Rhynchocephalia is an order of lizard-like reptiles that includes only one living species, the tuatara of New Zealand. Despite its current lack of diversity, during the Mesozoic the Rhynchocephalia included a wide array of genera within multiple lineages. The oldest known records of the group date to the Middle Triassic. Most rhynchocephalians belong to the group Sphenodontia ("wedge-teeth"), which are characterized by a hooked beak-like structure at the tip of the snout formed by enlarged premaxillary teeth. Their closest living relatives are lizards and snakes in the order Squamata.
Lepidosauromorpha is a group of reptiles comprising all diapsids closer to lizards than to archosaurs. The only living sub-group is the Lepidosauria: extant lizards, snakes and tuataras.
Tritylodontidae is an extinct family of small to medium-sized, highly specialized mammal-like cynodonts, bearing several mammalian traits like erect limbs, endothermy and details of the skeleton. They were the last-known family of the non-mammalian synapsids, persisting into the Early Cretaceous.
Halszka Osmólska was a Polish paleontologist who had specialized in Mongolian dinosaurs.
Sophineta is an extinct genus of small basal lepidosauromorph reptile known from the Early Triassic of Małopolska Province, southern Poland. It contains a single species, Sophineta cracoviensis.
Susan E. Evans is British palaeontologist and herpetologist. She is the author or co-author of over 100 peer-reviewed papers and book chapters.
Telmasaurus is an extinct genus of varanoid lizard from the Late Cretaceous of Mongolia. Fossils have been found from the Djadokha and Barun Goyot Formations that date between the early and middle Campanian stage from approximately 80 to 75 million years ago. The type species Telmasaurus grangeri was named in 1943.
Proplatynotia is an extinct genus of varanoid lizard from the Late Cretaceous of Mongolia. Fossils have been found in the Barun Goyot Formation, which is mid-Campanian in age. The type and only species, P. longirostratia, was named in 1984.
Barbaturex is an extinct genus of giant herbivorous iguanian lizards from the Eocene of Myanmar. It is represented by a single species, Barbaturex morrisoni, which is known from several partial dentaries and a fused pair of frontals, two bones that form part of the top of the skull. Based on the size of these bones, Barbaturex morrisoni is estimated to have been about 1 metre (3.3 ft) from snout to vent, and possibly up to 6 feet (1.8 m) including the tail. Barbaturex morrisoni was named after The Doors frontman Jim Morrison, a play on his epithet "The Lizard King". The genus's name is a portmanteau of the Latin words Barbatus and rex, meaning "bearded king", in reference to ridges along the mandible and the lizard's large size.
Carusia is an extinct genus of lizards from the Late Cretaceous of Mongolia. It is a close relative of the family Xenosauridae, which includes living knob-scaled lizards. Fossils of the type and only species Carusia intermedia come from the late-Campanian age Barun Goyot Formation and have been found in the Flaming Cliffs, Ukhaa Tolgod, and Kheerman Tsav fossil localities. Carusia was first described in 1985 under the name Carolina intermedia, but since the name Carolina was preoccupied by a genus of scarab beetles that had been named in 1880, it was renamed Carusia intermedia. Carusia had initially been known from fragmentary skull material, complicating efforts to determine its evolutionary relationships with other lizards; it had variously been described as an indeterminate scincomorph, a xenosaurid, or some other type of autarchoglossan lizard convergent with xenosaurids. However, the discovery of 35 complete skulls in the 1990s, three of which were described in a detailed 1998 monograph, revealed that Carusia was the sister taxon of Xenosauridae, compelling the authors of the monograph to create a new clade called Carusioidea to include both taxa.
Priscagamidae is an extinct family of iguanian lizards known from the Late Cretaceous of Mongolia and China and the Eocene of India, spanning a range from 75 to 54 million years ago. It includes the genera Heterodontagama, Mimeosaurus, Phrynosomimus, Priscagama, and possibly Pleurodontagama. The first fossils of priscagamids were found in the Djadochta and Khermeen Tsav formations of Mongolia. More recently they have been found in the Cambay Formation in India, leading to the naming of Heterodontagama in 2013. Priscagamidae was originally described as a subfamily of Agamidae called Priscagaminae in 1984, but it was reclassified as a distinct family in 1989. Most phylogenetic analyses still find a close relationship between Priscagamidae and Agamidae, although a 2015 study found it to be basal to all other iguanian clades, warranting its removal from Iguania and placement in a larger clade called Iguanomorpha.
Heterodontagama is an extinct genus of iguanian lizard from the Early Eocene of India. It belongs to the extinct family Priscagamidae, which is otherwise only known from the Late Cretaceous of Mongolia. The type species Heterodontagama borsukae was named in 2013 from several isolated upper and lower jaws found in an exposure of the Cambay Shale in an open-pit coal mine in Gujarat.
