Camarasaurus

Camarasaurus (/ˌkæmərəˈsɔːrəs/ KAM-ər-ə-SAWR-əs) was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America. Its fossil remains have been found in the Morrison Formation of Colorado and Utah, dating to the Late Jurassic epoch (Kimmeridgian to Tithonian stages), between 155 and 145 million years ago.

Camarasaurus presented a distinctive cranial profile of a blunt snout and an arched skull that was remarkably square. It likely travelled in herds, or at least in family groups.

The name means "chambered lizard", referring to the hollow chambers in its vertebrae (Greek καμαρα/kamara meaning "vaulted chamber", or anything with an arched cover, and σαυρος/sauros meaning "lizard").

Camarasaurus
Temporal range: Late Jurassic, 155–145 Ma
MUJA-Sauropod
Mounted skeletal cast at the Jurassic Museum of Asturias
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Clade: Camarasauromorpha
Clade: Camarasauridae
Subfamily: Camarasaurinae
Cope, 1878
Genus: Camarasaurus
Cope, 1877a
Type species
Camarasaurus supremus
Cope, 1877a
Species
  • C. supremus Cope, 1877a
  • C. grandis (Marsh, 1877)
  • C. lentus (Marsh, 1889)
Synonyms
  • Caulodon Cope, 1877c
  • Morosaurus Marsh, 1878
  • Uintasaurus Holland, 1924

Description

Camarasaurus Size Comparison by PaleoGeek
Scale diagram of three known species of Camarasaurus
Camarasaurs1
Restoration of a C. supremus herd

Camarasaurus is among the most common and frequently well-preserved sauropod dinosaurs. The maximum size of the most common species, C. lentus, was about 15 meters (49 ft) in length. The largest species, C. supremus, reached a maximum length of 23 meters (75 ft) and maximum estimated weight of 47 tonnes (51.8 tons).[1][2]

The arched skull of Camarasaurus was remarkably square and the blunt snout had many fenestrae, though it was sturdy and is frequently recovered in good condition by paleontologists. The 19 centimeter long (7.5 in) teeth were shaped like chisels (spatulate) and arranged evenly along the jaw. The strength of the teeth indicates that Camarasaurus probably ate coarser plant material than the slender-toothed diplodocids.

Each front limb bore five toes, with the inner toe having a large sharpened claw. Like most sauropods, the front limbs were shorter than the hind legs, but the high position of the shoulders meant there was little slope in the back.

Serving the purpose of weight-saving, as seen in other sauropods, many of the vertebrae were hollowed out, or pneumatic; that is, the vertebrae were riddled with passages and cavities for an intricate system of air sacs connected to the lungs. This feature was little understood at the time Camarasaurus was discovered, but its structure was the inspiration for the creature's name, meaning "chambered lizard". The neck and counterbalancing tail were shorter than usual for a sauropod of this size. Camarasaurus, like certain other sauropods, had an enlargement of the spinal cord near the hips. Palaeontologists originally believed this to be a second brain, perhaps necessary to co-ordinate such a huge creature. Indeed, while it would have been an area of intensive nervous system—probably reflex, or automatic—activity, it was not, however, a brain; and such enlargements are frequently found to some degree in vertebrate animals.

Camarasaurus grandis had a more robust radius than fellow sauropod Venenosaurus.[3]

A specimen of Camarasaurus called SMA 0002 (which has also been assigned to Cathetosaurus) from Wyoming’s Howe-Stephens Quarry, referred to as "E.T.", shows evidence of soft tissue. Along the jaw line, ossified remains of what appear to have been the animal's gums have been recovered, indicating that Camarasaurus had deep-set teeth covered by gums, with only the tips of the crowns protruding. The teeth were upon death, pushed further out from their sockets as the gums retracted dried, and tightened through decay. The examinations of the specimen also indicate that the teeth were covered by tough outer scales and possibly a beak of some variety, though this is not known for certain.[4]

History of discovery

OsbornMook1921-plate-LXXXII-ryder-camarasaurus
The earliest known skeletal reconstruction of a sauropod dinosaur: C. supremus by John A. Ryder, 1877
Sharp naturalhistory1921 camarasaurus
Reconstruction of the same species based on more complete material by E.S. Christman, 1921

The first record of Camarasaurus comes from 1877, when a few scattered vertebrae were located in Colorado, by Oramel W. Lucas. Pursuing his long-running and acrimonious competition (known as the Bone Wars) with Othniel Charles Marsh, the paleontologist Edward Drinker Cope paid for the bones and, moving quickly, named them in the same year. For his part, Marsh later named some of his sauropod findings Morosaurus grandis, but most paleontologists today consider them to be a species of Camarasaurus [1]. Such naming conflicts were common between the two rival dinosaur hunters, the most famous being Brontosaurus and Apatosaurus.

