Sonorasaurus is a genus of brachiosaurid dinosaur from the Early to Late Cretaceous (Albian to Cenomanian stages, around 112 to 93 million years ago). It was a herbivorous sauropod whose fossils have been found in southern Arizona in the United States. Its name, which means "Sonora lizard", comes from the Sonoran Desert where its fossils were first found. The type species is S. thompsoni, described by Ratkevich in 1998.

Temporal range: Early-Late Cretaceous, Albian–Cenomanian
Sonorasaurus thompsoni
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Family: Brachiosauridae
Genus: Sonorasaurus
Ratkevich, 1998
S. thompsoni
Binomial name
Sonorasaurus thompsoni
Ratkevich, 1998


Fossilized remains were discovered by geology student Richard Thompson, in November 1994, in the Chihuahua Desert region of the Sonoran Desert in southern Arizona. Thompson had investigated a previously almost unexplored region, where fossils proved to be plentiful and directly accessible on the surface. A relatively complete sauropod skeleton was weathering out on a rock wall. He informed paleontologist Ronald Paul Ratkevich of the Arizona-Sonora Desert Museum, Tucson of the find. Ratkevich assembled a team of volunteers and began securing the bones in the spring of 1995; excavations would only end in 1999. He assumed the fossils represented a sauropod but was no expert on that taxon. The curator of geology of the museum, David W. Thayer, thought it might be a therizinosaur, mistaking a tail chevron bone for the long hand claw typical of that group. In 1995, Ratkevich and Tayer first reported the find, already using the name "Sonorasaurus" but informally, so that it remained a nomen nudum.[1]

Both men now asked dinosaur expert Edwin Harris Colbert to identify the animal. Colbert, having seen only pictures, suggested it might be a member of the Hadrosauridae. Ratkevich and Thayer then visited the displays in the American Museum of Natural History, concluding their find was rather dissimilar to the hadrosaurid skeletons shown there, so that it must represent a species new to science. Ratkevich considered naming it "Chihuahuasaurus" but ultimately shied away from the comical contrast between the gigantic sauropod and the minute dog breed. In 1996, a subsequent article tried to fit the bones found, in a diagram of the hadrosaurid Kritosaurus. This attempt largely failed, with an ilium being mistaken for a shoulder blade. Again, the name "Sonorasaurus" was used but still invalidly.[2]

Sonorasaurus was finally formally described in 1998 by Ratkevich, who identified it as a brachiosaurid sauropod. Dating of the specimen found it to be the earliest known brachiosaurid to have lived in the 'middle' Cretaceous Period of North America.[3] On April 10, 2018, Sonorasaurus was declared the state dinosaur of Arizona.[4]


The holotype of Sonorasaurus, ASDM 500, is an incomplete skeleton consisting of various postcranial elements, many of which are fragmentary. A complete dorsal rib from the same horizon, ASDM 807, may also be referrable to S. thompsoni.[3] Sonorasaurus is estimated to have been about 15 meters long (49 ft) and 8.2 meters (27 feet) tall, about one third of the size of Brachiosaurus.


Ratkevich initially identified Sonorasaurus as a brachiosaurid.[3] However phylogenetic studies in the following years failed to find a consensus, with some finding it to lie within Brachiosauridae[5] and others outside of it.[6] In no analysis was the recovered phylogenetic position of Sonorasaurus strongly supported until D'Emic et al. (2016), which found Sonorasaurus to fall confidently within the Brachiosauridae. However the authors noted that additional data was still required to firmly establish its lower-level affinities.[7]


