List of informally named dinosaurs
Specimen ACM 7975, a jaw discovered in the Ojo Alamo Formation, New Mexico in 1924, has been tentatively identified as Gorgosaurus libratus but may instead belong to "Alamotyrannus" as per Dalman & Lucas (2013)[2] and McDavid (2022).
[12] "Amargastegos" is an informal genus of extinct stegosaurid ornithischian dinosaur known from the La Amarga Formation of Argentina, named by Roman Ulansky in 2014 on the basis of MACN N-43 (some dorsal osteoderms, the cervical and caudal vertebrae, and one skull bone), and the type species is "A.
The specific name referred to their hypothesis based on these specimens that nearly all Morrison diplodocid species are either growth stages or represent sexual dimorphism among members of the genus Amphicoelias,[16] but this analysis was met with skepticism and the publication itself has been disclaimed by its lead author, explaining that it is "obviously a drafted manuscript complete with typos, etc., and not a final paper.
Ulansky (2014) coined the name for skull elements, about 30 osteoderms, and the extremities of vertebrae and limbs, all preserved in the collections of the GSI and assigned to Ankylosauria by Nath et al.
[37] "Baguasaurus" (meaning "Bagua lizard") is the informal name given to an as yet undescribed genus of lithostrotian sauropod dinosaur from the Late Cretaceous (Campanian – Maastrichtian-aged) Chota Formation of Peru.
The proposed holotype, consisting of caudal vertebrae, was first mentioned in a review of the Chota Formation by Mourier et al. (1988),[38] and the name "Baguasaurus" was coined by Larramendi & Molina Pérez (2020).
It was discovered in the cliffs around Barnes High in 1992 and is currently owned by the privately run unaccredited Dinosaur Farm Museum near Brighstone,[42] the ownership situation was described as "complex" and the specimen is currently inaccessible to researchers.
[47] "Biconcavoposeidon" is the placeholder name for AMNH FARB 291, five consecutive posterior dorsal vertebrae of a brachiosaurid sauropod, from the Late Jurassic Morrison Formation, Wyoming.
The specimen consists of dentaries, teeth, a braincase, parts of the maxillae, forelimb elements, assorted vertebrae, and the pectoral girdle; this makes it unique compared to the other James Ross Island ornithopods, which do not have both cranial and postcranial remains.
The remains, NMMNH P-4569, consist of a partial skeleton including vertebral centra and hindlimb bones, and came from the Norian-age Upper Triassic Bull Canyon Formation of Guadalupe County.
[72] In the 1980s, researcher Peter Malcolm Galton reviewed all known stegosaur material from the Bathonian of England and concluded that Omosaurus vetustus was valid and should be tentatively referred to Lexovisaurus.
[85] "Francoposeidon" (meaning "French earthquake god") is the informal name given to an as yet undescribed genus of turiasaurian sauropod dinosaur from the Early Cretaceous (Hauterivian)-aged Angeac-Charente bonebed of France.
[87] "Futabasaurus" is an informal name for a genus of theropod dinosaur from the Late Cretaceous of Japan, known only from a partial shin bone of ~56 millimetres (2.2 in) wide that was discovered in the Coniacian-age Ashizawa Formation of the Futaba Group;[88] it was likely around 2 metres (6.6 ft) when fully grown.
[90] What may be the same animal is mentioned but not named by David B. Norman and Hans-Dieter Sues in a 2000 book on Mesozoic reptiles from Mongolia and the former USSR; this material, from the Soviet-Mongolian expeditions of the 1970s, had been listed as Arstanosaurus in the Russian Academy of Sciences, and was found in the Cenomanian-age Bayan Shireh Formation of Baishin Tsav.
"Lijiagousaurus" was only briefly mentioned in the Chongqing Natural History Museum guidebook (2001) and is thus a nomen nudum.The holotype consists of hindlimb bones, a scapula, an ischium and other fragments.
[143] "Lopasaurus" (meaning "Alberto Lopa's lizard") is the name given to an as yet undescribed genus of dromaeosaurid theropod, possibly belonging to Unenlagiinae due to its similarity to Buitreraptor, Neuquenraptor and Pamparaptor, from the Late Cretaceous (Maastrichtian)-aged Serra da Galga Formation in the Ponto 1 do Price site of Brazil.
The intended holotype, a partial right metatarsus showing metatarsals II, III and IV, was discovered by Alberto Lopa during the 1950s but the fossil was lost shortly after the death of Llewellyn Ivor Price in 1980 and it has not been located since.
[156] "Microcephale", also known as "Mycocephale", (meaning "tiny head") is the informal name of a genus of very small pachycephalosaurid dinosaur, otherwise known as the "North American dwarf species", which lived during the Late Cretaceous.
[160] "Microvenator chagyabi" is the informal name given to an as yet undescribed species of theropod dinosaur, likely belonging to Coelurosauria, from the Early Cretaceous Lura Formation of Tibet, China.
[162] "Mifunesaurus" (meaning 'Mifune lizard') is a nomen nudum given to an extinct non-avian non-maniraptoriform tetanuran theropod dinosaur from the Late Cretaceous (Cenomanian; ~96 Ma) Kabu Formation of Japan.
The species is based on the specimen BMNH R2912, an external mold of a dentary, which was discovered in the Late Triassic (Rhaetian) aged beds of the Lilstock Formation near Bridgend, Wales in 1898 and described by Edwin Tulley Newton in 1899.
[184] "Oharasisaurus" is the name given to an as yet undescribed genus of somphospondylian sauropod, possibly belonging to the Euhelopodidae, from the Early Cretaceous Kuwajima Formation (Facies III layer) of Japan.
The proposed holotype specimen includes fragmentary cervical and dorsal vertebrae, partial pectoral and pelvic girdles, humeri, femora, a tibia, and fibulae.
[210] A skeletal reconstruction was put on display in 2014 at the Museo del Desierto, which served to highlight its robust thighs and unusual hips that combine primitive and advanced features seen in ornithomimosaurs from both Asia and North America.
FMNH CUP 2338 was described in 2008 by Randall Irmis and Fabian Knoll, as one of the few definitive specimens of Ornithischia from the Early Jurassic based on features of the ankle and pes.
[242] In 2017, a preprint paper by Chase Brownstein concluded that the remains of L. macropus are a mixture of tyrannosauroid and ornithomimid elements with no distinguishing characteristics, rendering the species a chimera and a nomen dubium.
[248][249] "Tobasaurus" (meaning "Toba City lizard") is the informal name given to an as yet undescribed genus of sauropod dinosaur from the Euhelopodidae from the Early Cretaceous (Hauterivian – Barremian-aged) Matsuo Group of Japan.
[253] "Utetitan" is the informal name given to specimens of the titanosaur Alamosaurus from the Late Cretaceous (Maastrichtian) lower North Horn Formation of Utah US, by Gregory S. Paul in the third edition of The Princeton Field Guide to Dinosaurs in 2024.
It may belong to Noasauridae due to similarities with the foot of Velocisaurus, although inconsistencies within its brief description and a lack of comparison with other theropods within the article makes formal classification difficult.
The suggested "type species", "Yibinosaurus zhoui", is briefly mentioned in the Chongqing Natural History Museum guidebook (2001) as under description by Chinese paleontologist Ouyang Hui.
