This list of informally named dinosaurs is a listing of dinosaurs (excluding birds) that have never been given formally published scientific names. This list only includes names that were not properly published ("unavailable names") and have not since been published under a valid name (see list 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 the International 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. A nomen manuscriptum is equivalent to a nomen 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. Names published in predatory journals.
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Alamotyrannus
"Alamotyrannus" ("Ojo Alamo tyrant") is the informal placeholder name given to an as yet undescribed genus or species of tyrannosaurid from the Late Cretaceous period of North America. The fossils of this animal originate from the Ojo Alamo Formation in New 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.Dalman, S.G. and S.G. Lucas. (2013). A new large Tyrannosaurid Alamotyrannus brinkmani, n. gen., n. sp. (Theropoda: Tyrannosauridae), from the Upper Cretaceous Ojo Alamo Formation (Naashoibito Member), San Juan Basin, New Mexico. New Mexico Museum of Natural History and Science Bulletin "Alamotyrannus" lived during the early Maastrichtian.
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) and McDavid (2022). 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. Photograph taken by McDavid (2022) shows the specimen on display in the Beneski Museum of Natural History.
Alan the Dinosaur
"Alan the Dinosaur" is the name given to a sauropod caudal vertebra (YORYM:2001.9337) found in 1995 in the Saltwick 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 to Cetiosaurus.
The fossil of "Alan" is housed in the Yorkshire Museum, where it forms part of the Yorkshire's Jurassic World exhibit, featuring a VR recreation.
Allosaurus robustus
"Allosaurus robustus" is an informal name used for specimen "NMV P150070", a theropod astragalus known from the Wonthaggi Formation (Early Cretaceous) of Victoria, Australia. When first studied, it was thought to have belonged to a species of Allosaurus. 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 of Allosaurus, but could still represent an allosauroid.Glut, F. (2003). Dinosaurs – The Encyclopedia – Supplement 3. At the same time, Yoichi Azuma and Phil Currie noted that the astragalus resembled that of their new genus Fukuiraptor. It may well represent a theropod related to Australovenator, though some argue that it could represent an abelisauroid. A 2019 study strongly supported a megaraptoran (the group which contains both Fukuivenator and Australovenator) affinity for the astragalus.
The name "Allosaurus robustus", first confined as a museum label, was first published by Chure in 2000.Chure, Daniel. (2000). A new species of Allosaurus from the Morrison Formation of Dinosaur National Monument (UT-CO) and a revision of the theropod family Allosauridae.
Amargastegos
"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. brevicollum". In 2016, Peter Malcolm Galton and Kenneth Carpenter declared it a nomen nudum, establishing it as an indeterminate stegosaur.
Amphicoelias brontodiplodocus/Barackosaurus
"Barackosaurus" is the informal name created in 2010 which is used for a sauropod found in Kimmeridgian-aged sediments pertaining to the Morrison Formation, Wyoming. It was found in the Dana Quarry and "Barackosaurus" was supposedly 20 meters long and weighed 20 tons. 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 genus Amphicoelias, 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". As of 2015, they are now on display at the Lee Kong Chian Natural History Museum in Singapore.
Andhrasaurus "Andhrasaurus" is an informal genus of extinct armored ornithischian dinosaur from the Kota Formation of India. The proposed species is "A. indicus". 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. (2002).Nath, T. T., Yadagiri, P., and Moitra, A. K., 2002, First record of armoured dinosaur from the Lower Jurassic Kota Formation, Pranhita-Godavari Valley, Andhra Pradesh: Journal of the Geological Society of India, v. 59, p. 575-577. In 2016, Peter Malcolm Galton and Kenneth Carpenter noted that "Andhrasaurus" did not meet ICZN requirements and therefore declared it a nomen nudum, listing it as Thyreophora indet., while noting that the jawbones described by Nath et al. (2002) belonging to crocodylomorphs.Galton, Peter M. & Carpenter, Kenneth, 2016, "The plated dinosaur Stegosaurus longispinus Gilmore, 1914 (Dinosauria: Ornithischia; Upper Jurassic, western U.S.), type species of Alcovasaurus n. gen.", Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen 279(2): 185–208 The dermal armor informally named "Andhrasaurus" was redescribed by Galton (2019), referring the material to Ankylosauria.
Angeac ornithomimosaur The "Angeac ornithomimosaur" is an informal name given to an unnamed theropod taxon known from the Early Cretaceous (Berriasian ageRonan Allain, Romain Vullo, Lee Rozada, Jérémy Anquetin, Renaud Bourgeais, et al. Vertebrate paleobiodiversity of the Early Cretaceous (Berriasian) Angeac-Charente Lagerstätte (southwestern France): implications for continental faunal turnover at the J/K boundary. Geodiversitas, Museum National d'Histoire Naturelle Paris, In press. ffhal-03264773f) Angeac-Charente bonebed (part of the stratigraphy of the Aquitaine Basin) near Angeac-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. Some remains were described by Allain et al. (2014). While it was originally regarded as an ornithomimosaur, Cau and Paterna (2025) suggested ceratosaurian affinities instead, closely allied with Bahariasaurus, Berthasaura, Ligabueino, and Limusaurus.
Angloposeidon
"Angloposeidon" is the informal name given to a sauropod dinosaur from the Early Cretaceous (Barremian) Wessex Formation of the Isle of Wight in southern England. It was a possible brachiosaurid 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. However, he published it himself in his book Tetrapod Zoology Book One from 2010. The remains consist of a single cervical vertebra (MIWG.7306), which indicate it was a very large animal, 20 metres or greater in length.
Angustungui "Angustungui" is an informal genus of stegosaur from the Late Jurassic Qigu Formation in China. The intended type species is "A. qiketaiensis" and the holotype is specimen SS V16001 consisting of axial, pectoral girdle, pelvic girdle, limb and armor elements, while the paratype is specimen SS V16002, consisting of a right coracoid and a right scapula. Both specimens were discovered in 2016 by Li Daqing at Qiketai, Shanshan County, and the name was first announced in a bioRxiv pre-print article in October 2024, where it was recovered as sister taxon of Loricatosaurus.
Archaeoraptor
"Archaeoraptor" is the informal generic name for a fossil from China, initially hailed as an important transitional fossil, that was later discovered to have been fabricated from multiple unrelated fossils. The name was created in an article published in National Geographic magazine in 1999, where the magazine claimed that the fossil was a "missing link" between birds and terrestrial theropod 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. (2002) found that the head and upper body actually belong to a specimen of the primitive fossil bird Yanornis, while the tail is part of the holotype of Microraptor zhaoianus, a small winged dromaeosaur named in 2000. The legs and feet belong to an as yet unknown animal.
Archbishop
"The Archbishop" is a giant brachiosaurid sauropod dinosaur similar to Brachiosaurus and Giraffatitan. It was long considered a specimen of Brachiosaurus (now Giraffatitan) brancai due to being found in the same formation in Tendaguru, 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. 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 of Bristol University. In May 2018, Taylor started to work on describing the Archbishop.
Atlantohadros