  1. ^ Thayer D.W. and Ratkevich R., 1995, "In progress dinosaur excavation in the mid-cretaceous Turney Ranch Formation, southeastern Arizona", Proceedings of the Fossils of Arizona Symposium. Bulletin No.3., Mesa Southwest Museum, Southwest Paleontological Society
  2. ^ David W. Thayer, Ronald P. Ratkevich & Stan E. Krzyzanowski, 1996, "A new Dinosaur for the Arizona-Sonora Desert Museum Tucson, Arizona", Rocks & Minerals, 71(1): 34-38
  3. ^ a b c Ratkevich, R. (1998). "New Cretaceous brachiosaurid dinosaur, Sonorasaurus thompsoni gen. et sp. nov, from Arizona". Journal of the Arizona-Nevada Academy of Science. 31 (1): 71–82.
  4. ^
  5. ^ Royo-Torres, R. (2009). "El saurópodo de Peñarroya de Tastavins". Instituto de Estudios Turolenses-Fundación Conjunto Paleontológico de Teruel-Dinópolis: Monografías Turolenses. 6: 1–548.
  6. ^ D’Emic, M.D. (2012). "The early evolution of titanosauriform sauropod dinosaurs". Zoological Journal of the Linnean Society. 166: 624–671.
  7. ^ D'Emic, M.D.; Foreman, B.Z.; Jud, N.A. (2016). "Anatomy, systematics, paleoenvironment, growth, and age of the sauropod dinosaur Sonorasaurus thompsoni from the Cretaceous of Arizona, USA". Journal of Paleontology. 90 (1): 102–132. doi:10.1017/jpa.2015.67.

The Brachiosauridae ("arm lizards", from Greek brachion (βραχίων) = "arm" and sauros = "lizard") are a family or clade of herbivorous, quadrupedal sauropod dinosaurs. Brachiosaurids had long necks that enabled them to access the leaves of tall trees that other sauropods would have been unable to reach. In addition, they possessed thick spoon-shaped teeth which helped them to consume tough plants more efficiently than other sauropods. They have also been characterized by a few unique traits or synapomorphies; dorsal vertebrae with 'rod-like' transverse processes and an ischium with an abbreviated pubic peduncle.Brachiosaurus is one of the best-known members of the Brachiosauridae, and was once thought to be the largest land animal to ever live. Brachiosaurids thrived in the regions which are now North and South America, Africa, Europe, and Asia. They first appear in the fossil record in the Late Jurassic Period and disappear in the late Early Cretaceous Period. The broad distribution of Brachiosauridae in both northern and southern continents suggests that the group originated prior to the breakup of Pangaea. In the Early Cretaceous the distribution of the group is dramatically reduced. It is still unclear whether this reduction is due to local extinctions or to the limited nature of the Early Cretaceous fossil record.Brachiosauridae has been defined as all titanosauriforms that are more closely related to Brachiosaurus than to Saltasaurus. It is one of the three main groups of the clade Titanosauriformes, which also includes the Euhelopodidae and the Titanosauria.


Brasilotitan is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous (early Maastrichtian) Adamantina Formation of Brazil. The type species is Brasilotitan nemophagus.


Cetiosauridae is a family of sauropod dinosaurs. While traditionally a wastebasket taxon containing various unrelated species, some recent studies have found that it may represent a natural clade. Additionally, at least one study has suggested that the mamenchisaurids may represent a sub-group of the cetiosaurids, which would be termed Mamenchisaurinae.


Diplodocinae is an extinct subfamily of diplodocid sauropods that existed from the Late Jurassic to Early Cretaceous of North America, Europe and South America, about 161.2 to 136.4 million years ago. Genera within the subfamily include Tornieria, Supersaurus, Leinkupal, Galeamopus, Diplodocus, Kaatedocus and Barosaurus.Cladogram of the Diplodocidae after Tschopp, Mateus, and Benson (2015).


Eomamenchisaurus (meaning "dawn Mamenchisaurus") is a genus of mamenchisaurid sauropod dinosaur from the Middle Jurassic of Yuanmou, Yunnan, China. The type species is E. yuanmouensis, described by Lü Junchang et al. in 2008.


Ferganasaurus was a genus of dinosaur first formally described in 2003 by Alifanov and Averianov. The type species is Ferganasaurus verzilini. It was a sauropod similar to Rhoetosaurus. The fossils were discovered in 1966 in Kyrgyzstan from the Balabansai Formation and date to the Callovian stage of the Middle Jurassic.


Gravisauria is a clade of sauropod dinosaurs consisting of some genera, Vulcanodontidae and Eusauropoda.


Jiutaisaurus is a genus of sauropod dinosaur from the Quantou Formation of China. Jiutaisaurus was a sauropod which lived during the Cretaceous. The type species, Jiutaisaurus xidiensis, was described by Wu et al. in 2006, and is based on eighteen vertebrae.


