Mesozoic and Cenozoic Flashcards
Who died at the end of the Triassic? and what big group diversified after that?
96% of marine and terrestrial species animals (The Great Dying). Decreased O2, increased CO2, ocean acidification, and ocean warming. Dinosaurs diversified.
What makes a dinosaur’s pelvis different from the pelvis of other reptiles?
A dinosaur pelvis is different from the pelvis of other reptiles because their pelvis allows them to have an upright stance
Where did amniotes come from? What is a synapsid, anapsid, and diapsid? Which one are we?
Amniotes come from amniotic sacs that allow them to lay their eggs away from water. A synapsid has one fenestrae, a diapsid has two fenestrae, and an anapsid has no fenestrae. Fenestrae are defined as holes in the skull. Humans are synapsids.
Which clade of dinosaurs gave rise to birds?
Theropods
What are the two main clades of dinosaurs and how do we tell them apart based on their pelves?
The two main clades of dinosaurs are Saurischians (lizard dino) and Ornithischia (bird dino). We call to tell them apart because Saurishchians have their pelvis pointing forward and Ornithischia have their pelvis pointing backward.
Why is Archaeopteryx a great example of a transitional fossil? What features were already present in dinosaurs?
It shows a combination of traits that show it shared a common ancestor with both non-avian dinosaurs and birds. The features already present in dinosaurs were feathers; rudimentary and vaned feathers. Some more features include furcula (wishbone), pneumatic bones (hollow bones), and tridactyl foot with a big toe pointing backward.
When did angiosperms appear in the fossil record? When did putative angiosperm fossils appear?
Late Jurassic and early Cretaceous.
What happened at the end of the Cretaceous? How do we know, and how do we spot this event in the fossil record?
At the end of the Cretaceous, the final and last mass extinction occurred killing 76% of species. We know this was caused by a bolide impact. We know this because of the K-Pg boundary characteristics - the rare element of Iridium that is found on asteroids was found in Yucatan, Mexico.
The impact crater is in Mexico
All mass extinctions in the fossil record are spotted because all the taxa disappear.
shocked quartz and microtektites show something hot came in fast
What was the Great American Biotic Interchange and what kind of awesome mammals did North America get out of it?
Migration using land bridges led to the dispersal of mammals (Great American Interchange) and placental mammals from North America to Asia (Bering Land Bridge). Some really awesome mammals are Giant ground sloths, Giant armadillos (glyptodonts), camels, rhinoceros, mammoths, mastodons, and chalicotheres.
What happened at the end of the Pleistocene?
Extinction of mammal megafauna, the arrival of humans, end of glaciation. Some theories on why the mammal megafauna went extinct include hunting, warming climate, and hyper disease.
