Lecture 19: Dinosaurs and paleogeography Flashcards
Are vertebraes or intervertebraes more rare
vertebraes
What is Endemism?
Restriction to one area, migration routes may be shut down because of continental separation
What was the temporal distribution?
A new dinosaur genus occurred every 4-8 million years, could be longer if a mass extinction occurs
Ceratopsian Dinosaurs
Relatively complete fossil record, a new species every 1.9 million years, Stegosaurs produced 1 new species every 5.6 million yrs.
What is Minimum Divergence time?
Used as an estimation (based on earliest fossil finds) for fossil completeness, Minimum divergence time used with ceratopsian dinosaurs
Late triassic (231-208)
Time of pangea, a time of heat and aridity and strong seasons and low endemism. Small amount of dinosaurs in comparison to the jurassic and cretaceous
Who was around in the triassic?
therapsids Archosaurs Pterosaurs Early mammals Earliest dinosaurs (231-223ma) e.g., eoraptor
Fossil Localities of the triassic
China and India South Africa- Stromberg series (ancient fluvial system, beautifully preserved therapsids Prosauropod melanorosaurus) Several Localities in Europe South America (argentina) North American -Chinle formation -new mexico, utah and Arizona -Ghost ranch- Coelophysis
Early jurassic (208-178 Ma)
Dinosaurs become more dominant, slow break up of Pangea, no endemism yet
What was around during the jurassic?
Ornithischia (cerapoda, thyreophora) Prosauropods remained, true sauropods developed
Fossil localities of the early jurassic
Asia (china and India)
Africa (south Africa, Zimbabwe, morocco) (footprints and body fossils)
Europe, strata not well preserved
South america (trackways of theropods)
North america (fossils in lake sediments filling rift valleys, in the west fluvial)
Antartica (remains of theropods and large prosauropod)
Middle Jurassic (178-157 ma)
Few sediment sections are preserved, sea level lowstand in early to middle jurassic, time of erosion, gap in dinosaur record, no reflection of abundance
Fossil localities of middle jurassic
Asia (china has most diverse fauna, monolophosaurus and sinraptor)
Africa
Europe (england has footprints and megalosaurus)
South America (chile and argentina)
North America (footprints, ornithischian and theropod teeth, pterosaurs, crocodiles and mammals
Australia (footprints and one sauropod)
Late jurassic (157-145)
Climate warming, sea level rose, tethyan sea continued to widen, North and South America split, endemism, this was the age of dinosaurs. (sauropods became abundant, theropods, turtles, pterosaurs, archaeopteryx and crocodiles)
Fossil localities of the late jurassic
Theropods: -china -india and thailand African tendaguru beds -spectacular sauropods, small ornithopod,primitve stegosaurs and theropods Europe -Solnhofen (compsognathus and archaeopteryx) South america -trackways from chile and argentia
North american (fossil locality) of the late jurassic
Morrison formation
Extensive sedimentary package that was shed from the rocky mountains
rivers, lakes and coastal barrier bars
Fossils from Morrison Formation
Allosaurus Ceratosaurus Diplodocus Apatosaurus ultrasaurus supersaurus seismosaurus eggshells and trackways
Early cretaceous (145-97 ma)
Enhanced tectonic activity, increased greenhouse effect, warmer climate, increased endemism due to increased continental separation
Who Became dominant in the early cretaceous?
Ornithopoda replaced sauropods and stegosaurs as major herbivores
Ankylosaurs
Fossil localities of early cretaceous
Asia: wide distribution -Earliest ceratopsian psittacosaurus Africa (north) -important primitive ornithopods Europe -Wealden fossil beds in southern England South america North america (deinonychus) Australia- fossils indicate connection at the time with gondwana, separation from Antarctica during early tertiary
Late cretaceous (97-65ma)
High sea levels, advanced continental separation, increased endemism, warm climates, cooling trend over the last 30 million years
The late cretaceous had the greatest _____ of dinosaurs
Diversity; tyrannosaurids, duck billed dinosaurs, ceratopsian dinosaurs, pachycephalosauria
Evolution (late cretaceous)
Older taxa remained in south america, new taxa developed in north america, Stegosaurs left before extinction event
Similarities between North america and China
Cladisitc analysis indicates;
North american Fauna developed from china (mongolia)
Land bridge over bering strait
During pleistocene called beringia
