''Acronemus'' is an
extinct genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
euselachian from the
Middle Triassic of
Switzerland
Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...
. It is an enigmatic genus with uncertain relations to other groups. Though originally placed within
Ctenacanthiformes, it is now considered Euselachii ''
incertae sedis'', due to its mixture of features similar to
hybodontiforms and
neoselachians. Originally, teeth from this genus were attributed to "''
Acrodus bicarinatus''" while fin spines were named "''
Nemacanthus tuberculatus''". Associated material showed they were the same animal, with the older specific epithet (''tuberculatus'') taking precedence. The euselachian was given the new genus ''Acrocnemus'', containing a single species (''A. tuberculatus''). ''Acronemus'' is found in the
Anisian-age Grenzbitumenzone (also known as the
Besano Formation) of
Monte San Giorgio. It was a small animal measuring long. A 2018 study considered it to be closely related to the early Carboniferous genus ''
Tristychius'' as part of the family
Tristychiidae as a basal euselachian, with hybodonts more closely related to neoselachians than to Tristychiidae.
References
Elasmobranchii
{{paleo-shark-stub
Monotypic prehistoric cartilaginous fish genera