Question | Answer |
Skeleton of Osteichthyes | Fully ossified; Dermal plates in crnium; Teeth rooted in dermal bone |
Soft Tissue of Osteichtyes | Gas bladder; Operculum over gills |
Actinopterygians | Ray finned; Only radials; Heavy to light weight scales; Robust to flexible jaw for whole prey feeding; |
Actinopterygians Fins | Caudal fins are either heteroarcal or homocercal; Paired fins with pelvic fins moving anteriorly |
Actinopterygians Locomotions | Lateral ungulation in the form of anguilliform, carangiform and subcarangiform, astraciform; Dependent on frictional drag and inertial drag |
Actinopterygians Reproduction | Freshwater with high parental input in nests and large yolks; Marine with low parental input and small yolks for plankton feeding young; Aplacental viviparity |
Actinopterygians Diversity: Polypterids | Derived from basal node, so retain basal and radial elements |
Actinopterygians Diversity: Acipenseriforms | Sturgeon - Secondary loss of endochondral bone, reduced dermal bone, gas bladder for respiration, heterocercal tail; Paddlefish- Ram feeding, somewhat hetereocercal tail |
Actinopterygians Diversity: Neopterygians | Garpikes - no basals, lack complex mobile elements in jaw so no suction feeding; Bowfins - mobile maxilla for suction, pelvic fin shift |
Actinopterygians Diversity: Teleost | Premaxilla and maxilla mobile, pharyngeal jaws mobile, shift pelvic fins, very diverse |
Sarcopterygians | Extended endoskeletal elements in fins;
Retains two dorsal fins;
Devonian periods;
Coelacanths, Lungfish, and Tetrapods |
Sarcopterygian Diversity: Coelacanth | Fossils back 400 million years ago to present day;
Fatty filled swim bladder homologous to fish gas bladders;
Fleshy paired fins not for support but for windmill locomotion like tetrapod locomotion;
Advanced Neurological pathways |
Sacopterygian Diversity: Lungfish | Australian species is less derived with large heavy scales and aquatic fins;
South American and African species have wispy fins for substrate locomotion and lungs for breathing, ephemeral environments, burrowing and estivating |