AMPHIBIA

Two stages: many Paleozoic-Triassic groups and 3 modern groups
  with no claear connections from the ancient to the modern

modifications for support, feeding, respiration, locomotion, water balance, senses, reproduction

Beginnings: Late Devonian Ichthyostega
head support; opercle and gill loss in adults
shoulder girdle separate from skull
vert neural arches with zygapophyses
loss of fins except caudal
cranial kinesis mostly lost
limbs with flexible elbow and knee joints; 
humerus, radius, ulna, femur, tibia, fibula, fingers and toes
Panderichthys, Russia, head only

2 Palezoic grades
Labyrinthodonts (e.g. Ichthyostega near the base of the tree)
  later forms have otic notch for tympanum
  2 part occipital condyle
  infolded tooth enamel
  fangs in second row of teeth on palate
2 groups of Labyrinthodonts
1) Temnospondyls (100+ genera; Miss - Triass; 
     large intercentra (AV), small pleurocentra (postdorsal)
     4 toed manus
          Miss: elongate Greererpeton
          Penn Trimerorhachus
          advanced Temnospondyls (including Stereospondyls)
               Eryopids     \  (TX, Perm, 2m)
               Capitosaurs   \
               Metoposaurs    > examples on exhibit
               Plagiosaurs   /
               Trematosaurs  long snouted, marine
          Branchiosaurs are early growth stages or neotenic

     including Anthracosaurs, possible ancestors to Seymouriamorphs, Diadectes, and reptiles, with
          deep otic notch
          short trunk, well developed limbs
          trend to small, impedence matching stapes
          e.g., Proterogyrinus (primitive, Miss);
          Seymouria (TX, Perm, large, terrestrial, reptilian)
          
2) Lepospondyls
no fangs, no labyrinthine dentine, no otic notch
pleurocentrum in most "husk vertebrae"
single or wide 3-part occipital condyle
e.g. Aistopoda (few; Miss-Perm; long body, small limbs)
     Nectridia (few; Penn-Perm; aquatic, e.g., Diplocaulus)
     Microsauria (Miss-Perm; terrestrial; small with small limbs)
  -->Modern Amphibia (Lissamphibia: Anura, Uodella, Gymnophiona)