This list of informally named dinosaurs is a listing of dinosaurs (excludingAves; birds and their extinct relatives) that have never been given formally publishedscientific names. This list only includes names that were not properly published ("unavailable names") and have not since been published under a valid name (seelist of dinosaur genera for valid names). The following types of names are present on this list:

• Nomen nudum, Latin for "naked name": A name that has appeared in print but has not yet been formally published by the standards of theInternational Commission on Zoological Nomenclature.Nomina nuda (the plural form) are invalid, and are therefore not italicized as a proper generic name would be.
• Nomen manuscriptum, Latin for "manuscript name": A name that appears in manuscript but was not formally published. Anomen manuscriptum is equivalent to anomen nudum for everything except the method of publication, and description.
• Nomen ex dissertationae, Latin for "dissertation name": A name that appears in a dissertation but was not formally published.
• Nicknames or descriptive names given to specimens or taxa by researchers or the press.

"Alamotyrannus" ("Ojo Alamo tyrant") is the informal placeholder^[1] name given to an as yet undescribed genus or species oftyrannosaurid from theLate Cretaceous period of North America. The fossils of this animal originate from theOjo Alamo Formation inNew Mexico and they were discovered during the early 2000s. The suggested binomial "Alamotyrannus brinkmani", was created when the paper describing the genus was written in 2013.^[2] "Alamotyrannus" lived during the earlyMaastrichtian.

Specimen ACM 7975, a jaw discovered in theOjo Alamo Formation,New Mexico in 1924, has been tentatively identified asGorgosaurus libratus but may instead belong to "Alamotyrannus" as per Dalman & Lucas (2013)^[2] and McDavid (2022).^[3] This specimen has been mentioned in a 2016 publication by Dalman and Lucas as an indeterminate tyrannosaurid without generic attribution, and it's noted that the specimen is under study by the senior author.^[4] Photograph taken by McDavid (2022) shows the specimen on display in theBeneski Museum of Natural History.^[3]

"Alan the Dinosaur" is the name given to a sauropod caudal vertebra (YORYM:2001.9337) found in 1995 in theSaltwick Formation (Middle Jurassic,Aalenian) of Whitby, England. It is the oldest sauropod found in the United Kingdom, dating back 176-172 million years ago. Its name references that of its discoverer, Alan Gurr, and the fact that it is not identifiable to species level. An analysis done in 2015 found that it was a member of Eusauropoda, could be excluded from Diplodocoidea, and was most similar toCetiosaurus.^[5]

The fossil of "Alan" is housed in theYorkshire Museum, where it forms part of the Yorkshire's Jurassic World exhibit, featuring a VR recreation.^[6]

"Allosaurus robustus" is an informal name used for specimen "NMV P150070", a theropodastragalus known from theWonthaggi Formation (Early Cretaceous) of Victoria, Australia.^[7] When first studied, it was thought to have belonged to a species ofAllosaurus.Samuel Welles challenged this identification as he thought that the astragalus belonged to an ornithomimid, but the original authors defended their classification. Sometime in the early 2000s, Daniel Chure examined the bone and found that it did not represent a new species ofAllosaurus, but could still represent an allosauroid.^[8] At the same time, Yoichi Azuma andPhil Currie noted that the astragalus resembled that of their new genusFukuiraptor.^[9] It may well represent a theropod related toAustralovenator, though some argue that it could represent an abelisauroid.^[10] A 2019 study strongly supported amegaraptoran affinity for the astragalus.^[11]

The name "Allosaurus robustus", first confined as a museum label, was first published by Chure in 2000.^[12]

"Amargastegos" is an informal genus ofextinctstegosauridornithischian dinosaur known from theLa Amarga Formation of Argentina, named by Roman Ulansky in 2014 on the basis of MACN N-43 (some dorsalosteoderms, the cervical and caudal vertebrae, and one skull bone), and thetype species is "A. brevicollum".^[13] In 2016,Peter Malcolm Galton andKenneth Carpenter declared it anomen nudum, establishing it as an indeterminate stegosaur.^[14]

"Barackosaurus" is the informal name created in 2010 which is used for asauropod found inKimmeridgian-aged sediments pertaining to theMorrison Formation,Wyoming. It was found in the Dana Quarry and "Barackosaurus" was supposedly 20 meters long and weighed 20 tons.^[15] In 2010, an article was made available, but not formally published, by Henry Galiano and Raimund Albersdorfer in which they dubbed the Dana Quarry specimens which had already been referred to as "Barackosaurus" as "Amphicoelias brontodiplodocus". 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 genusAmphicoelias,^[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. In fact, no printing or distribution has been attempted".^[17] As of 2015, they are now on display at theLee Kong Chian Natural History Museum in Singapore.^[18][19]

"Andhrasaurus" is an informalgenus ofextinct armoredornithischian dinosaur from theKota Formation of India. The proposed species is "A. indicus". Ulansky (2014) coined the name for skull elements, about 30osteoderms, and the extremities of vertebrae and limbs, all preserved in the collections of the GSI and assigned toAnkylosauria by Nath et al. (2002).^[20] In 2016,Peter Malcolm Galton andKenneth Carpenter noted that "Andhrasaurus" did not meet ICZN requirements and therefore declared it anomen nudum, listing it asThyreophora indet., while noting that the jawbones described by Nath et al. (2002) belonging to crocodylomorphs.^[14] The dermal armor informally named "Andhrasaurus" was redescribed by Galton (2019), referring the material to Ankylosauria.^[21]

The "Angeac ornithomimosaur" is an informal name given to an unnamedornithomimosaur taxon known from the Early Cretaceous (previously thought to beHauterivian-Barremian in age,^[22] but now thought to beBerriasian aged^[23][24])Angeac-Charente bonebed (part of the stratigraphy of theAquitaine Basin) nearAngeac-Charente in western France. The taxon is toothless and is known from numerous disarticulated remains representing at least 70 individuals covering almost all of the skeleton,^[23] some remains were described by Allain et al. (2014).^[25]

"Angloposeidon" is the informal name given to asauropod dinosaur from the EarlyCretaceous (Barremian)Wessex Formation of theIsle of Wight in southern England.^[26] It was a possiblebrachiosaurid but has not been formally named.Darren Naish, a notable vertebrate palaeontologist, has worked with the specimen and has recommended that this name only be used informally and that it not be published.^[27] However, he published it himself in his bookTetrapod Zoology Book One from 2010.^[28] The remains consist of a single cervicalvertebra (MIWG.7306), which indicate it was a very large animal, 20 metres or greater in length.^[29]

"Angustungui" is an informal genus ofstegosaur from theLate JurassicQigu Formation inChina. The intendedtype species is "A. qiketaiensis" and the holotype is specimen SS V16001 consisting of axial, pectoral girdle, pelvic girdle, limb and armor elements, while theparatype is specimen SS V16002, consisting of a right coracoid and a right scapula. Both specimens were discovered in 2016 by Li Daqing atQiketai,Shanshan County, and the name was first announced in abioRxiv pre-print article in October 2024, where it was recovered as sister taxon ofLoricatosaurus.^[30]

"Archaeoraptor" is the informalgeneric name for an importantfossil from China that was later discovered to have been fabricated from multiple unrelated fossils. The name was created in an article published inNational Geographic magazine in 1999, where the magazine claimed that the fossil was a "missing link" between birds and terrestrialtheropod dinosaurs. Even prior to this publication there had been severe doubts about the fossil's authenticity. Further scientific study showed it to be a forgery constructed from rearranged pieces of real fossils from different species. Zhou et al. found that the head and upper body actually belong to a specimen of the primitive fossil birdYanornis, and another 2002 study found that the tail belongs to a small wingeddromaeosaur,Microraptor, named in 2000.^[31][32] The legs and feet belong to an as yet unknown animal.^[33][34]

"The Archbishop" is a giantbrachiosauridsauropod dinosaur similar toBrachiosaurus andGiraffatitan. It was long considered a specimen ofBrachiosaurus (nowGiraffatitan)brancai due to being found in the same formation inTendaguru, Tanzania. However, the "Archbishop" shows significant differences including a unique vertebral morphology and a proportionally longer neck, that indicates it is a different, previously unknown genus and species.^[35] It was discovered by Frederick Migeod in 1930. "The Archbishop" is a nickname that functions as a placeholder – the specimen currently has no scientific name. The specimen is currently housed in the Natural History Museum in London, and will eventually be re-described by Dr.Michael P. Taylor ofBristol University.^[36] In May 2018, Taylor started to work on describing the Archbishop.^[37]

"Atlantohadros", more commonly known as the "Merchantville hadrosaur", is an informally named hadosaurid dinosaur that lived in theMerchantville Formation in the northeastern United States. Brown (2021) found "Atlantohadros" to be more derived thanTethyshadros but less derived thanSaurolophinae andLambeosaurinae. The name was intended to be used in that publication, but was cut for unknown reasons; initial versions of Brown (2021) contained the word "Atlantohadros" superimposed over "Merchantville Taxon" in a cladogram; subsequent corrections have erased the genus name entirely.^[38]

Three specimens were discovered 8 kilometres (5.0 mi) northwest ofFreehold near Manalapan–Marlboro township line inMonmouth County during the 1970s. These are: YPM VPPU.021813, YPM VPPU.021813, and AMNH 13704, with YPM VPPU.021813 possibly belonging to the same individual as YPM VPPU.021813 due similar weathering, size and the same horizon. These specimens consist of both coracoids, both scapulae, a femur, a fragmentary proximal tibia, and a dentary from a cast of the specimen (the original likely lost in YPM's catalogue) in the adult specimen, as well as a rib, a femur and long bone portions in the juvenile. AMNH 13704, id a partial dentary of a probable perinate. Scattered bones associated with these include a quadrate, several partial maxilla portions, a partial jugal, skull roof fragments and several rib fragments.^[38]

"Baguasaurus" (meaning "Bagua lizard") is the informal name given to an as yet undescribedgenus oflithostrotian sauropod dinosaur from theLate 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),^[39] and the name "Baguasaurus" was coined by Larramendi & Molina Pérez (2020). "Baguasaurus" was estimated to be 12 metres (39 ft) long and weighed 4 tonnes (8,800 lb).^[40]

