Amphisbaenia is a group of typically legless lizards, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. As many species have a pink body and scales arranged in rings, they have a superficial resemblance to earthworms. While the genus Bipes retains forelimbs, all other genera are limbless. Recent phylogenetic studies suggest that they are nested within Lacertoidea, closed related to the lizard family Lacertidae. Amphisbaenians are widely distributed, occurring in North America, Europe, Africa, South America, Western Asia and the Caribbean. Most species are less than 6 inches (15 cm) long.
Bagaceratops is a genus of small protoceratopsid dinosaurs that lived in Asia during the Late Cretaceous, around 72 to 71 million years ago. Bagaceratops remains have been reported from the Barun Goyot Formation and Bayan Mandahu Formation. One specimen may argue the possible presence of Bagaceratops in the Djadochta Formation.
The Barun Goyot Formation is a geological formation dating to the Late Cretaceous Period. It is located within and is widely represented in the Gobi Desert Basin, in the Ömnögovi Province of Mongolia.
The Djadochta Formation is a highly fossiliferous geological formation situated in Central Asia, Gobi Desert, dating from the Late Cretaceous period, about 75 million to 71 million years ago. The type locality is the Bayn Dzak locality, famously known as the Flaming Cliffs. Reptile and mammal remains are among the fossils recovered from the formation.
Scincomorpha is an infraorder and clade of lizards including skinks (Scincidae) and their close relatives. These include the living families Cordylidae, Gerrhosauridae, and Xantusiidae, as well as many extinct taxa. Other roughly equivalent terms include the suborder Scinciformata, or the superfamily Scincoidea, though different authors use these terms in a broader or more restricted usage relative to true skinks. They first appear in the fossil record about 170 million years ago, during the Jurassic period.
Sineoamphisbaena is an extinct genus of squamate of uncertain phylogenetic placement. Its fossils have been found in Late Cretaceous deposits in Inner Mongolia, China. It contains a single species, Sineoamphisbaenia hexatabularis.
Huehuecuetzpalli mixtecus is an extinct lizard from the Early Cretaceous Tlayúa Formation in Tepexi de Rodríguez, Central Mexico. Although it is not the oldest known lizard, Huehuecuetzpalli may be amongst the most basal members of Squamata, making it an important taxon in understanding the origins of squamates.
Cryptolacerta is an extinct genus of lacertoid lizard which lived during the Eocene epoch in what is now Germany. It is known from a nearly complete and articulated skeleton including the skull, which was found in the Messel Pit locality of Germany. Cryptolacerta was named by Johannes Müller, Christy A. Hipsley, Jason J. Head, Nikolay Kardjilov, André Hilger, Michael Wuttke and Robert R. Reisz in 2011 and the type species is Cryptolacerta hassiaca. Cladistic analysis conducted by Müller et al. suggests that Cryptolacerta is a sister taxon to Amphisbaenia. However, later studies questioned its closeness to that group, and suggested that the similarities could be convergent due to both groups having a similar burrowing lifestyle, and it may be more closely related to Lacertidae instead.
Myrmecodaptria is an extinct genus of scleroglossan lizard from the Late Cretaceous Djadokhta Formation in Ukhaa Tolgod, Mongolia. The type and only species, Myrmecodaptria microphagosa, was named in 2000 by paleontologists Gao Keqin and Mark Norell. Myrmecodaptria is known from a single holotype skull and lower jaws. It is distinguished from all other lizards by its extremely elongated skull. The eyes are placed close to the snout, which is short and rounded. The top of the skull is covered in bony knobs called osteoderms. The parietal bone at the back of the skull is elongated and about as long as the frontal bones, which are the usually the longest bones along the top of the skull in lizards. The squamosal bone at the back of the skull reaches forward to connect with the jugal bone behind the eye, forming a thin arch between the temporal fenestrae. Myrmecodaptria also has fewer and more widely spaced teeth in its jaws than do most other lizards.
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 83.6 to 48.6 million years ago. Probably the earliest priscagamids on indeterminate genera were found in Aptian-Albian sediments in "Hobur", Mongolia. 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.
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.
