''Lessiniabatis'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of highly unusual

stingray Stingrays are a group of sea rays, which are cartilaginous fish related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatid ...

from the

Early Eocene In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

. It contains a single species, ''L. aenigmatica''. It is known from three specimens, one nearly complete, from the famous

Monte Bolca Monte Bolca is a lagerstätte near Verona, Italy that was one of the first fossil sites with high quality preservation known to Europeans, and is still an important source of fossils from the Eocene. Geology Monte Bolca was uplifted from the T ...

lagerstätte A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These for ...

Taxonomy

The specimen was initially assigned as the holotype of '' Arechia crassicaudata'', another fossil stingray from the same formation, which was found to be made in error as ''Lessiniabatis'' does not share any of the diagnostic traits of ''A. crassicaudata''. It was later described as its own genus and species in 2019. Phylogenetic analyses recover it as a derived member of the Dasyatoidea, and the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to the Dasyatidae and

Potamotrygonidae River stingrays or freshwater stingrays are Neotropical freshwater fishes of the family Potamotrygonidae in the order Myliobatiformes, one of the four orders of batoids, cartilaginous fishes related to sharks. They are found in rivers in tropic ...

. The genus name references Lessinia, the Italian geographical area where Monte Bolca is located, while the species name references its strange appearance.

Description

''Lessiniabatis'' is notable for its bizarre body plan, which has no analog in any other stingray, fossil or modern. It had a disc-shaped body akin to modern benthic stingrays, but its tail was highly reduced to become very short and slender, with an apparent loss of the tail sting. The pectoral radials were fused with one another, potentially as an adaptation to strengthen the undulations of its body as it swam.

Ecology

The unusual adaptations of ''Lessiniabatis'' may reflect an evolutionary radiation in new body plans by cartilaginous fish following either the Cretaceous-Paleogene extinction event or the Paleocene-Eocene Thermal Maximum. The Monte Bolca formation is thought to reflect a shallow tropical sea in the western

Tethys Ocean The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean that covered most of the Earth during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents ...

with scattered

coral reefs A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Co ...

. Due to its highly reduced tail, ''Lessiniabatis'' likely had a

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

lifestyle, propelling itself with its strengthened pectoral fins. Due to having no known close relatives to compare with, the exact depth range it inhabited is unknown.

References

{{Taxonbar, from=Q123561569 Myliobatiformes Eocene cartilaginous fish Fossils of Italy Eocene fish of Europe Fossil taxa described in 2019