Helodus
Extinct genus of cartilaginous fish
From Wikipedia, the free encyclopedia
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]
| Helodus Temporal range: | |
|---|---|
| |
| Tooth file of Helodus simplex | |
 | |
| Life restoration of Helodus simplex | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Holocephali |
| Order: | †Helodontiformes |
| Family: | †Helodontidae |
| Genus: | †Helodus Agassiz, 1838 |
| Type species | |
| Helodus simplex Agassiz, 1838 | |
| Synonyms | |
| |
Research history
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]
