''Thelodus'' (from , 'nipple' and , 'tooth') is an extinct genus of

thelodont Thelodonti (from Greek: "nipple teeth")Maisey, John G., Craig Chesek, and David Miller. Discovering fossil fishes. New York: Holt, 1996. is a class of extinct Palaeozoic jawless fishes with distinctive scales instead of large plates of armor. T ...

agnatha Agnatha (; ) or jawless fish is a paraphyletic infraphylum of animals in the subphylum Vertebrata of the phylum Chordata, characterized by the lack of jaws. The group consists of both extant taxon, living (Cyclostomi, cyclostomes such as hagfish ...

n that lived during the

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

period. Fossils have been found in Europe, Asia and North America.''Thelodus''
at

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org

Unlike many thelodonts, species of ''Thelodus'' are known not only from scales, but from impressions in rocks. Some species, such as the Canadian ''T. inauditus'', are thought to be comparable in size to other thelodonts, i.e., from 5 to 15 centimeters in length.Märss, Tiiu, Mark VH Wilson, and Raymond Thorsteinsson. "New thelodont (Agnatha) and possible chondrichthyan (Gnathostomata) taxa established in the Silurian and Lower Devonian of the Canadian Arctic Archipelago." Proceedings of the Estonian Academy of Sciences, Geology. Vol. 51. No. 2. Estonian Academy Publishers, 2002. The scales of the type species, ''T. parvidens'' ('' syn. T. macintoshi'') of Silurian Great Britain, however, reach the size of coins, and, if proportioned like other thelodonts, such as ''

Loganellia ''Loganellia'' is a genus of jawless fish which lived between 430 and 370 million years ago, during the Silurian and Devonian periods of the Paleozoic. ''Loganellia'' belonged to the Thelodonti class and like other Thelodonts possessed scales ins ...

'', the living animal would have been about one meter in length.Turner, Susan. Thelodus Macintoshi Stetson 1928: The Largest Known Thelodont (Agnatha: Thelodonti). Museum of Comparative Zoology, 1986.

References

Thelodonti genera Silurian jawless fish Prehistoric fish of Asia Prehistoric fish of Europe Prehistoric fish of North America Paleozoic life of New Brunswick Fossil taxa described in 1839 {{Paleo-jawless-fish-stub