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

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of sauropod

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

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

Period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the s ...

, North America. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...

the genus is based on, AC 663, is part of the collection of the Amherst College Museum of Natural History. It was collected by professor Frederic Brewster Loomis. 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 late ...

, dating from the

Late 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'', ...

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...

Discovery and naming

In 1963 the specimen was brought to the attention of

John Stanton McIntosh John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second ...

, 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 a ...

, 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 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 specime ...

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 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 ...

''locus'', "place", a reference to the paucity of data regarding the type locality of the fossil. The specific name is derived from Greek ''polys'', "many", and ''onyx'', "claw". The describers interpreted the remains, consisting of some limb bones, as those of a diplodocid 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. ''Ichnotaxa'' comes from the Greek ίχνος, ''ichnos'' meaning ''track'' and ταξις, ''taxis'' meaning ...

Brontopodus ''Brontopodus'' is an ichnogenus of dinosaur footprint. The footprint has diplodocid form, but four toes when almost every diplodocid has no more than three. This leaves '' Dyslocosaurus'' as the only known genus capable of producing the footpri ...

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 and a National Geographic "explorer-in-residence" who has discovered several new dinosaur species on several continents, including at sites ...

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 Cilici ...

: 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 (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

phalange The phalanges (singular: ''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. ...

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 Dicraeosaurids Late Jurassic dinosaurs of North America Dinosaurs of the Morrison Formation Taxa named by Dale Russell Fossil taxa described in 1992 Paleontology in Wyoming