It was not until 1925 that a complete skeleton of Camarasaurus was described, by Charles W. Gilmore. Because, however, it was the skeleton from a young Camarasaurus, many illustrations from the time show the dinosaur to be much smaller than it is now known to be.

Species

Cope Quarry
C. supremus quarry in 1877

The type species of Camarasaurus is Cope's original species, C. supremus (meaning "the biggest chambered lizard"), named in 1877. Other species since discovered include C. grandis ("grand chambered lizard") in 1877, C. lentus in 1889, and C. lewisi (originally described as a new genus Cathetosaurus) in 1988.

C. supremus, as its name suggests, is the largest known species of Camarasaurus and one of the most massive sauropods known from the late Jurassic Morrison Formation. Except for its huge size, it was nearly indistinguishable from C. lentus. C. supremus was not typical of the genus as a whole, and is known only from the latest, uppermost parts of the formation. Both C. grandis and C. lentus were smaller as well as occurring in the earlier stages of the Morrison.

Stratigraphic evidence suggests that chronological sequence aligned with the physical differences between the three species; and it describes an evolutionary progression within the Morrison Formation. C. grandis is the oldest species and occurred in the lowest rock layers of the Morrison. C. lentus appeared later, co-existing with C. grandis for several million years, possibly due to different ecological niches as suggested by differences in the spinal anatomy of the two species. At a later stage, C. grandis disappeared from the rock record, leaving only C. lentus. Then C. lentus too disappeared; at the same time C. supremus appeared in the uppermost layers. This immediate succession of species, as well as the very close similarity between the two, suggests that C. supremus may have evolved directly from C. lentus, representing a larger, later-surviving population of animals.[5]

Camarasaurus lewisi species was originally named as Cathetosaurus lewisi and later synonymized with Camarasaurus. A 2013 analysis split the two genera again.[6]

Classification

Camarasaurus skeletal
Skeletal diagram of C. grandis

The scientific classification of Camarasaurus, using the Linnaean system, is given in the box to the upper right but, among palaeontologists, this method of taxonomic classification of dinosaurs is being supplanted by the cladistics inspired phylogenetic taxonomy.

Simplified cladogram of Macronaria after D'Emic (2012) is shown below:[7]

Macronaria 

Camarasaurus

Tehuelchesaurus

Titanosauriformes 

Brachiosauridae

Somphospondyli 

Euhelopodidae

Chubutisaurus

Titanosauria

Camarasaurus is considered to be a basal macronarian, more closely related to the common ancestor of all macronarians than to more derived forms like Brachiosaurus.

Paleobiology

Camarasaurus lentus skull cast - Natural History Museum of Utah - DSC07235
C. lentus skull

Herding

There is a fossil record of two adults and a 12.2 meter (40 ft) long juvenile that died together in the Late Jurassic epoch, approximately 150 million years ago (in northeast Wyoming, United States).[note 1] It is assumed that their bodies were washed by a river in spate (flood) to their final resting place in alluvial mud. The scenario suggests that Camarasaurus traveled in herds or, at least, in family groups. At other sites fossil camarasaur eggs have been found in lines, rather than in neatly arranged nests as with some other dinosaurs, which suggests that, like most sauropods, Camarasaurus did not tend its young.