"Balochisaurus" (meaning "Balochi lizard", for theBaloch tribes of Pakistan) is an informal taxon oftitanosauriansauropod dinosaur from theLate Cretaceous of Pakistan. The proposed species is "B. malkani". The discovery was made (along with other dinosaur specimens) in 2001 near Vitariki by a team of paleontologists from the Geological Survey of Pakistan.^[41] Described in 2006 by M.S. Malkani, the genus isbased on seven tailvertebrae found in theMaastrichtian-age Vitakri Member of thePab Formation, with additional vertebrae and a partial skull assigned to it.Balochisaurus was assigned to the family "Balochisauridae" along with "Marisaurus". It was considered invalid by Wilson, Barrett and Carrano (2011).^[42]

The "Barnes High sauropod" is the informal name given to MIWG-BP001, an undescribed sauropod dinosaur specimen from theWessex Formation on the Isle of Wight. It was discovered in the cliffs around Barnes High in 1992 and is currently owned by the privately run unaccredited Dinosaur Farm Museum nearBrighstone,^[43] the ownership situation was described as "complex" and the specimen is currently inaccessible to researchers.^[44] It is roughly 40% complete and consists of a "Partial postcranial skeleton, including presacral vertebrae, anterior caudal vertebrae, girdle and limb elements" including a largely complete forelimb. It has been suggested to be abrachiosaurid and is possibly synonymous with the earlier namedEucamerotus due to similarities with the vertebrae.^[45]

"Bayosaurus" is the informal name given to an as yet undescribedgenus of theropod dinosaur. The name was coined bypaleontologistsRodolfo Coria,Philip J. Currie, and Paulina Carabajal in2006. It apparently was anabelisauroid from theTuronianCerro Lisandro Formation ofNeuquén, Argentina, around 4 m (13 ft) long. The specimen is MCF-PVPH-237, including dorsal and sacralvertebrae, a fragmentarypelvis, and other partial bones, which were discovered in 2000. The name was used in a phylogenetic analysis to indicate the position of MCF-PVPH-237.^[46]

"Beelemodon" is the informal name given to an undescribed theropod genus from theLate Jurassic, possibly belonging to acoelurosaur. The fossils include two teeth found inWyoming, United States. The name appeared in print in1997, when paleontologistRobert T. Bakker mentioned it in a symposium for theAcademy of Natural Sciences.^[47] The teeth are most similar toCompsognathus, but have no unique features and also share similarities withProtarchaeopteryx and dromaeosaurids.^[48]

"Biconcavoposeidon" is the placeholder name for AMNH FARB 291, five consecutive posterior dorsal vertebrae of abrachiosauridsauropod, from theLate JurassicMorrison Formation,Wyoming.^[49] Not much else is currently known about "Biconcaveoposeidon", except that it was discovered in the Bone Cabin quarry in 1898.^[50]

"Bihariosaurus" (meaning "Bihor lizard") is an invalid genus ofiguanodontian dinosaur fromEarly CretaceousBauxite of Cornet, Romania. Thetype species, "Bihariosaurus bauxiticus", was named but not described by Marinescu in 1989. It was similar toCamptosaurus, and was aniguanodont. The original publication of the taxon did not include sufficient description, and the illustrations cannot distinguish it from any other ornithopod.^[51][52]

"Biscoveosaurus" is the informal name of anornithopod dinosaur specimen from the EarlyMaastrichtian ageSnow Hill Island Formation ofJames Ross Island, Antarctica. It comes from the Cape Lamb Member of the formation, the same member asMorrosaurus, another basal ornithopod. As such, it's been suggested it may be a secondary specimen of that species, but as the holotype ofMorrosaurus is fragmentary and doesn't overlap with the material of "Biscoveosaurus", this can't as yet be tested. 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. It has been estimated the animal would have been about 4–5 metres (13–16 ft) in length.^[53]

"Capitalsaurus" is theinformal genus name given to atailbone belonging to a largetheropod dinosaur that lived during theEarly Cretaceous. It was discovered on 28 January 1898, by construction workers excavating a sewer at the intersection of Washington, D.C.'s First and F Streets SE. The only known specimen, it was assigned two different species designations –Creosaurus potens andDryptosaurus potens – and eventually overturned each time. In the 1990s, the paleontologist Peter Kranz asserted that it represented a unique type of dinosaur and assigned it the name "Capitalsaurus". He successfully campaigned through local schools to make "Capitalsaurus" theofficial dinosaur of Washington, D.C., which became law in 1998.^[54] A year later, the district further recognized F Street at the discovery site as Capitalsaurus Court. It designated 28 January 2001, as Capitalsaurus Day.^[55][56]

"Changdusaurus" (also known as "Changtusaurus") is the informal name given to agenus of dinosaur from theLate Jurassic Period. It lived in what is now China. "Changdusaurus" is classified as astegosaurid. Thetype species was named "Changdusaurus laminoplacodus" by Zhao in 1983,^[57] but it has never been formally described, and remains anomen nudum. One source indicates the fossils have been lost.^[58]

"Cinizasaurus" is anomen ex dissertationae forfossilized remains from theLate Triassic ofNew Mexico that were initially interpreted as belonging to atheropod dinosaur. The intended type species "Cinizasaurus hunti" was named in an unpublished 1997 thesis based on NMMNH P-18400, which consists of a tibia, vertebrae, and other fragments.^[59] In 2007, Nesbitt, Irmis and Parker classified both NMMNH P-18400 and NMMNH P-18401 as specimens of an indeterminatearchosauriform.^[60]

"Comanchesaurus" is anomen ex dissertationae forfossilized remains from theLate Triassic ofNew Mexico that were initially interpreted as belonging to atheropod dinosaur. The remains,NMMNH P-4569, consist of a partial skeleton includingvertebralcentra and hindlimb bones, and came from theNorian-ageUpper TriassicBull Canyon Formation ofGuadalupe County. Adrian Hunt, in his unpublished dissertation, proposed the name "Comanchesaurus kuesi" for the specimen, but the name was never adopted, and was first referred to in the scientific literature in a 2007 redescription of Late Triassic North American material thought to belong to dinosaurs (Nesbitt, Irmis, and Parker, 2007). In the redescription, the authors found the material to belong to a "possible indeterminatesaurischian".^[61]

"Cryptoraptor" is anomen ex dissertationae forfossilized remains from theLate Triassic ofNew Mexico that were initially interpreted as belonging to atheropod dinosaur. The remains,NMMNH P-17375, consist of a partial skeleton including partial hindlimb and pelvic bones, and came from theNorian-ageUpper TriassicBull Canyon Formation ofQuay County. Adrian Hunt, in his unpublished dissertation, proposed the name "Cryptoraptor lockleyi" for the specimen, but the name was never adopted, and was first referred to in the scientific literature in a 2007 redescription of Late Triassic North American material thought to belong to dinosaurs. In the redescription, the authors found the material to belong to an intermediate archosaur, as no features exclusive to dinosaurs could be identified.^[61]

"Cryptotyrannus" (meaning "secret/hidden tyrant"), more commonly known as the "Merchantville tyrannosauroid", is an informally named tyrannosauroid dinosaur that lived in theMerchantville Formation. It was informally named by Brown (2021), who found it to be the sister taxon ofDryptosaurus, reinstatingDryptosauridae.^[38] The name appeared in the initial version of Brown's paper, superimposed over "Merchantville Taxon" in a cladogram; a subsequent correction has erased the name entirely.

"Cryptotyrannus" is known from two specimens discovered during the 1970s, the holotype YPM VPPU.021795 and the paratype YPM VPPU.022416. Similar coloration and weathering indicate that these are probably the same individual. These are a partial foot bone and one caudal vertebrae. However, a skeletal produced for the paper depicts a hand claw. The foot morphology is consistent withtyrannosaurs, being extremely similar to theDryptosaurus aquilunguis. Autapomorphies include a metatarsal IV that is far more gracile and IV in proximal view also has a triangular, rather than subrectangular in outline. The holotype was once tentatively assigned to"Coelosaurus" antiquus. Shark bites present on the holotype suggest that the specimen's fragmentary nature is due to predation or scavenging by marine predators.^[38]

"Dachongosaurus" is the informal name given to anundescribedgenus ofsauropod dinosaur from theEarly Jurassic of China. It is known from fossils including at least a partial articulated skeleton from the Dark Red Beds of theLower Lufeng Series (Sinemurian stage) inYunnan.^[62] Possibly acetiosaur, the "type species" is "Dachongosaurus yunnanensis", coined by Zhao in 1985. An alternate spelling is "Dachungosaurus". As with other informal names coined by Zhao in 1985 and 1983, nothing has since been published, and the remains may have been redescribed under another name.^[63]

"Damalasaurus" (meaning "Damala lizard") is the informal name given to agenus ofherbivorous dinosaur from theEarly Jurassic. It was asauropod, though its exact classification within theclade is unknown. Fossils of "Damalasaurus", including a rib, have been found in the MiddleDaye Group ofTibet. Species attributed to this genus include "Damalasaurus laticostalis" and "D. magnus", although it is possible that both names refer to the same species.^[64][62]

"Dongshengosaurus" is the informal name given to an undescribed genus ofiguanodontian dinosaur from theEarly Cretaceous ofLiaoning, China. the "type species", "D. sinensis", was named by Pan Rui in his 2009 thesis. It is known from a partial juvenile skeleton discovered from theYixian Formation.^[65]

"Dubeynarainsaurus" is an informal genus of purported theropod dinosaurs from the Late CretaceousLameta Formation of India described by Malkani (2025) inScientific Research Publishing, a knownpredatory publisher. The proposed holotype is allegedly a partial dentary with associated teeth, collected in January 1944 by V. S. Dubey and Kedar Narain (who are referenced in the proposed genus name). The intended type species is "Dubeynarainsaurus sahni." The specimen was initially identified as a pterosaur mandible in 1946,^[66] although Malkani reclassified it as belonging to anoasaurid theropod.^[67]

"Duranteceratops" is a purported new taxon ofchasmosaurineceratopsid from theHell Creek Formation.^[68] In 2012, a ceratopsid skull supposedly distinguishable fromTriceratops was unearthed inSouth Dakota by a fossil poacher named John Carter.^[69][70][68] Though it has yet to be published, according to thePrehistoric Times issue no. 121 from Spring 2017, the specimen is to be named "Duranteceratops".

