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It is the largest class of vertebrates in existence today. Osteichthyes is divided into the ray-finned fish ( Actinopterygii ) and lobe-finned fish ( Sarcopterygii ). The oldest known fossils of bony fish are about 420 million years ago, which are also transitional fossils , showing a tooth pattern that is in between the tooth rows of sharks ...
They are noted for their denticle whorls - oropharyngeal denticles that lined their branchial bars - which are thought to be homologous with other, later gnathostome teeth. In this sense, Loganellia may possess the earliest known dental structures related to modern teeth, and would have evolved in the throat, rather than through dermal ...
Acanthodii or acanthodians is an extinct class of gnathostomes (jawed fishes).They are currently considered to represent a paraphyletic grade of various fish lineages basal to extant Chondrichthyes, which includes living sharks, rays, and chimaeras.
Conodont elements consist of mineralised teeth-like structures of varying morphology and complexity. The evolution of mineralized tissues has been puzzling for more than a century. It has been hypothesized that the first mechanism of chordate tissue mineralization began either in the oral skeleton of conodonts or the dermal skeleton of early ...
Chondrichthyes (/ k ɒ n ˈ d r ɪ k θ i iː z /; from Ancient Greek χόνδρος (khóndros) 'cartilage' and ἰχθύς (ikhthús) 'fish') is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage.
The ichthyosaur’s jawbone, or surangular, was a long, curved bone at the top of the lower jaw just behind the teeth, and it measured more than 6.5 feet (2 meters) long.
Agnatha (/ ˈ æ ɡ n ə θ ə, æ ɡ ˈ n eɪ θ ə /; [3] from Ancient Greek ἀ-(a-) 'without' and γνάθος (gnáthos) 'jaws') is a paraphyletic infraphylum [4] of non-gnathostome vertebrates, or jawless fish, in the phylum Chordata, subphylum Vertebrata, consisting of both living (cyclostomes) and extinct (conodonts, anaspids, and ostracoderms, among others).
A study on the phylogenetic relationships of cyathaspidids is published by Elliott, Lassiter & Blieck (2021). [5]Miyashita et al. (2021) report larval and juvenile forms of four stem lampreys from the Paleozoic era (Hardistiella, Mayomyzon, Pipiscius and Priscomyzon), including a hatchling-to-adult growth series of Priscomyzon, and report that the studied larvae display features that are ...