Burnhamia daviesi
Burnhamia daviesi
View age-specific evidence and explanation
| Age | Recorded Occurrences | Localities | Rarity |
|---|---|---|---|
| Ypresian | 5 | 5 | Not yet established |
These counts describe published LBPS Occurrence records with directly assigned, unambiguous geological-unit mappings—not specimen abundance. Records at restricted Localities and ambiguous or unsupported ages are excluded. Species-level age labels are not used as proof of an age-specific Occurrence.
Specimen-based rarity requires comparable, correctly identified physical fossils, geological provenance and publication permissions. It does not estimate your chance of finding a fossil or collecting access.
Quick Identification
What to look for Look for a broad, fairly low ray tooth with a shallow hollow or channel running across its chewing surface. Under magnification, a reasonably fresh crown may show a fine, grainy texture rather than a heavily worn, smooth grinding face. Teeth from nearer the centre of the jaw are much wider than those towards its edges.
Useful check Turn the tooth over. The root is divided into several separate ridges or lobes, with noticeable gaps between them; the number varies with tooth position. If several teeth remain together, check whether they decrease in width towards the sides of the dental surface.
How to compare it Other broad-toothed rays also produced pavement-like teeth. Do not use breadth alone to call a fossil Burnhamia: the shallow crown depression, surface texture and root structure need to agree. The delicate or scarcely worn appearance is a useful clue, but not a guaranteed difference after fossil wear.
Be careful Breakage can remove root lobes, and some unusual teeth may have extra ridges or small points, perhaps related to sex. A heavily worn single tooth may not be identifiable to species. Do not interpret every raised edge as a male tooth.
Summary
Burnhamia daviesi was an unusual ray that lived in the early Eocene seas, and its teeth may preserve clues to two very different parts of its life: how it fed and how it reproduced.
Its broad teeth resembled those of rays adapted to crushing hard food, but they showed surprisingly little wear. This difference has helped scientists investigate how the ancestors and relatives of today’s manta and devil rays evolved away from heavy crushing dentitions towards feeding on much smaller animals. Burnhamia may have been part of that transition, although we cannot say for certain that it filtered plankton like modern manta rays.
There is another intriguing possibility hidden among its fossils. Some teeth have small pointed or ridged edges, unlike the broader teeth normally associated with the species. Researchers have suggested that these might have belonged to mature males. In some living rays, males develop similarly modified teeth that help them grip females during mating. Whether Burnhamia behaved in the same way remains uncertain, but the comparison offers a fascinating glimpse of possible differences between the sexes.
An exceptional fossil from the London Clay of Sheppey preserves part of the jaws with teeth still associated with their supporting cartilage. Together with isolated teeth, it has allowed researchers to explore far more than the animal’s feeding equipment. The remains of this ancient ray may hold evidence of both a major change in feeding evolution and an intimate aspect of its reproductive biology.
Diagnostic Features
- Dentition and tooth rows: The type material was described with nine anteroposterior tooth series. A later examination of the partly associated lower dentition showed broad central teeth flanked by lateral teeth that become narrower towards the jaw corner. Counts from incomplete material should not be treated as a universal identification rule.
- Crown proportions: Median teeth are strongly transversely elongated, reported historically as approximately four times as broad as their front-to-back length. Lateral teeth are proportionately narrower.
- Crown surface: The low crown has a shallow transverse depression or channel, often with fine surface granulation and limited wear in the studied material. Abrasion may conceal these features.
- Root: Roots comprise multiple separated lobes or lamellae with intervening grooves; number and spacing vary with tooth position and size.
- Tooth contact: Woodward (1889) described anterior/posterior interlocking in the type material, whereas Underwood et al. (2017) reported only loose contact among certain adjacent teeth in the partially associated dentition. These observations should not be conflated into a universal tight-locking character.
- Possible sexual variation: Some unusual corrugated or slightly cuspate teeth were proposed to be associated with males. The sex attribution and behaviour are hypotheses, not independently demonstrated characteristics of fossil individuals.
- Associated jaw material: The holotype NHMUK P.1514 from Sheppey preserves part of the jaws and associated teeth, allowing direct investigation of the dentition and cartilage; these features are not normally available from loose teeth.
- Identification limit: Tooth width or wear state alone is insufficient for a confident species identification; combined crown shape, root structure and tooth position are preferable.
Fossil Details
Recorded Fossil Sites
London Clay Formation
Diagnostic Sources
- Underwood, C.J.; Kolmann, M.A.; Ward, D.J. (2017). Paleogene origin of planktivory in the Batoidea. Journal of Vertebrate Paleontology, 37(3), e1293068 View reference
References
- Hovestadt, D.C.; Hovestadt-Euler, M. (2013). Generic Assessment and Reallocation of Cenozoic Myliobatinae based on new information of tooth, tooth plate and caudal spine morphology of extant taxa. Palaeontos, 24, 1–66 View reference
- 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
- Reinecke, T.; Mollen, F.H.; Gijsen, B.; D’Haeze, B.; Hoedemakers, K. (2024). Batomorphs (Elasmobranchii: Rhinopristiformes, Rajiformes, Torpediniformes, Myliobatiformes) of the middle to late Ypresian, early Eocene, in the Anglo-Belgian Basin (south-western North Sea Basin) – a review and description of new taxa. Palaeontos, 35, 1–172 View reference
- Underwood, C.J.; Kolmann, M.A.; Ward, D.J. (2017). Paleogene origin of planktivory in the Batoidea. Journal of Vertebrate Paleontology, 37(3), e1293068 View reference