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- noun Plural form of
Sorry, no etymologies found.
The acanthodians are a group of fishes characterized by a shark-like appearance and the presence of numerous spines, whose relationships to modern jawed vertebrates are still poorly understood.
Among the structures most similar to true teeth in the acanthodians are cheek scales - multi-cusped scales on the outside of the mouth that looked like the tooth whorls set in the jaw.
As seen in the acanthodians from the site, teeth had already developed within some groups of jawed fish.
Among the fossils found here are acanthodians - the so-called "spiny sharks" which are thought to be the oldest vertebrates to possess true teeth - and what Blais and colleagues consider to be a chondrichthyan, or an early member of the group of cartilaginous fish which includes sharks, skates, and rays today.
According to the paper, the acanthodians have not been named yet but the chondrichthyan has been previously described as Obtusacanthus corroconis.
The braincase of Acanthodes resembles those of early bony vertebrates, a lineage that includes humans and other land vertebrates (for this reason, acanthodians are thought to be more closely related to bony fishes than to sharks).