The "EK troodontid" (specimen SPS 100/44) is an unnamedgenus oftroodontid dinosaur discovered in Mongolia. In the scientific literature it is referred to as the "EK troodontid", after theEarly Cretaceous sediments in which it was found. SPS 100/44 was discovered bySergei Mikhailovich Kurzanov during the 1979 Soviet-Mongolian Paleontological Expedition. It was found in deposits of theBarunbayaskaya Svita at the Khamareen Us locality, Dornogov (southeastern Gobi Desert), in the Mongolian People's Republic. SPS 100/44 was described byRinchen Barsbold and colleagues in 1987.^[71]

Itsfossil remains include an incomplete skeleton consisting of the braincase, posterior parts of the lower mandibles, a maxillary fragment with teeth, parts of five cervical vertebrae (cervicals ?2-?6), an articulated right manus with partial semilunate, left manusphalanx I-1, distal end of the left femur, and fragmentary left and right pedes. Barsbold pointed out that the specimen was smaller and from older sediments than other known troodontids, but it had some features of the skull that could have made it a juvenile. Barsbold also indicated the high degree of fusion of the bones of the skull and the unusual foot morphology to indicate that it might be an adult of an unknown taxon. Barsbold took the conservative position and did not name this specimen because it was not complete enough to rule out the possibility that it was a juvenile of a known genus of troodontid. Barsbold also noted that the naturally articulated manus of SPS 100/44 showed no signs of an opposable third digit, as was suggested forTroodon by Russell and Seguin in 1982. Turner and colleagues, in 2007, found the EK troodontid to be a distinctbasal genus of troodontid, in apolytomy withJinfengopteryx and aclade of morederived troodontids.^[72]

"Eoplophysis" is a genus ofstegosaur known from theMiddle JurassicCornbrash Formation,Sharp's Hill Formation, andChipping Norton Formation of England.^[73] It was originally namedOmosaurus vetustus by the renowned German paleontologistFriedrich von Huene.^[74] The holotype, OUM J.14000, is a 60-centimetre-long (2 ft) right femur of a juvenile individual from the Middle Jurassic (upperBathonian)Cornbrash Formation ofOxfordshire, England, although it was probably reworked from the slightly olderForest Marble Formation in view of its eroded nature. Because of the renaming ofOmosaurus, an occupied name, asDacentrurus,O. vetustus was renamed into aDacentrurus vetustus in 1964.^[75] In the 1980s, researcherPeter Malcolm Galton reviewed all known stegosaur material from the Bathonian of England and concluded thatOmosaurus vetustus was valid and should be tentatively referred toLexovisaurus.^[76][77] However, the species was later considered anomen dubium in both reviews of Stegosauria.^[78][79] In their alpha-taxonomic review of stegosaurs, Susannah Maidment and her colleagues noted that OUM J.14000 shares characters present in both sauropods and stegosaurs, but that it lackssynapomorphies exclusive toStegosauria and assigned it as a Dinosauria indet.^[80] Nevertheless, the amateur paleontologist Roman Ulansky coined the new genus "Eoplophysis" ("Dawn Armed Form") forO. vetustus, noting differences with the femora of other stegosaurs.^[13]

"Eugongbusaurus" is the informal name (nomen nudum) proposed for a neornithischian found in theOxfordian-ageShishugou Formation ofXinjiang, China. The intendedtype species,"Gongbusaurus" wucaiwanensis, was described byDong Zhiming in 1989 for two partial skeletons as a second species of the poorly known toothtaxonGongbusaurus. Fragmentary skeletonIVPP 8302, thetype specimen for the new species, included a partial lower jaw, three tailvertebrae, and a partial forelimb. Second specimen IVPP 8303 consisted of twohip vertebrae, eight tail vertebrae, and two complete hind limbs. Dong estimated it as around 1.3 to 1.5 meters (4.3 to 4.9 ft) long, and considered it to be a strong runner. He assigned the genusGongbusaurus to theHypsilophodontidae, a paraphyletic grade of small herbivorousbipedal dinosaurs.^[81] Because dinosaur teeth are generally not distinctive enough to hold a name, it is unsurprising that other paleontologists have suggested removing "G."wucaiwanensis fromGongbusaurus and giving it its own genus.^[82] The possible replacement name "Eugongbusaurus"^[83] leaked out accidentally and remains informal.

"Fendusaurus" is anomen ex dissertatione proposed by Fedak (2006) forFGM 998GF13-II, which includes askull. Other specimens referred to "Fendusaurus" are FGM998GF13-I, FGM998GF13-III, FGM998GF69, FGM998GF9, and FGM998GF18, all found by a crew from thePrinceton University. All the specimens includefemora andcoracoids, and although they each share slightly different features, the differences are credited to intra-specific variation. Known specimens of "Fendusaurus" were previously classified as cf.Ammosaurus. The femora and coracoids also help identify different individuals, andTimothy J. Fedak, the describer of the specimens, found that each block represented about one individual. "Fendusaurus" is known from theEarly Jurassic (Hettangian)McCoy Brook Formation ofWasson Bluff, Nova Scotia. It is the first non-avian dinosaur from Nova Scotia. As five specimens of "Fendusaurus" are from the McCoy Brook Formation, the formation is the richest prosauropod site in North America. The formation is also similar to other formations of North America and Asia, as it lacks any remains presently assigned toAnchisaurus. Fedak places "Fendusaurus" as a genus of the familyMassospondylidae.^[84]

The specimens of "Fendusaurus" include mostly crushedvertebrae, along with appendicular elements. They are distinguishable fromAnchisaurus by the morphology of both theilium andsacral vertebrae. However, in some specimens, the morphology of the femora and coracoids are quite different, which led Fedak to speculate that more than one species may have been present. "Fendusaurus", according to Fedak, can be distinguished from all closely relatedsauropodomorphs by the extreme elongation of the cervical vertebrae; a four vertebrae sacrum that includes a dorsosacral and caudosacral; the elongate postacetabular process of the ilium; and an expanded anterior distal process of the tibia.^[84]

"Ferganastegos" is a dubious genus ofstegosaur from theMiddle Jurassic (Callovian)Balabansai Formation ofFergana Valley, Kyrgyzstan.^[85] The holotype of "Ferganastegos callovicus", IGB 001, consists of four posterior dorsal vertebrae.^[86] Although Averianov et al. did not consider the vertebrae diagnostic to genus, the freelance Russian dinosaur enthusiast and amateur paleontologist Roman Ulansky decided that the differences between IGB 001 and other stegosaurs were sufficient to warrant a binomial for IGB 001, "Ferganastegos callovicus" (Callovian roof from Fergana Valley), despite the fact he did not examine the material himself.^[13] Other researchers still contend that the material is not diagnostic and that the genus is anomen dubium.^[87]

"Ferropectis" is anodosauridankylosaur from theLate Cretaceous (Cenomanian)Eagle Ford Group inTexas that was named in a 2018 dissertation by Matt Clemens. The intended type species is "Ferropectis brysorum", and in the phylogenetic analysis it was placed as the sister taxon toBorealopelta in a clade includingHungarosaurus,Europelta, andPawpawsaurus.^[88]

"Francoposeidon" (meaning "French earthquake god") is the informal name given to an as yet undescribedgenus ofturiasaurian sauropod dinosaur from theEarly Cretaceous (Hauterivian)-agedAngeac-Charente bonebed of France. The proposed type species is "F. charantensis",^[40] and the remains consist of a braincase, some skull bones, teeth, cervical, dorsal and caudal vertebrae, chevrons, pelvic girdle and all the limb bones" alongside isolated teeth, belonging to at least 7 individuals.^[89] The length of the femur was measured to be around 2.35 metres (7.7 ft), (± 0.5 metres (1.6 ft)), making "Francoposeidon" one of the largest known sauropods discovered in Europe.^[90]

"Futabasaurus" is an informal name for agenus oftheropod dinosaur from theLate Cretaceous of Japan, known only from a partialshin bone of ~56 millimetres (2.2 in) wide that was discovered in theConiacian-ageAshizawa Formation of theFutaba Group;^[91] it was likely around 2 metres (6.6 ft) when fully grown. It was first mentioned as "Futaba-ryu" by Hasegawa et al. (1987),^[92] and the name was coined by David Lambert in 1990 as a conversion from the Japanese nickname "Futaba-ryu", for an undescribed theropod.^[93]Dong Zhiming and coauthors briefly discussed the fossil shin bone it was based on that same year, publishing a photograph. They considered the bone to belong to an indeterminatetyrannosaurid.^[94] If the specimen is eventually described and named, it will require a different name, because the nameFutabasaurus has since been used for a genus ofplesiosaur.^[95]

"Gadolosaurus" is an informal name given to PIN, no. 3458/5^[96] an unnamedjuvenilehadrosauroid dinosaur specimen from theBayan Shireh Formation of Baishan Tsav, Mongolia. The name "Gadolosaurus" was first used in a 1979 book by Japanese paleontologist Tsunemasa Saito, in a caption for a photo of the specimen.^[97] This specimen represents an individual that was only about a meter long (39 inches). The specimen was part of a Soviet exhibition of fossils in Japan. Apparently, the name comes from a Japanese phonetic translation of theCyrillic wordgadrosavr, orhadrosaur, and was never meant by the Russians to establish a new generic name.^[98]

Despite the only name ever applied to it being merely a mistranslation ofgadrosavr, this specimen has appeared in many popular dinosaur books, with varying identifications.Donald F. Glut in 1982 reported it as either aniguanodont or hadrosaur, with no crest or boot on theischium (the lack of which are both characteristics of the crestedlambeosaurine duckbills), and suggested it could be the juvenile of a previously named genus likeTanius orShantungosaurus.^[99] David Lambert in 1983 classified it as an iguanodont,^[100] but changed his mind by 1990, when it was listed as asynonym ofArstanosaurus without comment.^[93] What may be the same animal is mentioned but not named byDavid B. Norman andHans-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 asArstanosaurus in theRussian Academy of Sciences, and was found in theCenomanian-ageBayan Shireh Formation of Baishin Tsav.^[101]

