FAUNAL EVOLUTION IN LATE TRIASSIC, NONMARINE
HUNT, Adrian P., Mesalands Dinosaur Museum, Mesa
Technical College, Tucumcari, NM 88401
LUCAS, Spencer G., NM Museum of Natural History and
Science, Albuquerque, NM 87104
HUBER, Phillip, Dept. of Education, University of
Bridgeport, Bridgeport, CT 06601
LOCKLEY, Martin G., Dept. of Geology, University of
Colorado at Denver, Denver. CO 80227
The Late Triassic encompasses one of the greatest faunal turnovers
among nonmarine tetrapods. During this time interval several
significant groups originated (e. g., mammals, dinosaurs and
pterosaurs), others became extinct (primitive crurotarsans =
"thecodonts") and others suffered a significant decline (non-
lissamphibian temnospondyls and non-mammalian therapsids).
Late Carnian (early Tuvalian) faunas are the most
cosmopolitan as evidenced by the distribution of the parasuchian
Paleorhinus and the metoposaurid Buettneria. Late Tuvalian and
Norian faunas exhibit increased provinciality (e.g., distribution of
aetosaur Paratypothorax). By the late Norian-Rhaetian there are no
cosmopolitan body-fossil taxa although ichnotaxa, which probably
represent Linnaean families, such as "Pseudotetrasauropus" have
broad ranges. Early Jurassic faunas are again cosmopolitan.
Three broad biogeographic provinces existed in the Carnian-
Norian: northern Laurasia (Europe, Greenland, ?northeastern North
America), southern Laurasia and northern Gondwana (Western North
America, Morocco) and southern Gondwana (India, South Africa,
Dinosaurs are rare in late Carnian faunas and become more
numerous and speciose in the Norian and Rhaetian. Taphonomic data
indicates that dinosaurs were ecologically separated from "typical"
semi-aquatic, crurotarsan-dominated faunas and lived in drier
environments. There is a prosauropod acme zone in the late Norian-
There is no evidence for a major end-Carnian extinction.
Extinction, or near extinction, of several groups (dicynodonts,
rhynchosaurs, trilophosaurs) was insignificant in comparison to the
diversity of those that were unaffected. The end-Rhaetian event is
essentially the extinction of primitive crurotarsans, many of which
were associated with semi-aquatic communities.
go back to "MEETING SCHEDULE"