Dystrophaeus

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Dystrophaeus
Temporal range: Late Jurassic, 158  Ma
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Dystrophaeus viaemalae Cope, 1877.jpg
Metacarpals from the holotype (USNM 2364)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade:† Sauropodomorpha
Clade:† Sauropoda
Genus:† Dystrophaeus
Cope, 1877
Species:
†D. viaemalae
Binomial name
†Dystrophaeus viaemalae
Cope, 1877

Dystrophaeus is an extinct genus of sauropod dinosaur. Its type and only species is Dystrophaeus viaemalae, named by Edward Drinker Cope in 1877. Its fossils were found in the Tidwell Member of the Morrison Formation 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.

Contents

Dystrophaeus viaemalae is known from a single fragmentary specimen, the holotype USNM 2364. The specimen initially consisted of a partial dorsal vertebra, a partial scapula, a nearly complete ulna, [lower-alpha 1] a partial radius, and three metacarpals. [1] More recent excavations have discovered additional parts of the same specimen, including a phalanx, [2] teeth, and additional vertebrae from the back and tail. [3] The specimen was found in the Tidwell Member of the Morrison Formation and is approximately 158 million years old, making it the oldest species of sauropod from the Morrison Formation by several million years. [3]

History

Discovery and naming

Illustration of John Strong Newberry, discoverer of Dystrophaeus circa 1890s. John Strong Newberry.jpg
Illustration of John Strong Newberry, discoverer of Dystrophaeus circa 1890s.

Few dinosaur fossils had been collected in the American West until the 1850s, [4] with expeditions by naturalists like Joseph Leidy and Ferdinand Vandeveer Hayden in South Dakota and Montana finding fragmentary fossils, mostly teeth, from dinosaurs in 1855 and 1856. [4] 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 and Colorado Rivers, his crew camped south of what is now Moab, Utah. [5] [6] In August, a geologist from the crew named John Strong Newberry, unearthed several large fossil bones in sandstone rocks elevated in a canyon wall near the camp. [5] [6] 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. [7] [6] The fossils excavated consisted of only one partial skeleton, the holotype USNM 2364, which includes a 76.5 centimetres (30.1 in) long humerus, a possible ulna, a scapula, a partial radius, and some metacarpals. The specimen was from the Late Jurassic Morrison Formation, and was notably from the older Tidwell Member of the Oxfordian, [6] and is one of the few dinosaurs known from the member. [6] The fossils were turned over to Joseph Leidy in Philadelphia, and later to Edward Drinker Cope, 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. [5] The specific name reads as Latin viae malae, "of the bad road", a reference to the various arduous routes taken to find, reach and salvage the remains. [5]

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. [6] The rediscovery was confirmed by David Gillette and in 2014 John Foster created the Dystrophaeus Project, [8] which launched another expedition to the site the same year to recover additional material left behind by the Macomb Expedition. [8] [6] Another expedition was launched in 2017, the two recent expeditions recovering various elements including teeth, vertebrae, and additional limb bones, though many remain unprepared. [6]

Description

Ulna of the holotype Dystrophaeus viaemalae holotype ulna.png
Ulna of the holotype

Not much can be surmised due to the fragmentary nature and uncertain phylogenetic position of Dystrophaeus. [6] [1] 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 13 metres (43 ft) long, [lower-alpha 2] with a mass of roughly 7–12 tonnes (7.7–13.2 short tons). [lower-alpha 3] The ulna of the only known specimen is 76.4 centimetres (30.1 in) long; [12] for comparison, the ulna of the holotype of Camarasaurus lewisi is 77.5 centimetres (30.5 in). [13] The scapula bears a subtriangular projection on the base of the scapular blade, which Tschopp et al.'s analysis found to be an autapomorphy of the taxon, though this trait also occurs in various other sauropods. [1] The ulna is very slender, and the metacarpals are relatively short. [14]

Classification

The classification of Dystrophaeus has been rather confusing. Cope in 1877 merely concluded it was some Triassic dinosaur. [5] Henri-Émile Sauvage in 1882 understood it was a sauropod, assigning it to the Atlantosauridae. Othniel Charles Marsh however, in 1895 stated it belonged to the Stegosauridae. Friedrich von Huene, 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. [12] Only in 1908 von Huene realised his mistake and classified it in the sauropod family Cetiosauridae, refining this in 1927 to the Cardiodontinae. Alfred Romer in 1966 put it in the Brachiosauridae, in a subfamily Cetiosaurinae.

