Dinosauria

Dinosaur Park Formation in Dinosaur Provincial Park, Alberta

The distictive banding of the Morrison Formation, a group of rock layers that occur throughout Dinosaur National Monument. The formation originated as muds and sands laid down by ancient rivers, and some of its outcrops have been found to contain 150-million-year-old dinosaur fossils like those found at the monument's Dinosaur Quarry.

Wide angle photo from the visitor’s walkway inside Lark Quarry Dinosaur Trackways, Australia. Here, the camera is pointing towards the south west corner of the building. On the top (in the far corner) is the natural landscape. In the middle ground of the photo, some of the overburden has been cleared. In the foreground is the dinosaur tracks.

The Natural Science Museum at El Chocón, in the northwestern Argentine Patagonia (the Comahue region). Fossil of dinosaur

historická budova Národního muzea v Praze - západní dvorana s proskleným stropem a kostrou dinosaura / historic building of the National Museum in Prague - West hall with glass ceiling and dinosaur skeleton location: Prague, Czech Republic author: Jan Helebrant www.juhele.blogspot.com license CC0 Public Domain Dedication

Nyasasaurus is a basal dinosauromorph that may be the earliest known dinosaur. It was a small bipedal animal at about 2-3 m in length. Nyasasaurus is difficult to classify due to inconclusive fossil evidence, but if it is a true dinosaur, it pushes the dinosaur lineage back about 12 million years to the Middle Triassic.

Sidersaura is a rebbachisaurid sauropod dinosaur from the Late Cretaceous of Argentina. Rebbachisaurids are the last known dipldocoids, and lived alongside the titanosaurs until fairly late in the Cretaceous before disappearing from the fossil record, presumably going extinct. They have long tails and relatively short necks, by sauropod standards. Sidersaura one of the most recent rebbachisaurids yet found, living in the Cenomanian–Turonian ages of the Late Cretaceous. It was large for a rebbachisaurid, growing to about 20 m in length.

Fossil of Mei long (holotype), on temporary display at the Shanghai Natural History Museum as part of the exhibition "China's Dinosaur World". Shot on July 22, 2025.

Achelousaurus horneri skull, collected in Glacier County, Montana, at the Museum of the Rockies in Bozeman, Montana. The Ceratopsidae are those dinosaurs with head frills. There are three large subgroups of Ceratopsidae: Centrosaurinae, Ceratopsinae, and Chasmosaurinae. The Triceratopsini are a "tribe" of the Chasmosaurinae -- a genus so vast that it gets the special name "tribe". The Pachyrhinosaurini are a "tribe" within the Centrosaurinae. Achelousaurus is a genus within the Pachyrhinosaurini. So far, only three skulls and some limited skeletal remains have been collected anywhere in the world -- and all of them in Montana. Their bony frills are quite similar to the Styracosaurus albertensis, although their other skull features (such as big bony bosses on the nose and behind the eyes) are not.

Known fossil pieces after Aviatyrannis jurassica (Dinosauria, Theropoda, Coelurosauria, Tyrannosauroidea).[1] Sources ↑ Rauhut O.W.M. (2003), "A tyrannosaurid dinosaur from the Upper Jurassic of Portugal", Paleontology 46(5): p. 903-910.

Anterior dorsal vertebra of the sauropod dinosaur Tendaguria tanzaniensis.

Picture of Justin Hofmann holding the right hindlimb of his self-named dinosaur, Nedcolbertia justinhofmanni.