Averianov, Lopatin, and Tsogtbaatar in 2022 provided a preliminary description of this specimen and its taxonomic position, finding that the specimen may represent a juvenile of a novel taxon that was closely related to but more derived than the contemporary hadrosauroidGobihadros.^[96]

"Gallimimus mongoliensis" is an informal nameRinchen Barsbold used for a nearly complete skeleton (IGM 100/14) known from the Bayan Shireh Formation, but since it differs fromGallimimus in some details, Yoshitsugu Kobayashi and Barsbold proposed in 2006 that it probably belongs to a different genus.^[102] It was recently included in a phylogenetic analysis, which recovered it as closely related toTototlmimus.^[103]

"Gspsaurus" (anomen manuscriptum) is a titanosaurian sauropod dinosaur from the Late Cretaceous Vitakri Member of thePab Formation of Sulaiman Basin of Pakistan.^[104] It has been suggested to be synonymous with the also invalid taxon "Maojandino", also proposed by Malkani. The intended holotype, MSM-79-19 and MSM-80-19, consisting of parts of the skull, including a rostrum, was discovered in 2001, and parts of the holotype were initially referred to "Marisaurus jeffi".^[105][106]

"Grusimimus" (or "Tsurumimus") is an informal name for an undescribed genus ofornithomimid from the Early Cretaceous (Hauterivian–Barremian) agedShinekhudag Formation of Mongolia. Known from a skeleton including all regions except the skull, "Grusimimus" was given an invalid name in1997 byRinchen Barsbold, who also suggested the species name "tsuru". The specimen (GIN 960910KD) was found in 1996 and examined by Barsbold before he suggested the informal name, anomen nudum. An abstract and poster were presented on the taxon by Kobayashi & Barsbold in 2002, and the former published a thesis paper on the specimen (referred to as "Ornithomimosauria indet.") which found the taxon to be close toHarpymimus phylogenetically but possible more derived.^[107] A recent phylogenetic analysis recovered "Grusimimus" closely related toBeishanlong andGarudimimus.^[103]

"Hanwulosaurus" is theinformal name given to an as-yet undescribedgenus of dinosaur from theLate Cretaceous. It was anankylosaur around 9 m (30 ft) long, which is long for an ankylosaur. Itsfossils were found inInner Mongolia, China. Much of a skeleton, including a completeskull,vertebrae, ribs, ascapula, anulna,femora, bones from theshin, andarmor, was discovered; this may be the most complete ankylosaurianskeleton yet found in Asia, according to early reports.Zhao Xijin, who has studied it, suggests that it may belong to its own subgroup within the Ankylosauria. The name first surfaced in news reports in 2001.^[108]

The "Haute Moulouya Sauropod", also known as NHMUK PV R36834, consisted originally of two complete cervical vertebrae recovered from theLower Jurassic sediments of theHaute Moulouya Basin, likely theAganane Formation, on centralMorocco.^[109] This material was initially identified as belonging to an early member ofEusauropoda, if so, the oldest member of the group.^[109] Additional material was previously recovered, SNSB-BSPG 2014 I 106 that consists of dorsal vertebrae and a pubis fragment.^[110] A recent revision suggest both specimens belong to the same taxon, that likely comes from a higher stratigraphic level (Likely LatePliensbachian) and that represents a valid more basal taxon, related withAmygdalodon.^[111] Tought other analisis still recover it alternatively as an Eusauropod, in a polytomy withBarapasaurus.^[112][113]

"Heilongjiangosaurus" (meaning "Heilongjiang lizard") is the informal name given to an as-yet undescribedgenus ofduckbilled dinosaur from theLate Cretaceous. It possibly was alambeosaurine, and may in fact be the same animal asCharonosaurus. Thefossils were found inMaastrichtian-age rocks in Heilongjiang, China. As anomen nudum, it is unclear what material it was intended to be based on, but might be connected to thenomen nudum"Mandschurosaurus" jiainensis,^[114] informally named in a 1983 publication.^[115]

The "type species" is "H. jiayinensis", and it was coined in 2001 in afaunal list by Li and Jin.^[116]

"Hironosaurus" (meaning "Hirono lizard") is the informal name given to an as-yet undescribedgenus of dinosaur from theLate Cretaceous. Found inHirono, Fukushima, Japan, it was probably a type ofhadrosaur, although no subfamily identification has been made. Thefossils are quite fragmentary, and consist of teeth and avertebra, possibly from the tail. Since the fossils have never been fully described in a scientific paper, "Hironosaurus" is considered anomen nudum. It was first mentioned by Hisa in an obscure 1988 publication^[117] and was later (1990) brought to a wider audience by David Lambert.^[93]Dong Zhiming, Y. Hasegawa, and Y. Azuma regarded the material as belonging to ahadrosaurid, but lacking any characteristics to allow more precise identification (thus indeterminate).^[94]

"Hisanohamasaurus" (meaning "Hisano-hama lizard") is the informal name given to an as yet undescribedgenus of dinosaur from theLate Cretaceous. It is anomen nudum known only from teeth that first appeared in a general-audience dinosaur book byDavid Lambert in 1990. Although initially identified adiplodocid,^[118] it later re-identified as anemegtosaurid similar toNemegtosaurus.^[119] As its name suggests, its fossils were found in Japan. The location is part ofIwaki, Fukushima.

The "Hughenden sauropod" is an informal name given to atitanosauriformsauropod specimen (QM F6142) discovered from the Early Cretaceous (Albian)Toolebuc Formation of Australia. It is uncertain whether the specimen can be referred toAustrosaurus from theAllaru Formation, which overlies the Toolebuc Formation.^[120]

"Ikqaumishan" is an informal genus of titanosaurian dinosaurs from the Late Cretaceous (Maastrichtian)Vitakri Formation of Pakistan described by Malkani (2023) inScientific Research Publishing, a knownpredatory publisher. The assigned fossil material includes multiple humeri. Caudal vertebrae and osteoderms found nearby may also be referrable to "Ikqaumishan". The intended type species is "Ikqaumishan smqureshi."^[121]

"Imrankhanhero" is an informal genus of titanosaurian dinosaurs from the Late Cretaceous (Maastrichtian) Vitakri Formation of Pakistan described by Malkani (2023) inScientific Research Publishing, a knownpredatory publisher. The assigned fossil material includes a humerus, a femur, fibulae, a tibia, and a metatarsal. Caudal vertebrae found nearby may also be referrable to "Imrankhanhero". The intended type species is "Imrankhanhero zilefatmi."^[121]

"Imrankhanshaheen" is an informal genus of titanosaurian dinosaurs from the Late Cretaceous (Maastrichtian) Vitakri Formation of Pakistan described by Malkani (2024) inScientific Research Publishing, a knownpredatory publisher. The proposed holotype includes a braincase, vertebrae, a humerus, ulnae, a radius, metacarpals, a tibia, fibulae, ribs, girdle bones, and osteoderms. The intended type species is "Imrankhanshaheen masoombushrai."^[122]

"Jeholraptor" is the informal replacement genus name given to themicroraptorineSinornithosaurus haoiana—resulting in thenew combination "Jeholraptor"haoiana—byGregory S. Paul in the third edition ofThe Princeton Field Guide to Dinosaurs in 2024. TheS. haoiana fossil is known from the Early Cretaceous (Barremian) upperYixian Formation of China. The specimen, which is nearly complete, is about 1.2 metres (3.9 ft) long and was probably close to 3 kilograms (6.6 lb) in weight. Paul suggested that, due to similarities in thequadratojugal, "Jeholraptor" may have been a close relative ofWulong.^[123]

"Jiangjunmiaosaurus" (meaning "temple of the general lizard") is an informal name created by an anonymous author in 1987 for a possible chimaera ofMonolophosaurus andSinraptor.^[124]Paul (1988) tentatively placed "Jiangjunmiaosaurus" withinAllosauridae and commented on the nasal ridges and orbital horn combining to form low, rugose-surfaced crests, and mentioned that "other excellent bones" may also be referable to "Jiangjunmiaosaurus".^[125]

"Jindipelta" (Lei et al., 2019; in press) is the currently informal name given to anankylosaur from theZhumapu Formation in China. It is known from a partial skeleton found inCenomanian rocks and the intendedtype species is "J. zouyunensis". The name was first announced in the 2019 SVP abstract book, alongside themegalosauroidYunyangosaurus.^[126]

"Julieraptor" is the nickname of adromaeosaurid fossil found in theJudith River Formation,Montana in 2002. Parts of the same skeleton were illegally excavated and nicknamed Sid Vicious in 2006, and the poacher responsible subsequently served jail time for the theft.Bob Bakker therefore also nicknamed the specimen "Kleptoraptor". The skeleton was arranged to be sold toRoyal Ontario Museum.^{[127][128][129]} It is known from a skeleton consisting of an almost complete skeleton missing most of its skull, most tail vertebra, part of the femur, some spinal and neck vertebra, one claw but it has a well preserved braincase.