Feeding

Previously, scientists have suggested that Camarasaurus and other sauropods may have swallowed gastroliths (stones) to help grind the food in the stomach, regurgitating or passing them when they became too smooth. More recent analysis, however, of the evidence for stomach stones suggests this was not the case. The strong, robust teeth of Camarasaurus were more developed than those of most sauropods and were replaced on average every 62 days (M. D'Emic et al.), indicating that Camarasaurus may have masticated food in its mouth to some degree before swallowing.[8] Other findings indicate that Camarasaurus preferred vegetation different from other sauropods, allowing them to share the same environment without competing.[9]

Growth

Long-bone histology enables researchers to estimate the age that a specific individual reached. A study by Griebeler et al. (2013) examined long bone histological data and concluded that the Camarasaurus sp. CM 36664 weighed 14,247 kilograms (15.7 short tons), reached sexual maturity at 20 years and died at age 26.[10]

Metabolism

Eagle et al. performed clumped isotope thermometry on the enamel covering the teeth of various Jurassic sauropods, including Camarasaurus. Temperatures of 32.4–36.9 °C (90.3–98.4 °F) were obtained, which is comparable to that of modern mammals.[11]

Paleopathology

Camarasaurus lentus Carnegie
The first known complete skeleton, C. lentus, in a "death pose"

A Camarasaurus pelvis recovered from Dinosaur National Monument in Utah shows gouging attributed to Allosaurus.[12]

In 1992, a partial Camarasaurus grandis skeleton was discovered at the Bryan Small Stegosaurus Quarry of the Morrison Formation near Canon City, Colorado.[13] This specimen preserved a partial right humerus catalogued as DMNH 2908 as well as associated vertebrae from the back and tail.[13] In 2001, Lorie McWhinney, Kenneth Carpenter, and Bruce Rothschild published a description of a pathology observed on the humerus.[14] They noted a juxtacortical lesion 25 by 18 cm wide made of bone that resembled woven fibers.[15] Although woven bone forms in accessory dental bone, in other locations it is a sign of injury or illness.[15] The woven bone's "undulating fibrous bundles" were observed oriented in the direction of the M. brachialis.[15] The lesion's fusion and lack of porosity at its near and far ends indicate the periostitis was inactive or healed.[15] McWhinney and the other researchers argued that this injury would have been a continuous source of hardship for the animal.[16] It would have exerted pressure on the muscles.[14] This pressure would have compressed the muscles' blood vessels and nerves, reducing the range of motion of both the limb's flexor and extensor muscles.[14] This effect would have hindered the M. brachialis, M. brachoradialis, and to a lesser degree the M. biceps brachii to the lesion's position on the humerus.[14] The researchers inferred that the inflammation of the muscles and periosteum would have caused additional complications in the lower region of the forelimb as well.[17] The lesion would also have caused long-term fasciitis and myosistis.[14] The cumulative effect of these pathological processes would have moderate to severe effects on the ability of the limb to move and "made everyday activities such as foraging for food and escaping predators harder to accomplish."[16]

To help determine the cause of the pathology, McWhinney and the other researchers performed a CT scan in 3 mm increments.[18] The CT scan found that the mass had a consistent radiodensity and was separated from the cortex of the bone by a radioleucent line.[19] No evidence of stress fracture or infectious processes like osteomyelitis or infectious periostitis.[18] They also ruled out osteochondroma because the axis of the spur is 25 degrees relative to the vertical axis of the humerus, whereas an osteochondroma would have formed at 90 degrees to the axis of the humerus.[15] Other candidates identified by the scientists for the origin of the spur-bearing lesion included:

  1. Hypertrophic osteoarthropathy – Although this was ruled out by the presence of the spur-like process.[20]
  2. Osteoid osteoma – But this wouldn't explain the spur or osteoblastic reaction.[21]
  3. Shinsplints or tibial stress syndrome – A possible origin, as many symptoms would be held in common, but shinsplints wouldn't explain the spur.[22]
  4. Myositis ossificans traumatica (circumscripta) – Possible, but unlikely source.[23]
  5. Avulsion injury – McWhinney and the other researchers considered an avulsion injury caused by "repetitive overexertion of the muscles" to be the most likely source for the lesion on the humerus.[14] The researchers believed the lesion to have originated with the avulsion of the M. brachialis causing the formation of "a downward sloping elliptical mass".[16] The bone spur was caused by an osteoblastic response following a tear at the base of the M. brachioradialis caused by its flexor motion.[16]

Paleoecology

Habitat

Dinosaur National Monument Camarasaurus
Skull in mudstone matrix, Dinosaur National Monument

