''Morturneria'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of plesiosaur from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

of what is now

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

History of research

The Lopez de Bertodano Formation is located on

Seymour Island Seymour Island or Marambio Island, is an island in the chain of 16 major islands around the tip of the Graham Land on the Antarctic Peninsula. Graham Land is the closest part of Antarctica to South America. It lies within the section of the isla ...

, with exposures present in all but the northernmost third of the island. During the summers of 1981–1982, 1983–1984, and 1984–1985,

paleontological Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...

expeditions recovered eight partial plesiosaur skeletons in the formation. One of these, TTU P9219, consisted of a

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

and some cervical vertebrae. It was found in the upper part of the formation, informally known as the 'molluscan units', high up in a ravine. It was preserved within a tough, calcareous nodule, from which it was difficult to remove. While excavating the specimens, the dig teams faced difficulty in removing the strata above the fossils, due to the presence of permafrost. The cold temperatures also prevented the

plaster Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. In English, "plaster" usually means a material used for the interiors of buildings, while "re ...

from setting, so the teams used camp stoves and aluminium foil to heat it up, allowing it to harden. The specimen was prepared with the usage of power tools and acetic acid to remove the surrounding rock. In 1989,

Sankar Chatterjee Sankar Chatterjee (born May 28, 1943) is a paleontologist, and is the Paul W. Horn Professor of Geosciences at Texas Tech University and Curator of Paleontology at the Museum of Texas Tech University. He earned his Ph. D. from the University of ...

and Bryan Small named the new

and

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

''Turneria seymourensis'' to contain TTU P9219. The specific name refers to Seymour Island, while the generic name honored Dr. Mort Turner, who was interested in the paleontological studies taking place there. However, the name ''

Turneria ''Turneria'' is a genus of ants that belongs to the subfamily Dolichoderinae Dolichoderinae is a subfamily of ants, which includes species such as the Argentine ant (''Linepithema humile''), the erratic ant, the odorous house ant, and th ...

'' was

preoccupied The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linn ...

, already in use for a genus of hymenopteran

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

. In light of this, Chatterjee and Benjamin Creisler published a new name for the plesiosaur, ''Morturneria'', in 1994. As before, the generic name honors Mort Turner. However, a 2003 study by Zulma Gasparini and colleagues found ''Morturneria'' to be so similar to ''

Aristonectes ''Aristonectes'' (meaning 'best swimmer') is an extinct genus of plesiosaur from the Late Cretaceous Paso del Sapo Formation of what is now Argentina, the Quiriquina Formation of Chile and the Lopez de Bertodano Formation of Antarctica. The ...

'', they found it most likely that it was merely a juvenile ''A. parvidens''. Since ''Aristonectes'' was named first, they concluded that ''Morturneria'' was a junior synonym of this genus. In 2017, a study led by F. Robin O'Keefe reanalyzed the skull of ''Morturneria''. While they agreed with Gasparini and colleagues that the specimen was a juvenile, they found it to be distinct from ''Aristonectes'' and a valid genus once more. They also found that the

Texas Tech University Texas Tech University (Texas Tech, Tech, or TTU) is a public research university in Lubbock, Texas. Established on , and called Texas Technological College until 1969, it is the main institution of the five-institution Texas Tech University Sy ...

collections from Seymour Island contain

postcranial Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated s ...

material from adult plesiosaurs that, while similar to ''Aristonectes'', definitely belonged to a different taxon, further supporting the separation of the two genera. In a 2019 thesis, Elizabeth Lester assigned another specimen found by the expeditions that recovered the holotype of ''Morturneria seymourensis'' to the species. This specimen, TTU P9217, consists of more cervical vertebrae, a right humerus, a nearly complete left forelimb missing the

proximal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

end of the humerus, and a left

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

. Additionally, more material pertaining to the holotype was reported; a possible humeral head, an epipodial (lower limb bone), a possible

carpal The carpal bones are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, the ...

, and three phalanges.

Description

The external naris (nostril opening) is formed by the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

on the inner and most of the front edge, the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

on the rest of the front and the outer edge, and the

frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music * The Front (band), an American rock band signed to Columbia Records and active in the 1980s and e ...

and prefrontal on the rear edge. The upper surfaces of the premaxillae and maxillae bore many

foramina In anatomy and osteology, a foramen (;Entry "foramen"
in

(pits). The premaxillae each bore at least eight teeth. After the frontmost five

alveoli Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * ...

(tooth sockets) in the upper jaw, the borders of the alveoli become poorly defined or absent, with the upper tooth row appearing to be a groove on the maxilla. Instead of being directed downwards, the teeth were pointed outwards, where they interlocked. The upper edge of the

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

(eye opening) is composed of the frontal, with the prefrontal participating in the region intermediate between the upper and front edges. There is a prominent bend in the frontal, with the front region flaring outwards. This may have protected the eye. The outer margin of the orbit is bowed inwards, thanks to an enlargement on the maxilla.

Paleobiology

In 2003, Gasparini interpreted the ''M. seymourensis'' holotype as a juvenile because of its smaller size and the lack of fusion of the neural arches to the vertebrae. The downward-curving teeth of the lower jaw indicate that unlike most plesiosaurs, ''Morturneria'' was capable of filter-feeding, scooping sand from sediments, ejecting sediment-laden water, and preying on amphipods and other tiny prey organisms.

References

{{Taxonbar, from=Q21447726 Elasmosaurids Late Cretaceous plesiosaurs Plesiosaurs of Antarctica Fossil taxa described in 1994 Sauropterygian genera

History of research

Description

Paleobiology

See also

References