Search results
Results from the WOW.Com Content Network
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. While their endoskeletons are mainly cartilaginous, their head and ...
Placoderms were extinct by the end of the Devonian. [5] Placodermi is a paraphyletic group of the clade Gnathostomata, which includes all jawed vertebrates. [5] It is unclear exactly when gnathostomes emerged, but the scant early fossil record indicates that it was sometime in the Early Palaeozoic era. [6]
Arthrodira (Greek for "jointed neck") is an order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetrating most marine ecological niches. Arthrodires were the largest and most diverse of all groups of placoderms. [1]
Evolution of fish. The Devonian period (419–359 Mya), also known as the Age of Fishes, saw the development of early sharks, armoured placoderms and various lobe-finned fish, including the tetrapod transitional species. The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early ...
Romundina is a small, heavily armored extinct genus of acanthothoracid placoderms which lived in shallow marine environments in the early Devonian (Lochkovian). [1][2] The name Romundina honors Canadian geologist and paleontologist Dr. Rómundur (Raymond) Thorsteinsson of Calgary, Alberta, Canada. Romundina are believed to have lived on Earth ...
† Placodermi (plate-skinned) is an extinct class of armoured prehistoric fish, known from fossils, which lived from the late Silurian to the end of the Devonian Period. Their head and thorax were covered by articulated armoured plates and the rest of the body was scaled or naked, depending on the species.
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 ...
Acanthothoraci. Acanthothoraci ( spine chests) is an extinct group of chimaera-like placoderms closely related to the rhenanid placoderms. Superficially, the acanthoracids resembled scaly chimaeras and (relatively) heavily armored ptyctodonts. They were distinguished from chimaeras by their large scales and plates, a pair of large spines that ...