| Picrocleidus Temporal range: Middle Jurassic, | |
|---|---|
 | |
| Fossils from both specimens of P. beloclis | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | † Sauropterygia |
| Order: | † Plesiosauria |
| Family: | † Cryptoclididae |
| Genus: | † Picrocleidus Andrews, 1910 |
| Type species | |
| †Picrocleidus beloclis Andrews, 1910 | |
| Synonyms | |
| |
Picrocleidus is an extinct genus of plesiosaur from the Middle Jurassic Oxford Clay Formation (Callovian stage) of the United Kingdom.
The holotype was discovered in the Oxford Clay Formation in Peterborough, England. [1] [2] It was initially assigned to Muraenosaurus as M. beloclis by Seeley (1892). [3] M. beloclis was moved to its own genus Picrocleidus by Andrews (1910). [2] [4]
Two specimens are known:
The holotype specimen BMNH R2429, consisting of posterior cervical vertebrae, pectorals and the first dorsal, some dorsal ribs, the shoulder-girdle, and the left humerus. [2]
And specimen BMNH R2739, consisting of a basisphenoid and parasphenoid, cervical vertebrae, sacrals with the sacral ribs, an anterior caudal, some ventral ribs, both radii, odd paddle-bones, portions of ilia, ischia, and pubes. [1]
Picrocleidus has previously been considered synonymous with Muraenosaurus although there are doubts in the relationship between the two groupings. [5]
Picrocleidus is currently classified as a member of the Cryptoclididae. [4]
Plesiosaurus is a genus of extinct, large marine sauropterygian reptile that lived during the Early Jurassic. It is known by nearly complete skeletons from the Lias of England. It is distinguishable by its small head, long and slender neck, broad turtle-like body, a short tail, and two pairs of large, elongated paddles. It lends its name to the order Plesiosauria, of which it is an early, but fairly typical member. It contains only one species, the type, Plesiosaurus dolichodeirus. Other species once assigned to this genus, including P. brachypterygius, P. guilielmiimperatoris, and P. tournemirensis have been reassigned to new genera, such as Hydrorion, Seeleyosaurus and Occitanosaurus.
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.
Cetiosauriscus is a genus of sauropod dinosaur that lived between 166 and 164 million years ago during the Callovian in what is now England. A herbivore, Cetiosauriscus had – by sauropod standards – a moderately long tail, and longer forelimbs, making them as long as its hindlimbs. It has been estimated as about 15 m (49 ft) long and between 4 and 10 t in weight.
Yimenosaurus is an extinct genus of plateosaurid sauropodomorph dinosaur that lived in China in the Early Jurassic. The genus was first named in 1990 by Ziqi Bai, Jie Yang and Guohui Wang, along with its type and only species, Yimenosaurus youngi. The species name honours renowned Chinese paleontologist Yang Zhongjian, the father of Chinese paleontology, known as C.C. Young in English. Known material includes the holotype, an almost complete skull and mandible, as well as incomplete cervical and dorsal vertebrae, a mostly complete sacrum, an ilium, ischia, partial ribs and complete femur, and a paratype, a well-preserved postcrania with a fragmentary skull. In 2010 Paul estimated its length at 9 metres (30 ft) and its weight at 2 tonnes.
Ornithopsis is a genus of sauropod dinosaur, from the Early Cretaceous of England and possibly Germany. The type species, which is the only species seen as valid today, is O. hulkei, which is only known from fragmentary remains.
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 plesiosaurs present at the end of the Cretaceous alongside Polycotylidae.
Muraenosaurus is an extinct genus of cryptoclidid plesiosaur reptile from the Oxford Clay of Southern England. The genus was given its name due to the eel-like appearance of the long neck and small head. Muraenosaurus grew up to 5.2 metres (17 ft) in length and lived roughly between 160 Ma and 164 Ma in the Callovian of the middle Jurassic. Charles E. Leeds collected the first Muraenosaurus which was then described by H. G. Seeley. The specimen may have suffered some damage due to the casual style of Charles Leeds’ collection. The first muraenosaur was recovered with pieces missing from the skull and many of the caudal vertebrae absent. Because the animal was described from Charles Leeds’ collection it was given the name Muraenosaurus Leedsi. M. leedsi is the most complete specimen belonging to the genus Muraenosaurus and also the only species that is undoubtedly a member of the genus. Two other species have been tentatively referred to as members of the genus Muraenosaurus: M. reedii and Muraenosaurus beloclis Seeley 1892, which in 1910 became the separate genus Picrocleidus.
