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Exactly why the trilobites became extinct is not clear; with repeated extinction events (often followed by apparent recovery) throughout the trilobite fossil record, a combination of causes is likely. After the extinction event at the end of the Devonian period, what trilobite diversity remained was bottlenecked into the order Proetida.
However, pinpointing the extinction of these different land reptile groups is difficult, as the last stage of the Triassic, the Rhaetian, and the first stage of the Jurassic, the Hettangian, each have few records of large land animals; some paleontologists have considered only phytosaurs and procolophonids to have become extinct at the Triassic ...
Trilobites are an extinct group of ancient marine Arthropods that lived from the early Cambrian period (roughly 541 mya) to the great Permian extinction (252 mya). The name trilobite refers to the three lobes every trilobite body has: the axial lobe, running down the center of the animal, and the pleural lobes, located on either side of the ...
It is often considered to be the second-largest known extinction event just behind the end-Permian mass extinction, in terms of the percentage of genera that became extinct. [ 2 ] [ 3 ] Extinction was global during this interval, eliminating 49–60% of marine genera and nearly 85% of marine species. [ 4 ]
Wanneria is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the later part of the Botomian stage, [3] which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period. [3] W. walcottana and W. cranbrookense are the only known species in this ...
Angelina Salter, 1859, [1] is a genus of ptychopariid trilobite belonging to the Family Olenidae, Suborder olenina. It lived during the Tremadocian Stage, lowermost of the two standard worldwide divisions forming the Lower Ordovician Series and lowest of the seven stages within the Ordovician System. It encompasses all rocks formed during ...
Redlichia is a genus of redlichiid trilobite in the family Redlichiidae, with large to very large species (up to 35 centimetres or 14 inches long).Fossils of various species are found in Lower Cambrian ()-aged marine strata from China, Korea, Pakistan, the Himalayas, Iran, Spain, southern Siberia, and Antarctica, and from Middle Cambrian ()-aged marine strata of Australia.
Hydrocephalus ("water head") is an extinct genus of redlichiid trilobite that was very common during the Middle Cambrian of Eurasia and North America, which lasted from 508 to 497 million years ago. This trilobite is up to 20 cm long and more widely built than others of the time. In comparison to other members of its family, its glabella ...