Kolihapeltis chlupaci hollardi trilobite clearly showing the scimitar-shaped cephalic spines.
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.
A 3-D model of
clearly showing the cephalic spines on it's head. Hybodus
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
from the Lissodus selachos Late Cretaceous Lance Formation of Whyoming.
A cephalic spine from
of the Continental Sandstone Deposits of Khouribga, Morocco. 16mm across.
Welton, Bruce J., Ph.D. The Collector's Guide to Fossil Sharks and Rays from the Cretaceous of Texas. pp. 28.