"Kagasaurus" (meaning "Kaga lizard") is the informal name given to an as yet undescribedgenus oftheropod dinosaur from theEarly Cretaceous of what is now Japan. Thetype species was named by Hisa in 1988, but is known from only two teeth with no formal description, so it is considered anomen nudum. It may belong to either a non-maniraptoriform coelurosaur or a dromaeosaurid.^[130]

"Katsuyamasaurus" is an informal name for a genus of intermediate theropod known from the Early Cretaceous (Barremian) of theKitadani Formation, Japan. Known from a single middle caudal vertebra and an ulna, the taxon was informally called "Katsuyama-ryu", until Lambert (1990) made it into an invalid genus name, "Katsuyamasaurus". The caudal vertebra was suggested to belong to anornithopod by Chure (2000), and Olshevsky (2000) suggested the material was a synonym ofFukuiraptor. However, the ulna differs fromFukuiraptor, and the largeolecranon suggests the taxon falls outsideManiraptoriformes.^[131]

"Khanazeem" is an informal genus oftitanosauriansauropod from theLate CretaceousVitakri Formation of Pakistan. The holotype is a partial skeleton and consists of a dentary with teeth, caudal vertebrae, femora, humeri, and tibiae. The intended type species is "Khanazeem saraikistani" and was first mentioned by Malkani (2022).^[132]

"Khetranisaurus" (meaning "Khetran lizard", for theKhetran people of Pakistan) is an informal taxon oftitanosauriansauropod from theLate Cretaceous ofBalochistan, western Pakistan (also spelled "Khateranisaurus" in some early reports).^[133] The proposed species is "K. barkhani", described by M. Sadiq Malkani in 2006, and it isbased on a tailvertebra, found in theMaastrichtian-age Vitakri Member of thePab Formation. It was assigned to "Pakisauridae" (used as a synonym ofTitanosauridae), along with "Pakisaurus" and "Sulaimanisaurus". It was considered invalid by Wilson, Barrett and Carrano (2011).^[42]

"Koreanosaurus" (meaning "Korean lizard") is the informal name given to an as-yet unnamedgenus of dinosaur from theEarly Cretaceous (Aptian-Albian). It was a possibledromaeosaur (or similartheropod) which was discovered in theGugyedong Formation ofSouth Korea,^[134] although at times it has been referred to theTyrannosauridae,Hypsilophodontidae andHadrosauridae. Based solely on DGBU-78(=DGBU-1978B), afemur, the name was coined by Kim in 1979,^[135] but by 1993 Kim decided that it was a species ofDeinonychus, and created the informal name "D." "koreanensis".^[136] Kim et al. (2005) referred the specimen toEumaniraptora based on a proximolateral ridge, shelf-like posterior trochanter, and absence of an accessory trochanter and mediodistal crest. The presence of a large fourth trochanter was noted to be similar toAdasaurus andVelociraptor.^[137]

"Kunmingosaurus" is an informally named primitivesauropod which lived during theEarly Jurassic. Its fossils were found inYunnan, China in 1954. Thetype and only species is "Kunmingosaurus wudingensis", invalidly coined by Zhao in 1985. It is known from fossils found in theFengjiahe Formation (or theLower Lufeng Series), includingpelvic, hind limb, andvertebral material.^{[62][138][139][140]}

"Lancanjiangosaurus" (alternative spelling "Lanchanjiangosaurus"; meaning "Lancangjiang lizard", named after theLancangjiang River of China) is the informal name given to an as yet undescribedgenus ofsauropod dinosaur from theMiddle Jurassic. The "type species", "L. cachuensis", was coined by Zhou in 1983, but remains anomen nudum. It is known from theDapuka Group ofTibet.^[62]

"Lijiagousaurus" (meaning "Lijiagou lizard") is theinformal name given to an as yet undescribedgenus ofherbivorousiguanodontian dinosaur from theLate Cretaceous of what is nowSichuan, China. It has not been formally described yet, but the formal publication is forthcoming, from ChinesepaleontologistOuyang Hui. "Lijiagousaurus" was only briefly mentioned in theChongqing Natural History Museum guidebook (2001) and is thus anomen nudum.The holotype consists of hindlimb bones, a scapula, an ischium and other fragments.^{[141][142][143]}

"Likhoelesaurus" (meaning "Li Khole lizard") is the name given to an as yetundescribedgenus of archosauriform, either a dinosaur orrauisuchian, from theLate Triassic of what is now South Africa. The name was coined by Ellenberger in 1970, and the "type species" is "Likhoelesaurus ingens".^[144] It is named after the town in Lesotho where the fossils were found. The only fossils recovered have been teeth, from thelate Carnian–early Norian-ageLower Elliot Formation.^[145] Ellenberger (1972) regarded the genus as a giant carnosaur, and Kitching and Raath (1984) treated it as possibly referable toBasutodon.^[146][147] Knoll listed "Likhoelesaurus" as a rauisuchian, also he noted that could also be a rauisuchian.^[148]

"Lopasaurus" (meaning "Alberto Lopa's lizard") is the name given to an as yet undescribedgenus ofdromaeosauridtheropod, possibly belonging toUnenlagiinae due to its similarity toBuitreraptor,Neuquenraptor andPamparaptor, from theLate Cretaceous (Maastrichtian)-agedSerra da Galga Formation in the Ponto 1 do Price site of Brazil. The intendedholotype, a partial right metatarsus showing metatarsals II, III and IV, was discovered byAlberto Lopa during the 1950s but the fossil was lost shortly after the death ofLlewellyn Ivor Price in 1980 and it has not been located since. "Lopasaurus" was briefly mentioned by Brum et al. in their description ofYpupiara lopai, where it was tentatively referred toUnenlagiinae. Brum et al. (2021) also did not refer "Lopasaurus" toYpupiara, which was found in the same formation as "Lopasaurus".^[149]

"Magulodon" is the name given to an as yet undescribedgenus of dinosaur from theEarly Cretaceous (Aptian toAlbianstages, approximately 112 million years ago). It was a possibleornithischian, either anornithopod or basalceratopsian, which was discovered in theArundel Formation ofMaryland, United States. Thetype species, "Magulodon muirkirkensis", was coined by Kranz in 1996.^[150] It is a tooth taxon, based solely on a single tooth. Since it has not been formally described, it is also anomen nudum. It was considered to be an indeterminate specimen in a paper which cited the intended type specimen but avoided using the name to prevent taxonomic clutter.^[151]

"Maltaceratops" is the informal name given to an as yet undescribedgenus ofcentrosaurineceratopsian from theLate Cretaceous (Campanian-aged)Judith River Formation ofMontana. The proposed type species is "M. hammondorum",^[152][153] and the proposed holotype is a possible skull.^[154] It had been previously nicknamed the "Malta new taxon".^[155]

"Mangahouanga" (named afterthe stream of the same name), or the "Joan Wiffen's theropod" is an informal name given to thetheropod discovered in theTahora Formation, New Zealand byJoan Wiffen, who considered it to be a possiblemegalosaurid in 1975. The vertebra was described by Molnar 1981,^[156] and it was ruled as an indeterminate theropod in 2010 by Agnolin et al.^[157] The name "Mangahouanga" was coined by Molina-Pérez & Larramendi (2016) and no species name was given.^[158] They estimated it to reach up to 3.5 metres (11 ft) long and weigh up to 130 kilograms (290 lb) and is represented by of a single vertebra.

"Maojandino" is an informally named taxon of titanosaurid sauropod dinosaur from the Late CretaceousMaastrichtian stage of Pakistan. The intended type species is "Maojandino alami."

"Marisaurus" (meaning "Mari lizard", for the Mari tribe of Pakistan) is an informal taxon oftitanosauriansauropod from theLate Cretaceous ofBalochistan, western Pakistan. Thetype species is "M. jeffi", described by Muhammad Sadiq Malkani in 2004,^[159] and it isbased on tailvertebrae, found in theMaastrichtian-age Vitakri Member of thePab Formation. Much additional material, including a partial skull, many vertebrae, and a few hindlimb bones, was referred to this genus. "Marisaurus" was assigned to "Balochisauridae" with "Sulaimanisaurus", although the family was used as a synonym ofSaltasauridae.^[160] It was considered invalid by Wilson, Barrett and Carrano (2011).^[42]

"Maroccanoraptor" is an informal name suggested for a supposedunenlagiinetheropod from theKem Kem Formation of Morocco, however, it lacks the requirements to become a valid taxon, thus leaving it as a naked name. The intended type species is "M. elbegiensis", first described by Singer (2015) on the basis of a single coracoid.^[161] The fossil was later suggested to belong to a non-dinosauriancrocodyliform.^[162]

"Megacervixosaurus" (meaning "big neck lizard") is the informal name given to an as yet undescribedgenus ofherbivorous dinosaur from theLate CretaceousZonggo Formation ofTibet. It was a titanosaursauropod which lived in what is now China Thetype species, "Megacervixosaurus tibetensis", was coined by ChinesepaleontologistZhao Xijin in 1983. "Megacervixosaurus" has never been formally described, and remains anomen nudum.^[163]

"Megapleurocoelus" is an informally namedsauropod belonging toFlagellicaudata, from theKem Kem Formation of Morocco, however, it lacks the requirements to become a valid taxon, thus leaving it as a naked name. The intended type species is "M. menduckii", first described by Singer (2015) and the holotype is JP Cr376, a single centrum from a dorsal vertebra.^[161]

"Microcephale", also known as "Mycocephale", (meaning "tiny head") is theinformal name of agenus of very smallpachycephalosaurid dinosaur, otherwise known as the "North American dwarf species", which lived during theLate Cretaceous. Its fossils were found in thelate Campanian-ageDinosaur Park Formation, inAlberta, Canada. Not much is known about this dinosaur, as it has not yet been fully described; it is therefore anomen nudum. The fossils of "Microcephale", including tiny skull caps, were first mentioned bypaleontologistPaul Sereno in 1997, in a list of pachycephalosaurids.^[164] These skull caps measure less than 5 cm (2 in) each. No potential species name was given.

"Microdontosaurus" (meaning "tiny-toothed lizard") is the name given to an as yetundescribedgenus ofsauropod dinosaur from China. It was named from fossils from theMiddle Jurassic-ageDapuka Group ofXinjiang. The intendedtype species is "M. dayensis."^[62] As with other informal names created by Zhao in 1985 or 1983, it has not been used since then, and may have been redescribed under another name.^[165]

"Microvenator chagyabi" is the informal name given to an as yetundescribedspecies oftheropod dinosaur, likely belonging toCoelurosauria, from theEarly CretaceousLura Formation ofTibet, China. It was coined by Zhao (1985)^[166] and the proposed holotype consists of a specimen including teeth.^[167]

"Mifunesaurus" (meaning 'Mifune lizard') is anomen nudum given to anextinctnon-avian non-maniraptoriformtetanurantheropod dinosaur from theLate Cretaceous (Cenomanian; ~96 Ma)Kabu Formation of Japan.^[168] The intendedholotype, stored at theMifune Dinosaur Museum, with the tooth on display, of "Mifunesaurus" consists only of a few bones, among which are atibia, aphalanx, ametatarsus and a single tooth (tooth catalogued as YNUGI 10003; rest of the skeleton catalogued as MDM 341), discovered by N. & K. Wasada in 1979.^[169] The genus was informally coined by Hisa in 1985 and no epithet was given.^[170] The known tooth was too thick to be the tooth of aceratosaurid, and too tall to belong to anabelisaurid, which means that "Mifunesaurus" was probably amegalosauroid or acarnosaur based on the shape of the known tooth.

