Thespesius (meaning "wondrous one") is a dubious genus of hadrosaurid dinosaur from the late Maastrichtian-age Upper Cretaceous Lance Formation of South Dakota.

Temporal range: Late Cretaceous, 66 Ma
Thespesius occidentalis
The syntype fossils
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Suborder: Ornithopoda
Family: Hadrosauridae
Subfamily: Saurolophinae
Genus: Thespesius
Leidy, 1856
T. occidentalis
Binomial name
Thespesius occidentalis
Leidy, 1856


In 1855 geologist Ferdinand Vandiveer Hayden sent a number of fossils to paleontologist Joseph Leidy in Philadelphia. Hayden had collected them from the surface of a rock formation then known as the Great Lignite Formation (now recognized as part of the Lance Formation) in the Nebraska Territory, near the Grand River (present-day South Dakota). Among them were two caudal vertebrae and a phalanx. In 1856 Leidy named the type species Thespesius occidentalis for these three bones.[1][2] The generic name is derived from Greek θεσπεσιος, thespesios, "wondrous", because of the colossal size of the remains. Leidy avoided using the suffix "saurus" in the genus name because Vandiveer Hayden had claimed the bones came from a layer from the Miocene so there was a chance that the animal would turn out to be a mammal, though Leidy himself was convinced it was a dinosaurian. The specific name means "western" in Latin.

The caudal vertebrae, USNM 219 and USNM 221, and the middle toe phalanx, USNM 220, form the original syntype series.


Like Trachodon, another duckbill genus named by Joseph Leidy, Thespesius is a historically-important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists. Around 1900 the name was used by some authors to indicate all late Maastrichtian hadrosaurids in North America.[3] In 1875, E.D. Cope stated that he considered Agathaumas milo, known from partial limb bones and some vertebrae, to be a synonym of T. occidentalis (which he considered a species of Hadrosaurus at the time).[4] In 1900, a short piece published in Science by F.A. Lucas noted that Leidy's original Thespesius occidentalis fossils were indistinguishable from more complete specimens which had been referred in the late 1800s to the species Claosaurus annectens. Therefore, Lucas argued, the name T. occidentalis should be used for this animal.[5]

Lucas' opinion was supported by Charles W. Gilmore in a 1915 paper for Science re-evaluating the use of the genus Trachodon. A wide variety of hadrosaurid species had been classified as Trachodon or "trachodonts", most notably the large "duck-billed" specimens collected by E.D. Cope and mounted in the American Museum of Natural History. Gilmore noted that the holotype fossils of T. occidentalis were "inadequate", but that geologic work showed that they undoubtedly came from the same fossil beds as Claosaurus annectens, and that therefore the older name (T. occidentalis) should be used for the Lance-aged "trachodonts."[6] Many later researchers, including L.S. Russell and Charles M. Sternberg, continued to use the names Thespesius occidentalis or Thespesius annectens for the Lance hadrosaurids through the 1920s and 1930s.[7][8][9]

However, as early as 1913, paleontologist Lawrence Lambe regarded the type fossils of Thespesius occidentalis as inadequate and that any inferences based on them were too conjectural, as was the case for Trachodon. In an influential 1942 paper on hadrosaurids by Richard S. Lull and Nelda E. Wright, the authors classified most specimens of Thespesius annectens in the new genus Anatosaurus, and referred Cope's giant "duck-billed" specimens to Anatosaurus copei. Though they noted that T. occidentalis could possibly be distinguished from Anatosaurus based on its shorter tail vertebrae, they ultimately agreed with Lambe that, despite its historical importance, Thespesius occidentalis was too incomplete for good comparison.[2] It has been generally ignored as a nomen dubium ever since.

A referred species of Thespesius, T. saskatchewanensis, was named by Sternberg in 1926,[10] but Nicolás Campione and David Evans found that it was a synonym of Edmontosaurus annectens in a 2011 study of edmontosaur diversity.[11] Campione and Evans also found Thespesius edmontoni, named by Gilmore in 1924,[12] to be a synonym of Edmontosaurus regalis.[11]

