Sauropterygia is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria became extinct at the end of that period. The plesiosaurs would continue to diversify until the end of the Mesozoic. Sauropterygians are united by a radical adaptation of their pectoral girdle, adapted to support powerful flipper strokes. Some later sauropterygians, such as the pliosaurs, developed a similar mechanism in their pelvis. It is possible that sauropterygians are a distant relatives of turtles, uniting them under the group Pantestudines, although this is still debatable as sauropterygians might be archosauromorphs or completely unrelated to both.
Nothosaurs were Triassic marine sauropterygian reptiles. They averaged about 3 metres (10 ft) in length, with a long body and tail. The feet were paddle-like, and are known to have been webbed in life, to help power the animal when swimming. The neck was quite long, and the head was elongated and flattened, and relatively small in relation to the body. The margins of the long jaws were equipped with numerous sharp outward-pointing teeth, indicating a diet of fish and squid.
Nothosaurus is an extinct genus of sauropterygian reptile from the Triassic period, approximately 240–210 million years ago, with fossils being distributed throughout the former Tethys Ocean, from North Africa and Europe to China. It is the best known member of the nothosaur order.
Placodonts are an extinct order of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. They were part of Sauropterygia, the group that includes plesiosaurs. Placodonts were generally between 1 and 2 m in length, with some of the largest measuring 3 m (9.8 ft) long.
Cryptoclidus is a genus of plesiosaur reptile from the Middle Jurassic period of England, France, and Cuba.
Cymbospondylus is an extinct genus of large ichthyosaurs, of which it is among the oldest representatives, that lived from the Lower to Middle Triassic in what are now North America and Europe. The first known fossils of this taxon are a set of more or less complete vertebrae which were discovered in the 19th century in various mountain ranges of Nevada, in the United States, before being named and described by Joseph Leidy in 1868. It is in the beginning of the 20th century that more complete fossils were discovered through several expeditions launched by the University of California, and described in more detail by John Campbell Merriam in 1908, thus visualizing the overall anatomy of the animal. While many species have been assigned to the genus, only five are recognized as valid, the others being considered synonymous, doubtful or belonging to other genera. Cymbospondylus was formerly classified as a representative of the Shastasauridae, but more recent studies consider it to be more basal, view as the type genus of the Cymbospondylidae.
Ceresiosaurus is an extinct aquatic genus of lariosaurine nothosaurid sauropterygian known from the Middle Triassic of Monte San Giorgio, southern Switzerland and northern Italy. Ceresiosaurus, meaning "Lizard of Ceresio". The type species, Ceresiosaurus calcagnii, was named by Bernhard Peyer in 1931. C. calcagnii is known from both the Cava superiore and Cava inferiore beds of the Lower Meride Limestone at Monte San Giorgio, dating to the latest Anisian of the Middle Triassic. Rieppel (1998) suggested that the back then monospecific genus Ceresiosaurus, is a junior synonym of the better known Lariosaurus, yet he kept it type species as a separate species under the new combination L. calcagnii. In 2004, however, this synonymy was objected by Hänni who described and name a second species of Ceresiosaurus, C. lanzi - a separation supported by several other authors since. This species is known only from the stratigraphically younger Cassima beds of Monte San Giorgio, although also from the Lower Meride Limestone, dating to possibly the lowest Ladinian age. The species in a subtropical lagoonal environment with varying open marine influences, and alongside many related but smaller species of nothosaurids and pachypleurosaurids. Ceresiosaurus represents one of the largest vertebrate of up to 3 m (9.8 ft) snout-tail length from the very diversified paleoenvironment of the Middle Triassic Monte San Giorgio.
Pistosaurus is an extinct genus of aquatic sauropterygian reptile closely related to plesiosaurs. Fossils have been found in France and Germany, and date to the Middle Triassic. It contains a single species, Pistosaurus longaevus. Pistosaurus is known as the oldest "subaquatic flying" reptile on earth.
Serpianosaurus is an extinct genus of pachypleurosaurs known from the Middle Triassic deposits of Switzerland and Germany. It was a small reptile, with the type specimen of S. mirigiolensis measuring 75 cm (2.46 ft) long.
Phalarodon is an extinct genus of mixosaurid ichthyosaur known from the Middle Triassic. Its name is derived from the Greek φάλαρα (phálara) and odon ("tooth"). The genus has had a tumultuous history since its classification in 1910, with different workers describing species under different genera or declaring the genus to be a nomen dubium. Currently three species are recognized, but more have been identified in the past.
The Guanling Formation is a Middle Triassic geologic formation in southwestern China.
The Favret Formation is a Triassic geologic formation. The Favret outcrops in the Augusta, New Pass and Fish Creek ranges of north central Nevada and consists of limestone, shale and siltstone.
Sinosaurosphargis is an extinct genus of basal marine saurosphargid reptile known from the Middle Triassic Guanling Formation of Yunnan and Guizhou Provinces, southwestern China. It contains a single species, Sinosaurosphargis yunguiensis.
Pistosauroidea is a group of marine reptiles within the superorder Sauropterygia that first appeared in the latter part of the Early Triassic and were the ancestors of plesiosaurs. Pistosauroids are rare in Triassic marine assemblages, and are represented by only a few fossils from central Europe, the United States, and China. Recent phylogenetic analyses consider the Triassic pistosauroids to be a paraphyletic grouping, meaning that they do not form a true clade. Plesiosauria is now placed within Pistosauroidea, while the traditional pistosauroids are successively more basal, or primitive, sauropterygians.
Hanosaurus is an extinct genus of marine reptiles that existed during the Triassic period in what is now China. The type species is Hanosaurus hupehensis. It was a small animal, with specimens measuring 79.4 cm (31.3 in) long in total body length, which likely fed on soft-bodied prey.
Thalattoarchon is a genus of large, Middle Triassic predatory ichthyosaur from North America, containing the single species T. saurophagis. The taxon was described in 2013 from a single specimen discovered in the Favret Formation in Nevada. The generic name, meaning "ruler of the seas", refers to its status as an apex predator, while the specific epithet, meaning "lizard eater", alludes to its carnivorous diet. The classification of this genus within the ichthyosaurs is much debated, being either classified within the clade Merriamosauria or in the more basal family Cymbospondylidae.
The Prida Formation is a geologic formation in northwestern Nevada. It preserves fossils dating back to the Triassic period.
Saurosphargidae is an extinct family of marine reptiles known from the Early Triassic and early Middle Triassic of Europe and China.
The Fossil Hill Member is a Middle Triassic-aged rock unit. The Fossil Hill unit occurs as a member of both the Prida and Favret formations. It outcrops in multiple locations across Northwestern Nevada including the western Humboldt Range, Tobin Range, Augusta Mountains, and China Mountain. Calcareous shale, mudstone, and black limestones are the most common lithologies present within the unit. The member was named for Fossil Hill, Nevada, a locality within the Humboldt Mountains where large quantities of Anisian-aged marine fossils were discovered in the early 20th century. Fossils are common throughout the Fossil Hill, and the unit is well known for preserving the remains of some of the earliest marine reptiles, including several genera of ichthyosaurs and a pistosaur. Other fossils include bony fish, hybodont sharks, and invertebrates with ceratitid ammonoids being especially abundant.
