Ischnacanthiformes is a prehistoric order of "
acanthodian
Acanthodii or acanthodians is an extinct class of Gnathostomata, gnathostomes (jawed fishes). They are currently considered to represent a paraphyletic Evolutionary grade, grade of various fish lineages Basal (phylogenetics), basal to extant tax ...
"
stem-
chondrichthyans found in
Canada
Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
,
Ukraine
Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...
and
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
. Members of this order were
nektonic carnivore
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant
Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...
s,
eating animals that swim rather than plankton. They had slender builds, light armor, deeply inserted spines, shark-like teeth, and two
dorsal fin
A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...
s.
Some species were around 2 meters (6.56 feet) long.
It was described by Berg in 1940.
References
Prehistoric cartilaginous fish orders
{{Acanthodii-stub