| Morturneria Temporal range: Late Cretaceous, Maastrichtian | |
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| Life restoration | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | † Sauropterygia |
| Order: | † Plesiosauria |
| Family: | † Elasmosauridae |
| Genus: | † Morturneria Chatterjee and Creisler, 1994 |
| Species | |
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Morturneria is an extinct genus of plesiosaur from the Late Cretaceous of what is now Antarctica.
The Lopez de Bertodano Formation is located on Seymour Island, Antarctica, with exposures present in all but the northernmost third of the island. During the summers of 1981–1982, 1983–1984, and 1984–1985, paleontological expeditions recovered eight partial plesiosaur skeletons in the formation. One of these, TTU P9219, consisted of a skull 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 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. [1]
In 1989, Sankar Chatterjee and Bryan Small named the new genus and species 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. [1] However, the name Turneria was preoccupied, already in use for a genus of hymenopteran insect. 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. [2]
However, a 2003 study by Zulma Gasparini and colleagues found Morturneria to be so similar to Aristonectes , 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. [3] 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 collections from Seymour Island contain postcranial material from adult plesiosaurs that, while similar to Aristonectes, definitely belonged to a different taxon, further supporting the separation of the two genera. [4] 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 end of the humerus, and a left femur. Additionally, more material pertaining to the holotype was reported; a possible humeral head, an epipodial (lower limb bone), a possible carpal, and three phalanges. [5]
The external naris (nostril opening) is formed by the premaxilla on the inner and most of the front edge, the maxilla on the rest of the front and the outer edge, and the frontal and prefrontal on the rear edge. The upper surfaces of the premaxillae and maxillae bore many foramina (pits). The premaxillae each bore at least eight teeth. After the frontmost five alveoli (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 (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. [4]
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. [3] 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. [4]
Elasmosaurus (;) is a genus of plesiosaur that lived in North America during the Campanian stage of the Late Cretaceous period, about 80.5 million years ago. The first specimen was discovered in 1867 near Fort Wallace, Kansas, US, and was sent to the American paleontologist Edward Drinker Cope, who named it E. platyurus in 1868. The generic name means "thin-plate reptile", and the specific name means "flat-tailed". Cope originally reconstructed the skeleton of Elasmosaurus with the skull at the end of the tail, an error which was made light of by the paleontologist Othniel Charles Marsh, and became part of their "Bone Wars" rivalry. Only one incomplete Elasmosaurus skeleton is definitely known, consisting of a fragmentary skull, the spine, and the pectoral and pelvic girdles, and a single species is recognized today; other species are now considered invalid or have been moved to other genera.
Alwalkeria is a genus partly based on basal saurischian dinosaur remains from the Late Triassic, living in India. A thighbone found indicates a small bipedal form. It has been seen as a chimera.
Gasparinisaura is a genus of herbivorous ornithopod dinosaur from the Late Cretaceous.
Antarctopelta was a genus of ankylosaurian dinosaur with one known species, A. oliveroi, which lived in Antarctica during the Late Cretaceous Period. It was a medium-sized ankylosaur, reaching 4 meters in length or more, and showed characteristics of two different families, making more precise classification difficult. The single known fossil specimen was discovered on James Ross Island in 1986, constituting the first dinosaur remains ever discovered on Antarctica, although it is the second dinosaur from the continent to be formally named.
Macroplata is an extinct genus of Early Jurassic rhomaleosaurid plesiosaur which grew up to 4.65 metres (15.3 ft) in length. Like other plesiosaurs, Macroplata probably lived on a diet of fish, using its sharp needle-like teeth to catch prey. Its shoulder bones were fairly large, indicating a powerful forward stroke for fast swimming. Macroplata also had a relatively long neck, twice the length of the skull, in contrast to pliosaurs.
Mauisaurus is a dubious genus of plesiosaur that lived during the Late Cretaceous period in what is now New Zealand. Numerous specimens have been attributed to this genus in the past, but a 2017 paper restricts Mauisaurus to the lectotype and declares it a nomen dubium.
Edgarosaurus is a genus of polycotylid plesiosaur from the Thermopolis Shale, containing one species, E. muddi. The type specimen was found in Early Cretaceous rocks in the state of Montana in the United States. At the time, this location was covered by part of the Western Interior Seaway. Edgarosaurus was one of the first polycotylids that evolved to become native to the Western Interior Seaway.