Diagram depicting the currently named Dinosauria from the Late Cretaceous Allen Formation of Argentina. Dinosaur taxa: Aeolosaurus sp. → Salitral Moreno locality, Río Negro Province.[1] Length = 15 meters.[2] Austroraptor cabazai → Santa Rosa Basin locality, Río Negro Province.[3][4] Length = 6 meters.[2] Bonapartenykus ultimus → Salitral Ojo de Agua locality, Río Negro Province.[5] Length = 2.5 meters.[5] Bonapartesaurus rionegrensis → Salitral Moreno locality, Río Negro Province.[6] Length = ∼6 meters.[1] Bonatitan reigi → Salitral de Santa Rosa locality, Río Negro Province.[7] Length = Extrapolated after relatives. Kelumapusaura machi → Cerro Matadero locality, Río Negro Province.[8] 9 meters.[8] Lamarqueavis australis → Cerro Tortugas locality, Río Negro Province.[9] Length = ∼House sparrow-sized.[9] Lapampasaurus cholinoi → Islas Malvinas locality, La Pampa Province.[10] Length = ∼7 meters.[2] Limenavis patagonica → Salitral Moreno locality, Río Negro Province.[11] Length = Extrapolated after relatives. Menucocelsior arriagadai → Salitral Ojo de Agua locality, Río Negro Province. Niebla antiqua → Cerro Matadero locality, Río Negro Province.[12] Length = 4.5 meters.[12] Panamericansaurus schroederi → Bodega Familia Schroeder locality, Neuquén Province.[13] Length = 11 meters.[2] Patagopelta cristata → Salitral Moreno locality, Río Negro Province. Quilmesaurus curriei → Salitral Ojo de Agua locality, Río Negro Province.[14] Length = 5.3 meters.[12] Rocasaurus muniozi → Salitral Moreno locality, Río Negro Province.[15] Length = Extrapolated after relatives. Excluded taxa: Willinakaqe salitralensis is considered a nomen dubium,[16] and its paratype has been reassigned to Bonapartesaurus rionegrensis.[6] Laplatasaurus araukanicus has been restricted to its lectotype which hails from the Anacleto Formation.[17] Abelisaurus comahuensis could either belong to the Allen or Anacleto formations.[12] Pellegrinisaurus powelli could either belong to the Allen or Anacleto formations.[18][19] References ↑ (2013). "The titanosaur sauropods from the late Campanian-early Maastrichtian Allen Formation of Salitral Moreno, Río Negro, Argentina". Acta Palaeontologica Polonica 58 (2): 269–284. DOI:10.4202/app.2011.0055. ↑ a b c (2007) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Random House ISBN: 9780375824197. Genus List for Holtz 2012 Weight Information ↑ (2008). "A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids". Proceedings of the Royal Society B: Biological Sciences 276 (1659): 1101–7. DOI:10.1098/rspb.2008.1554. ISSN 1471-2954. ↑ (2012). "A New Specimen of Austroraptor cabazai Novas, Pol, Canale, Porfiri and Calvo, 2008 (Dinosauria, Theropoda, Unenlagiidae) from the Latest Cretaceous (Maastrichtian) of Río Negro, Argentina". Ameghiniana 49 (4): 662–667. DOI:10.5710/AMGH.30.8.2012.574. ↑ a b Federico L. Agnolin (2012). "New alvarezsaurid (Dinosauria, Theropoda) from uppermost Cretaceous of north-western Patagonia with associated eggs". Cretaceous Research 35: 33–56. DOI:10.1016/j.cretres.2011.11.014. ↑ a b (2017). "Bonapartesaurus rionegrensis, a new hadrosaurine dinosaur from South America: implications for phylogenetic and biogeographic relations with North America". Journal of Vertebrate Paleontology 37 (2): 1–16. DOI:10.1080/02724634.2017.1289381. ↑ Salgado L., Gallina P.A. and Paulina Carabajal A. 2014. "Redescription of Bonatitan reigi (Sauropoda: Titanosauria), from the Campanian–Maastrichtian of the Río Negro Province (Argentina)". Historical Biology: An International