''Macrosqualodelphis'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

river dolphin River dolphins are a polyphyletic group of fully aquatic mammals that reside exclusively in freshwater or brackish water. They are an informal grouping of dolphins, which itself is a paraphyletic group within the infraorder Cetacea. Extant riv ...

s from the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was prece ...

(Burdigalian) Chilcatay Formation of the

Pisco Basin Pisco Basin ( es, Cuenca de Pisco) is a sedimentary basin extending over in southwestern Peru.Solís Mundaca, 2018, p.1 The basin has a thick sedimentary fill, which is about half the thickness of more northern foreland basins in Peru. The old ...

, Peru. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''M. ukupachai''.

Description

''Macrosqualodelphis'' is distinguished from other squalodelphinids by its larger size () and a less abrupt anterior tapering of rostrum in dorsal view, U-shaped left antorbital notch prominent nuchal crest higher than the frontals and nasals at the vertex, a thinner, blade-like lateral margin of the posterior portion of the rostrum, and a more voluminous temporal fossa and larger teeth.Giovanni Bianucci, Giulia Bosio, Elisa Malinverno, Christian de Muizon, Igor M. Villa, Mario Urbina and Olivier Lambert. 2018
"A New Large Squalodelphinid (Cetacea, Odontoceti) from Peru Sheds Light on the Early Miocene Platanistoid Disparity and Ecology"
. Royal Society Open Science. 5(4) DOI: 10.1098/rsos.172302 CC-BY icon

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References

River dolphins Prehistoric toothed whales Miocene cetaceans Miocene mammals of South America Neogene Peru Fossils of Peru Fossil taxa described in 2018 {{Paleo-whale-stub