Dystrophaeus Viaemalae
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''Dystrophaeus'' is an extinct
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 ...
of
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 ...
. Its
type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...
and only species is ''Dystrophaeus viaemalae'', named by
Edward Drinker Cope Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontology, paleontologist, comparative anatomy, comparative anatomist, herpetology, herpetologist, and ichthyology, ichthyologist. Born to a wealthy Quaker fam ...
in 1877. Its fossils were found in the Tidwell Member of the
Morrison Formation The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston ...
of Utah. Due to the fragmentary condition of its only known specimen, the affinities of ''Dystrophaeus'' are uncertain, although excavations carried out at the discovery site since 1989 have uncovered more of the original specimen and hold the potential for an improved understanding of the taxon. ''Dystrophaeus viaemalae'' is known from a single fragmentary specimen, 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 ...
USNM 2364. The specimen initially consisted of a partial
dorsal vertebra In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae of intermediate size between the cervical and lumbar ve ...
, a partial
scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...
, a nearly complete
ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...
, a partial
radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...
, and three
metacarpals In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular skeleton, appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones (wrist, wris ...
. More recent excavations have discovered additional parts of the same specimen, including a phalanx, teeth, and additional vertebrae from the back and tail. The specimen was found in the Tidwell Member of the
Morrison Formation The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston ...
and is approximately 158 million years old, making it the oldest species of sauropod from the Morrison Formation by several million years.


History


Discovery and naming

Few dinosaur fossils had been collected in the
American West The Western United States (also called the American West, the Western States, the Far West, the Western territories, and the West) is census regions United States Census Bureau As American settlement in the U.S. expanded westward, the mea ...
until the 1850s,Breithaupt, B. H. (1999). The first discoveries of dinosaurs in the American West. ''Vertebrate Paleontology in Utah'', 59-65. with expeditions by naturalists like
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 becoming a professor of natural history at Swarth ...
and
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 A ...
in South Dakota and Montana finding fragmentary fossils, mostly teeth, from dinosaurs in 1855 and 1856. The next discovery came accidentally in 1859 when while Captain John N. Macomb was leading a U.S. Army Engineers survey from Santa Fe to the confluence of the
Green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a com ...
and Colorado Rivers, his crew camped south of what is now
Moab, Utah Moab () is the largest city in and the county seat of Grand County in eastern Utah in the western United States, known for its dramatic scenery. The population was 5,366 at the 2020 census. Moab attracts many tourists annually, mostly visitor ...
. In August, a geologist from the crew named
John Strong Newberry John Strong Newberry (December 22, 1822 – December 7, 1892) was an American physician, geologist and paleontologist. He participated as a naturalist and surgeon on three expeditions to explore and survey the western United States. During the C ...
, unearthed several large fossil bones in sandstone rocks elevated in a canyon wall near the camp. Newberry successfully excavated several of the bones with several other crew members while using poor equipment, but several fossils remained in the sandstone rocks due to the team's time constraints of the expedition. The fossils excavated consisted of only one partial skeleton, 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 ...
USNM 2364, which includes a long
humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...
, a possible
ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...
, a
scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...
, a partial
radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...
, and some
metacarpals In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular skeleton, appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones (wrist, wris ...
. The specimen was from the
Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...
Morrison Formation The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston ...
, and was notably from the older Tidwell Member of the Oxfordian, and is one of the few dinosaurs known from the member. The fossils were turned over to
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 becoming a professor of natural history at Swarth ...
in Philadelphia, and later to
Edward Drinker Cope Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontology, paleontologist, comparative anatomy, comparative anatomist, herpetology, herpetologist, and ichthyology, ichthyologist. Born to a wealthy Quaker fam ...
, who described them in the ''Proceedings of the American Philosophical Society'' in 1877. Cope named the remains ''Dystrophaeus viaemalae'', the genus name means "coarse joint" from Greek ''dys'', "bad", and ''stropheus'', "joint", a reference to the pitted joint surfaces serving as an attachment for
cartilage Cartilage is a resilient and smooth type of connective tissue. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints ...
. 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 ...
reads as
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 ...
''viae malae'', "of the bad road", a reference to the various arduous routes taken to find, reach and salvage the remains.


