''Plesioelasmosaurus'' is an extinct
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
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 ...
from the Late Cretaceous (middle
Cenomanian
The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...
)
Greenhorn Limestone
The Greenhorn Limestone or Greenhorn Formation is a geologic formation in the Great Plains Region of the United States, dating to the Cenomanian and Turonian ages of the Late Cretaceous period. The formation gives its name to the Greenhorn cycle ...
of
Kansas
Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the ...
,
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
. The genus contains a single species, ''P. walkeri'', known from a partial skeleton.
Discovery and naming
The
holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
specimen,
UNSM 50134, was discovered by Joe Purzer, an oil field geologist, in 1931 near the town of
Holyrood, Kansas. He notified
George F. Sternberg and
Myrl V. Walker, and the excavation of the specimen commenced later in the year. It was collected over a period of ten days in October 1931. The specimen became known as the 'Holyrood elasmosaur' and was eventually sold to the
University of Nebraska State Museum
The University of Nebraska State Museum, also known as Morrill Hall, founded in 1871, is a natural history museum featuring Nebraska biodiversity, paleontology, and cultural diversity, located on the University of Nebraska–Lincoln City Campus nea ...
in 1935, where it was prepared and placed into storage. Everhart (2007) noted that Harold Ehler used photographs of the holotype to identify the type locality, but no further remains of ''Plesioelasmosaurus'' resulted from Ehler's discovery. The holotype consists of both
ilia, partial hind
paddles
A paddle is a handheld tool with an elongated handle and a flat, widened distal end (i.e. the ''blade''), used as a lever to apply force onto the bladed end. It most commonly describes a completely handheld tool used to propel a human-powered w ...
, a nearly complete fore paddle, vertebrae from all sections of the vertebral column (
cervical
In anatomy, cervical is an adjective that has two meanings:
# of or pertaining to any neck.
# of or pertaining to the female cervix: i.e., the ''neck'' of the uterus.
*Commonly used medical phrases involving the neck are
**cervical collar
**cerv ...
, 'pectoral',
dorsal
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
* Dorsal co ...
,
sacral
Sacral may refer to:
*Sacred
Sacred describes something that is dedicated or set apart for the service or worship of a deity; is considered worthy of spiritual respect or devotion; or inspires awe or reverence among believers. The property ...
, and
caudal),
ribs
The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels.
The sternum, together known as the thoracic cage, is a semi- ...
and
gastralia
Gastralia (singular gastralium) are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods. They are found between the sternum and pelvis, and do not articulate with the vertebrae. In these ...
, two teeth, and more than two hundred
gastroliths
A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In oth ...
, all from a single individual. One of these front paddles is still on display at the UNSM today.
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
words "plesio", meaning "near to", "elasmo" meaning "metal plate", and "saurus", meaning "lizard". The specific name, "''walkeri''", honors paleontologist Myrl Walker, one of the collectors of the holotype.[
]
Description
A photograph of a front flipper of ''Plesioelasmosaurus'', taken in the 1930s by George F. Sternberg, was captioned as belonging to "a large plesiosaur, which would have measured from 40 to 60 feet in length" (12.2 to 18.3 m). Accodring to Everhart (2007), ''Plesioelasmosaurus'' was a "large ..elasmosaur", but no further size estimates were given.[
]
Classification
Schumacher & Everhart (2022) confidently identified ''Plesioelasmosaurus'' as a basal member of the Elasmosauridae
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 ...
.
References
{{Taxonbar, from=Q115163268
Late Cretaceous plesiosaurs of North America
Fossil taxa described in 2022
Elasmosaurids
Sauropterygian genera