Pharyngolepis
Encyclopedia
Pharyngolepis is an extinct genus of primitive jawless fish
that lived in the Silurian
period of what is now Norway
.
Pharyngolepis had well-developed anal an caudal fins, but no paired or dorsal fin
s that would have helped stabilise it in the water, and so was probably a poor swimmer, remaining close to the sea bottom. The pectoral fins were instead replaced by bony spines, possibly for protection against predators, and there was a row of spines along the back. It probably scooped up food from the ocean floor.
Agnatha
Agnatha is a superclass of jawless fish in the phylum Chordata, subphylum Vertebrata. The group excludes all vertebrates with jaws, known as gnathostomes....
that lived in the Silurian
Silurian
The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
period of what is now Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
.
Pharyngolepis had well-developed anal an caudal fins, but no paired or dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
s that would have helped stabilise it in the water, and so was probably a poor swimmer, remaining close to the sea bottom. The pectoral fins were instead replaced by bony spines, possibly for protection against predators, and there was a row of spines along the back. It probably scooped up food from the ocean floor.