Mahajangasuchus is an extinct genus of crocodyliform which had blunt, conical teeth. The type species, M. insignis, lived during the Late Cretaceous; its fossils have been found in the Maevarano Formation in northern Madagascar. It was a fairly large predator, measuring up to 4 metres (13 ft) long.
Anatosuchus is an extinct genus of notosuchian crocodylomorph discovered in Gadoufaoua, Niger, and described by a team of palaeontologists led by the American Paul Sereno in 2003, in the Journal of Vertebrate Paleontology. Its duck-like snout coincidentally makes it resemble a crocoduck, an imagined hybrid animal with the head of a crocodile and the body of a duck.
Goronyosaurus is an extinct genus of marine lizard belonging to the mosasaur family. Fossils of Goronyosaurus are exclusively known from the Dukamaje Formation of Niger and Nigeria and also the Rima Formation of Nigeria, and are both Maastrichtian in age. The holotype was first described in 1930 as Mosasaurus nigeriensis, but subsequent remains revealed a highly unique set of adaptations that prompted the species to be reclassified as the only species of the new genus Goronyosaurus in 1972. These unique adaptations have made Goronyosaurus notoriously difficult to classify within the Mosasauridae and it is often left out of phylogenetic analyses, although most authors agree that Goronyosaurus belonged to Mosasauridae.
Tuarangisaurus is an extinct genus of elasmosaurid known from New Zealand. The type and only known species is Tuarangisaurus keyesi, named by Wiffen and Moisley in 1986.
Taniwhasaurus is an extinct genus of mosasaurs who lived during the Late Cretaceous in what is now New Zealand and Antarctica, possibly even in other continents. The genus belongs to the subfamily Tylosaurinae, a lineage of mosasaurs characterized by a long toothless conical rostrum.
Aristonectes 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 type species is Aristonectes parvidens, first named by Cabrera in 1941.
Jesairosaurus is an extinct genus of early archosauromorph reptile known from the Illizi Province of Algeria. It is known from a single species, Jesairosaurus lehmani. Although a potential relative of the long-necked tanystropheids, this lightly-built reptile could instead be characterized by its relatively short neck as well as various skull features.
Gasparinisuchus is an extinct genus of peirosaurid notosuchian known from the Late Cretaceous of Neuquén and Mendoza Provinces, western central Argentina. It contains a single species, Gasparinisuchus peirosauroides.
Anningasaura is an extinct genus of basal plesiosaur. It is known from a single type species, A. lymense, discovered in Early Jurassic rocks of Lyme Regis in the United Kingdom.
This timeline of plesiosaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, taxonomic revisions, and cultural portrayals of plesiosaurs, an order of marine reptiles that flourished during the Mesozoic Era. The first scientifically documented plesiosaur fossils were discovered during the early 19th century by Mary Anning. Plesiosaurs were actually discovered and described before dinosaurs. They were also among the first animals to be featured in artistic reconstructions of the ancient world, and therefore among the earliest prehistoric creatures to attract the attention of the lay public. Plesiosaurs were originally thought to be a kind of primitive transitional form between marine life and terrestrial reptiles. However, now plesiosaurs are recognized as highly derived marine reptiles descended from terrestrial ancestors.
Kaikaifilu is a genus of mosasaur from the Late Cretaceous part of the Lopez de Bertodano Formation of Antarctica, just before the Cretaceous–Paleogene extinction event. It is thought to be among the largest members of the tylosaurines, a group of marine lizards that lived during the Cretaceous, and the only really large Antarctic tylosaurine. However, some researchers disagree with this classification.
Kawanectes is a genus of elasmosaurid plesiosaur, a type of long-necked marine reptile, that lived in the marginal marine (estuarine) environment of Late Cretaceous Patagonia. It contains one species, K. lafquenianum, described in 2016 by O'Gorman.
Eardasaurus is a genus of thalassophonean pliosaurid from the middle Jurassic Oxford Clay Formation. The animal would have measured over 4.7 m (15 ft) long and possessed a high amount of teeth relative to other pliosaurs. Its teeth show distinct ridges formed by the tooth enamel, some of which are very pronounced and similar to carinae, giving the teeth a cutting edge.
