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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.
Trilobites were hit hard by both phases of the extinction, with about 70% of genera and 50% of families going extinct between the Katian and Silurian. The extinction disproportionately affected deep water species and groups with fully planktonic larvae or adults.
Asaphellus is an extinct genus of trilobites reported from the Ordovician. It is seen in Argentina, Bolivia, Mexico, America, Algeria, Iran, Spain, Portugal, France, Great Britain, Czech Republic, Norway, Sweden and China. [1] [2] [3]
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 ...
Most trilobites with this life history strategy lived in warm, low latitude waters, in which planktonic, non-adult like larvae may be ideal at surviving in. During the Ordovician-Silurian extinction event, the widespread onset of cold water conditions and anoxia may have instead favoured species that produced small numbers of large eggs, from ...
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 ...
Swimming off the coast of Mexico in the Gulf of California live the few remaining vaquitas on earth. This endangered cetacean is not only the smallest porpoise species, but the most rare. Where ...
Calymene Brongniart, 1822, is a genus of trilobites in the order Phacopida, suborder Calymenina, that are found throughout North America, North Africa, and Europe in primarily Silurian outcrops. [2] Calymene is closely related to Flexicalymene, and both genera are frequently found enrolled. [3] Calymene trilobites are small, typically 2 cm in ...