Explore: Acanthodii

Acanthodii or acanthodians is an extinct class of gnathostomes (jawed fishes). They are currently considered to represent a paraphyletic grade of various

extinct (armored gnathostomes) └Eugnathostomata (true jawed vertebrates) ├─Acanthodii (stem cartilaginous fish) └─Chondrichthyes (true cartilaginous fish) ├─Holocephali

comprehensive listing of all genera that have ever been included in the subclass Acanthodii, excluding purely vernacular terms. The list includes all commonly accepted

gnathostomes) Class Chondrichthyes (cartilaginous fish; 900+ species) Class †"Acanthodii" (Paleozoic "spiny sharks"; paraphyletic in relation to Chondrichthyes)

relatives) Class †"Placodermi" (armoured fish, paraphyletic) Class †"Acanthodii" ("spiny sharks", sometimes classified under Actinopterygii and paraphyletic)

animals not in it. The only extinct classes shown are Placodermi and Acanthodii. Note that there are many other extinct chordate groups that are not shown

updated cladogram (Zhu et al., 2016): Paleontology portal Fish portal Acanthodii List of placoderms Ostracoderm Chondrichthyes Entelognathus If paraphyletic

Olfactores Subphylum: Vertebrata Groups included "Agnatha" †"Placodermi" †"Acanthodii" Chondrichthyes Osteichthyes Actinopterygii Sarcopterygii (including tetrapods)

Females attain a larger size than males. The largest of the now-extinct Acanthodii was Xylacanthus grandis, an ischnacanthiform based on a ~35 cm (14 in)

fish known as placoderms, which evolved from the ostracoderms; and the Acanthodii (or spiny sharks). The jawed fish that are still extant in modern days