''Nakonanectes bradti'' is an

elasmosaurid Elasmosauridae, often called elasmosaurs or elasmosaurids, is an extinct family of plesiosaurs that lived from the Hauterivian stage of the Early Cretaceous to the Maastrichtian stage of the Late Cretaceous period (c. 130 to 66 mya). The taxo ...

plesiosaur The Plesiosauria or plesiosaurs are an Order (biology), order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period (geology), Period, possibly in the Rhaetian st ...

of the late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

found in 2010 the

state State most commonly refers to: * State (polity), a centralized political organization that regulates law and society within a territory **Sovereign state, a sovereign polity in international law, commonly referred to as a country **Nation state, a ...

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

in the United States. It is one of the most recently known elasmosaurids to have lived in North America. Unlike other elasmosaurids, it has a relatively short neck.

Description

In November 2010, hunter David Bradt stumbled on an

elasmosaur Elasmosauridae, often called elasmosaurs or elasmosaurids, is an extinct family (biology), family of plesiosaurs that lived from the Hauterivian Stage (stratigraphy), stage of the Early Cretaceous to the Maastrichtian stage of the Late Cretaceou ...

fossil at the bottom of a narrow canyon on the Charles M. Russell National Wildlife Refuge. Before it could be salvaged in the spring of 2011, the shale nodule was partly destroyed by flooding. The specimen proved to be a new, short-necked species of elasmosaur, subsequently named ''Nakonanectes bradti''. The generic name refers to the

Assiniboine The Assiniboine or Assiniboin people ( when singular, Assiniboines / Assiniboins when plural; Ojibwe: ''Asiniibwaan'', "stone Sioux"; also in plural Assiniboine or Assiniboin), also known as the Hohe and known by the endonym Nakota (or Nakoda ...

. The

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

, MOR 3072, was nearly complete. This included the skull, a part not often found intact in Elasmosauridae fossils. Other elements of the fossil included the anterior cervical vertebrae, partial dorsal and caudal vertebrae, incomplete fore and hindlimbs, gastralia, partial pectoral and pelvic girdles, and ribs. The fossil was found in the

Bearpaw Formation The Bearpaw Formation, also called the Bearpaw Shale, is a geologic formation of Late Cretaceous (Campanian) age. It outcrops in the U.S. state of Montana, as well as the Canadian provinces of Alberta and Saskatchewan, and was named for the Bear ...

, a late

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

/early

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

rock, making it one of the last known elasmosaurids to have lived in the

Western Interior Seaway The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, or the Western Interior Sea) was a large inland sea (geology), inland sea that existed roughly over the present-day Great Plains of ...

. ''N. bradti'' was only in length, making it one of the smallest elasmosaurids known. It also had a much shorter neck that most elasmosaurids, with only 39 to 42 cervical vertebrae.

Classification

Danielle Serratos, Patrick Druckenmiller, and Roger Benson found that ''N. bradti'', established by them to be a styxosaurine, is convergent in build to the Aristonectinae, short-necked elasmosaurids known from fossils collected in South America. This indicates that short-necked elasmosaurids evolved in multiple locations on the globe.

References

{{Taxonbar, from=Q48835661 Elasmosauridae Fossil taxa described in 2017 Sauropterygian genera Paleontology in Montana