''Dyslocosaurus'' (meaning "hard-to-place lizard") is the name given in 1992 to a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...

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

from the Late

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

Period Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (o ...

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

the genus is based on, AC 663, is part of the collection of the

Amherst College Museum of Natural History The Beneski Museum of Natural History, Amherst College, is located on the campus of Amherst College in Amherst, Massachusetts. It showcases fossils and minerals collected locally and abroad, many by past and present students and professors. Th ...

. It was collected by professor

Frederic Brewster Loomis Frederic Brewster Loomis (November 22, 1873 – July 28, 1937) was an American paleontologist. Educated at Amherst College and the Ludwig Maximilian University of Munich, he spent his entire professional career at Amherst. His specialty was verte ...

. However, the only available information regarding its provenance is that given on the label: " Lance Creek", a county in east

. Loomis himself thought that it stemmed from 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 lates ...

, dating from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent 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 ''cre ...

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

Discovery and naming

In 1963 the specimen was brought to the attention of

John Stanton McIntosh John Stanton "Jack" McIntosh ( - ) was an American physicist and paleontologist who heavily influenced the study of sauropods. McIntosh worked professionally as a physicist at Wesleyan University until retirement in 1998, pursuing the study of sa ...

, who in 1992, together with William Coombs and

Dale Russell Dale Alan Russell (27 December 1937 – 21 December 2019) was an American-Canadian geologist and palaeontologist. Throughout his career Russell worked as the Curator of Fossil Vertebrates at the Canadian Museum of Nature, Research Professor at ...

, decided to create a new genus and species for it.McIntosh, J., Coombs, W. and Russell, D., 1992, "A new diplodocid sauropod (Dinosauria) from Wyoming, U.S.A.". ''Journal of Vertebrate Paleontology'', Volume 12, Number 2: 158-167 The

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

is ''Dyslocosaurus polyonychius''. The genus name is derived from Greek ''dys'', "bad, "poor", and

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''locus'', "place", a reference to the paucity of data regarding the type locality of the fossil. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

is derived from Greek ''polys'', "many", and ''onyx'', "claw". The describers interpreted the remains, consisting of some limb bones, as those of a

diplodocid Diplodocids, or members of the family Diplodocidae ("double beams"), are a group of sauropod dinosaurs. The family includes some of the longest creatures ever to walk the Earth, including '' Diplodocus'' and '' Supersaurus'', some of which may ha ...

dinosaur. From this they concluded that it in fact dated from the Late

Period, like most diplodocids. The species would then be unique in having four, or perhaps five, claws on the foot, whereas other diplodocids have only three — hence the specific name. A species similar to ''Dyslocosaurus'' would have made the tracks of the

ichnospecies An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxon'' comes from the Ancient Greek (''íchnos'') meaning "track" and English , itself derived from ...

Brontopodus ''Brontopodus'' is an ichnogenus of dinosaur footprint by sauropod trackmaker. This ichnogenus is mainly characterized by a wide-gauge trackway, which is distinguishable from narrow-gauge sauropod tracks like '' Breviparopus'' or '' Parabrontopod ...

birdi'' from the Early Cretaceous, that also features four claws. In 1998

Paul Sereno Paul Callistus Sereno (born October 11, 1957) is a professor of paleontology at the University of Chicago who has discovered several new dinosaur species on several continents, including at sites in Inner Mongolia, Argentina, Morocco and Niger. ...

and Jeffrey A. Wilson gave an alternative interpretation: the specimen would come from the Lance Formation after all but be a

chimera Chimera, Chimaera, or Chimaira (Greek for " she-goat") originally referred to: * Chimera (mythology), a fire-breathing monster of ancient Lycia said to combine parts from multiple animals * Mount Chimaera, a fire-spewing region of Lycia or Cilicia ...

: in this case a mix up of

titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

limb bones and

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

phalange The phalanges (: phalanx ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. Structure ...

s. In their taxonomic revision of Diplodocidae, Tschopp ''et al.'' in 2015 noted that a pedal phalanx included in AC 663 is apparently not from the same individual as the rest of AC 663 given differences in preservation and coloration among individual bones, raising doubts on whether ''Dyslocosaurus'' had more than three claws on the feet. Although fragmentary, ''Dyslocosaurus'' was recovered as a member of Dicraeosauridae, potentially making it the second record of a dicraeosaurid from North America (the other being ''

Suuwassea ''Suuwassea'' is a genus of Dicraeosauridae, dicraeosaurid sauropod dinosaur found in the Upper Jurassic strata of the Morrison Formation, located in southern Carbon County, Montana, Carbon County, Montana, United States. The fossil remains were ...

'').Tschopp, E.; Mateus, O. V.; Benson, R. B. J. (2015). "A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)". PeerJ 3: e857. .

References

{{Taxonbar, from=Q2006215 Dicraeosauridae Dinosaur genera Kimmeridgian dinosaurs Morrison Formation Taxa named by Dale Russell Fossil taxa described in 1992 Dinosaurs of the United States