How long did the Triassic Period last? The new conditions at the beginning of the Triassic Period paved the way for reptiles to become the dominant animal group. Although dinosaurs appeared in the Triassic Period, they were not to become dominant until the Jurassic Period. Instead it was the fearsome, crocodile-like Pseudosuchians that would rule the Triassic world.
The period that came before the Triassic Period was the Permian Period. This was the last period of the Paleozoic era; with the end of the Permian Period came not just the start of the Triassic Period, but also the start of the Mesozoic Era.
The other periods of the Mesozoic Era are the Jurassic Period, which spanned from Like all of the periods in the Geologic time scale, it corresponds to a certain layer or layers of rock. These fragments gradually settled, accumulated and hardened into rock. The first corals appeared, though other reef-building organisms were already present. Giant reptiles such as the dolphin-shaped ichthyosaurs and the long-necked and paddle-finned plesiosaurs preyed on fish and ancient squid.
The bottom rung of the food chain was filled with microscopic plants called phytoplankton; two of the major groups still in the oceans today first appeared. Frogs, salamanders, crocodiles, turtles, and snakes slunk and slithered on and off the Triassic coast, lakes, and rivers. Pterosaurs, a group of flying reptiles, took to the air. On firm ground, moss, liverwort, and ferns carpeted forests of conifers, ginkgoes, and palm-like cycads. Spiders, scorpions, millipedes, and centipedes thrived.
Grasshoppers appeared. But perhaps the biggest changes came with the evolution of dinosaurs and the first mammals in the late Triassic, starting around million years ago.
One of the earliest true mammals was the three-foot-long one-meter-long Eozostrodon. The shrewlike creature laid eggs but fed its young mother's milk. Among the first dinosaurs was the two-footed carnivore Coelophysis , which grew up to 9 feet 2. It showed up about million years ago.
A few million years later came the The Triassic closed in the same way it began. Something—perhaps a volcanic belch or an asteroid collision—caused another mass extinction. Dinosaurs, however, survived and went on to dominate the Jurassic. All rights reserved. Fleeing Nothosaurs An artist's rendering shows hatchling nothosaurs heading for the safety of water as a hungry but terrestrial Ticinosuchus attacks near a lagoon in ancient Switzerland.
Pangaea By the start of the Triassic, all the Earth's landmasses had coalesced to form Pangaea, a supercontinent shaped like a giant C that straddled the Equator and extended toward the Poles. Triassic Animal Life The oceans teemed with the coiled-shelled ammonites, mollusks, and sea urchins that survived the Permian extinction and were quickly diversifying. Appearance of Mammals But perhaps the biggest changes came with the evolution of dinosaurs and the first mammals in the late Triassic, starting around million years ago.
Share Tweet Email. Read This Next Wild parakeets have taken a liking to London. Article Triassic Period— Triassic age trace fossil of a horseshoe crab Kouphichnium isp. Reptiles were probably derived from an amphibious ancestor during the Pennsylvanian Period. Once established they underwent several evolutionary bursts in which diverse kinds of reptiles occupied a variety of habitats.
Among the most spectacular were the terrestrial dinosaurs, see Jurassic Period —the Golden Age of Dinosaurs. The marine plesiosaurs were formidable hunters of Mesozoic fish. Their limbs were modified into efficient paddles, perfectly adapted for sculling through the water. Though pterosaurs flying reptiles had their origin in the Triassic, they became widespread and varied during the following Jurassic and Cretaceous periods. The pterosaurs had membranous wings like present-day bats.
Unlike bats, however, some of them grew to enormous size, and the front support for the wing was provided by only one extremely long, extended finger. Breakup of Pangaea.
Pangaea began to break apart during the Triassic but dispersed mostly during the Jurassic. Just as the formation of Pangaea influenced geologic and biologic events during the Paleozoic Era, the breakup of this supercontinent profoundly affected geologic and biologic events during the Mesozoic Era. The movement of continents affected ocean circulation and climatic regimes.
Populations became isolated and were brought into contact with other populations, leading to evolutionary changes in the biota. The breakup of Pangaea can be separated into three phases. When Pangaea broke up, the re-formed Gondwana continent was not precisely the same as before Pangaea formed; for example, areas that had been part of Gondwana remained attached to North America, such as the land that became Florida.
Seafloor spreading at divergent plate boundaries along the mid-ocean ridge of the Tethys Ocean, the body of water between Gondwana and Laurasia, caused the movement of the two continents.
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