Archipelepidiformes is an order of extinct

jawless fish Agnatha (, Ancient Greek 'without jaws') is an infraphylum of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts and ostracoderms) species. Among recent animals, cyclostomes ...

es in the class

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

. Archipelepidiforms are regarded as the basalmost thelodonts primarily because the histology and morphology of archipelepidiforms have many similarities with the histology and morphology of pteraspidomorphs, hinting that the two groups share a common ancestor, and hinting that archipelepidiforms retain many primitive features from this common ancestor.Soehn, K. L., Märss, T., Caldwell, M. W. & Wilson, M. V. H., 2001: New and biostratigraphically useful thelodonts from the

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 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 shortest period of the Paleozo ...

of the

Mackenzie Mountains The Mackenzie Mountains are a Canadian mountain range forming part of the Yukon-Northwest Territories boundary between the Liard and Peel rivers. The range is named in honour of Canada's second prime minister, Alexander Mackenzie. Nahanni Nat ...

, Northwest Territories, Canada. Journal of Vertebrate Paleontology, 21: 651-65

/ref> Wilson, Mark VH, and Tiiu Märss. "Thelodont phylogeny revisited, with inclusion of key scale-based taxa." Estonian Journal of Earth Sciences 58.4 (2009): 297œ310

/ref> Currently, only whole body fossils of ''

Archipelepis ''Archipelepis'' is a genus of extinct thelodont agnathans, and are the most primitive recognized thelodonts of which whole body fossils are known.Wilson, Mark VH, and Tiiu Märss. "Thelodont phylogeny revisited, with inclusion of key scale-base ...

'' are known: these fossils show that archipelepids were tadpole-like animals with no fins aside from a forked caudal fin.Märss, Tiiu, VH Wilson, Mark, & Thorsteinsson, Raymond. "New thelodont (Agnatha) and possible chondrichthyan (Gnathostomata) taxa established in the Silurian and Lower Devonian of the

Canadian Arctic Archipelago The Arctic Archipelago, also known as the Canadian Arctic Archipelago, is an archipelago lying to the north of the Canadian continental mainland, excluding Greenland (an autonomous territory of Denmark). Situated in the northern extremity of No ...

."Proceedings of the Estonian Academy of Sciences, Geology. Vol. 51. No. 2. Estonian Academy Publishers, 2002.

References

External links

* Thelodonti Prehistoric jawless fish orders Telychian first appearances Llandovery taxonomic orders Wenlock taxonomic orders Sheinwoodian extinctions {{Paleo-jawless-fish-stub