Anchaurosaurus is an extinct genus of iguanian lizard from the Late Cretaceous of Inner Mongolia, China. It belongs to an extinct clade of iguanians called Gobiguania that was endemic to the Gobi Desert during the Late Cretaceous. The type species, Anchaurosaurus gilmorei, was named in 1995 on the basis of a well-preserved skull and incomplete skeleton from the Djadochta Formation. Compared to other iguanians, Anchaurosaurus has a relatively elongated skull, large eye sockets, and higher tooth crowns. Phylogenetic analysis indicates that among gobiguanians, Anchaurosaurus is most closely related to Zapsosaurus from Mongolia. Below is a cladogram from Daza et al. (2012) showing the phylogenetic relationships of Anchaurosaurus:
Norellius is an extinct genus of scleroglossan lizard from the Early Cretaceous Öösh Formation of Mongolia. It is known from a well-preserved skull that was collected by an American Museum of Natural History expedition to Mongolia in 1923 and cataloged as AMNH FR 21444. After its initial cataloging, the specimen was not mentioned again in the scientific literature until 2004, when it was recognized as belonging to a potential early relative of modern groups of squamates such as gekkotans, amphisbaenians, dibamids, and snakes. AMNH FR 21444 was more fully described in a 2006 study that used high-resolution computed tomography to examine the skull and its braincase, and was described as a new genus and species, Norellius nyctisaurops, in 2015. The genus name honors paleontologist Mark Norell. The 2006 study incorporated the specimen into a phylogenetic analysis and found it to be a basal member of an evolutionary grouping called Gekkonomorpha, a stem-based taxon that includes living geckos and legless lizards (pygopodids) and all taxa more closely related to them than to any other living lizard. Norellius lies outside the node-based taxon Gekkota, a more strictly-defined subgroup of Gekkonomorpha that includes geckos, pygopodids, and all descendants of their most recent common ancestor. Therefore, while Norellius is more closely related to geckos and pygopodids than it is to any other living group of lizards, it branched off before the most recent common ancestor of these two groups. Below is a cladogram showing the position of Norellius according to this phylogeny:
Eichstaettisaurus is a genus of lizards from the Late Jurassic and Early Cretaceous of Germany, Spain, and Italy. With a flattened head, forward-oriented and partially symmetrical feet, and tall claws, Eichstaettisaurus bore many adaptations to a climbing lifestyle approaching those of geckoes. The type species, E. schroederi, is among the oldest and most complete members of the Squamata, being known by one specimen originating from the Tithonian-aged Solnhofen Limestone of Germany. A second species, E. gouldi, was described from another skeleton found in the Matese Mountains of Italy. Despite being very similar to E. schroederi, it lived much later, during the Albian stage. Fossils of both species show exceptional preservation due to deposition in low-oxygen marine environments.
Ardeosauridae is an extinct family of lizards known from the Late Jurassic of Germany and North America and Early Cretaceous of Mongolia, with other potential species elsewhere from Europe and Asia over the same time period.
Durotrigia is a genus of extinct lizard from the Early Cretaceous of southern England. The type and only species is Durotrigia triconidens, named in 1967 by R. Hoffstetter for jaw material in a review of the lizard fauna of the Berriasian Lulworth Formation. The genus was found in the Mammal Bed near the base of the formation alongside the other lizards Paramacellodus, Becklesius, Pseudosaurillus, Dorsetisaurus, Saurillus and Parviraptor. Durotrigia is likely a genus within the family Globauridae.
Globauridae is a family of extinct scincomorph lizards that first appeared in the Late Jurassic of England and persisting until the Late Cretaceous of Mongolia. The group is distinguished by having a diploglossopalatinar palate anatomy, lacking osteoderms, having conical two- or three-cusped teeth, and a unique postorbital-parietal contact. The type genus Globaura was originally classified within the now-polyphyletic group Lacertoidea, before being reclassified within its own family within Ardeosauroidea. However, Meyasaurus has also been found to be closer to Barbatteiidae.
Pseudosaurillus is a genus of extinct lizard from the Early Cretaceous of southern England. The type and only species is Pseudosaurillus becklesi, named in 1967 by R. Hoffstetter limited jaw and tooth material from the Berriasian Lulworth Formation. A large amount of material that was additionally referred to Saurillus by Hoffstetter was reassigned to Pseudosaurillus in 1983 by Estes, but this has since been reclassified within its own genus Parasaurillus by Susan E. Evans and Belinda Searle in 2002. The taxon was found in the Mammal Bed near the base of the formation alongside the other lizards Becklesius, Dorsetisaurus, Durotrigia, Paramacellodus, Parasaurillus, Parviraptor and Saurillus. Like Becklesius, Pseudosaurillus may be a member of the family Paramacellodidae.
Ondogurvel is a genus of alvarezsaurid dinosaur from the Late Cretaceous (Campanian) Barun Goyot Formation in southern Mongolia. The type and only species is O. alifanovi, known from a partial skeleton consisting of fragments of two last dorsal vertebrae, three anterior sacral vertebrae, right ilium, left and right pubis and ischium, articulated right tibia, fibula, metatarsals II and IV, and phalanges IV-1 and IV-2, right carpometacarpus, left and right manual phalanx II-1, right femur, left pedal phalanx II-1, and fragments of unidentified phalanges.
The Dzunbain Formation is a geological formation in Mongolia, dating to the Early Cretaceous (Aptian-Albian). The formation contains fossils of mammals, reptiles, turtles and dinosaurs. The Dzunbain Formation is equivalent to the Khuren Dukh Formation.
