placed under main axis of body
How does locomotion change
from later undulation alone to later undulation with movement of individual limbs in a specific sequence
tripod of support must be maintained within center of gravity for balance
difficulties in ID of species
In many cases, interpretation and identification of elements has been difficult.
Often animals are initially described as one species, and later changed to be included in different groups.
Different growth stages may affect species identification.
Lower Carboniferous of W. Virginia
long bodied, 40 vertebrae, broad tail, short limbs
lateral lines indicates aquatic lifestyle
Mammals are pleural centrum dominant
Legs under body vs sprawled locomotion with limbs to the outside