| Leurospondylus Temporal range: Late Cretaceous, ~ | |
|---|---|
 | |
| Dorsal view of the holotype spine of L. ultimus | |
| Scientific classification | |
| Kingdom: | |
| Phylum: | |
| Class: | |
| Superorder: | |
| Order: | |
| Suborder: | |
| Family: | |
| Genus: | †Leurospondylus Brown, 1913 |
| Binomial name | |
| †Leurospondylus ultimus Brown, 1913 | |
Leurospondylus is an extinct genus of plesiosaur from the Horseshoe Canyon Formation of Canada whose family is currently disputed, but is suggested to be Elasmosauridae. [1]
The name Leurospondylus comes from a fusion of two Greek words, leuros (λευρός) meaning "even", "flat" or "smooth", and spondylos (σπόνδυλος) meaning "vertebra." [1] The name of the type species L. ultimus comes from the Latin ultimus meaning "last." It was so named because this genus was the latest known occurrence of a fossil plesiosaur when it was described in 1913." [1]
The holotype of L. ultimus was a juvenile. [2] The fossil included 12 vertebrae but the animal is thought to have had twice that number, [2] and was estimated to be roughly 2 meters long as a juvenile. [2] Samuel Paul Welles noted that the vertebrae are short and similar to those of pliosaurs, [3] while the scapulae and coracoids bear resemblance to those of elasmosaurids, [3] thus making it difficult to determine to which family it belongs. [3] There is some speculation that the Leurospondylus specimen is either a juvenile of a known species, or in its own, unrecognized taxonomic group. [1]
The holotype was found in the brackish paleoenvironment represented by the Edmonton beds located on the present-day Red Deer River. This area is part of the Horseshoe Canyon Formation in Alberta, Canada. [1] The occurrence of this juvenile fossil in an identifiably brackish environment led to the conclusion that plesiosaurs spent their early lives in rivers and estuaries. [1] However, some plesiosaurs spent their adult lives in fresh water also; whether Leurospondylus grew up and then left, or grew up and stayed in a fresh water ecosystem has not been determined. [1]
Albertosaurus is a genus of large tyrannosaurid theropod dinosaur that lived in northwestern North America during the early to middle Maastrichtian age of the Late Cretaceous period, about 71 million years ago. The type species, A. sarcophagus, was apparently restricted in range to the modern-day Canadian province of Alberta, after which the genus is named, although an indeterminate species has been discovered in the Corral de Enmedio and Packard Formations of Mexico. Scientists disagree on the content of the genus and some recognize Gorgosaurus libratus as a second species.
Pachyrhinosaurus is an extinct genus of centrosaurine ceratopsid dinosaur from the Late Cretaceous period of North America. The first examples were discovered by Charles M. Sternberg in Alberta, Canada, in 1946, and named in 1950. Over a dozen partial skulls and a large assortment of other fossils from various species have been found in Alberta and Alaska. A great number were not available for study until the 1980s, resulting in a relatively recent increase of interest in Pachyrhinosaurus.
Anchiceratops is an extinct genus of chasmosaurine ceratopsid dinosaur that lived approximately 72 to 71 million years ago during the latter part of the Cretaceous Period in what is now Alberta, Canada. Anchiceratops was a medium-sized, heavily built, ground-dwelling, quadrupedal herbivore that could grow up to an estimated 4.3 metres (14 ft) long. Its skull featured two long brow horns and a short horn on the nose. The skull frill was elongated and rectangular, its edges adorned by coarse triangular projections. About a dozen skulls of the genus have been found.
Edmontonia is a genus of panoplosaurin nodosaurid dinosaur from the Late Cretaceous Period. It is part of the Nodosauridae, a family within Ankylosauria. It is named after the Edmonton Formation, the unit of rock where it was found.
Montanoceratops is an extinct genus of small ceratopsian dinosaur that lived approximately 70 million years ago during the latter part of the Cretaceous Period in what is now Montana and Alberta. Montanoceratops was a small sized, moderately-built, ground-dwelling, quadrupedal herbivore, that could grow up to an estimated 2.5 m (8.2 ft) in length and 170 kg (370 lb) in body mass.
Anodontosaurus is an extinct genus of ankylosaurid dinosaurs within the subfamily Ankylosaurinae. It is known from the entire span of the Late Cretaceous Horseshoe Canyon Formation of southern Alberta, Canada. It contains two species, A. lambei and A. inceptus.
The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. It takes its name from Horseshoe Canyon, an area of badlands near Drumheller.