The Morrison Formation, situated along the eastern flank of the Rocky Mountains, is home to a fossil rich stretch of Late Jurassic rock. A large number of dinosaur species can be found here, including relatives of Camarasaurus such as Diplodocus, Apatosaurus and Brachiosaurus; but camarasaurs are the most abundant of the dinosaurs in the formation.[24] There have been a number of complete skeletons recovered from Colorado, New Mexico, Utah, and Wyoming, usually found in stratigraphic zones 2-6.[25] According to radiometric dating, the Morrison sedimentary layers range between 156.3 million years old (mya) at the base, to 146.8 mya at the top, which places it in the late Oxfordian, Kimmeridgian, and early Tithonian stages of the Late Jurassic period.[26][27] Its environment is interpreted as semiarid with distinct wet and dry seasons.

Dinosaur and trace fossils are found particularly in the Morrison Basin, which stretches from New Mexico to Alberta and Saskatchewan and was formed when the precursors to the Front Range of the Rocky Mountains started pushing up to the west. Eroded material from their east-facing drainage basins was carried by streams and rivers and deposited in swampy lowlands, lakes, river channels and floodplains.[28] The formation is similar in age to the Solnhofen Limestone Formation in Germany and the Tendaguru Formation in Tanzania. In 1877 it became the center of the Bone Wars, a fossil-collecting rivalry between early paleontologists Othniel Charles Marsh and Edward Drinker Cope.

Paleofauna

The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs such as Barosaurus, Diplodocus, Apatosaurus, Brontosaurus, and Brachiosaurus. Dinosaurs living alongside Camarasaurus included the herbivorous ornithischians Camptosaurus, Gargoyleosaurus, Dryosaurus, Stegosaurus and Othnielosaurus. Predators in this paleoenvironment included the theropods Saurophaganax, Torvosaurus, Ceratosaurus, Marshosaurus, Stokesosaurus, Ornitholestes;[29] and Allosaurus, which accounted for up to 75% of theropod specimens, and was at the top trophic level of the Morrison food web.[30][31] Camarasaurus is commonly found at the same sites as Allosaurus, Apatosaurus, Stegosaurus, and Diplodocus.[32]

Other organisms in this region included bivalves, snails, ray-finned fishes, frogs, salamanders, turtles, sphenodonts, lizards, terrestrial and aquatic crocodylomorphans, and several species of pterosaur like Harpactognathus and Mesadactylus. Early mammals present were docodonts (such as Docodon), multituberculates, symmetrodonts, and triconodonts. The flora of the period has been revealed by fossils of green algae, fungi, mosses, horsetails, cycads, ginkgoes, and several families of conifers. Vegetation varied from river-lining forests of tree ferns, and ferns (gallery forests), to fern savannas with occasional trees such as the Araucaria-like conifer Brachyphyllum.[33]

Notes

  1. ^ Excavated by the Division of Vertebrate Paleontology of the University of Kansas Natural History Museum and Biodiversity Center, during the 1997 and 1998 field seasons.

