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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 .
Helicoprion is a genus of extinct shark-like [1] eugeneodont fish. Almost all fossil specimens are of spirally arranged clusters of the individuals' teeth, called "tooth whorls", which in life were embedded in the lower jaw. As with most extinct cartilaginous fish, the skeleton is mostly unknown.
The shape of Megapiranha's teeth is inferred to effectively focus stress at the tip of the teeth while piercing flesh before distributing its impact stresses throughout the base of the tooth while crushing hard material such as bones in a similar fashion to how pacus crack hard-shelled fruits and nuts.
A few living forms, such as the coelacanth are also referred to as prehistoric fish, or even living fossils, due to their current rarity and similarity to extinct forms. Fish which have become recently extinct are not usually referred to as prehistoric fish. Lists of various prehistoric fishes include: List of prehistoric jawless fish; List of ...
Brachydegma is an extinct genus of prehistoric freshwater ray-finned fish that lived during the Leonardian age (Cisuralian/lower Permian) in what is now Texas, United States.It is known from two fossils, which were recovered from the Clear Fork Formation.
Within cartilaginous fish, approximately 80% of the sharks, rays, and skates families survived the extinction event, [114] and more than 90% of teleost fish (bony fish) families survived. [115] There is evidence of a mass kill of bony fishes at a fossil site immediately above the K–T boundary layer on Seymour Island near Antarctica ...
Panderichthys is a genus of extinct sarcopterygian (lobe-finned fish) from the late Devonian period, about 380 Mya. Panderichthys, which was recovered from Frasnian (early Late Devonian) deposits in Latvia, is represented by two species.
Holocephali ("complete heads"), sometimes given the name Euchondrocephali ("true cartilage heads"), is a subclass of cartilaginous fish in the class Chondrichthyes. [1] The earliest fossils are of teeth and come from the Devonian period.