Acanthodes

Acanthodes is an extinct genus of small, spiny jawed fishes in the extinct class Acanthodii, commonly known as spiny sharks. It is one of the better-known genera from the group and helps illuminate early evolution of jawed vertebrates. Fossils of Acanthodes date to the Paleozoic, with specimens reported from the Silurian and Devonian periods, and by some accounts extending into the Early Carboniferous. Fossils have been found in what were once different parts of the ancient continents, including Europe, North America, and Australia, indicating a broad geographic distribution.

The typical morphology of Acanthodes includes a streamlined body covered with small, tooth-like denticles and several elongated fin spines supporting the dorsal and paired fins. As with other acanthodians, its skeleton is interpreted as primarily cartilaginous. The skull and jaw apparatus carried dentitions that indicate a jawed lifestyle, though soft-tissue details are rarely preserved.

In terms of paleobiology, the ecology of Acanthodes is incompletely known; most evidence suggests a small to medium-sized, carnivorous or omnivorous fish living in marine or estuarine environments, feeding on crustaceans and other small invertebrates, and possibly small fish. The group as a whole is important for understanding early jawed vertebrates because it shows a mosaic of primitive and derived features relative to both jawed cartilaginous and bony fishes.

The genus name Acanthodes derives from Greek acanthos “spine” and -odes “resembling.” The genus was established in the 19th century and includes several species described from various Paleozoic deposits.