-
Cambrian period
During the Cambrian Period there was an 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. -
Ordovician period
Life was still primarily found underwater, but there were more different species than ever before. The trilobites did not die out with the mass extinction at the end of the Cambrian period. Trilobites lived The Rise of The CephalopodsNew animal forms developed, too. The cephalopods became the dominant predators of this period. Cephalopods are a group of mollusks that are related to octopus and squid.The orthoceras was a straight-shelled cephalopod that lived in the largest open end of its shell. -
Silurian period
During this time, continental landmasses were low and sea levels were rising. This meant rich shallow sea ecosystems with new ecological niches. Silurian fossils show evidence of extensive reef building and the first signs that life beginning to colonize the new estuary, fresh water and terrestrial ecosystems. -
Devonian period
It is often known as the “Age of Fishes,” although significant events also happened in the evolution of plants, the first insects and other animals.By the mid-Devonian, the fossil record shows evidence that there were two new groups of fish that had true bones, teeth, swim bladders and gills.The Lobe-finned fish were more common during the Devonian than the Ray fins, but largely died out. -
Carboniferous period
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.New plants developed in the warm, humid climate and swampy conditions of this period. -
Permian peirod
The Permian period represented the last gasp for much early prehistoric life. The period, and the Paleozoic era, came to a calamitous close 251 million years ago, marking a biological dividing line that few animals crossed. The Permian extinction—the worst extinction event in the planet's history—is estimated to have wiped out more than 90 percent of all marine species and 70 percent of land animals. -
Triassic period
The Mesozoic Era is often known as the Age of Reptiles. Two groups of animals survived the Permian Extinction: Therapsids, which were mammal-like reptiles, and the more reptilian Archosaurs. The first mammals evolved near the end of the Triassic Period from the nearly extinct Therapsids. -
Jurassic period
Ferns and gingkoes, complete with roots and vascular tissue to move water and nutrients and a spore system of reproduction, were the dominant plants of the early Jurassic.. Reptiles were the dominant animal life forms during the Jurassic Period. Early mammals were mostly very small herbivores or insectivores and were not in competition with the larger reptiles. Marine life of the Jurassic Period was also highly diversified. The largest marine carnivores were the Plesiosaurs. -
Cretaceous period
One of the hallmarks of the Cretaceous Period was the development and radiation of the flowering plants. During the Cretaceous Period, birds replaced the Pterosaurs in the air. About 65 million years ago, nearly all large vertebrates and many tropical invertebrates became extinct in what was clearly a geological, climatic and biological event with worldwide consequences. -
Tertiary period
By the middle of the tertiary, during the Oligocene Epoch, the climate began to cool. This cooling trend continued and by the Pliocene Epoch an ice age had begun.he 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. During the Pliocene the first hominids appeared; these were our human ancestors!. -
Quaternary period
The entire Quaternary Period, including the present, is referred to as an ice age. 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 and dire wolves.It is clear that Homo sapiens and Homo neanderthalensis were contemporaries for a time.
