''Nakonanectes bradti'' is an

elasmosaurid Elasmosauridae is an extinct family of plesiosaurs, often called elasmosaurs. They had the longest necks of the plesiosaurs and existed from the Hauterivian to the Maastrichtian stages of the Cretaceous, and represented one of the two groups of p ...

plesiosaur The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared ...

of the late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

found in 2010 the

state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * ''The State'' (newspaper), a daily newspaper in Columbia, South Carolina, United States * ''Our S ...

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...

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 is an extinct family of plesiosaurs, often called elasmosaurs. They had the longest necks of the plesiosaurs and existed from the Hauterivian to the Maastrichtian stages of the Cretaceous, and represented one of the two groups of p ...

fossil in a canyon on the Charles M. Russell National Wildlife Refuge. The specimen proved to be a new, short-necked species of elasmosaur, subsequently named ''Nakonanectes bradti''. The

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

, 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 hind limbs, 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 P ...

, 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. Campanian s ...

/early

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

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, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient sea, ...

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

Classification

Danielle Serratos, Patrick Druckenmiller, and Roger Benson found that ''N. bradti'' is similar to the

Aristonectinae Aristonectinae is a clade of plesiosaurs in the family Elasmosauridae. It includes the Late Cretaceous plesiosaurs ''Aristonectes'' and '' Kaiwhekea'', traditionally grouped with the Late Jurassic ''Tatenectes'' and ''Kimmerosaurus'' in the famil ...

, short-necked elasmosaurids known from fossils collected in South America. This indicates that short-necked elasmosaurids evolved in multiple locations on the globe.

References

Elasmosaurids Fossil taxa described in 2017 Sauropterygian genera {{cretaceous-reptile-stub