''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 gr ...

from the Rupelian age of the

Oligocene epoch The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but th ...

. It is a monotypic genus, containing only ''L. vandenbroeki''. It is considered closely related to '' Isurolamna'' 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, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...

and the Uzunbas Formation of

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References

Prehistoric shark genera Animals described in 1999 Lamnidae {{Paleo-shark-stub