Helodus
| Helodus Temporal range:
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|---|---|
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| Tooth file of Helodus simplex | |
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| Life restoration of Helodus simplex | |
| Scientific classification Edit this classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Holocephali |
| Order: | †Helodontiformes |
| Family: | †Helodontidae |
| Genus: | †Helodus Agassiz, 1838 |
| Type species | |
| Helodus simplex Agassiz, 1838
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| Synonyms | |
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Helodus (from Greek: ἧλος helos, 'stud' and Greek: ὀδούς odoús 'tooth')[1] is an extinct genus of cartilaginous fish from the Upper Devonian through Lower Permian.[2] While the type species, H. simplex from the Late Carboniferous (Moscovian ~ 315 million years ago)[3] of England is known from articulated specimens, the rest of the species in this genus are known only from isolated teeth.[4] Over seventy species have been attributed to this genus, many of which may be anterior teeth of other cartilaginous fish. This makes Helodus as broadly defined a wastebasket taxon.[5]: 53–60 Only the type species can be confidently attributed to this genus until articulated remains of other species are found.[4] H. simplex was around 30 centimeters (1 foot) long,[2] and males had a large, tooth-bearing clasping organ on their heads. The teeth of H. simplex, which were arranged in tooth-whorls, were transitional between elasmobranch-like separated teeth and the tooth plates of living chimaeras.[3]
Research history
[edit | edit source]The genus Helodus was named by naturalist Louis Agassiz in 1838 to refer to isolated bead-like teeth from the late Paleozoic. Parts of the cartilaginous skeleton were first described in 1890.[6][7]
References
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- ^ a b Arno Hermann Müller: Textbook of paleozoology. Volume III, Vertebrates, Part 1. Gustav Fischer Verlag, 1985.
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Itano, W.M., Lambert, L.L. A new cochliodont anterior tooth plate from the Mississippian of Alabama (USA) having implications for the origin of tooth plates from tooth files. Zoological Lett 4, 12 (2018). Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
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