The "Mitchell ornithopod" is the informal nickname of anornithopod dinosaur discovered nearMitchell, Oregon, being the first described dinosaur fromOregon but not the first discovered; ahadrosaurid sacrum was discovered in theLate Cretaceous (Campanian)-agedCape Sebastian Sandstone nearCape Sebastian during the 1960s and excavated in 1994 by Dave Taylor, but the remains of the Cape Sebastian ornithopod were not prepared for peer review and described until 2019, merely weeks after the Mitchell ornithopod was described.^{[171][172][173]} The single known bone, F118B00, was a toe bone, specifically the thirdphalanx of the central digit of the right hindlimb foot, and was discovered by Gregory Retallack in 2015 while on an annual field trip with his students, in a layer of theAlbian-agedHudspeth Shale Formation;^[174] in 2021, Gloria Carr discovered another bone, this time a vertebra, that likely belonged to the same species ofornithopod.^[175] No excavation was required – the bone was found resting on the ground and Retallack immediately knew it was different from the various marine fossils scattered nearby.^[171] The bone was described in 2018 by Gregory Retallack, Jessica Theodor, Edward Davis, Samantha Hopkins and Paul Barrett.^[174] It was part of a bloated carcass swept out into the ocean, likely originating fromIdaho, although further discoveries, such as Strommer (2021), dispute this claim and suggest it may have been deposited by amudflow.^[175]

The bone was later compared to more complete remains of other ornithopods and the "Mitchell ornithopod" bone most closely matched those ofhadrosaurs andiguanodonts, although it was likely abasal ornithopod.^[174] Rettalack believes that the bone belonged to a new genus, although there is not enough sufficient remains to base this claim on.^[171]

Hisa (1985) used "Moshisaurus" (or "Moshi-ryu") for the incomplete sauropod humerus NSM PV17656, from the Early CretaceousMiyako Group of Japan. Dong et al. (1990) and Hasegawa et al. (1991) referred them toMamenchisaurus, but Azuma & Tomida (1998) and Barrett et al. (2002) assigned them to Sauropoda indet.^{[176][177][178]}

"Newtonsaurus" is an informally named genus erected for thetheropod dinosaur speciesZanclodon cambrensis. The species is based on the specimen BMNH R2912, anexternal mold of a dentary, which was discovered in theLate Triassic (Rhaetian) aged beds of theLilstock Formation nearBridgend, Wales in 1898 and described byEdwin Tulley Newton in 1899.^[179] The taxon was reassigned to ?Megalosaurus by Molnar in 1990, which was followed byPeter Galton in publications in 1998 and 2005. The species is considered to be anomen dubium, as it has no diagnostic features, and is considered to be acoelophysoid grade theropod outsideAverostra based on the lowinterdental plates and possession of only a singlemeckelian foramen.^[180] It has alternatively been suggested to possibly represent another indeterminate predatory archosaur.^[181]

The name "Newtonsaurus" was coined in 1999 by Stephan Pickering, in reference the describer. Paleontologists have avoided using the name "Newtonsaurus" since its appearance in 1999 in private publications, although "Zanclodon"cambrensis orMegalosaurus cambrensis have both been used for this taxon.^[182][183]

"Ngexisaurus" is the informal name given to an as yetundescribedgenus oftheropod dinosaur, likely belonging toAvetheropoda, from theMiddle JurassicDapuka Group ofTibet, China. Thetype species, "Ngexisaurus dapukaensis", was coined by Zhao in 1983.^{[184][166][185]} A synonym of "Ngexisaurus" coined by Zhao (1985) is "Megalosaurus" dapukaensis^[166] andFossilworks lists "M." dapukaensis as amegalosauridtetanuran separate from "Ngexisaurus" proper.^[186]

"Nicksaurus" is an informally named Titanosaurian sauropod dinosaur from theLate Cretaceous red muds of theVitakri Formation of theSulaiman Basin, Pakistan. The dinosaur shared a habitat with other sauropod dinosaurs includingKhetranisaurus,Sulaimanisaurus,Pakisaurus,Gspsaurus,Saraikimasoom, andMaojandino.^[187]

The intended type species is "Nicksaurus razashahi" and was first used by Malkani (2019).^[187]

"Nurosaurus" (Nur-o-saw-rus, meaning "Nur lizard") is theinformal name for agenus ofsauropod dinosaur. It is known from a partial, large skeleton, that was presented as soon-to-be-described byZhiming Dong in1992, where he gave the proposed binomial "Nurosaurus qaganensis". It was discovered in theQagannur Formation ofInner Mongolia, 65 km (40 mi) southeast ofErenhot. The deposit is younger than thePsittacosaurus-bearingGuyang Group, but is stillEarly Cretaceous. It was found alongside the plates and scapula of a stegosaur.^[188]

The foot of "Nurosaurus" is notable for a stress fracture present on the firstphalanx of the fourth digit of the left foot, which was the first identified fracture of its kind, and have since been identified on the phalanges and metatarsals ofApatosaurus,Barosaurus,Brachiosaurus,Camarasaurus, andDiplodocus.^[189]

"Oharasisaurus" is the name given to an as yet undescribedgenus ofsomphospondyliansauropod, possibly belonging to theEuhelopodidae, from theEarly CretaceousKuwajima Formation (Facies III layer) of Japan. The name "Oharasisaurus" was coined by Larramendi & Molina Pérez (2020)^[40] and the holotype, a tooth, was first mentioned by Matsuoka (2000).^[190]

"Orcomimus" (Pronounced or-coh-mEYEm-us) is the name given to an as yet undescribedgenus of dinosaur from the LateCretaceous period 66 million years ago. The dinosaur was anornithomimid which lived in what is nowSouth Dakota, in the United States. Thetype was coined by Michael Triebold in 1997, but has never been formally described and is currently anomen nudum. "Orcomimus" was abipedaltheropod, but the dinosaur is known from only apelvis and a hindlimb. "Orcomimus" is thought to be relatively advanced for other ornithomimids at the time, although this is hard to tell from the limited amount of specimens found of the dinosaur.^[191] It may be referable to one of the ornithomimosaur species currently known from theHell Creek Formation, where theholotype of "Orcomimus" was found.

"Oshanosaurus" (meaning "Oshan lizard") is the informal name given to an as yet undescribedgenus ofsauropod dinosaur from theEarly Jurassic period ofYunnan, China. Its fossils were found in theLower Lufeng Series. The intended "type species", "Oshanosaurus youngi", was coined by Zhao in 1985.^[62] It has sometimes been associated withheterodontosaurids, which appears to be due to the juxtaposition of a species ofDianchungosaurus (formerly thought to be a heterodontosaurid) in the text of Zhao (1985).^[192]

In 1971Zhao Xijin discovered a dinosaur fossil atDianchung inEshan county, giving it the informal name "Oshanosaurus youngi".^[62] In their 2019 popular bookDinosaur Facts and Figures: The Theropods, Molina-Perez and Larramendi suggested that it belonged to thetheropodEshanosaurus, but without elaboration.

"Osteoporosia" is an informally namedtheropod, either belonging toCarcharodontosauridae orMegaraptora, from theKem Kem Formation of Morocco, however, it lacks the requirements to become a valid taxon, thus leaving it as a naked name. The intended type species is "O. gigantea", first described by Singer (2015) and the holotype is JP Cr340, a tooth, with an indeterminate posterior or dorsal neural arch also known.^[161]

A 2019 theropod faunal list found "Osteoporosia" to be a possible synonym ofSauroniops pachytholus.^[193]

"Otogosaurus" is an informally named sauropod from Inner Mongolia, China. The supposed type species is "Otogosaurus sarulai". It is known from partial postcranial remains, including a tibia 2.2 meters (7.2 ft) long and several footprints.^[194] It is named afterOtog Banner in Inner Mongolia where it was discovered, and Sarula, the girl who discovered the fossils. Despite sometimes being presented as a valid taxon, sometimes accompanied by citations to Zhao (2004) or Zhao & Tan (2004),^[40] scholars have not been able to locate such a source,^[194][195] so it remains informal until a paper is discovered.

"Pakisaurus" (meaning "Pakistan lizard") is an informal taxon oftitanosauriansauropod from theLate Cretaceous ofBalochistan, western Pakistan, and alsoGujarat, India. The proposed species is "P. balochistani", and it was named by M. Sadiq Malkani in 2006, based on isolated tail vertebrae found in theMaastrichtian-age Vitakri Member of thePab Formation. In 2023, a femur discovered in theLameta Formation of India was assigned to "Pakisaurus".

It was considered invalid by Wilson, Barrett and Carrano (2011) during their description of aJainosaurus cf. septentrionalis skeleton.^[42]

"Anokhadino mirliaquati" was synonymised with "Pakisaurus balochistani" by Malkani (2019).^[196]

The "Paw Paw scuteling" is the name used for a juvenilenodosaurid discovered in 1990 from thePaw Paw Formation of northernFort Worth, Texas. It was discovered by John C. Maurice, the 12-year-old son of fossil collector John M. Maurice. The specimen consists of a partial skeleton including a third of the backbone, part of the skull, and both leg and arm elements.^{[197][198][199]} It is one of two or three nodosaurs known from the formation alongsidePawpawsaurus andTexasetes, and one of the very few known specimens of a baby nodosaur. Some phylogenetic analyses have recovered it as sister toNiobrarasaurus.^[200] Although taxonomically indeterminate due to its life stage and fragmentary nature,^[201] it is often used in phylogenetic analyses for determining the taxonomic affinity of other nodosaur genera.^{[202][203][204]}

"Podischion" is an informal genus ofhadrosaurid dinosaur known from a skeleton discovered in 1911 on theRed Deer River in Alberta by a crew led byBarnum Brown. The remains were tentatively named "Podischion", which was not mentioned in published literature until Dingus & Norell (2010).^[205][124] It is possible that the skeleton represents an individual ofHypacrosaurus.^[124]

"Qaikshaheen" is an informal genus of titanosaurian dinosaurs from the Late Cretaceous (Maastrichtian)Vitakri Formation of Pakistan described by Malkani (2023) inScientific Research Publishing, a knownpredatory publisher. The proposed holotype specimen includes fragmentary cervical and dorsal vertebrae, partial pectoral and pelvic girdles, humeri, femora, a tibia, and fibulae. Other bones, including several vertebrae, ribs, a humerus, ulnae, metacarpals, metatarsals, a femur, and a partial pelvic girdle, were also referred. The intended type species is "Qaikshaheen masoomniazi."^[121]

"Ronaldoraptor", also known as the "Mitrata" Oviraptorid, is an undescribedoviraptorid from Mongolia^[206] and has been listed as "Oviraptor sp."^[207] The name was first used byLuis Rey in 2003, in his bookA Field Guide to Dinosaurs: The Essential Handbook for Travelers in the Mesozoic, where he drew anillustration, captioning it "Ronaldoraptor".^[206] "Ronaldoraptor" may have been closely related toCitipati osmolskae.