Peloneustes is a genus of pliosaurid plesiosaur from the Middle Jurassic of England. Its remains are known from the Peterborough Member of the Oxford Clay Formation, which is Callovian in age. It was originally described as a species of Plesiosaurus by palaeontologist Harry Govier Seeley in 1869, before being given its own genus by naturalist Richard Lydekker in 1889. While many species have been assigned to Peloneustes, P. philarchus is currently the only one still considered valid, with the others moved to different genera, considered nomina dubia, or synonymised with P. philarchus. Some of the material formerly assigned to P. evansi have since been reassigned to "Pliosaurus" andrewsi. Peloneustes is known from many specimens, including some very complete material.
Adriosaurus is an extinct genus of squamate which lived in what is now Slovenia and other parts of Europe during the Late Cretaceous. It was a small, snake-like reptile, with the type species Adriosaurus suessi measuring up to 30 cm (12 in) in length. Adriosaurus represents the first occurrence of vestigial limbs in fossil lizards, having lost its manus and forearm completely in order to elongate its axial skeleton. These unique anatomical features led to discussions of the evolutionary patterns of limb reduction in Squamata.
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.
Colymbosaurus is a genus of cryptoclidid plesiosaur from the Late Jurassic (Callovian-Tithonian) of the UK and Svalbard, Norway. There are two currently recognized species, C. megadeirus and C. svalbardensis.
Brancasaurus is a genus of plesiosaur which lived in a freshwater lake in the Early Cretaceous of what is now North Rhine-Westphalia, Germany. With a long neck possessing vertebrae bearing distinctively-shaped "shark fin"-shaped neural spines, and a relatively small and pointed head, Brancasaurus is superficially similar to Elasmosaurus, albeit smaller in size at 3.26 metres (10.7 ft) in length as a subadult.
Pantosaurus is an extinct genus of plesiosaur from the Late Jurassic (Oxfordian) of what is now Wyoming. It lived in what used to be the Sundance Sea. It was originally named Parasaurus by Othniel Charles Marsh in reference to Plesiosaurus, but that name was preoccupied, and Marsh changed it. The species Muraenosaurus reedii is in fact a junior synonym of Pantosaurus. The holotype YPM 543 is a partial articulated skeleton, partially prepared to yield a distal humerus, four articulated carpals, a fragment of the coracoid, and several isolated cervical vertebrae from the Upper Member of the Sundance Formation. Other material includes USNM 536963, USNM 536965, UW 3, UW 5544 and UW 15938.
Eurycleidus is an extinct genus of large-bodied rhomaleosaurid known from the Early Jurassic period of the United Kingdom. It contains a single species, E. arcuatus.
Tatenectes is a genus of cryptoclidid plesiosaur known from the Upper Jurassic of Wyoming. Its remains were recovered from the Redwater Shale Member of the Sundance Formation, and initially described as a new species of Cimoliosaurus by Wilbur Clinton Knight in 1900. It was reassigned to Tricleidus by Maurice G. Mehl in 1912 before being given its own genus by O'Keefe and Wahl in 2003. Tatenectes laramiensis is the type and only species of Tatenectes. While the original specimen was lost, subsequent discoveries have revealed that Tatenectes was a very unusual plesiosaur. Its torso had a flattened, boxy cross-section and its gastralia exhibit pachyostosis (thickening). The total length of Tatenectes has been estimated at 2–3 meters (6.6–9.8 ft).
Sthenarosaurus is an extinct genus of rhomaleosaurid pliosauroid discovered in the Toarcian-aged 'Main Alum Shale' in Whitby, England. The type species, Sthenarosaurus dawkinsi, was named and described in 1909 by D. M. S. Watson. The type specimen is MMUM LL 8023, a set of postcrania discovered in Whitby. Other indeterminate specimens are known, including a pectoral girdle described in 1911. Plesiosaurian fossils were acquired for the Manchester Museum by William Boyd Dawkins who is honoured by the specific name.
Pachycostasaurus is an extinct Pliosauroid from the Oxford Clay formation of Peterborough, England.
Spitrasaurus is an extinct genus of cryptoclidid plesiosauroid plesiosaur known from the uppermost Jurassic of central Spitsbergen, Norway and likely also Kimmeridge, England. It is named after a syllabic abbreviation for Spitsbergen Travel.
Lusovenator is a genus of carcharodontosaurian theropod dinosaur, from the Late Jurassic (Kimmeridgian) Praia de Amoreira Porto-Novo Member and the Late Jurassic-Early Cretaceous (Tithonian-Berriasian) Assenta Member of the Lourinhã Formation in present-day Portugal. It includes one species, Lusovenator santosi.
Thalassodraco is an extinct genus of ophthalmosaurid ichthyosaur from the Late Jurassic (Tithonian) Kimmeridge Clay Formation of England. The type species, T. etchesi, was named in 2020, with the epithet in honour of the discoverer of the holotype, Steve Etches.
