Odontogriphus
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Odontogriphus Temporal range: Burgess Shale |
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| Odontogriphus from the Burgess Shale. From Smith (2014). | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Superphylum: | Lophotrochozoa |
| Family: |
Odontogriphidae Conway Morris, 1976 |
| Genus: |
Odontogriphus Conway Morris, 1976 |
| Species | |
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Odontogriphus (literally "toothed riddle") is a genus of soft-bodied animals known from middle Cambrian Lagerstätte. Reaching as much as 12.5 centimetres (4.9 in) in length, Odontogriphus is a flat, oval bilaterian which apparently had a single muscular foot, and a "shell" on its back that was moderately rigid but of a material unsuited to fossilization.
Originally it was known from only one specimen, but 189 new finds in the years immediately preceding 2006 made a detailed description possible. (221 specimens of Odontogriphus are known from the Greater Phyllopod bed, where they comprise 0.42% of the community.) As a result, Odontogriphus has become prominent in the debate that has gone on since 1990 about the evolutionary origins of molluscs, annelid worms and brachiopods. A group of scientists think that Odontogriphus’s feeding apparatus, which is "nearly identical" to Wiwaxia’s, is an early version of the molluscan radula, a chitinous "tongue" that bears multiple rows of rasping teeth. Hence they classify Odontogriphus and Wiwaxia as close to the ancestors of the first true molluscs. One scientist has presented a different analysis, arguing since 1990 that Wiwaxia is not closely related to molluscs but is much more like a polychaete worm. He argues that the supposed "radula" is nothing of the sort; he classifies Odontogriphus as a basal lophotrochozoan, in other words close to the last common ancestor of molluscs, annelid worms and brachiopods.
Charles Doolittle Walcott found one specimen during one of his field trips to the Burgess Shale between 1910 and 1917. In the 1970s Simon Conway Morris re-examined the specimen and tentatively concluded that it was a swimming lophophorate, in other words related to the ancestors of molluscs, annelid worms and brachiopods. In 2006 Caron, Scheltema et al. published a new analysis based on 189 recently collected specimens, all from the Burgess Shale.
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