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Kambrian period 570-500NYA
The climate at the beginning of this period was cold, but over time the climate in all parts of the Earth grew warmer. This made the seas a good place for many species to live. The continents were still forming.
explosion of life forms. Most of these were in the water. Many animals with no backbones lived in the shallow seas. These animals were invertebrates.most fearsome hunters in the Cambrian seas was the Anomalocaris.Cambrian were mostly simple, one-celled algae. -
Ordvician asted almost 45 million years, beginning 488.3 million years ago and ending 443.7 million years ago.
a rich variety of marine life flourished in the vast seas and the first primitive plants began to appear on land—before the second largest mass extinction of all time ended the period.Most of the world's landmasses came together to create the supercontinent of Gondwana, Earth's climate was warm and wet, with sea levels rising as much as 1,970 feet (600 few complete fossils that have been found suggest they were finned, eel-like creatures with large eyes for locatingmeters) above those of today. -
Silurian 7%
Much of the landmass that would become western North America was under a shallow ocean for much of the Silurian Period. These shallow waters enabled sunlight to penetrate, and marine animals underwent rapid differentiation. Silurian fossils show extensive coral reefs built from tabulate and horn corals with calcium carbonate skeletons. In the early Silurian, a class of jawless fish, Agnatha, similar to modern hagfish and lampreys, was most common. is earliest fish known to have developed jaws. -
Devonian 9% 1954
The plant-covered lands made a good home for the first wingless insects and spiders. Even a primitive vertebrate, the tetrapod or four-footed vertebrate, developed the ability to live outside the water and move on land.. These fish were called Ostracoderms. Their name means “shell-skins.” These reef building work of the sponges and corals went on through the Paleozoic Era. They built some of the largest reefs in the world. Invertebrateanimals appear in rock from the late Silurian.Fish with Jaws. -
Carboniferous
The trilobite was less and less common during the early Carboniferous.The placoderms, or armored fish, that had ruled the Devonian seas, became extinct with the end of the Devonian period. They were replaced with fish that looked more like our modern fish. Many species of fish and sharks developed during the late Carboniferous.huge trees and ferns died, they fell into waters that did not have bacteria to help them decompose. These plants formed peat beds. Eventually, with the weight of layers. -
Permian
The lobe-finned and spiny fishes that gave rise to the amphibians of the Carboniferous were being replaced by true bony fish. Sharks and rays continued in abundance.mossy plants that depended on spores for reproduction were being replaced by the first seed-bearing plants, the gymnosperms. True bugs, with mouthparts modified for piercing and sucking plant materials, evolved during the Permian. Other new groups included the cicadas and beetles.earliest, most primitive Synapsids were the Pelycosau -
Trassic
The oceans teemed with the coiled-shelled ammonites, mollusks,sea urchins that survived the Permian extinction, were quickly diversifying. first corals appeared, though other reef-building organisms were already present. Giant reptiles such as the dolphin-shaped ichthyosaurs, the long-necked and paddle-finned plesiosaurs preyed on fish and ancient squid. 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 -
Jurassic
The largest marine carnivores were the Plesiosaurs. These carnivorous marine reptiles typically had broad bodies and long necks with four flipper shaped limbs. Ichthyosaurus was a more fish-shaped reptile that was most common in the early Jurassic.Early mammals were mostly very small herbivores or insectivores and were not in competition with the larger reptiles.Adelobasileus, a shrew-like animal,had the differentiated ear, jaw bones of a mammal and dates from the late Triassic.reptiles domiante -
cretaceous
nearly all large vertebrates and many tropical invertebrates became extinct in what was clearly a geological, climatic and biological event with worldwide consequences. birds replaced the Pterosaurs in the air.In the “ground up” hypothesis flight may have evolved from the ability of small Theropods to leap high to grasp prey. Feathers probably evolved from early body coverings whose primary function, at least at first, was thermoregulation. -
Tertiary 11%
extinction event at the close of the Cretaceous Period wiped out the dinosaurs, large reptiles, and many other species. This left room for new animals to develop. The mammals became the dominant animals. With the dinosaurs and other large reptiles gone mammals grew in size, numbers and diversity. The table above shows what mammals came on the scene with each new epoch.During the Pliocene the first hominids appearedalso many large flightless birds that are now extinct -
Quaternary Peroid
referred to as an ice age due to the presence of at least one permanent ice sheet (Antarctica); however, the Pleistocene Epoch was generally much drier and colder than the present time. These steppes supported enormous herbivores such as mammoth, mastodon, giant bison and woolly rhinoceros, which were well adapted to the cold. These animals were preyed upon by equally large carnivores such as saber toothed cats, cave bears, dire wolves.first hypothesis is that the species originated in Africa
