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Thelodonti ('feeble-teeth') are a group of small, extinct jawless fishes with distinctive scales instead of large plates of armour. There is much debate over whether the group of Palaeozoic fish known as the Thelodonti (formerly coelolepids [11]) represent a monophyletic grouping, or disparate stem groups to the major lines of jawless and jawed ...
The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, the osteostracans, especially the Devonian species, were among the most advanced of all known ...
Lepidaspis serrata ("serrated scaly shield") is an extinct heterostracan jawless fish from Early Devonian Canada. Its scientific name refers to the fact that the armor is composed of hundreds of tiny scales with serrated edges. Lepidaspis serrata cast. Mackenzie Mountains, Northwest Territories . At the Royal Tyrrell Museum of Palaeontology.
Dorsal view of right-bending (left) and left-bending (right) jaw morphs adapted for eating fish scales [68] Lepidophagy (Ancient Greek for scale-eating) is a specialised feeding behaviour in fish that involves eating the scales of other fish. [69] Lepidophagy has independently evolved in at least five freshwater families and seven marine ...
Arandaspida is a taxon of very early, jawless prehistoric fish which lived during the Ordovician period. Arandaspids represent some of the oldest known vertebrates. The group represents a subclass within the class Pteraspidomorphi, and contains only one order, the Arandaspidiformes.
The body had a mobile tail covered with small protective plate-like scales of less than 1 mm (0.039 in) and a forebody covered with plate-like scales larger than 2 mm (0.079 in). The specimen from North America (described by Sansom et al., 1997) is to have had relatively large, laterally-positioned eyes and a series of eight gill openings on ...
A newfound fossil of a jawless fish is the oldest known vertebrate cranium preserved in 3D. The 455 million-year-old find could illuminate how vertebrate heads evolved.
Furcacaudiformes is an extinct order of jawless fish in the class Thelodonti. [1]Because the paucity of intact fossils, especially since some families are known entirely from scale fossils, taxonomy of thelodonts is based primarily on scale morphology.