''Acuetzpalin'' (meaning "water lizard" in Classical Nahuatl) is an extinct genus of

platypterygiine Platypterygiinae is an extinct subfamily of ophthalmosaurid thunnosaur ichthyosaurs from the early Late Jurassic to the early Late Cretaceous (Kimmeridgian - Cenomanian) of Asia, Australia, Europe, North America and South America. Currentl ...

ophthalmosaurid Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous (Bajocian - Cenomanian) worldwide. Almost all ichthyosaurs from the Middle Jurassic onwards belong to the family, until the e ...

ichthyosaur Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...

found in the

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxford ...

La Casita Formation The La Casita Formation is a geologic formation in Mexico. It preserves fossils dating back to the Kimmeridgian to lowermost Berriasian. It is laterally equivalent to the La Caja Formation and the Pimienta Formation. The ichthyosaurs ''Jabalisauru ...

Mexico Mexico ( Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guate ...

. It is known from a partial skeleton (missing the limbs), of which the skull is surprisingly well preserved. Its length is estimated to have been more than long, considering the missing parts of the holotype. It was the first ichthyosaur described in 2020 and the first new ichthyosaur genus described since 2017 (both ''

Gengasaurus ''Gengasaurus'' is an extinct genus of ophthalmosaurid ichthyosaur from the Jurassic. The type and only species, ''Gengasaurus nicosiai'', was named in 2017, after the locality of Genga, Marche. It lived in Italy about 152 million years ago. His ...

'' and ''

Keilhauia ''Keilhauia'' is a genus of ophthalmosaurid ichthyosaur, a type of dolphin-like, large-eyed marine reptile, from the Early Cretaceous shallow marine Slottsmøya Member of the Agardhfjellet Formation in Svalbard, Norway. The genus contains a sin ...

'' were described in 2017).

Classification

A phylogenetic analysis conducted in 2020 reveals that ''Acuetzpalin'' is a member of the subfamily

Platypterygiinae Platypterygiinae is an extinct subfamily of ophthalmosaurid thunnosaur ichthyosaurs from the early Late Jurassic to the early Late Cretaceous (Kimmeridgian - Cenomanian) of Asia, Australia, Europe, North America and South America. Currently ...

and is located among the most-derived platypterygiines.

Phylogeny

The following cladogram shows a possible phylogenetic position of ''Acuetzpalin'' in Ophthalmosauridae according to the analysis performed by Zverkov and Jacobs (2020).

References

Fossil taxa described in 2020 Late Jurassic ichthyosaurs Jurassic reptiles of North America Ichthyosauromorph genera {{Jurassic-reptile-stub