Catshark skulls and labial cartilages

Labial cartilages are widespread in modern sharks, and they are also found in their relatives: rays, chimaeras and are known in several fossil form. They are paired (up to three pairs) cartilage structures supporting the mouth corners, come in a variety of shapes and sizes and may help with suction feeding in some species.

 Skull of Squatina sp., showing the massive labial cartilages (in green). Source unknown.

Despite some references in the literature (for example Parker's 1876 work), I completely missed them in the first catshark skulls I cleaned. In Scyliorhinus canicula, there is two pairs of thin rod-shaped labial cartilages.

Skull in the cleaning process where labial cartilages have been removed.

Labial cartilages are so thin in this species, it is difficult to keep them in place during cleaning. The best option might be to carefully remove them while taking good reference pictures to be sure to put them back in the right place afterward.

Close up on the upper right labial cartilage.

Couple of finished Scyliorhinus canicula skulls with the labial cartilages in place. Scale bar: 1cm

Next step is to try to preserve the scleral rings for this species, as they are so thin they tend to shrink beyond recognition during the drying process.

References: ParkerW.K., 1876. On the structure and development of the skull in sharks and skates.