Ferns appeared, as did the first trees. At the same time, the first vertebrates were colonizing the land. These vertebrates were called tetrapods , and they were widely diverse: Their appearance ranged from lizardlike to snakelike, and their size ranged from 4 inches 10 cm long to 16 feet 5 meters long, according to a study released in in the Journal of Anatomy. As the tetrapods took over, they had company: The Devonian Period saw the rise of the first land-living arthropods, including the earliest ancestors of spiders.
Life continued its march in the late Paleozoic. The Carboniferous Period, which lasted from about million years ago to million years ago, answered the question, "Which came first — the chicken or the egg? Long before birds evolved, tetrapods began laying eggs on land for the first time during this period, allowing them to break away from an amphibious lifestyle.
Trilobites were fading as fish became more diverse. The ancestors of conifers appeared, and dragonflies ruled the skies. Tetrapods were becoming more specialized, and two new groups of animals evolved. The first were marine reptiles, including lizards and snakes.
The second were the archosaurs, which would give rise to crocodiles, dinosaurs and birds. Terrestrial leaf and insect fossils have been found.
Mass extinction occurred at the end of this period. Pennsylvanian subperiod million years ago to million years ago : Cycles of shallow seas, swamps, and river channels resulted in deposits of limestone, sandstone, and shale that are found at the surface in eastern Kansas.
In southeast Kansas, rivers and streams flowed into the sea during the Pennsylvanian and deposited sand and other sediments in estuaries and deltas.
The resulting thick sandstones form the Chautauqua Hills. Likewise, the shales and sandstones deposited during the early Pennsylvanian subperiod form the Cherokee Lowlands of southeast Kansas and are the second oldest rocks found at the surface in the state. Folding and faulting of rock layers during this period created the Central Kansas Uplift, a mountain ridge now deeply buried.
Pennsylvanian marine animal fossils include brachiopods, bryozoans, coral, crinoids, mollusks, and one-cell fusilinids. Jurassic: Triassic: Permian: Pennsylvanian: Mississippian: Devonian: Silurian: Ordovician: Cambrian: to Employees in the News.
Emergency Management. Survey Manual. Life was primitive during the Paleozoic and included many invertebrates animals without backbones and the earliest fish and amphibians. Paleozoic signposts are colored green. The images show the art on the Trek Through Time signposts. The name of each period is a link to the entire plaque installed on the Trek Through Time. Artist's rendition of life in the Cambrian Sea.
For a long time, these fossils were the oldest scientists had found. What animals were on Earth during the Cambrian Period?
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