"Rutellum" is the pre-Linnaean name given to a dinosaur specimen from theLate Jurassic (Oxfordian)-agedCoralline Oolite Formation. It was asauropod, possibly acetiosaurid,^[209] which lived in what is now England. The specimen (OU 1352), called "Rutellum impicatum", was described in 1699 byEdward Lhuyd alongside specimen OU 1358, what is now believed to be aMegalosaurus tooth crown,^[208] and is notable as the earliest named entity that is recognizable as a dinosaur.^[209] It was based on atooth collected from Caswell, nearWitney, Oxfordshire.^[210]

Because "Rutellum impicatum" was named before 1758 (the official starting date for zoological nomenclature according to theICZN), it is not considered a part of modern biological nomenclature.

"Sabinosaurus" or "Sabinosaurio" is a name used for PASAC-1,^[211] a partial skeleton of ahadrosaur that was discovered in the Sabinas Basin in Mexico in 2001. It was initially described asKritosaurus sp. by Jim Kirkland and colleagues (2006),^[212] but considered an indeterminatesaurolophine by Prieto-Márquez (2014).^[213] This skeleton is about 20% larger than other known specimens, around 11 m (36 ft) long, and with a distinctively curvedischium, and represents the largest known well-documented North American saurolophine. Unfortunately, the nasal bones are also incomplete in the skull remains from this material.^[212]

"Saldamosaurus" is an informalgenus ofstegosaurid dinosaur known from a complete braincase discovered in the Early CretaceousSaldam Formation ofSiberia, Russia. The type species, "Saldamosaurus tuvensis", was named in 2014^[13] but according to Galton and Carpenter (2016) it did not meet the requirements of theInternational Code of Zoological Nomenclature and is hence anomen nudum.^[214]

"Saltillomimus" is an informal name for anornithomimid theropod from the Late Cretaceous (lateCampanian) of theCerro del Pueblo Formation in Mexico. It is known from SEPCP 16/237, a partial tail, most of a hindlimb, and forelimb bones, discovered in 1998, and the possible juvenile specimen SEPCP 16/221, a partial leg and hip bone, that was given the name "Saltillomimus rapidus" by Martha Carolina Aguillón Martinez in2010.^[215] 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. Named in Martinez' 2010 thesis, the taxon name is an invalidnomen ex dissertatione.^[107]

"Sanchusaurus" (meaning "Lizard from Sanchu") or "Sanchu-ryu"^[216] is aninformal name for possibleornithomimosaur dinosaur from theEarly Cretaceousperiod of Asia. It is only known by a partialtailvertebra,^[94] found in Nakasato, Japan.^[217] Dong (1990)^[94] considered it synonymous withGallimimus but the large discrepancy in both age and location between the two species renders this opinion untenable. The genus has not been formally described and is considered anomen nudum. It was first mentioned by Hisa in 1985.^[218] In 2006, it is shown that this animal is not fully grown, and characters of tail vertebra is not unique to that of ornithomimosaur.^[216]

"Saraikimasoom" (meaning 'Innocent one') is an invalid species oftitanosaur dinosaur from theVitakri Formation in Pakistan. The type species,Saraikimasoom vitakri, was described by Sadiq Malkhani in 2015, in a paper describing multiple Pakistani dinosaurs, such asGspsaurus, "Nicksaurus" and "Maojandino".^[219]Saraikimasoom is currently recognised as anomen manuscriptum.

"Saraikisaurus" (meaning "Saraiki lizard") is an invalid genus name proposed for a putative reptile found in theLate Cretaceous (Maastrichtian)-agedVitakri Formation ofPakistan and possibly also theLameta Formation of India. The intended type species is "Saraikisaurus minhui", known from the proposed holotype—a fragmentary dentary (GSP/MSM-157-16)—and a referred specimen—an incomplete vertebra (GSP/MSM-64-15). Malkani initially interpreted the dentary as belonging to a basalpterodactyloid and created the furthermonotypic family "Saraikisauridae" and subfamily "Saraikisaurinae" to house it. The name "Saraikisaurus" was first proposed by M. Sadiq Malkani in a 2013 conference.^[220] A later endeavor to describe it in 2015 was notpeer-reviewed.^[221] In 2021, Malkani attempted to formally describe "Saraikisaurus" and other taxa inScientific Research Publishing, a knownpredatory publisher.^[222] In 2024, he reinterpreted the specimen as instead belonging to anoasaurid theropod, redescribing it as a novel taxon in another unreviewed paper onResearchGate. He assigned the fragmentary vertebra to this genus on the basis of compatible size and preservation styles, and apparent similarities to the corresponding bones inLaevisuchus.^[223]

The "Shake-N-Bake theropod" is an undescribed species of coelophysoid from theKayenta Formation, known from partial skeleton MCZ 8817 within the collection ofHarvard Museum of Natural History.^[224][225]

"Shansaraiki" (meaning "respected Saraiki peoples") is an informal genus oftheropod that was probably anabelisaur. The holotype was found in the Shalghara locality of theLate CretaceousVitakri Formation of Pakistan and consists of GSP/ MSM-140-3 (symphysis), GSP/MSM-5-3 (mid-ramus with partial teeth bases) and GSP/MSM-57-3 (dorsal vertebrae), although they may belong to separate specimens as they were found apart from each other. The intended type species is "Shansaraiki insafi" and was first mentioned by Malkani (2022).^[132]

"Siamodracon" is an extinctgenus ofinvalidstegosaurid dinosaur known from a singledorsal vertebra found in Thailand'sPhu Kradung Formation. The type species, "Siamodracon altispinax", was named by Ulansky in 2014.^[13] According to Galton and Carpenter (2016) it did not meet the requirements of theInternational Code of Zoological Nomenclature.^[13][214] "Siamodracon" was the firstthyreophoran dinosaur discovered inSouth East Asia.

"Sidormimus" is an informal genus ofnoasaurid discovered in theElrhaz Formation in Niger. It was discovered in 2000 by Chris Sidor and it was immediately named as "Sidormimus" by Lyon on the Project Exploration website, with a photograph of the intended holotype.^[226] During the same year, on theNational Geographic website, the same photograph of the specimen was labelled "Dogosaurus", and it was noted that the neck and ribs were exposed when the specimen was discovered.^[227] It has also been referred to as the "Gadoufaoua noasaurid" or the "unnamed Niger noasaurid",^[228][229] and Sidor himself confirmed via personal communication in 2005 that "Sidormimus" was the Elrhaz noasaurid.^[230] In a 2010 conference abstract, this articulated specimen was suggested to have possiblefossorial (digging) adaptations, which led paleontologists including Paul Sereno to refer the specimen to as the "digging raptor".^{[231][232][233]}

"Sinopeltosaurus" is adubiousgenus ofextinctthyreophoranornithischian dinosaur described by Roman Ulansky. Thetype and only species is "S. minimus" of the lowerJurassicLufeng Formation ofYunnan China, based on an articulated set of ankle bones.^[13] The specimen is FMNH CUP 2338, and includes the distal tibia and fibula, distal tarsals, most metatarsals, and some phalanges. 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.^[234] In 2016,Peter Malcolm Galton andKenneth Carpenter identified it as anomen dubium, and listed it as Ornithischia indet., possible Thyreophora indet. Ulansky variously referred to it as "Sinopeltosaurus minimus" or "Sinopelta minima"; Galton and Carpenter, as the first revisers underICZN, made the former official.^[14]

"Skaladromeus" or the "Kaiparowits ornithopod" is anornithopod from theKaiparowits Formation named in a 2012 thesis by Clint Boyd. The intended type species is "Skaladromeus goldenii".^[235][236]

"Sousatitan" is the name given to an as yetundescribedgenus oftitanosauriansauropod dinosaur from theEarly Cretaceous-agedRio Piranhas Formation of Brazil. The intended holotype consists of a left fibula, and "Sousatitan" was coined by Ghilardi et al. (2016).^[237]

"Stegotitanus" is the informal replacement genus name given to thestegosaurStegosaurus ungulatus—resulting in thenew combination "Stegotitanus"ungulatus—byGregory S. Paul in the third edition ofThe Princeton Field Guide to Dinosaurs in 2024.Stegosaurus ungulatus fossils are known from the Late Jurassic (Kimmeridgian) upperMorrison Formation of Wyoming, US. "Stegotitanus" was one of the largest stegosaurs, at about 7 metres (23 ft) long and 4.2 metric tons (4.1 long tons; 4.6 short tons) in weight.^[123]

A fossiltheropod (possibly atyrannosaur) nicknamed "Suciasaurus rex" was discovered in 2012 atSucia Island State Park inSan Juan County of the U.S.State of Washington. It was the first dinosaur discovered inWashington state. The finding was announced whenBurke Museumpaleontologists published a discovery paper inPLoS ONE.^[238][239] Prompted by a petition from students at an elementary school atParkland, near Tacoma, theWashington State Legislature introduced a bill in 2019 to make it the official state dinosaur.^{[240][241][242]} A renewed push came in 2021, though House Republicans, like Minority leaderJ. T. Wilcox, called it low priority versus the ongoingCOVID-19 pandemic, and eventually the bill failed to pass,^[243][244] though in 2023 it passed.^[245]

