Tannudiscus
From Wikipedia, the free encyclopedia
| Tannudiscus Temporal range: | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | †Trilobita (?) |
| Order: | †Agnostida |
| Family: | †Weymouthiidae |
| Genus: | †Tannudiscus Pokrovskaya, 1959 |
| Species | |
| |
Tannudiscus Pokrovskaya (1959) [1] is a genus of eodiscinid trilobites belonging to the family Weymouthiidae Kobayashi T. (1943),[2] Order Agnostida (Salter 1864).[3] It lived during the late Lower Cambrian, with remains found in Canada (Newfoundland), China (Gansu), The United Kingdom (England), and the Russian Federation (Tuva, Gorno-Altayskaya).[4]
TYPE SPECIES: T. tannulaicus Pokrovskaya, 1959.
The Weymouthiid family shows a trend of shortening the occipital ring. In Chelediscus and Tannudiscus the occipital ring is entirely obliterated as in the Agnostina suborder. Tannudiscus has some other characters it shares with the Agnostina, such as a glabella consisting of two lobes and the occipital ring divided into basal glabellar lobes. Both the glabella and pygidial axis are isolated from the border furrow, and the latter is undivided. It is therefore considered likely that the Agnostina descended directly from a species assignable to Tannudiscus. The earliest known Agnostina is Archaeagnostus (Peronopsidae).[4] According to Cotton and Fortey (2005) Tannudiscus is polyphyletic.[5]