Casieria casieri

Casieria casieri

Cappetta, 1976

Common Name: Catshark

Fossil Group: Sharks & Rays
Order: Carcharhiniformes
Family: Scyliorhinidae
Genus: Casieria

Summary

Casieria casieri was a small extinct catshark that lived in European seas during the Eocene. It is known primarily from isolated teeth and is a recognised member of the London Clay shark fauna.

Its teeth have a strong pointed central cusp with one relatively large pointed side cusplet on either side. Unlike several other small Eocene catsharks, additional outer pairs of cusplets are not normally a major feature.

One of the most distinctive characteristics is the presence of strong vertical folds running up both faces of the crown. These folds can extend almost all the way to the tip of the central cusp, giving well preserved teeth a noticeably ribbed appearance.

The combination of a strong central point, one pair of tall side points, heavy vertical crown folds and a broad deeply grooved root makes a complete Casieria casieri tooth relatively distinctive among London Clay catsharks.

Geological Age & Range Notes

Early to Middle Eocene, with Casieria casieri particularly well documented from Ypresian deposits and additional records extending into the Middle Eocene.

The species was originally described from the Ypresian London Clay Formation at Burnham-on-Crouch. Later literature records Casieria casieri from other European Eocene deposits, including Middle Eocene faunas.

For the London Basin database, its most important occurrence is therefore the Early Eocene, Ypresian London Clay Formation.

Known Localities

Diagnostic Features

Key features used to recognise and identify this species:

  • Teeth are small, typically only a few millimetres in size.
  • The middle of the tooth forms a tall, strong and sharply pointed central cusp.
  • Teeth from near the front of the mouth are generally more upright and symmetrical.
  • Teeth from farther around the side of the jaw become broader and less symmetrical.
  • There is normally one pointed side cusplet on each side of the main cusp.
  • These side points are quite large for a catshark tooth rather than appearing as tiny bumps.
  • Each side point can reach approximately half the exposed height of the main central cusp. This is one of the original diagnostic features of the species.
  • The side cusplets are straight and sharply pointed.
  • Unlike species such as Foumtizia pattersoni or Pachyscyllium gilberti, a typical C. casieri tooth does not rely on several pairs of small side points for identification.
  • The surface of the crown has strong vertical folds or ridges.
  • These folds occur on both the front and back surfaces of the tooth.
  • The folds are fairly straight rather than strongly wavy.
  • On strongly ornamented specimens, the ridges may run almost all the way to the tip of the central cusp.
  • Similar ridges can also continue up the side cusplets.
  • The cutting edges themselves are smooth and unserrated.
  • The root is broad and relatively flat underneath.
  • A large, deep groove runs through the centre of the root.
  • On some teeth from the far sides of the jaw, this groove can become partly or completely closed as the root changes shape.

    Quick Identification

    Look for:

    small catshark tooth + strong pointed central cusp + ONE large side point on each side + strong vertical ridges running high up the crown + broad root with a deep central groove.

    The combination of one pair of large cusplets and very strong crown folds is particularly useful.

Identification Notes

The easiest mistake with Casieria casieri is to look only at the general catshark shape.

Many London Clay catsharks have:

  • a tall central point
  • side cusplets
  • a broad root
  • some form of crown ornamentation

For C. casieri, the important feature is the combination of the side points and the crown decoration.

Look at the side points

A typical tooth should have:

one large side point + tall central point + one large side point.

The lateral cusplets are relatively well developed and sharply pointed.

Cappetta’s original diagnosis specifically emphasised that the exposed part of each side cusplet could reach roughly half the height of the central cusp.

This immediately gives the tooth a different appearance from species with several much smaller side points.

Look at the crown ridges

This is probably the most useful feature after the side cusplets.

Both sides of the crown carry strong vertical folds.

Rather than being restricted to the very bottom of the tooth, these can extend a long distance upwards and may reach almost to the tip of the central cusp.

Under magnification, a good specimen therefore has a distinctly ribbed or lined appearance.

If you have a smooth central cusp with decoration only along the very bottom of the crown, another catshark should be considered.

Check both sides of the tooth

It is particularly useful to photograph and examine:

  1. the front surface
  2. the back surface
  3. the underside of the root

The strong folds should be visible on both crown faces, while the underside reveals the broad root and deep central groove.

Teeth change around the jaw

Teeth from different positions will not all be identical.

Front and more central teeth tend to be:

  • taller
  • more upright
  • more symmetrical

Teeth farther around the sides become:

  • broader
  • increasingly asymmetrical
  • lower in appearance

Very lateral teeth may also show changes to the central groove of the root, which can become partly closed.

This means that the root groove should not be used by itself to reject an otherwise convincing lateral specimen.

The root is useful

On a complete tooth, the underside of the root should be broad and fairly flat.

A wide, deep groove runs through the middle of most teeth.

Because several small catsharks have superficially similar crowns, retaining the root significantly increases confidence in an identification.

Similar Species

References & Literature

Cappetta, H. (1976). Sélaciens nouveaux du London Clay de l’Essex (Yprésien du Bassin de Londres). Geobios, 9(5), 551–575.
Original description of the species as Scyliorhinus casieri, based on material from Burnham-on-Crouch.

Ward, D.J. (1980). The distribution of sharks, rays and chimaeroids in the English Palaeogene. Tertiary Research, 3(1), 13–19.
Important reference for the distribution of British Palaeogene sharks.

Kemp, D.J. (1982). Fossil sharks, rays and chimaeroids of the English Tertiary period. Gosport Museum.
Useful illustrated reference for British Palaeogene elasmobranchs.

Bor, T.J. (1985). Elasmobranch teeth (Vertebrata, Pisces) from the Dongen Formation (Eocene) in the Netherlands. Mededelingen van de Werkgroep voor Tertiaire en Kwartaire Geologie, 22(2), 73–122.

Noubhani, A. & Cappetta, H. (1997). Les Orectolobiformes, Carcharhiniformes et Myliobatiformes des Bassins à phosphate du Maroc (Maastrichtien–Lutétien basal). Palaeo Ichthyologica, 8, 1–327.
Establishes the genus Casieria.

Adnet, S. (2006). Nouvelles faunes de sélaciens de l’Éocène des Landes (Sud-Ouest, France). Palaeo Ichthyologica, 10, 1–128.
Useful for Eocene shark faunas and additional records of Casieria.

Rayner, D., Mitchell, T. & Rayner, M. (2009). London Clay Fossils of Kent and Essex. Medway Fossil and Mineral Society, 228 pp.
Important illustrated reference for the London Clay fauna.

Cappetta, H. (2012). Chondrichthyes: Mesozoic and Cenozoic Elasmobranchii: Teeth. Handbook of Paleoichthyology, Volume 3E.
Major modern reference for fossil shark tooth morphology and taxonomy.

Adnet, S., Feichtinger, I., Harzhauser, M. & Pollerspöck, J. (2021). A mesopelagic selachian fauna from the middle Eocene of St. Pankraz (Austria) reveals homogeneity in deep-marine environments during the warm period in Europe. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 301(1), 25–63.