"Sugiyamasaurus" (meaning "Sugiyama lizard") is the informal name given to a fewspatulate teeth belonging to atitanosauriform, possiblyFukuititan, which lived in Japan during theEarly Cretaceous. The name was first printed byDavid Lambert in 1990 in theDinosaur Data Book, and also appears in Lambert'sUltimate Dinosaur Book and in many on-line lists of dinosaurs. Since it has not been formally described, "Sugiyamasaurus" is anomen nudum. Remains were found nearKatsuyama City and were initially referred toCamarasauridae, but might belong toFukutitan because they were unearthed in the same quarry as theFukuititan material.^{[246][247][248]}

"Sulaimanisaurus" (meaning "Sulaiman lizard", for the Sulaiman foldbelt) is an informal taxon oftitanosauriansauropod from theLate Cretaceous ofBalochistan, western Pakistan (also spelled "Sulaimansaurus" in some early reports).^[133] The proposed species is "S. gingerichi", described by M. Sadiq Malkani in 2006, and it isbased on seven tailvertebra, found in theMaastrichtian-age Vitakri Member of thePab Formation. Four additional tail vertebrae have been assigned to it. It was considered to be related to "Pakisaurus" and "Khetranisaurus" in the family "Pakisauridae" (used as a synonym ofTitanosauridae). It was considered invalid by Wilson, Barrett and Carrano (2011).^[42]

"Teihivenator" ("strong hunter") is an improperly named taxon oftyrannosauroidcoelurosaur from theNavesink Formation ofNew Jersey. It was suggested to contain the species, "T."macropus, originally classified as a species ofDryptosaurus (= "Laelaps", a name preoccupied bya mite). It was suggested as a separate genus in 2017 by Chan-gyu Yun.^[249] The name "Teihivenator" is invalid because the publication naming it is online-only, which means that a registration withZooBank is required to be present in the article when published. However, the ZooBank registry was only added in after initial publication, meaning that it fails the requirement to be a validly published taxon.^[250]

In 2017, a preprint paper by Chase Brownstein concluded that the remains ofL. macropus are a mixture of tyrannosauroid andornithomimid elements with no distinguishing characteristics, rendering the species a chimera and anomen dubium.^[251] In 2018, Brownstein stated that a tibia ofL. macropus catalogued as specimen AMNH FARB 2550 represents a tyrannosauroid that probably was distinct fromDryptosaurus, but not sufficiently to base a taxon on.^[252]

"That Which Cannot Be Named" is the name given byDarren Naish to an undescribed associated skeleton of a small coelurosaur from the Wessex Formation of the Isle of Wight. The specimen is in private ownership and is currently inaccessible to researchers.^[253] It has been suggested that the specimen is possibly a tyrannosauroid.^[254][255]

"Tiantaisaurus", alternatively spelled "Tiantaiosaurus", is the name given to a specimen oftherizinosaur from theAptian ageLaijia Formation ofZhejiang, China. According to correspondence through the Dinosaur Mailing List, the former name (from a 2012 study) was the one intended to be use for an official description. After being discovered in 2005, it was first mentioned named in an unpublished manuscript written in 2007. The given species was named "T. sifengensis". The specimen consists of anischium, anastragalus, atibia, afemur, an incompletepubis andilium, and a large number ofvertebrae from across the body.^[256][257]

"Tobasaurus" (meaning "Toba City lizard") is the informal name given to an as yet undescribedgenus of sauropod dinosaur from theEuhelopodidae from theEarly Cretaceous (Hauterivian –Barremian-aged)Matsuo Group of Japan. The proposed holotype is a partial skeleton (mostly limb bones),^[258] and "Tobasaurus" grew up to 20 metres (66 ft) when fully grown.^[40] It is the inspiration for the Vivosaur "Toba" in the video gameFossil Fighters.

"Tonouchisaurus" (meaning "Tonouchi lizard") is theinformal name given to an as yet undescribedgenus of coelurosaurian dinosaur from the EarlyCretaceousPeriod of Mongolia. The suggested "type species", "Tonouchisaurus mongoliensis", was first informally mentioned in a Japanese news article. It was notably small: less than 0.91 m (3 ft) in length. The specimen informally dubbed "Tonouchisaurus mongoliensis" is based on limb material, and the manual and pedal remains were initially reported to incorporate a complete didactylmanus and completepes, and Rinchen Barsbold therefore initially interpreted "Tonouchisaurus" as a tyrannosauroid, but he later noted that the manus is actually tridactyl and that the pes has a sub-arcometatarsalian condition.^[259]

"Ubirajara" (meaning "Lord of the Spear") is an informal genus ofcompsognathid theropod known from the Early CretaceousCrato Formation of Brazil; it was discovered in 1995 and was named in 2020 in an "In Press" article that was later withdrawn due to the specimen having been illegally smuggled from Brazil to Germany.^[260] It is considered anomen manuscriptum.^[261]

"Utetitan" is the informal name given to specimens of the titanosaurAlamosaurus from the Late Cretaceous (Maastrichtian) lowerNorth Horn Formation of Utah US, byGregory S. Paul in the third edition ofThe Princeton Field Guide to Dinosaurs in 2024. Other titanosaurian bones from the upperBlack Peaks Formation or Texas, US, may also be referrable to this taxon. "Utetitan" was reportedly about 20 metres (66 ft) long and 20 metric tons (20 long tons; 22 short tons) in weight. The intended type species is "Utetitan zellaguymondeweyae."^[123]

In 1982 Justin Delair informally named the genus "Vectensia" based on specimen GH 981.45, an armour plate. Like the holotype ofPolacanthus it was found at Barnes High, but reportedly in an older layer, of theLower Wessex Formation.^[262] Blows in 1987 tentatively referred it toPolacanthus.^[263]

"Vitakridrinda" is agenus ofabelisauridtheropod dinosaur from theLate Cretaceous ofBalochistan, western Pakistan. The intendedtype species is "V. sulaimani". The discovery was made (along with other dinosaur specimens) near Vitariki by a team of palaeontologists from the Geological Survey of Pakistan, in rocks from theMaastrichtian-age Vitakri Member of thePab Formation.^[264] Informally named in an abstract by M.S. Malkani in 2004 (to which Malkani [2006] attributes the name), it isbased on partial remains including twothigh bones, and a tooth. A partial snout and braincase were originally referred to the holotype, and additionalvertebrae may also belong to this genus. However, the snout was later reclassified as a new genus of mesoeucrocodylian,Induszalim, while the braincase was later referred toGspsaurus.^{[265][264][266][267]}Thomas Holtz gave a possible length of 6 meters (19.7 feet).^[268]

"Vitakrisaurus" is agenus ofnoasauridtheropod dinosaurs represented by only one knownspecies, "Vitakrisaurus saraiki", which is the intended type species. It lived in the lateCretaceous period, approximately 70 million years ago, during theMaastrichtian, in what is today theIndian subcontinent. Itsfossils were found in Pakistan'sVitakri Formation. The holotype specimen, MSM-303-2 is a right foot with a seemingly tridactyl form and robust phalanges. It may belong toNoasauridae due to similarities with the foot ofVelocisaurus, although inconsistencies within its brief description and a lack of comparison with othertheropods within the article makes formal classification difficult. The generic name references the Vitakri Member of thePab Formation and combines this with the Greek suffix "saurus", meaning "reptile". The specific name honours theSaraiki people, who primarily live in southern Pakistan. However, like most dinosaur taxa named by M. Sadiq Malkani, it is probably anomen nudum. Some authors consider "Vitakrisaurus" to be the same animal as "Vitakridrinda".^[269]

Bones of the White Rock spinosaurid

"White Rock spinosaurid" is the nickname of a giantspinosaur from theVectis Formation of theIsle of Wight described in 2022.^[270] Its remains are so fragmentary that the describers refrained from naming it, but considered the name "Vectispinus". With vertebrae comparable in dimensions toSpinosaurus, it was likely among the largest theropods with a length exceeding 10 metres (33 ft).^[271]

"Xinghesaurus" was the name given to a species ofsauropod dinosaur, possibly a titanosauriform, in 2009, in the guidebook for the dinosaur expo "Miracle of Deserts", written by Hasegawa et al.^[272] No species name was given for the genus.^[273][274] Based on the skeletal mount, "Xinghesaurus" was likely around 15.4 metres (51 ft) long and weighed around 6 tonnes (13,000 lb).^[275]

"Yibinosaurus" (meaning "Yibin lizard") is theinformal name given to an as yet undescribedgenus ofherbivorous dinosaur from theEarly Jurassic. It was asauropod which lived in what is nowSichuan, China. The suggested "type species", "Yibinosaurus zhoui", is briefly mentioned in theChongqing Natural History Museum guidebook (2001) as under description by Chinese paleontologistOuyang Hui. It was coined as anomen ex dissertationae by Ouyang (2003), and is based on a specimen referred toGongxianosaurus sp. nov. by Luo and Wang (1999).^{[141][142][276][277]}

"Yunxianosaurus" is the provisional name for a genus oftitanosaurian dinosaurs from theLate Cretaceous of what is nowHubei, China. Thetype species, "Yunxianosaurus hubeinensis", was proposed by Chinesepaleontologist Li Zhengqi in 2001. Thefossils of "Yunxianosaurus" were found near theNanyang Prefecture. Li stated that the name "Yunxianosaurus" was a temporary label for ease of description, but that further field work and study of the fossils would be required before the genus could be given an official name.^[278][279]

Zamyn Khondt oviraptorid is a nickname for oviraptorid specimen IGM or GIN 100/42. Since the type skull ofOviraptor is so poorly preserved and crushed, the skull of IGM 100/42 has become the quintessential depiction of that dinosaur, even appearing in scientific papers with the labelOviraptor philoceratops.^[280] However, this distinctive-looking, tall-crested species has more features of the skull in common withCitipati than it does withOviraptor and it may represent a second species ofCitipati or possibly an entirely new genus, pending further study.^[281]

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