Search results
Results from the WOW.Com Content Network
Actinopterygii (/ ˌ æ k t ɪ n ɒ p t ə ˈ r ɪ dʒ i aɪ /; from Ancient Greek ἀκτίς (aktis) 'having rays' and πτέρυξ (ptérux) 'wing, fins'), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish [2] that comprise over 50% of living vertebrate species. [3]
Fish portal; Actinopteri (/ æ k t ɪ ˈ n ɒ p t ə r aɪ /) is the sister group of Cladistia in the class Actinopterygii (ray-finned fish).. Dating back to the Permian period, the Actinopteri comprise the Chondrostei (sturgeons and paddlefish), the Holostei (bowfins and gars), and the teleosts; in other words, all extant ray-finned fish other than the bichirs.
Acropholis stensioei (fossil at the Geological Museum in Copenhagen) is a taxon referred to Palaeonisciformes based on superficial resemblance with Palaeoniscum. The systematics of fossil and extant fishes has puzzled ichthyologists since the time of Louis Agassiz, who first grouped all Palaeozoic ray-finned fishes together with Chondrostei (sturgeons, paddlefishes), gars, lungfishes, and ...
Teleostei (/ ˌ t ɛ l i ˈ ɒ s t i aɪ /; Greek teleios "complete" + osteon "bone"), members of which are known as teleosts (/ ˈ t ɛ l i ɒ s t s, ˈ t iː l i-/), [4] is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, [a] and contains 96% of all extant species of fish.
Cladistia is a clade of bony fishes whose only living members are the bichirs of tropical Africa. [1] Their major synapomorphies are a heterocercal tail in which the dorsal fin has independent rays, and a posteriorly elongated parasphenoid.
However, due to insufficient knowledge of Palaeoniscum and many other early actinopterygians, and because most of these taxa have never been included in cladistic analyses, it is still uncertain which genera other than Palaeoniscum should be placed in Palaeoniscidae sensu stricto to make this a monophyletic group.
In actinopterygians, the pelvic fin consists of two endochondrally-derived bony girdles attached to bony radials. Dermal fin rays (lepidotrichia) are positioned distally from the radials. There are three pairs of muscles each on the dorsal and ventral side of the pelvic fin girdle that abduct and adduct the fin from the body.
Its type species, A. arcanus, is only known from poorly preserved single specimen, which makes hard to classify existing orders of Cretaceous actinopterygians. It was tentatively categorized as a palaeoniscoids but given its recent age and fragmentary nature this placement is unlikely.