Cephalic spines (head spines) are spines or "horns" on the heads of animals, either for display,or sexual dimorphism. They are most commonly seen in trilobites, particularly those from Morocco, and hybodont sharks.

SharksEdit

In hybodont sharks, cephalic spines are thought to represent secondary sexual structures found in adult male hybodont sharks, and may have aided in the grasping of a female during copulation.

One or more spines were positioned behind each eye on the cheek area. The tip of the spine often bears a single barb.

Cephalic spines are often found in association with fin spines and teeth of the hybodontid shark Lissodus selachos from the Late Cretaceous Lance Formation of Whyoming.

Cephalic spines from Hybodus sp. From the Cretaceous of Sussex, UK

A cephalic spine from Hybodus sp. From the Middle Cretaceous of the Continental Sandstone Deposits of Khouribga, Morocco. 16mm across.

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ReferencesEdit

• Welton, Bruce J., Ph.D. The Collector's Guide to Fossil Sharks and Rays from the Cretaceous of Texas. pp. 28.