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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]
Fossilized skeleton of the Middle Triassic amphibian Mastodonsaurus †Mastodonsaurus †Mastodonsaurus durus – type locality for species †Orthodactylus †Orthodactylus howelli – type locality for species †Otozoum – tentative report †Otozoum minus †Pagiophyllum †Palaeoctonus †Palaeoctonus appalachianus †Palaeosaurus
Several authors have suggested that terrestrial eggs evolved from amphibian eggs laid on land to avoid predation on the eggs and competition from other labyrinthodonts. [62] [63] The amniote egg would necessarily have had to evolve from one with an anamniote structure, as those found in fish and modern amphibians. [59]
Synapsids (precursors to mammals) separate from sauropsids (reptiles) in late Carboniferous. [88] 305 Ma The Carboniferous rainforest collapse occurs, causing a minor extinction event, as well as paving the way for amniotes to become dominant over amphibians and seed plants over ferns and lycophytes. First diapsid reptiles (e.g. Petrolacosaurus ...
Lissamphibia (extant amphibians) retain many features of early amphibians but they have only four digits (caecilians have none). 330-300 Ma Hylonomus. From amphibians came the first amniotes: Hylonomus, a primitive reptile, is the earliest amniote known.
Pelycosaur (/ ˈ p ɛ l ɪ k ə ˌ s ɔːr / PEL-ih-kə-sor) [1] is an older term for basal or primitive Late Paleozoic synapsids, excluding the therapsids and their descendants. Previously, the term mammal-like reptile had been used, [2] and pelycosaur was considered an order, but this is now thought to be incorrect and outdated.
This list of mammals in Pennsylvania consists of 66 species currently believed to occur wild in the state. This excludes feral domesticated species such as feral cats and dogs . Several species recently lived wild in Pennsylvania, but are now extirpated (locally, but not globally, extinct).
This list of the Paleozoic life of Pennsylvania contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Pennsylvania and are between 538.8 and 252.17 million years of age.