''Thespesius'' (meaning "wondrous one") is a

dubious Doubt is a mental state in which the mind remains suspended between two or more contradictory propositions, unable to be certain of any of them. Doubt on an emotional level is indecision between belief and disbelief. It may involve uncertainty, ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

hadrosaurid Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which inclu ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

from the late Maastrichtian-age

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

Lance Formation The Lance (Creek) Formation is a division of Late Cretaceous (dating to about 69 - 66 Ma) rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the late ...

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota people, Lakota and Dakota peo ...

History

In 1855 geologist

Ferdinand Vandeveer Hayden Ferdinand Vandeveer Hayden (September 7, 1829 – December 22, 1887) was an American geologist noted for his pioneering surveying expeditions of the Rocky Mountains in the late 19th century. He was also a physician who served with the Union Ar ...

sent a number of fossils to

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

Joseph Leidy Joseph Mellick Leidy (September 9, 1823 – April 30, 1891) was an American paleontologist, parasitologist and anatomist. Leidy was professor of anatomy at the University of Pennsylvania, later was a professor of natural history at Swarthmore ...

Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...

. 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 The Territory of Nebraska was an organized incorporated territory of the United States that existed from May 30, 1854, until March 1, 1867, when the final extent of the territory was admitted to the Union as the State of Nebraska. The Nebraska ...

, near the Grand River (present-day

). Among them were two caudal

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

e and a

phalanx The phalanx ( grc, φάλαγξ; plural phalanxes or phalanges, , ) was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar pole weapons. The term is particularly use ...

. In 1856 Leidy named the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

''Thespesius occidentalis'' for these three bones.Leidy, J. (1856). "Notice of extinct Vertebrata, discovered by 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. 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 Vandeveer Hayden had claimed the bones came from a layer from the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

so there was a chance that the animal would turn out to be a

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

, though Leidy himself was convinced it was a dinosaurian. The specific name means "western" in

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

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

syntype In biological nomenclature, a syntype is any one of two or more biological types that is listed in a description of a taxon where no holotype was designated. Precise definitions of this and related terms for types have been established as part of ...

series.

Classification

Like ''

Trachodon ''Trachodon'' (meaning "rough tooth") is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-age Upper Cretaceous Judith River Formation of Montana, U.S.Leidy, J. (1856). "Notice of remains of extinct reptiles and fishes, d ...

'', another duckbill genus named by

, ''Thespesius'' is a historically-important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur

s. Around 1900 the name was used by some authors to indicate all late Maastrichtian hadrosaurids in North America.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. 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 ''Hadrosaurus'' (; ) is a genus of hadrosaurid ornithopod dinosaurs that lived in North America during the Late Cretaceous Period in what is now the Woodbury Formation about 80 million to 78 million years ago. The holotype specimen was found in f ...

'' at the time).Cope, E. D. (1875). ''Report on the vertebrate paleontology of Colorado''. US Government Printing Office. 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 ''Edmontosaurus annectens'' (meaning "connected lizard from Edmonton") is a species of flat-headed and duck-billed (hadrosaurid) dinosaur from the very end of the Cretaceous Period, in what is now North America. Remains of ''E. annectens'' have b ...

''. Therefore, Lucas argued, the name ''T. occidentalis'' should be used for this animal.Lucas, F.A. (1900). "Paleontological Notes." ''Science'', 12(308): 809-810

/ref> 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 The American Museum of Natural History (abbreviated as AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. In Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 26 inter ...

. 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."Gilmore, C.W. (1915). "On the Genus ''Trachodon.''" ''Science'', 41(1061): 658-660. 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.Russell, L.S. (1930). "Upper Cretaceous dinosaur faunas of North America." ''Proceedings of the American Philosophical Society'', 69(1): 133-159.Sternberg, C.M. (1936). "The systematic position of ''Trachodon''." ''Journal of Paleontology'', 10(7): 652-655.Sternberg, C.M. (1939). "Were there Proboscis-bearing Dinosaurs? Discussion of Cranial Protuberances in the Hadrosauridae." ''Journal of Natural History'', 3(17): 556-560. 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 ''Edmontosaurus annectens'' (meaning "connected lizard from Edmonton") is a species of flat-headed and duck-billed ( hadrosaurid) dinosaur from the very end of the Cretaceous Period, in what is now North America. Remains of ''E. annectens'' have ...

'', 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.Lull, R.S. & Wright, N.E. (1942). "Hadrosaurian dinosaurs of North America." ''Geological Society of America Special Papers'', 40: 1-272. It has been generally ignored as a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

'' ever since. A referred species of ''Thespesius'', ''T. saskatchewanensis'', was named by Sternberg in 1926,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. but Nicolás Campione and David Evans found that it was a synonym of ''

Edmontosaurus annectens ''Edmontosaurus annectens'' (meaning "connected lizard from Edmonton") is a species of flat-headed and duck-billed (hadrosaurid) dinosaur from the very end of the Cretaceous Period (geology), Period, in what is now North America. Remains of ''E. ...

'' in a 2011 study of edmontosaur diversity. Campione and Evans also found ''Thespesius edmontoni'', named by Gilmore in 1924,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. to be a synonym of ''

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 yea ...

''.

References

{{Taxonbar, from=Q762249 Late Cretaceous dinosaurs of North America Saurolophines Nomina dubia Fossil taxa described in 1856 Taxa named by Joseph Leidy Paleontology in South Dakota Maastrichtian genus first appearances Maastrichtian genus extinctions Ornithischian genera

History

Classification

See also

References