''Archipelepis'' is a genus of extinct

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

agnatha 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, cyclosto ...

ns, 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-based taxa." Estonian Journal of Earth Sciences 58.4 (2009): 297œ310

/ref> Fossils of bodies and scales are currently known from Late

Telychian In the geologic timescale, the Telychian is the geologic age, age of the Llandovery Epoch of the Silurian geologic period, Period of the Paleozoic geologic era, Era of the Phanerozoic geologic eon, Eon. The Telychian Age was between 438.5 ± 1.2 ...

to Wenlock-aged marine strata of northern

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

.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>

Anatomy

Both species have similar body morphology, in that both resembled tadpoles with forked tails. Scale morphology differs in that ''A. bifurcata'' has forked scales with two prong-like spires, and that ''A. turbinata'' has bulbous, pointed scales that resemble upside-down

spinning top A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect. Once set in motion, a top will usually wobble for a few se ...

References

External links

* Thelodonti genera Silurian jawless fish Paleozoic life of the Northwest Territories Canadian Arctic Archipelago Silurian first appearances Silurian extinctions Paleozoic life of Nunavut {{Paleo-jawless-fish-stub