Democrinus londinensis
Democrinus londinensis
Summary
Democrinus londinensis was a stalked crinoid, or sea lily, that raised a crown of feathery feeding arms above the sea floor. Crinoids are suspension feeders: tube feet on the arms capture small organic particles and plankton from moving water and pass them towards the mouth.
The animal was attached to or anchored within the substrate by its lower stalk structures. In the fossil record the articulated crown is much less likely to survive than the calcitic stem and cup plates, so London Clay knowledge of the species is dominated by disarticulated ossicles and partial skeletal elements.
Quick Identification
Look for: small crinoid columnals or cup plates from a slender stalked sea lily; species-level identification requires the combination of columnal shape, articular surface and cup-plate proportions rather than simply recognising a circular crinoid stem piece.
Diagnostic Features
- Stalk composed of a series of calcitic columnals with specialised articular faces.
- Columnals are relatively slender, consistent with a small bourgueticrinine/rhizocrinid sea lily.
- Cup construction includes proportionally high basal elements described for the London Clay species.
- Articular facets and central lumen provide key characters when well preserved.
- Isolated generic columnals without diagnostic facet morphology should remain Crinoidea indet.
Fossil Details
Similar Species
Recorded Fossil Sites
No fossil-site occurrences have yet been recorded for this species.
References
- Forbes, E. (1852). Monograph of the Echinodermata of the British Tertiaries. Palaeontographical Society Monograph View reference
- Roux, M.; Martinez, A.; Vizcaïno, D. (2021). A diverse crinoid fauna (Echinodermata, Crinoidea) from the Lower Eocene of the Gulf of Languedoc (Corbières, Aude, southern France). Zootaxa, 4963(2), 201–242 View reference