Render of Xenacanthus, a prehistoric shark Click to enlarge image
Render of Xenacanthus, a prehistoric shark. Image: Nobu Tamura
© CC BY-SA 4.0

Fast Facts

  • IUCN Conservation Status
    EXTINCT (EX)
  • Classification
    Genus
    Xenacanthus
    Family
    Xenacanthidae
    Order
    Xenacanthida
    Superorder
    Selachimorpha
    Class
    Chondrichthyes
    Kingdom
    Animalia
  • Size Range
    Between 1 - 2 meters in length

Introduction

About the Xenacanthus

The Xenacanthus (ancient greek for “foreign spine”) is an extinct genus of prehistoric shark. Unique to this group is the modified dorsal spine that projected from the back of their heads. Their distinctive V-shaped teeth indicate that members of Xenacanthus likely fed on small crustaceans and fish. Almost everything scientists know about Xenacanthus is based upon the fossilised remains of their teeth and spines, with few preserved bodies actually found.


Identification

What did it look like?

Xenacanthus were freshwater sharks, growing between one and two metres long. They possessed a ribbonlike dorsal fin that ran the entire length of their back, resembling modern conger eels. Interestingly, the highly unusual dorsal fin spine can tell us a lot about the biology of these animals. Studies have shown that the spine grew with annulated rings as the animal aged, allowing scientists to simply count the number of years the animal was alive. The size also appears to have been important, with female xenacanthid sharks having larger spines than males.


Render of Xenacanthus, a prehistoric shark
Render of Xenacanthus, a prehistoric shark. Image: Nobu Tamura
© CC BY-SA 4.0

Habitat

Where did it live?

‘The location of fossil remains indicates that Xenacanthus once populated freshwater bodies across Europe, India, Australia and the United States of America.


Feeding and diet

What did it eat?


References

Turner, S., 1982. Middle Palaeozoic elasmobranch remains from Australia. Journal of Vertebrate Paleontology, 2(2), pp.117-131.