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Stensioella. Synonyms. Placodermata. Placoderms (from Greek πλάξ (plax, plakos) ' plate ' and δέρμα (derma) 'skin') [ 1 ] are vertebrate animals of the class Placodermi, an extinct group of prehistoric fish known from Paleozoic fossils during the Silurian and the Devonian periods.
Timeline of fish evolution. The evolution of fishes took place over a timeline which spans the Cambrian to the Cenozoic, including during that time in particular the Devonian, which has been dubbed the "age of fishes" for the many changes during that period. The Late Devonian extinctions played a crucial role in shaping the evolution of fish ...
Evolution of fish. The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnatha, or jawless fish.
Plotted is the extinction intensity, calculated from marine genera. The Late Devonian extinction consisted of several extinction events in the Late Devonian Epoch, which collectively represent one of the five largest mass extinction events in the history of life on Earth. The term primarily refers to a major extinction, the Kellwasser event ...
A fish (pl.: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits.Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians.
In this end-Devonian extinction, most marine and freshwater groups became extinct or were reduced to a few lineages, although the precise mechanism of the extinction is unclear. [7] Before the event, oceans and lakes were dominated by lobe-finned fishes and armored fishes called placoderms . [ 7 ]
The population of early humans dwindled to around 1,280 individuals during a time of dramatic climate change and remained that small for about 117,000 years, the study said.
This list of placoderms is an attempt to create a comprehensive listing of all genera from the fossil record that have ever been considered to be members of the class Placodermi. This list excludes purely vernacular terms. It includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (nomina dubia), or were ...