See also


  1. ^ Leidy, J. (1856). "Notice of extinct Vertebrata, discovered by Dr. F. V. Hayden during the expedition to the Sioux country under the command of Lieut. G.K. Warren." Proceedings of the Academy of Natural Science Philadelphia, 8(December 30): 311-312.
  2. ^ a b Lull, R.S. & Wright, N.E. (1942). "Hadrosaurian dinosaurs of North America." Geological Society of America Special Papers, 40: 1-272.
  3. ^ Creisler, B.S. (2007). "Deciphering duckbills." Pp. 185-210 in Carpenter, K. (ed.), Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Bloomington and Indianapolis: Indiana University Press. ISBN 0-253-34817-X
  4. ^ Cope, E. D. (1875). Report on the vertebrate paleontology of Colorado. US Government Printing Office.
  5. ^ Lucas, F.A. (1900). "Paleontological Notes." Science, 12(308): 809-810. [1]
  6. ^ Gilmore, C.W. (1915). "On the Genus Trachodon." Science, 41(1061): 658-660.
  7. ^ Russell, L.S. (1930). "Upper Cretaceous dinosaur faunas of North America." Proceedings of the American Philosophical Society, 69(1): 133-159.
  8. ^ Sternberg, C.M. (1936). "The systematic position of Trachodon." Journal of Paleontology, 10(7): 652-655.
  9. ^ Sternberg, C.M. (1939). "Were there Proboscis-bearing Dinosaurs? Discussion of Cranial Protuberances in the Hadrosauridae." Journal of Natural History, 3(17): 556-560.
  10. ^ Sternberg, C.M. (1926). A new species of Thespesius from the Lance Formation of Saskatchewan. Canada Department of Mines Geological Survey Bulletin (Geological Series) 44(46):73-84.
  11. ^ a b Campione, N. S. E.; Evans, D. C. (2011). "Cranial Growth and Variation in Edmontosaurs (Dinosauria: Hadrosauridae): Implications for Latest Cretaceous Megaherbivore Diversity in North America". PLoS ONE. 6 (9): e25186. Bibcode:2011PLoSO...625186C. doi:10.1371/journal.pone.0025186. PMC 3182183. PMID 21969872.
  12. ^ Gilmore, C.W. (1924). A new species of hadrosaurian dinosaur from the Edmonton Formation (Cretaceous) of Alberta. Canada Department of Mines Geological Survey Bulletin (Geological Series) 38(43):13-26.

Aralosaurini is a tribe of basal lambeosaurine hadrosaurs endemic to Eurasia. It currently contains Aralosaurus (from the Aral sea of Kazakhstan) and Canardia (from Toulouse, Southern France).


Canardia is an extinct genus of aralosaurin lambeosaurine dinosaur known from the Late Cretaceous Marnes d’Auzas Formation (late Maastrichtian stage) of Toulouse, Haute-Garonne Department, southern France. The type species Canardia garonnensis was first described and named by Albert Prieto-Márquez, Fabio M. Dalla Vecchia, Rodrigo Gaete and Àngel Galobart in 2013.


Edmontosaurus ( ed-MON-tə-SAWR-əs) (meaning "lizard from Edmonton") is a genus of hadrosaurid (duck-billed) dinosaur. It contains two known species: Edmontosaurus regalis and Edmontosaurus annectens. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago, while those of E. annectens were found in the same geographic region but in rocks dated to the end of the Maastrichtian stage of the Cretaceous, 66 million years ago. Edmontosaurus was one of the last non-avian dinosaurs, and lived alongside dinosaurs like Triceratops, Tyrannosaurus, Albertosaurus and Pachycephalosaurus shortly before the Cretaceous–Paleogene extinction event.

Edmontosaurus included some of the largest hadrosaurid species, measuring up to 12 metres (39 ft) long and weighing around 4.0 metric tons (4.4 short tons). Evidence does exist in the form of two fossilized specimens housed at the Museum of the Rockies for an even greater maximum size of 15 m (49 ft) and weighing 9.07 metric tons (10.00 short tons) for Edmontosaurus annectens. Several well-preserved specimens are known that include not only bones, but in some cases extensive skin impressions and possible gut contents. It is classified as a genus of saurolophine (or hadrosaurine) hadrosaurid, a member of the group of hadrosaurids which lacked large, hollow crests, instead having smaller solid crests or fleshy combs.The first fossils named Edmontosaurus were discovered in southern Alberta (named after Edmonton, the capital city), in the Horseshoe Canyon Formation (formerly called the lower Edmonton Formation). The type species, E. regalis, was named by Lawrence Lambe in 1917, although several other species that are now classified in Edmontosaurus were named earlier. The best known of these is E. annectens, named by Othniel Charles Marsh in 1892; originally as a species of Claosaurus, known for many years as a species of Trachodon, and later as Anatosaurus annectens. Anatosaurus and Anatotitan are now generally regarded as synonyms of Edmontosaurus.

