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"Blastoidea", from Ernst Haeckel's Art Forms of Nature, 1904. Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm, often referred to as sea buds. [1] They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississippian subperiod of the Carboniferous period.
Cystoidea was defined as a class of extinct paleozoic blastozoan echinoderms established to encompass stalked taxa that were neither crinoids nor blastoids. It was shown to be polyphyletic in the late 1960s but continues to be used even in recent (as of 2022) literature to discuss both rhombiferans and diploporitans .
Blastozoa is a subphylum of extinct echinoderms characterized by the presence of specialized respiratory structures and brachiole plates used for feeding. [1] It ranged from the Cambrian to the Permian. A significant species has been found at the Zaouïa Formation. [2]
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 ]
The Eocrinoidea were an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, brachiole-bearing echinoderms, and were the most common echinoderms during the Cambrian.
Eight of the extinct bird species were found in Hawaii, including the Po`ouli, which was last seen in 2004. The Po`ouli is the most recently seen species of all 21 animals on the list.
The Triassic–Jurassic (Tr-J) extinction event (TJME), often called the end-Triassic extinction, marks the boundary between the Triassic and Jurassic periods, . It is one of five major extinction events, profoundly affecting life on land and in the oceans. In the seas, about 23–34% of marine genera disappeared.
The BBC notes, "of the 41 communities researchers studied, arapaima populations were extinct in eight of them." And the giant fish, which typically weighs in at more than 400 pounds, is rapidly ...