Umoonasaurus is an extinct genus of plesiosaur belonging to the family Leptocleididae. This genus lived approximately 115 million years ago during the Early Cretaceous period, in shallow seas covering parts of what is now Australia. It was a relatively small animal around 2.5 metres (8.2 ft) long. An identifying trait of Umoonasaurus is three crest-ridges on its skull.
Edmontosaurus regalis is a species of comb-crested hadrosaurid dinosaur. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian age of the Cretaceous Period 73 million years ago, but it may have possibly lived into the early Maastrichtian.
Leptocleidus is an extinct genus of plesiosaur, belonging to the family Leptocleididae. It was a small plesiosaur, measuring only up to 3 m (9.8 ft).
Megalneusaurus is an extinct genus of large pliosaurs that lived during the Oxfordian and Kimmeridgian stages of the Late Jurassic in what is now North America. It was provisionally described as a species of Cimoliosaurus by the geologist Wilbur Clinton Knight in 1895, before being given its own genus by the same author in 1898. The only species identified to date is M. rex, known from several specimens identified in the Redwater Shale Member, within the Sundance Formation, Wyoming, United States. A specimen discovered in the Naknek Formation in southern Alaska was referred to the genus in 1994. In Ancient Greek, the generic name literally translates to "large swimming lizard", due to the measurement of the fossils of the holotype specimen.
Callawayasaurus is a genus of plesiosaur from the family Elasmosauridae. When the holotype was first described by Samuel Paul Welles in 1962, it was described as Alzadasaurus colombiensis before being moved into its current genus by Kenneth Carpenter in 1999.
Aristonectes is an extinct genus of large elasmosaurid plesiosaurs that lived during the Maastrichtian stage of the Late Cretaceous. Two species are known, A. parvidens and A. quiriquinensis, whose fossil remains were discovered in what are now Patagonia and Antarctica. Throughout the 20th century, Aristonectes was a difficult animal for scientists to analyze due to poor fossil preparation, its relationships to other genera were uncertain. After subsequent revisions and discoveries carried out from the beginning of the 21st century, Aristonectes is now recognised as the type genus of the subfamily Aristonectinae, a lineage of elasmosaurids characterized by an enlarged skull and a reduced length of the neck.
Morturneria is an extinct genus of plesiosaur from the Late Cretaceous of what is now Antarctica.
Bathyspondylus is an extinct genus of plesiosaur from the Kimmeridge Clay Formation of Swindon, England. Because it is known only from its fossil vertebrae, paleontologists are not entirely sure of the taxonomy of Bathyspondylus; the family it belongs to is not currently known. The type, and only known, species is B. swindoniensis, which was described from the same material as its genus.
Polycotylus is a genus of plesiosaur within the family Polycotylidae. The type species is P. latippinis and was named by American paleontologist Edward Drinker Cope in 1869. Eleven other species have been identified. The name means 'much-cupped vertebrae', referring to the shape of the vertebrae. It lived in the Western Interior Seaway of North America toward the end of the Cretaceous. One fossil preserves an adult with a single large fetus inside of it, indicating that Polycotylus gave live birth, an unusual adaptation among reptiles.
Within the earth science of geology, the Edmonton Group is a Late Cretaceous to early Paleocene stratigraphic unit of the Western Canada Sedimentary Basin in the central Alberta plains. It was first described as the Edmonton Formation by Joseph Burr Tyrrell in 1887 based on outcrops along the North Saskatchewan River in and near the city of Edmonton. E.J.W. Irish later elevated the formation to group status and it was subdivided into four separate formations. In ascending order, they are the Horseshoe Canyon, Whitemud, Battle and Scollard Formations. The Cretaceous-Paleogene boundary occurs within the Scollard Formation, based on dinosaurian and microfloral evidence, as well as the presence of the terminal Cretaceous iridium anomaly.
Albertonectes is an extinct genus of elasmosaurid plesiosaur known from the Late Cretaceous Bearpaw Formation of Alberta, Canada. It contains a single species, Albertonectes vanderveldei. Albertonectes is the longest elasmosaur, and more generally plesiosaur, known to date both in neck and total body length.
Apatoraptor is a genus of caenagnathid dinosaur which contains a single species, A. pennatus. The only known specimen was discovered in the Campanian-age Horseshoe Canyon Formation of Alberta.
Unktaheela is an extinct genus of polycotylid plesiosaur from the Late Cretaceous Sharon Springs Formation of the United States. The genus contains a single species, U. specta, known from two partial skeletons. Unktaheela represents the smallest known polycotylid.
