''Lethenia'' is an extinct genus of

mackerel shark The Lamniformes (, from Greek ''lamna'' "fish of prey") are an order of sharks commonly known as mackerel sharks (which may also refer specifically to the family Lamnidae). It includes some of the most familiar species of sharks, such as the g ...

from the Rupelian age of the Oligocene epoch. It is a

monotypic genus In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

, containing only ''L. vandenbroeki''. It is considered closely related to ''

Isurolamna ''Isurolamna'' is an extinct genus of Lamnidae, mackerel shark from the Paleogene, Paleogene period. It contains at least three species and a fourth is sometimes placed in it. It is thought to be closely related to ''Macrorhizodus'', ''Isurus'', ...

'' and sometimes included within it. It differs in the morphology of its teeth, which are much more gracile than ''Isurolamna'' and has larger spacing between its crown and lateral cusps. ''Lethenia'' is rare and only known from isolated teeth. It is best known from the Boom Clay Formation of

Belgium Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...

and the Uzunbas Formation of

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...

References

Prehistoric shark genera Fossil taxa described in 1999 Lamnidae Monotypic prehistoric cartilaginous fish genera {{Paleo-shark-stub