Genus author:
Serratos, Druckenmiller, and Benson (2017)
Bearpaw Shale, lower Maastrichtian, Upper Cretaceous
Phillips County, Montana, U.S.A.
Referred material (sp.):
Type species:

N. bradti

N. bradti
Species author:
Serratos, Druckenmiller, and Benson 2017
Type specimen:
MOR 3072, a complete skull and partial skeleton
lower Maastrichtian, Upper Cretaceous
Geological formation:
Baculites baculus–B. grandis zones, Bearpaw Shale
Type location:
Near Fort Peck Reservoir, Charles M. Russell National Wildlife Refuge (CM Russell NWR), Phillips County, Montana, USA
Referred material:

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.

The articulated type specimen of Nakonanectes. From Serratos et al. (2017)
Nakonanectes skull, left side. Laser scan and line drawing. Fig 5 from Serratos et al. (2017)
Nakonanectes skull, right side. Laser scan and line drawing. Fig 4 from Serratos et al. (2017)