Journal of Paleobiology 27(5): 525-548 ↑ a b (2022). "A new hadrosaurid (Dinosauria: Ornithischia) from the Late Cretaceous of northern Patagonia and the radiation of South American hadrosaurids". Journal of Systematic Palaeontology. DOI:10.1080/14772019.2021.2020917. ↑ a b (2010). "[https://pdfs.semanticscholar.org/f6f4/c6eb05d224719916c0b20634f54dfeb37d3f.pdf An avian coracoid from the Upper Cretaceous of Patagonia, Argentina]". Studia Geologica Salmanticensia 46 (2): 99-119. ISSN 0211-8327. ↑ Rodolfo A. Coria, Bernardo González Riga and Silvio Casadío (2012). "Un nuevo hadrosáurido (Dinosauria, Ornithopoda) de la Formación Allen, provincia de La Pampa, Argentina". Ameghiniana 49 (4): 552–572. ↑ Clarke and Chiappe, 2001. A new carinate bird from the Late Cretaceous of Patagonia (Argentina). American Museum Novitates. 3323, 1-23. ↑ a b c d (in English) Aranciaga Rolando, Mauro (2020). "A new medium-sized abelisaurid (Theropoda, Dinosauria) from the late cretaceous (Maastrichtian) Allen Formation of Northern Patagonia, Argentina". Journal of South American Earth Sciences: 102915. DOI:10.1016/j.jsames.2020.102915. ISSN 0895-9811. ↑ (2010). "Panamericansaurus schroederi gen. nov. sp. nov. Un nuevo Sauropoda (Titanosauridae-Aeolosaurini) de la Provincia del Neuquén, Cretácico Superior de Patagonia, Argentina". Brazilian Geographical Journal: Geosciences and Humanities research medium 1: 100–115. ↑ Coria, R.A. (2001) "A new theropod from the Late Cretaceous of Patagonia" in Tanke, Darren H., ed. Mesozoic Vertebrate Life, Life of the Past, Indiana University Press, pp. 3–9 ISBN: 978-0-253-33907-2. ↑ Salgado, L. and C. Azpilicueta. 2000. Un nuevo saltasaurino (Sauropoda, Titanosauridae) de la provincia de Río Negro (Formacíon Allen, Cretácico Superior), Patagonia, Argentina archive copy at the Wayback Machine. Ameghiniana 37 (3):259-264. ↑ (2016). "Revisiting the hadrosaurid diversity of the Allen Fm.: Re-evaluation of the taxonomic validity of Willinakaqe salitralensis (Ornithopoda, Hadrosauridae) from Salitral Moreno, Río Negro Province, Argentina". Ameghiniana 53 (2): 231–237. DOI:10.5710/AMGH.25.09.2015.2943. ↑ Pablo A. Gallina & Alejandro Otero (2015) Reassessment of Laplatasaurus araukanicus (SAUROPODA: TITANOSAURIA), from the Late Cretaceous of Patagonia, Argentina. Ameghiniana 52 (5):487–501. doi:10.5710/AMGH.08.06.2015.2911. ↑ (1996). "Pellegrinisaurus powelli nov. gen. et sp. (Sauropoda, Titanosauridae) from the Upper Cretaceous of Lago Pellegrini, Northwestern Patagonia, Argentina". Ameghiniana 33 (4): 355–365. ISSN 1851-8044. ↑ Heredia, S., & Salgado, L. (2014). Posición estratigráfica de los estratos supracretácicos portadores de dinosaurios en Lago Pellegrini, Patagonia septentrional, Argentina. Ameghiniana, 36(2), 229-234.

Selmasaurus johnsoni mounted skull in the Rocky Mountain Dinosaur Resource Center in Woodland Park, Colorado

Yandusaurus hongheensis, a neornithischian dinosaur.

Figure 1: Geographic provenance and speculative reconstruction of the gigantic titanosaurian sauropod dinosaur Notocolossus gonzalezparejasi gen. et sp. nov. (a) Type locality of Notocolossus (indicated by star) in southern-most Mendoza Province, Argentina. (b) Reconstructed skeleton and body silhouette in right lateral view, with preserved elements of the holotype (UNCUYO-LD 301) in light green and those of the referred specimen (UNCUYO-LD 302) in orange. Scale bar, 1 m. (All images were hand drawn by the senior author [B.J.G.R.] and subsequently edited using Adobe Illustrator software.)