Edmontosaurus was widely distributed across western North America. The distribution of Edmontosaurus fossils suggests that it preferred coasts and coastal plains. It was a herbivore that could move on both two legs and four. Because it is known from several bone beds, Edmontosaurus is thought to have lived in groups, and may have been migratory as well. The wealth of fossils has allowed researchers to study its paleobiology in detail, including its brain, how it may have fed, and its injuries and pathologies, such as evidence for tyrannosaur attacks on a few edmontosaur specimens.

Edmontosaurus annectens

Edmontosaurus annectens (meaning "connected lizard from Edmonton) is a species of flat-headed or saurolophine hadrosaurid ornithopod dinosaur (a "duck-billed dinosaur") from the very end of the Cretaceous Period, in what is now North America. Remains of E. annectens have been preserved in the Frenchman, Hell Creek, and Lance Formations. All of these formations are dated to the late Maastrichtian stage of the Late Cretaceous Period, representing the last three million years before the extinction of the dinosaurs (between 68 and 66 million years ago). Also, E. annectens is also from the Laramie Formation, and magnetostratigraphy suggests an age of 69-68 Ma for the Laramie Formation. Edmontosaurus annectens is known from numerous specimens, including at least twenty partial to complete skulls, discovered in the U.S. states of Montana, South Dakota, North Dakota, Wyoming and Colorado and the Canadian province of Saskatchewan. It was a large animal, up to approximately 12 metres (39 ft), potentially up to 15 m (49 ft) in length, with an extremely long and low skull. E. annectens exhibits one of the most striking examples of the "duckbill" snout common to hadrosaurs. It has a long taxonomic history, and specimens have at times been classified in the genera Diclonius, Trachodon, Hadrosaurus, Claosaurus, Thespesius, Anatosaurus and Anatotitan, before being grouped together in Edmontosaurus.

Edmontosaurus regalis

Edmontosaurus regalis is a species of comb-crested hadrosaurid (duck-billed) dinosaur. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago.

E. regalis was one of the largest hadrosaurids, measuring up to 12 metres (39 ft) long and weighing around 4.0 metric tons (4.4 short tons). It is classified as a genus of saurolophine (or hadrosaurine) hadrosaurid, a member of the group of hadrosaurids which lacked large, hollow crests, instead having smaller solid crests or fleshy combs. The distribution of E. regalis fossils suggests that it preferred coasts and coastal plains. It was a herbivore that could move on both two legs and four. Because it is known from several bone beds, E. regalis is thought to have lived in groups. The wealth of fossils has allowed researchers to study its paleobiology in detail, including its brain, how it may have fed, and its injuries and pathologies.


Elasmaria is a clade of iguanodont ornithopods known from Cretaceous deposits in South America, Antarctica, and Australia.


Huxleysaurus (meaning "Huxley's lizard") is a genus of herbivorous styracosternan ornithopod dinosaur.


Iguanodontia (the iguanodonts) is a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous. Some members include Camptosaurus, Dryosaurus, Iguanodon, Tenontosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodontians were one of the first groups of dinosaurs to be found. They are among the best known of the dinosaurs, and were among the most diverse and widespread herbivorous dinosaur groups of the Cretaceous period.


Jaxartosaurus is a genus of hadrosaurid dinosaur similar to Corythosaurus which lived during the Late Cretaceous. Its fossils were found in Kazakhstan.


Laiyangosaurus ("Laiyang lizard") is a genus of saurolophine hadrosaurid from the Late Cretaceous of China. It is known from one species, L.youngi, found in the Laiyang Basin within the province of Shandong.


Lapampasaurus is an extinct genus of hadrosaurid known from the Late Cretaceous Allen Formation (late Campanian or early Maastrichtian stage) of La Pampa Province, Argentina. It contains a single species, Lapampasaurus cholinoi.The generic name refers to the Argentine province of La Pampa. The specific name honours the late collector José Cholino. The material includes cervical, dorsal, sacral and caudal vertebrae, the forelimb girdle, and the partial hindlimb.


Palaeoscincus (meaning "ancient skink" from the Greek παλαιός and σκίγγος) is a dubious genus of ankylosaurian dinosaur based on teeth from the mid-late Campanian-age Upper Cretaceous Judith River Formation of Montana. Like several other dinosaur genera named by Joseph Leidy (Deinodon, Thespesius, and Trachodon), it is an historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists. Because of its wide use in the early 20th century, it was somewhat well known to the general public, often through illustrations of an animal with the armor of Edmontonia and the tail club of an ankylosaurid.


