origins Flashcards
sauropsida
ancestor that gave rise to turtles, lizard, snakes, and birds
synapsida
ancestor that gave rise to mammals in the pleozoic
anapsid skull
skull with no temporal hole ex: turtles
synapsid skull
skull with one temporal hole ex: mammals; postorbital and squamosal bones are above the temporal hole
diapsid skull
skull with two temporal holes ex: birds and reptiles; temporal holes lie between the postorbital and squamosal bones
rise of mammals
synapsids -> therapsids -> cynodonts -> Mammalia -> theria
dentary-squamosal jaw articulation
developed to allow more free articulation for transmission of sounds and vibrations; gave rise to the development of the middle ear
therapsids
evolved from a common ancestor with the pelycosaurs; appeared in the middle Permian period; include early cynodonts; have an enlarged temporal opening, sagittal crest, zygomatic arch, and upper canines, deep acetabulum, upright limb posture
synapsids
dominated terrestrial habitats in early Triassic; many went extinct during the Permian extinction; include the pelycosaurs which began thermoregulation
stem mammals
first examples of dentary-squamosal jaw articulation; double rooted cheek teeth; diphyodont with 2 sets of teeth; mammary glands; viviparity giving live birth
theria
modern mammals; have tribosphenic molars; supraspinous fossa on scapula; spiral cochlea allows for improved hearing
eutherians
true mammals
metatherians
marsupials
protherians
monotremes
Mesozoic mammals
herbivores and omnivores; appear similar to rodents; retained cervical ribs; unusual chewing mechanisms; declined in late Paleocene
