Nakonanectes

Nakonanectes is a small elasmosaurid plesiosaur from the Bearpaw Shale of Montana, USA. It is known from a single moderately complete specimen including a particularly fine skull. It has a relatively short neck for an elasmosaur consisting of ‘only’ 39-42 neck vertebrae. However, 16–19 of the neck vertebrae were lost in a “heavy spring runoff that occurred between the time of discovery and excavation” (Serratos et al. 2017, p6). Nakonanectes also has a proportionally short snout, so its eyes appear to be positioned towards the front of the head.

Nakonanectes is the stratigraphically youngest plesiosaur known from the Western Interior Seaway. It is slightly younger (Maastrichtian) than Albertonectes and Terminonatator, two other Bearpaw Shale elasmosaurids from the older (Campanian) part.

Nakonanectes is a styxosaurine elasmosaurid. Other styxosaurines have a much longer neck, so Nakonanectes represents a second independent evolution of short necks within Elasmosauridae, separate from the short-necked aristonectine elasmosaurids. Nakonanectes is also notable for having a small adult body size compared to other larger styxosaurines, it was only 5.1–5.6 m long.

The genus name is derived from Nakona, the name for native Assiniboine people of northeastern Montana, while the Greek ‘nectes’ means “swimmer”. The species name refers to David Bradt, who discovered the specimen.