Offacolus
Offacolus is an extinct genus of euchelicerate, a group of chelicerate arthropods. Its only species, O. kingi, has been found in deposits from the Silurian period (Homerian epoch) in the Wenlock Series Lagerstätte of Herefordshire, England. It is the only member of the monotypic family Offacolidae, and classified as a basal ("primitive") genus in the clade Euchelicerata, along with Dibasterium and Prosomapoda. The genus is named after Offa, a king from the ancient kingdom of Mercia, and colus, a person who dwelled among (this time referring to) the Offa's Dyke. The species name honors Robert Joseph King, a British mineralogist who found the fossils of Offacolus.
| Offacolus Temporal range: Homerian, ~ | |
|---|---|
| Reconstruction of Offacolus kingi | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Chelicerata |
| Clade: | Euchelicerata |
| Family: | †Offacolidae Sutton et al., 2002 |
| Genus: | †Offacolus Orr et al., 2000 |
| Type species | |
| †Offacolus kingi Orr et al., 2000 | |
Similar to Dibasterium, Offacolus possess limb-like exopods (outer limb branches) on appendage II to V, a character suggest to be plesiomorphic (observable in the putative stem-chelicerate taxon Habeliida) and lost within the prosomapod clade.