More recently, an analysis by David Gillette concluded it was a member of the Diplodocidae. [2] [15] 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. [1] However, many researchers consider the taxon to be a nomen dubium . [1] Newer finds of Dystrophaeus have led paleontologist John Foster and colleagues to suggest it was most closely related to Macronarian or Eusauropod dinosaurs, [6] although much material has yet to be prepared. [6] According to Foster, the newly found caudal vertebrae rule out diplodocid affinities. [3]

Notes

  1. ↑ Initially misidentified as a humerus by Cope
  2. ↑ Paul (2016) estimated its length as 13 m (43 feet). [9] Holtz (2007) regarded its length as unknown. [10]
  3. ↑ Paul (2016) estimated its mass as 7 tonnes. [9] Foster estimated its mass as approximately 12,000 kg in 2003, based on comparison to diplodocids. [11] In 2020, no longer considering it to have affinities to diplodocids, he estimated its mass as approximately 10,000 kg. [3] Holtz, refraining from giving numerical estimates to avoid false precision, simply indicated it was about the size of an elephant. [10]

Related Research Articles

<i>Apatosaurus</i> Sauropod dinosaur genus from Late Jurassic period

Apatosaurus is a genus of herbivorous sauropod dinosaur that lived in North America during the Late Jurassic period. Othniel Charles Marsh described and named the first-known species, A. ajax, in 1877, and a second species, A. louisae, was discovered and named by William H. Holland in 1916. Apatosaurus lived about 152 to 151 million years ago (mya), during the late Kimmeridgian to early Tithonian age, and are now known from fossils in the Morrison Formation of modern-day Colorado, Oklahoma, New Mexico, Wyoming, and Utah in the United States. Apatosaurus had an average length of 21–23 m (69–75 ft), and an average mass of 16.4–22.4 t. A few specimens indicate a maximum length of 11–30% greater than average and a mass of approximately 33 t.

<i>Supersaurus</i> Extinct genus of dinosaurs

Supersaurus is a genus of diplodocid sauropod dinosaur that lived in North America during the Late Jurassic period. The type species, S. vivianae, was first discovered by Vivian Jones of Delta, Colorado, in the middle Morrison Formation of Colorado in 1972. The fossil remains came from the Brushy Basin Member of the formation, dating between 153 to 145 million years ago. It is among the longest dinosaurs ever discovered, with the three known specimens reaching 33–40 meters (108–131 ft) in length, with the largest individual possibly exceeding 40 meters (130 ft) in size. Mass estimates for the WDC and BYU specimens tend to be around 35–44 metric tons in body mass. A potential second species, S. lourinhanensis (Dinheirosaurus), is known from Portugal and has been dated to a similar time.

<i>Camarasaurus</i> Camarasaurid sauropod dinosaur genus from Late Jurassic Period

Camarasaurus was a genus of quadrupedal, herbivorous dinosaurs and is the most common North American sauropod fossil. Its fossil remains have been found in the Morrison Formation, dating to the Late Jurassic epoch, between 155 and 145 million years ago.

<span class="mw-page-title-main">Diplodocidae</span> Extinct family of dinosaurs

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<span class="mw-page-title-main">Morrison Formation</span> Rock formation in the western United States

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, siltstone, and limestone and is light gray, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.

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<i>Cetiosauriscus</i> Genus of reptiles (fossil)

Cetiosauriscus is a genus of sauropod dinosaur that lived between 166 and 164 million years ago during the Callovian in what is now England. A herbivore, Cetiosauriscus had – by sauropod standards – a moderately long tail, and longer forelimbs, making them as long as its hindlimbs. It has been estimated as about 15 m (49 ft) long and between 4 and 10 t in weight.

<i>Brontosaurus</i> Genus of diplodocid sauropod dinosaur

Brontosaurus is a genus of herbivorous sauropod dinosaur that lived in present-day United States during the Late Jurassic period. It was described by American paleontologist Othniel Charles Marsh in 1879, the type species being dubbed B. excelsus, based on a partial skeleton lacking a skull found in Como Bluff, Wyoming. In subsequent years, two more species of Brontosaurus were named: B. parvus in 1902 and B. yahnahpin in 1994. Brontosaurus lived about 156 to 146 million years ago (mya) during the Kimmeridgian and Tithonian ages in the Morrison Formation of what is now Utah and Wyoming. For decades, the animal was thought to have been a taxonomic synonym of its close relative Apatosaurus, but a 2015 study by Emmanuel Tschopp and colleagues found it to be distinct. It has seen widespread representation in popular culture, being the archetypal "long-necked" dinosaur in general media.

Suuwassea is a genus of dicraeosaurid sauropod dinosaur found in the Upper Jurassic strata of the Morrison Formation, located in southern Carbon County, Montana, United States. The fossil remains were recovered in a series of expeditions during a period spanning the years 1999 and 2000 and were described by J.D. Harris and Peter Dodson in 2004. They consist of a disarticulated but associated partial skeleton, including partial vertebral series and limb bones.

<span class="mw-page-title-main">Dicraeosauridae</span> Extinct family of dinosaurs

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<i>Australodocus</i> Extinct genus of dinosaurs

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<i>Camarasaurus supremus</i> Species of sauropod dinosaur

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<span class="mw-page-title-main">Apatosaurinae</span> Extinct subfamily of dinosaurs

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<i>Camarasaurus lentus</i> Species of sauropod

Camarasaurus lentus is an extinct species of sauropod dinosaur that lived during the Jurassic period in what is now the western United States. It is one of the four valid species of the well-known genus Camarasaurus. C. lentus fossils have been found in Wyoming, Colorado, and Utah. It is the species of Camarasaurus found in Dinosaur National Monument and the middle layers of the Morrison Formation. Camarasaurus lentus is among the best-known sauropod species, with many specimens known. A juvenile specimen of C. lentus, CM 11338, is the most complete sauropod fossil ever discovered.

