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A subclass of bony fish, the ray-finned fishes (Actinopterygii), have become the dominant group in the post-Paleozoic and modern world, with some 30,000 living species. Meanwhile, another subclass of bony fish, the lobe-finned fishes, became the dominant group on land. Sea levels in the Devonian were generally high.
The recent discovery of Entelognathus strongly suggests that bony fish (and possibly cartilaginous fish, via acanthodians) evolved from early placoderms. [33] A subclass of the Osteichthyes, the ray-finned fish ( Actinopterygii ), have become the dominant group of fish in the post-Paleozoic and modern world, with some 30,000 living species.
[9] [10] [11] Early bony fish did not have fin spines like most modern fish, but instead had the fleshy paddle-like fins similar to other non-bony clades of fish, although the lobe-finned fish evolved articulated appendicular skeletons within their paired fins, which gave rise to tetrapods' limbs.
Placoderms were among the first jawed fish (their jaws likely evolved from the first pair of gill arches), as well as the first vertebrates to have true teeth. They were also the first fish clade to develop pelvic fins , the second set of paired fins and the homologous precursor to hindlimbs in tetrapods .
However, a newly described Silurian placoderm, Entelognathus, which has jaw anatomy shared with bony fish and tetrapods, has led to revisions of this phylogeny: acanthodians were then considered to be a paraphyletic assemblage leading to cartilaginous fish, while bony fish evolved from placoderm ancestors. [4]
The phylogeny of Acipenseridae, as in the cladogram, shows that they evolved from the bony fishes. [13] [14] [15] Approximate dates are from Near et al., 2012. [13]
In ichthyology the difference between Euteleostomi and Osteichthyes is that the former presents a cladistic view, i.e. that the terrestrial tetrapods evolved from lobe-finned fish (Sarcopterygii). Until recently, the view of most ichthyologists has been that Osteichthyes were paraphyletic and include only bony fishes. [8]
Euteleostei, whose members are known as euteleosts, is a clade of bony fishes within Teleostei that evolved some 240 million years ago, although the oldest known fossil remains are only from the Early Cretaceous. [1]