Xiphodolamia ensis
Xiphodolamia ensis
Summary
Xiphodolamia ensis was a highly specialised lamniform shark with an unusually narrow, blade-like dentition. Its distinctive teeth show that it followed a feeding strategy different from the more conventional grasping dentitions of many Palaeogene lamniform sharks.
The strongly compressed crowns were suited to cutting or gripping relatively soft-bodied prey. Fishes are likely to have been important, but the exact way the teeth functioned in the mouth is difficult to reconstruct because the animal is known almost entirely from isolated dental material.
Xiphodolamia represents a distinctive extinct branch of the lamniform radiation. Its unusual dentition is valuable not simply for identification but as evidence of the wide range of predatory adaptations that had evolved among sharks by the early Eocene.
Quick Identification
Look for: a narrow, strongly compressed blade-like tooth with a long sharp cusp and a distinctive broad two-lobed root; complete teeth have a more knife-like profile than typical sand-tiger teeth.
Diagnostic Features
- Crown is very narrow and strongly laterally compressed.
- Principal cusp is elongate, sharp and smooth edged.
- Crown-root junction produces a distinctive blade-like overall profile.
- Root is broad and bilobed relative to the narrow crown.
- Complete morphology is markedly different from the more cylindrical piercing cusps of odontaspidid sand-tiger teeth.
Fossil Details
Recorded Fossil Sites
London Clay Formation
References
- Rayner, D.; Mitchell, T.; Rayner, M. (2009). London Clay Fossils of Kent and Essex. 228 pp.. Medway Fossil and Mineral Society, Rochester, Kent View reference
- Ward, D.J. (1980). The distribution of sharks, rays and chimaeroids in the English Palaeogene. Tertiary Research, 3(1), 13–19 View reference