Scombrinus nuchalis
Scombrinus nuchalis
View age-specific evidence and explanation
| Age | Recorded Occurrences | Localities | Rarity |
|---|---|---|---|
| Ypresian | 3 | 3 | 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: Begin with a reasonably complete skull, not a detached tooth. In side view, the hinge between the upper and lower jaws lies behind the halfway point of the eye socket. The bones framing the eye are relatively large.
Useful check: First locate the eye opening, then trace backwards to the jaw joint. If the top of the skull is intact, inspect the area immediately in front of the raised supraoccipital region: it should not form a distinct depression.
How to tell it apart: Tiny teeth alone cannot separate this species from other fossil fishes. The position of the jaw joint, eye-surrounding bones and skull roof must be considered together; no named alternative has yet been validated for a reliable public comparison.
Be careful: Crushing or missing bone may change the apparent jaw-joint position or create false hollows. Without substantial skull material, keep the identification broader.
Summary
The fossil skulls assigned to Scombrinus nuchalis once helped create the picture of a formidable, large-toothed fish in the early Eocene seas of south-east England. The original material tells a more interesting story. The skull that anchors this name carries very small teeth, not the impressive jaws once associated with it.
When researchers reassessed the museum specimens, they found that some skulls had been grouped together even though they belonged to different fishes. Correcting those identifications changed more than a catalogue entry: it revealed distinct animals where an earlier interpretation had blended their anatomy together.
We can recognise features of Scombrinus around the eyes, jaws and skull roof, yet the fossils do not establish its precise diet, speed or full-body appearance. Its value lies partly in that restraint. A careful look at old specimens recovered some of the true variety of fishes living in the London Clay sea.
Diagnostic Features
- Jaw articulation: positioned posterior to the orbital midpoint in sufficiently complete lateral material.
- Circumorbital series: comparatively large bones border the orbit.
- Anterior supraoccipital region: the skull roof immediately anterior to the supraoccipital is not depressed.
- Dentition: minute teeth; tooth size supports the cranial interpretation but is not diagnostic in isolation.
- Diagnostic basis: recognition depends on the combination of associated cranial characters rather than an isolated tooth or jaw fragment.
Fossil Details
Recorded Fossil Sites
London Clay Formation
Diagnostic Sources
References 1889 and 1845 support the revised cranial diagnosis, including jaw-joint position, circumorbital morphology and the limited diagnostic value of the teeth.
- Casier, E. (1966). Faune ichthyologique du London Clay. 496 pp.. Trustees of the British Museum (Natural History), London View reference
- Monsch, K. A. (2005). Revision of the scombroid fishes from the Cenozoic of England. Transactions of the Royal Society of Edinburgh: Earth Sciences, 95(3–4), 445–489 View reference
References
- Casier, E. (1966). Faune ichthyologique du London Clay. 496 pp.. Trustees of the British Museum (Natural History), London View reference
- Friedman, M.; Beckett, H. T.; Close, R. A.; Johanson, Z. (2016). The English Chalk and London Clay: two remarkable British bony fish Lagerstätten. Geological Society, London, Special Publications, 430(1), 165–200. Geological Society of London, London View reference
- Monsch, K. A. (2005). Revision of the scombroid fishes from the Cenozoic of England. Transactions of the Royal Society of Edinburgh: Earth Sciences, 95(3–4), 445–489 View reference