Laurasiformes (meaning "Laurasian forms") is an extinct clade of sauropod dinosaurs from the late Early Cretaceous of Europe, North and South America. It was defined in 2009 by the Spanish paleontologist Rafael Royo-Torres as a clade containing sauropods more closely related to Tastavinsaurus than to Saltasaurus. Genera purported to form part of this clade include Aragosaurus, Galvesaurus, Phuwiangosaurus, Venenosaurus, Cedarosaurus, Tehuelchesaurus, Sonorasaurus and Tastavinsaurus.Its exact position and validity is uncertain and varies between authors. A cladistics analysis found a similar grouping outside Titanosauriformes and basal within the Camarasauromorpha, while others have placed them inside Somphospondyli or Brachiosauridae, consequently, it has been suggested that Tehuelchesaurus along with others of the previously mentioned genera, form two different clades outside titanosauriformes (Carbadillo et al., 2011) while a more recent cladistics analysis found no support for the existence of the clade, with a revision of its supporting features finding them problematic due to being poorly defined, not present on most of the "laurasiforms" or being features present in many sauropods of other clades.

List of Arizona state symbols

The following is a list of symbols of the U.S. state of Arizona. The majority of the items in the list are officially recognized after a law passed by the state legislature. Most of the symbols were adopted in the 20th century. The first symbol was the motto, which was made official in 1864 for the Arizona Territory. Arizona became the second state to adopt a "state firearm" after Utah adopted the Browning M1911.

List of U.S. state dinosaurs

This is a list of U.S. state dinosaurs in the United States, including the District of Columbia. A large number of states also have dinosaurs as state fossils, but this list only includes those that have been officially designated as "state dinosaurs". All U.S. states also have a state bird, the direct evolutionary descendants of dinosaurs.


Microcoelus is a dubius genus of small Titanosaurian sauropod dinosaur native to Argentina. It is known from only a single dorsal vertebra. A left humerus was formerly referred to this species, but it is now considered to belong to Neuquensaurus. This species may be a synonym of the contemporary sauropod Neuquensaurus australis.It was described by British paleontologist Richard Lydekker in 1893.


Pilmatueia is a diplodocoid sauropod belonging to the family Dicraeosauridae that lived in Argentina during the Early Cretaceous.


Ruyangosaurus (Ruyang County lizard) is a genus of titanosauriform sauropod dinosaur recovered from the Early Cretaceous Haoling Formation of China. The type species is R. giganteus, described in 2009 by Lü Junchang et al. Along with Huanghetitan and Daxiatitan, Ruyangosaurus is among the largest dinosaurs discovered in Cretaceous Asia.


Tambatitanis is an extinct genus of titanosauriform dinosaur from the Early Cretaceous (probably early Albian) of Japan. It is known from a single type species, Tambatitanis amicitiae. It was probably around 14 meters long and its mass was estimated at some 4 tonnes. It was a basal titanosauriform and possibly belonged to the Euhelopodidae.


Tastavinsaurus is a genus of sauropod dinosaur belonging to the Titanosauriformes. It is based on a partial skeleton from the Early Cretaceous of Spain. The type species is Tastavinsaurus sanzi, named in honor of the Rio Tastavins in Spain and Spanish paleontologist José Luis Sanz.


Tengrisaurus (meaning "Tengri lizard") is a genus of lithostrotian sauropod, from the Early Cretaceous (Barremian-Aptian), of the Murtoi Formation, Russia. It was described in 2017 by Averianov & Skutschas. The type species is T. starkovi.

Turney Ranch Formation

The Turney Ranch Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.Vertebrate Paleofauna

Sonorasaurus thompsoni - "Fragmentary postcranial elements."


The Early Jurassic sauropod dinosaurs Zizhongosaurus, Barapasaurus, Tazoudasaurus, and Vulcanodon may form a natural group of basal sauropods called the Vulcanodontidae. Basal vulcanodonts include some of the earliest known examples of sauropods. The family-level name Vulcanodontidae was erected by M.R. Cooper in 1984. In 1995 Hunt et al. published the opinion that the family is synonymous with the Barapasauridae. One of the key morphological features specific to the family is an unusually narrow sacrum.


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