GEOL 1003 Lecture : The Early Mesozoic Student Notes
Document Summary
Notable for an adaptive radiation marine and terrestrial life following the end-permian ext. Conifers, ginkgos, and reptiles, dominate the dry land. Life of triassic life: bound by mass extinctions. 3 categories of organisms: holdovers from paleozioc-lycopods, seed plants, therapsids(lystrosaurus!) Ray-finned fishes-still diff. from modern:slightly overlapping scales, parts of skeletons still cartilage, simple jaws. Their swim bladder evolved from early lungs, it regulates buoyancy: briefly flourished orgs- stromatolites returned to shallow water because fewer predators. Many grazers had gone extinct. : dominate mesozoic-bivalves, gastropods, conifers, dinosaurs. New reef organisms-hexacorals, dominant reef builder of modern oceans(hexacorals). Marine reptiles-nothosaurs may be the first marine reptiles. Pleesiosaurs- evolved from noth. s, carnivorious organisms. placadonts- blunt-toothed shell crushers. Upper portion of legs extended straight downwardsrather than sprawling out. These descendants are:dinosaurs-bipedal, diff. skull, more highly developed teeth. Endothermic (aka warm-blooded)- organisms whose source of body is thru internal metabolic regulation, usually can maintain temp. at constant level.