Mimeosaurus is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia. It is part of an extinct family of iguanians called Priscagamidae, and was the first priscagamid to have been described, having been named by American paleontologist Charles W. Gilmore in 1943. Currently only one species, the type species Mimeosaurus crassus, belongs within the genus. A second species, M. tugrikinensis, was named in 1989, but later studies argued that the specimens on which the new name is based are not sufficiently different from M. crassus specimens to warrant being classified as a separate species. Mimeosaurus is unique among iguanians in having premaxilla bones at the tip of the snout that are reduced in size, as well as having two pairs of enlarged canine-like teeth in the maxilla.
Priscagama is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia and China. It belongs to an extinct family of iguanians called Priscagamidae. Several incomplete skulls have been found in the Barun Goyot and Djadochta formations, and were originally referred to the genus Mimeosaurus; the type species Priscagama gobiensis was named in 1984 when it was recognized that these skulls belonged to a distinct species. Priscagama differs from most other priscagamids in having a more elongate, lightly-built skull. It is very similar in appearance to another priscagamid called Pleurodontagama, as the two can only be distinguished by the shape of their teeth.
Phrynosomimus is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia belonging to the extinct family Priscagamidae. The type species Phrynosomimus asper was named in 1996. Fossils have been found in the Barun Goyot and Djadochta formations and include several complete skulls. Phrynosomimus has a short, triangular skull with bony spikes projecting from the back, stemming from the squamosal and parietal bones. These spikes give it a similar appearance to the modern horned lizard Phrynosoma and inspire its name, which means "Phrynosoma mimic". Like other priscagamids it has an acrodont dentition, meaning that its teeth grow from the margins of the jaws rather than their inner surfaces, as is the case for the pleurodont dentitions of most lizards.
Polrussia is an extinct genus of iguanian lizards dating to the Late Cretaceous epoch, found in what is now Mongolia. It belongs to a group of extinct iguanians called Gobiguania that was endemic to the Gobi Desert during the Late Cretaceous. The type species Polrussia mongoliensis was named in 1991 on the basis of a skull found in the Barun Goyot Formation. The genus name refers to the Polish and Russian paleontologists who worked together to find and describe the material. Polrussia has a short skull, slightly pointed and flattened snout, and large eye sockets. The teeth each have one cusp, as opposed to the multiple cusps seen in some other gobiguanians. The skull is only 1.2 centimetres (0.47 in) long, making Polrussia one of the smallest gobiguanians.
Igua is an extinct genus of iguanian lizards belonging to a group called Gobiguania that was endemic to the Gobi Desert during the Late Cretaceous. The type species Igua minuta was named in 1991 on the basis of a skull from the Barun Goyot Formation in Mongolia. The skull itself is very small, only 14 millimetres (0.55 in) long, and may have belonged to a juvenile given that it possesses a large fontanelle and that many of the bones are unfused. The snout-vent length of the individual is estimated to have been 55 to 65 millimetres. Igua differs from related gobiguanians like Polrussia in having a more rounded skull. It is similar in appearance to the living genera Liolaemus and Tropidurus. The teeth are tricuspid and pleurodont, meaning they are attached to inner surfaces of the jaws.
Gueragama is an extinct genus of iguanian lizard from the Late Cretaceous of Brazil. It belongs to a group of iguanians called Acrodonta, whose living members include chameleons and agamids and are currently restricted to the Old World. Gueragama is the only acrodont known from South America, providing evidence that the group once ranged across much of Gondwana and only became restricted to the Old World after the supercontinent broke apart. The type species, Gueragama sulamericana, was named in 2015 on the basis of an isolated lower jaw from the Turonian- to Campanian-age Goio-Erê Formation in the Bauru Basin, which was deposited in a desert environment. Unlike modern acrodontans, whose teeth implant on the margins of the jaws, Gueragama has teeth that implant along the inner surface of the lower jaw, a feature common in most non-acrodontan lizards and characteristic of the second major group of iguanians, Pleurodonta. The non-acrodont dentition of Gueragama is evidence of its basal position within Acrodonta, and is shared with the taxon of Late Cretaceous acrodontan relatives, the family Priscagamidae.
Bharatagama is an extinct genus of lepidosaur from the Early Jurassic of India. It is sugguested to be one of the oldest known lizards and the oldest known iguanian. The type and only species is Bharatagama rebbanensis, named in 2002. Over one hundred fossils of Bharatagama have been found in the Kota Formation, which outcrops in the Pranhita–Godavari Basin and dates back to about 190 million years ago (Ma). Despite its abundance, Bharatagama is known only from isolated jaw bones mixed together in microvertebrate assemblages with equally fragmentary remains of fish, sphenodontians, dinosaurs, crocodylomorphs, and mammals. These fossils represent all stages of development, from hatchlings to adults. The total length of the skull in adult specimens is estimated to have been about 15 millimetres (0.59 in). Later analysis suggested that the taxon might be a member of Rhynchocephalia.
Acrodonta are a subclade of iguanian squamates consisting almost entirely of Old World taxa. Extant representation include the families Chamaeleonidae (chameleons) and Agamidae, with at least over 500 species described. A fossil genus, Gueragama, was found in Brazil, making it the only known American representative of the group.