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<i>Diplodocus</i> Genus of diplodocid sauropod dinosaurs (fossil)

Diplodocus is an extinct genus of diplodocid sauropod dinosaurs known from the Late Jurassic of North America. The first fossils of Diplodocus were discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek διπλός (diplos) "double" and δοκός (dokos) "beam", in reference to the double-beamed chevron bones located in the underside of the tail, which were then considered unique.

<i>Kaatedocus</i> Extinct genus of reptiles

Kaatedocus is a genus of flagellicaudatan sauropod known from the middle Late Jurassic of northern Wyoming, United States. It is known from well-preserved skull and cervical vertebrae which were collected in the lower part of the Morrison Formation. The type and only species is Kaatedocus siberi, described in 2012 by Emanuel Tschopp and Octávio Mateus.

<i>Galeamopus</i> Extinct genus of dinosaurs

Galeamopus is a genus of herbivorous diplodocid sauropod dinosaurs. It contains two known species: Galeamopus hayi, known from the Late Jurassic lower Morrison Formation of Wyoming, United States, and Galeamopus pabsti, known from the Late Jurassic fossils from Wyoming and Colorado. The type species is known from one of the most well preserved diplodocid fossils, a nearly complete skeleton with associated skull.

References

  1. 1 2 3 4 5 Tschopp, Emanuel; Mateus, Octávio; Benson, Roger B. J. (2015-04-07). "A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)". PeerJ. 3: e857. doi: 10.7717/peerj.857 . ISSN   2167-8359. PMC   4393826 . PMID   25870766.
  2. 1 2 Gillette, D.D., 1996, "Origin and early evolution of the sauropod dinosaurs of North America -- the type locality and stratigraphic position of Dystrophaeus viaemalae Cope 1877", In: Huffman, A.C., Lund, W.R., and Godwin, L.H. (eds), Geology and resources of the Paradox Basin, Utah Geological Association Guidebook, 25: 313-324
  3. 1 2 3 4 Foster, John Russell (2020). Jurassic West: the dinosaurs of the Morrison Formation and their world. Life of the past (2 ed.). Bloomington, Indiana: Indiana University Press. ISBN   978-0-253-05158-5.
  4. 1 2 Breithaupt, B. H. (1999). The first discoveries of dinosaurs in the American West. Vertebrate Paleontology in Utah, 59-65.
  5. 1 2 3 4 5 Cope, E. D. (1877). "On a dinosaurian from the Trias of Utah". Proceedings of the American Philosophical Society. 16 (99): 579–584. JSTOR   982482.
  6. 1 2 3 4 5 6 7 8 9 10 11 Foster, J. R.; Irmis, R. B.; Trujillo, K. C.; McMullen, S. K.; Gillette, D. D. (2016). "Dystrophaeus viaemalae Cope from the basal Morrison Formation of Utah: Implications for the origin of eusauropods in North America". Journal of Vertebrate Paleontology, Program and Abstracts: 138.
  7. ↑ "Skeleton of dinosaur first unearthed 155 years ago now being excavated". KSTU. 2014-08-29. Retrieved 2022-03-19.
  8. 1 2 Foster, R. H. (2014). "The Dystrophaeus Project".
  9. 1 2 Paul, Gregory S. (2016). The Princeton Field Guide to Dinosaurs. Princeton University Press. p. 196. ISBN   978-1-78684-190-2. OCLC   985402380.
  10. 1 2 Holtz, Thomas R. (23 October 2007). Dinosaurs: the most complete, up-to-date encyclopedia for dinosaur lovers of all ages. New York: Random House. ISBN   978-0-375-82419-7.
  11. ↑ Foster, John R. (2003). "Paleoecological Analysis of the Vertebrate Fauna of the Morrison Formation (Upper Jurassic), Rocky Mountain Region, U.S.A.". New Mexico Museum of Natural History and Science Bulletin. 23: 1–95. ISSN   1524-4156.
  12. 1 2 von Huene, Friedrich (1904). "Dystrophaeus viaemalae Cope in neuer Beleuchtung". Neues Jahrbuch für Geologie und Paläontologie Beilage-Band. 19: 319–333.
  13. ↑ McIntosh, John S; Miller, Wade E; Stadtman, Kenneth L; Gillette, David D (1996). "The osteology of Camarasaurus lewisi (Jensen, 1988)". Brigham Young University Geology Studies. 41: 73–115. ISSN   0068-1016.
  14. ↑ McIntosh, J. S. (1990). "Sauropoda". In Weishampel, D. B.; Dodson, P.; Osmólska, H. (eds.). The Dinosauria (1 ed.). Berkeley: University of California Press. pp. 345–401.
  15. ↑ 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
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