A new genus and species of aristonectine elasmosaurid plesiosaur has been described from a partial skeleton found in central Chile.
The newly-discovered plesiosaur lived approximately 67 million years ago during the Maastrichtian stage of the Cretaceous period.
Dubbed Wunyelfia maulensis, the animal belongs to Aristonectinae, a group of plesiosaurs in the family Elasmosauridae.
It is only the second representative of this group known to date in the southeastern Pacific during the late Maastrichtian stage.
“The Aristonectinae was a monophyletic lineage of elasmosaurid plesiosaurs morphologically and ecologically distinct from other typically long-necked elasmosaurids,” said University of Chile paleontologists Dr. Rodrigo Otero and Dr. Sergio Soto-Acuña.
“The first were characterized by the acquisition of enlarged skulls, an increased tooth number, as well as shortened and thickened necks, which spanned mostly along the Weddellian Province during the Late Cretaceous.”
“They are frequent in the Maastrichtian of the southern hemisphere, with occurrences in Argentinean Patagonia, central and southern Chile, New Zealand and Antarctica.”
“The growing body of evidence currently shows that among austral elasmosaurid plesiosaurs, at least one monophyletic lineage (Aristonectinae) reached a provincial diversity with endemic forms in Antarctica, New Zealand and southern South America during the Late Cretaceous.”
The near adult, partial postcranial skeleton of Wunyelfia maulensis was recovered from the upper Maastrichtian levels of the Quiriquina Formation in central Chile.
“The studied skeleton was recovered from strata exposed in the locality of Mariscadero, south of Pelluhue, 320 km (199 miles) southwest from Santiago,” the researchers explained.
“The specimen was found 20 cm (7.9 inches) above a second partial postcranial skeleton of an indeterminate elasmosaurid.”
“Its small almost adult size differs from coeval larger forms previously described in South America, particularly Aristonectes parvidens and Aristonectes quiriquinensis, with estimated lengths over 10 m (33 feet),” they noted.
Aristonectines seem to have exploited a unique trophic niche unrecorded among other plesiosaurs.
“The presence of Aristonectes and Wunyelfia during the late Maastrichtian of central Chile may correlate with a highly productive ecosystem able to support a taxonomic diversity within this distinctive ecomorphotype,” the scientists said.
“Further studies on this new taxon and other early aristonectines will be key to understanding the origin and evolution of this singular clade of elasmosaurids.”
The discovery is reported in a paper in the February 2021 issue of the journal Cretaceous Research.
R.A. Otero & S. Soto-Acuña. Wunyelfia maulensis gen. et sp. nov., a new basal aristonectine (Plesiosauria, Elasmosauridae) from the Upper Cretaceous of central Chile. Cretaceous Research 118: 104651; doi: 10.1016/j.cretres.2020.104651