Rediscovery

''Dystrophaeus'' received little attention besides its classification since before the 1970s until amateur Moab geologist Fran Barnes attempted to rediscover Newberry's original ''Dystrophaeus'' locality, eventually rediscovering the site in 1987. The rediscovery was confirmed by David Gillette and in 2014 John Foster created the ''Dystrophaeus'' Project, which launched another expedition to the site the same year to recover additional material left behind by the Macomb Expedition. Another expedition was launched in 2017, the two recent expeditions recovering various elements including teeth, vertebrae, and additional limb bones, though many remain unprepared.


Description

Not much can be surmised due to the fragmentary nature and uncertain phylogenetic position of ''Dystrophaeus''. As a sauropod, ''Dystrophaeus'' would have been a large, long-necked herbivore. It would have been of moderate size for a sauropod; it may have been approximately long, with a mass of roughly . The
ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...
of the only known specimen is long; for comparison, the ulna of the holotype of '' Camarasaurus lewisi'' is . The scapula bears a subtriangular projection on the base of the scapular blade, which Tschopp et al.'s analysis found to be an
autapomorphy In phylogenetics, an autapomorphy is a distinctive feature, known as a Synapomorphy, derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or Outgroup (cladistics), outgroup taxa, not ...
of the taxon, though this trait also occurs in various other sauropods. The ulna is very slender, and the metacarpals are relatively short.


Classification

The classification of ''Dystrophaeus'' has been rather confusing. Cope in 1877 merely concluded it was some Triassic dinosaur. Henri-Émile Sauvage in 1882 understood it was a sauropod, assigning it to the Atlantosauridae.
Othniel Charles Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of paleontology. A prolific fossil collector, Marsh was one of the preeminent paleontologists of the nineteenth century. Among his legacies are the discovery or ...
however, in 1895 stated it belonged to the
Stegosauridae Stegosauria is a group of herbivorous ornithischian dinosaurs that lived during the Jurassic and early Cretaceous periods. Stegosaurian fossils have been found mostly in the Northern Hemisphere (North America, Europe and Asia), Africa and South ...
.
Friedrich von Huene Baron Friedrich Richard von Hoyningen-Huene (22 March 1875 – 4 April 1969) was a German nobleman paleontologist who described a large number of dinosaurs, more than anyone else in 20th-century Europe. He studied a range of Permo-Carbonife ...
, the first to determine it was of Jurassic age, in 1904 created a special family for it, the Dystrophaeidae, which he assumed to be herbivorous
theropods 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 ...
. Only in 1908 von Huene realised his mistake and classified it in the sauropod family
Cetiosauridae Cetiosauridae is a family of sauropod dinosaurs which was first proposed by Richard Lydekker in 1888. While traditionally a wastebasket taxon containing various unrelated species, some recent studies have found that it may represent a natural cla ...
, refining this in 1927 to the
Cardiodon ''Cardiodon'' (meaning "heart tooth", in reference to the shape) was a herbivorous genus of sauropod dinosaur, based on a tooth from the late Bathonian-age Middle Jurassic Forest Marble Formation of Wiltshire, England. Historically, it is very ...
tinae.
Alfred Romer Alfred Sherwood Romer (December 28, 1894 – November 5, 1973) was an American paleontologist and biologist and a specialist in vertebrate evolution. Biography Alfred Romer was born in White Plains, New York, the son of Harry Houston Romer an ...
in 1966 put it in the
Brachiosauridae 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 le ...
, in a subfamily Cetiosaurinae. More recently, an analysis by David Gillette concluded it was a member of the
Diplodocidae 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 ...
.Gillette, D.D., 1996, "Stratigraphic position of the sauropod ''Dystrophaeus viaemalae'' Cope and its evolutionary implications", In: Morales, Michael, editor, ''The continental Jurassic'', Museum of Northern Arizona Bulletin 60: 59-68 Tschopp and colleagues included ''D. viaemalae'' in a phylogenetic analysis in 2015, and found its phylogenetic position to be highly unstable. They concluded that positions in Dicraeosauridae or Camarasauridae were equally well-supported, but that it was probably not a diplodocid, and concluded that further study was required to determine its affinities. However, many researchers consider the taxon to be 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 ...
''. Newer finds of ''Dystrophaeus'' have led paleontologist John Foster and colleagues to suggest it was most closely related to Macronarian or Eusauropod dinosaurs, although much material has yet to be prepared. According to Foster, the newly found caudal vertebrae rule out diplodocid affinities.


Notes


References

{{Taxonbar, from=Q1990928 Sauropoda Dinosaur genera Tithonian dinosaurs Morrison Formation Fossil taxa described in 1877 Taxa named by Edward Drinker Cope Dinosaurs of the United States