Pareisactus (from the Greek "pareisaktos", meaning "intruder", referring to being represented as a single element among hundreds of hadrosaurid bones) is a genus of rhabdodontid ornithopod dinosaur from the Late Cretaceous Conquès Member of the Tremp Formation in the Southern Pyrenees of Spain. The type and only species is P. evrostos, known only from a single scapula.


Plesiohadros is an extinct genus of hadrosauroid dinosaur. It is known from a partial skeleton including the skull collected at Alag Teg locality, from the Campanian Djadochta Formation of southern Mongolia. The type species is Plesiohadros djadokhtaensis.

T. occidentalis

T. occidentalis can refer to a few different species. The specific epithet occidentalis means 'western.'

Talpa occidentalis, the Spanish mole

Telfairia occidentalis, a vine known as fluted gourd, fluted pumpkin, ugu, or ikong-ubong

Thespesius occidentalis, a dinosaur in the genus Thespesius

Thuja occidentalis, a tree known as northern white-cedar or eastern arborvitae

Titanites occidentalis, an ammonite in the genus Titanites

Torodora occidentalis, a moth in the family Lecithoceridae

Tradescantia occidentalis, a forb called the western spiderwort or prairie spiderwort

Trichromia occidentalis, a moth in the family Erebidae

Trimeresurus occidentalis, a synonym for Trimeresurus gramineus, the bamboo pit viper

Triodopsis occidentalis, the western three-toothed land snail

Turpinia occidentalis, a tree known as muttonwood

Thespesius of Cappadocia

Thespesius was a martyr, who died during the persecutions of Emperor Severus Alexander. His name is Greek for "Wondrous One".

Timeline of hadrosaur research

This timeline of hadrosaur research is a chronological listing of events in the history of paleontology focused on the hadrosauroids, a group of herbivorous ornithopod dinosaurs popularly known as the duck-billed dinosaurs. Scientific research on hadrosaurs began in the 1850s, when Joseph Leidy described the genera Thespesius and Trachodon based on scrappy fossils discovered in the western United States. Just two years later he published a description of the much better-preserved remains of an animal from New Jersey that he named Hadrosaurus.The early 20th century saw such a boom in hadrosaur discoveries and research that paleontologists' knowledge of these dinosaurs "increased by virtually an order of magnitude" according to a 2004 review by Horner, Weishampel, and Forster. This period is known as the great North American Dinosaur rush because of the research and excavation efforts of paleontologists like Brown, Gilmore, Lambe, Parks, and the Sternbergs. Major discoveries included the variety of cranial ornamentation among hadrosaurs as scientist came to characterize uncrested, solid crested, and hollow crested species. Notable new taxa included Saurolophus, Corythosaurus, Edmontosaurus, and Lambeosaurus. In 1942 Richard Swann Lull and Wright published what Horner, Weishampel, and Forster characterized as the "first important synthesis of hadrosaurid anatomy and phylogeny".More recent discoveries include gigantic hadrosaurs like Shantungosaurus giganteus from China. At 15 meters in length and nearly 16 metric tons in weight it is the largest known hadrosaur and is known from a nearly complete skeleton.Hadrosaur research has continued to remain active even into the new millennium. In 2000, Horner and others found that hatchling Maiasaura grew to adult body sizes at a rate more like a mammal's than a reptile. That same year, Case and others reported the discovery of hadrosaur bones in Vega Island, Antarctica. After decades of such dedicated research, hadrosaurs have become one of the best understood group of dinosaurs.


Tsintaosaurini is a tribe of basal lambeosaurine hadrosaurs native to Eurasia. It currently contains only Tsintaosaurus (from China) and Pararhabdodon (from Spain ).Koutalisaurus, also known from late Cretaceous Spain and formerly referred to Pararhabdodon

, may also be a tsintaosaurin because of its association with the latter genus; some recent work also suggests it may indeed be referrable to Pararhabdodon.


Xuwulong is a genus of hadrosauroid dinosaur from the Early Cretaceous period. It lived during the early Cretaceous period (Aptian-Albian age) in what is now Yujingzi Basin in the Jiuquan area, Gansu Province of northwestern China. It is known from the holotype – GSGM F00001, an articulated specimen including a complete cranium, almost complete axial skeleton, and complete left pelvic girdle from Xinminpu Group. Xuwulong was named by You Hailu, Li Daqing and Liu Weichang in 2011 and the type species is Xuwulong yueluni.


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