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The popular name "spiny sharks" is because they were superficially shark-shaped, with a streamlined body, paired fins, a strongly upturned tail, and stout, largely immovable bony spines supporting all the fins except the tail—hence, "spiny sharks".
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]
Ischnacanthiformes is a prehistoric order of "acanthodian" stem-chondrichthyans found in Canada, Ukraine and United Kingdom.Members of this order were nektonic carnivores, [1] eating animals that swim rather than plankton.
Cheiracanthus (from Greek: χείρ kheír, 'hand' and Greek: ἄκανθα akantha, 'spine') [1] is an extinct genus of a group of fish called Acanthodii (or "spiny sharks"). [2] It was a deep-bodied acanthodian about 12 in. (30 cm) in length. It had a blunt head, upturned tail, and fins protected by spines.
Diplacanthus is an extinct genus of Mid to Late Devonian fish in the class Acanthodii, known as spiny sharks. Classification
The oldest total-group chondrichthyans, known as acanthodians or "spiny sharks", appeared during the Early Silurian, around 439 million years ago. [13] The oldest confirmed members of Elasmobranchii sensu lato (the group containing all cartilaginous fish more closely related to modern sharks and rays than to chimaeras) appeared during the ...
Sharks portal; The Squaliformes / ˌ s k w ɒ l ɪ ˈ f ɔːr m iː z / are an order of sharks that includes about 126 species in seven families.. Members of the order have two dorsal fins, which usually possess spines, they usually have a sharp head, no anal fin or nictitating membrane, and five to seven gill slits.
The first shark-like chondrichthyans appeared in the oceans 400 million years ago, [1] developing into the crown group of sharks by the Early Jurassic. [2] Listed below are extant species of shark. Sharks are spread across 556 described and 23 undescribed species in eight orders. The families and genera within the orders are listed in ...