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The evolution of the digestive system has formed a significant influence in mammal evolution. With the emergence of mammals, the digestive system was modified in a variety of ways depending on the animal's diet. For example, cats and most carnivores have simple large intestines, while the horse as a herbivore has a voluminous large intestine. [127]
Local mammals diversified significantly during the Jurassic. The Morrison Formation is the best source of Jurassic mammal fossils in North America. [67] Local dinosaurs included the ornithopod Camptosaurus, the sauropods Apatosaurus and Diplodocus, and the theropod Allosaurus. [68]
c. 45 Ma – Camels evolve in North America. c. 40 Ma – Age of the Catarrhini parvorder; first canines evolve. Lepidopteran insects become recognizable. Gastornis goes extinct. Basilosaurus evolves. c. 37 Ma – First Nimravids. c. 33.9 Ma – End of Eocene, start of Oligocene epoch. c. 35 Ma – Grasslands first appear.
Rapid dominance of conifers and ginkgos in high latitudes, along with mammals becoming the dominant species. First psammobiid bivalves. Earliest rodents. Rapid diversification in ants. 63 Ma Evolution of the creodonts, an important group of meat-eating (carnivorous) mammals. 62 Ma Evolution of the first penguins. 60 Ma
The Mesozoic era followed and the dinosaurs began their rise to dominance, spreading into the country before Pangaea split up. During the latter Jurassic Morrison Formation dinosaurs lived in the western states. During the Cretaceous, the Gulf of Mexico expanded until it split North America in half. Plesiosaurs and mosasaurs swam in its waters.
“For over 100 million years when dinosaurs were the dominant predators, mammals were generally small, nocturnal, and short-lived.” The pressure to stay alive eliminated the genes needed for ...
Fossils from a newly discovered species of mammal in Colorado may offer clues into how life rebounded after Earth’s last mass extinction that killed off the dinosaurs, researchers say.
Like the strepsirrhine adapiforms, omomyids were diverse and ranged throughout Eurasia and North America. The phylogeny of omomyids, tarsiers, and simians is currently unknown. For many years, it was assumed that primates had first evolved in Africa, and this assumption and the excavations that resulted from it yielded many early simian fossils ...