References

  1. ^ Benton, Michael J. (2012). Prehistoric Life. Edinburgh, Scotland: Dorling Kindersley. pp. 270–271. ISBN 978-0-7566-9910-9.
  2. ^ Foster, John (2007). Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 201, 248. ISBN 978-0-253-34870-8.
  3. ^ "Forelimb", Tidwell, Carpenter, and Meyer (2001). Page 148.
  4. ^ "Looking Camarasaurus in the Mouth".
  5. ^ "Camarasaurus grandis," Foster (2007). Page 204.
  6. ^ Mateus, O., & Tschopp E. (2013). Cathetosaurus as a valid sauropod genus and comparisons with Camarasaurus. Journal of Vertebrate Paleontology, Program and Abstracts, 2013. 173.
  7. ^ D'Emic, M. D. (2012). "The early evolution of titanosauriform sauropod dinosaurs". Zoological Journal of the Linnean Society. 166 (3): 624–671. doi:10.1111/j.1096-3642.2012.00853.x.
  8. ^ Wings and Sander (2006).
  9. ^ "High tooth replacement rates in largest dinosaurs contributed to their evolutionary success".
  10. ^ Griebeler, EM; Klein, N; Sander, PM (2013). "Aging, Maturation and Growth of Sauropodomorph Dinosaurs as Deduced from Growth Curves Using Long Bone Histological Data: An Assessment of Methodological Constraints and Solutions". PLoS ONE. 8 (6): e67012. doi:10.1371/journal.pone.0067012. PMC 3686781. PMID 23840575.
  11. ^ Eagle, R.A.; Tütken, T.; Martin, T.S.; Tripati, A.K.; Fricke, H.C.; Connely, M.; Cifelli, R.L.; Eiler, J.M. (2011-07-22). "Dinosaur Body Temperatures Determined from Isotopic (13C-18O) Ordering in Fossil Biominerals". Science. 333 (6041): 443–445. doi:10.1126/science.1206196. PMID 21700837.
  12. ^ "Camarasaurus", Dodson, et al. Page 56.
  13. ^ a b "Introduction", McWhinney, Carpenter, and Rothschild (2001); page 365.
  14. ^ a b c d e f "Abstract", McWhinney, Carpenter, and Rothschild (2001); page 364.
  15. ^ a b c d e "Description", McWhinney, Carpenter, and Rothschild (2001); page 367.
  16. ^ a b c d "Conclusions", McWhinney, Carpenter, and Rothschild (2001); page 376.
  17. ^ "Description", McWhinney, Carpenter, and Rothschild (2001); page 369.
  18. ^ a b "Description", McWhinney, Carpenter, and Rothschild (2001); page 370.
  19. ^ "Description", McWhinney, Carpenter, and Rothschild (2001); pages 370-371.
  20. ^ "Discussion", McWhinney, Carpenter, and Rothschild (2001); pages 373-373.
  21. ^ "Discussion", McWhinney, Carpenter, and Rothschild (2001); pages 373-374.
  22. ^ "Discussion", McWhinney, Carpenter, and Rothschild (2001); page. 374.
  23. ^ "Discussion", McWhinney, Carpenter, and Rothschild (2001); pages 374-375.
  24. ^ "Camarasaurus supremus," Foster (2007). Page 201. "Abundances and Diversities," ibid. Page 248.
  25. ^ "Appendix", Foster (2007). Page 328.
  26. ^ Trujillo, K.C.; Chamberlain, K.R.; Strickland, A. (2006). "Oxfordian U/Pb ages from SHRIMP analysis for the Upper Jurassic Morrison Formation of southeastern Wyoming with implications for biostratigraphic correlations". Geological Society of America Abstracts with Programs. 38 (6): 7.
  27. ^ Bilbey, S.A. (1998). "Cleveland-Lloyd Dinosaur Quarry - age, stratigraphy and depositional environments". In Carpenter, K.; Chure, D.; and Kirkland, J.I. (eds.) (eds.). The Morrison Formation: An Interdisciplinary Study. Modern Geology 22. Taylor and Francis Group. pp. 87–120. ISSN 0026-7775.CS1 maint: Uses editors parameter (link)
  28. ^ Russell, Dale A. (1989). An Odyssey in Time: Dinosaurs of North America. Minocqua, Wisconsin: NorthWord Press. pp. 64–70. ISBN 978-1-55971-038-1.
  29. ^ Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327-329.
  30. ^ Foster, John (2007). "Allosaurus fragilis". Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Bloomington, Indiana: Indiana University Press. pp. 170–176. ISBN 978-0-253-34870-8. OCLC 77830875.
  31. ^ 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. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. p. 29.
  32. ^ Dodson, Peter; Behrensmeyer, A.K.; Bakker, Robert T.; McIntosh, John S. (1980). "Taphonomy and paleoecology of the dinosaur beds of the Jurassic Morrison Formation". Paleobiology. 6 (2): 208–232. doi:10.1017/S0094837300025768.
  33. ^ Carpenter, Kenneth (2006). "Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus". In Foster, John R.; and Lucas, Spencer G. (eds.) (eds.). Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin, 36. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. pp. 131–138.CS1 maint: Uses editors parameter (link)

Sources

External links

Abrosaurus

Abrosaurus (; 'delicate lizard' from the Greek αβρος meaning 'delicate' or 'dainty' and σαυρος meaning 'lizard') is a genus of macronarian sauropod dinosaur from the Middle Jurassic Period of what is now Asia, one of many dinosaurs found at the Dashanpu Quarry in the Sichuan Province of China. Like most sauropods, Abrosaurus was a quadrupedal herbivore but it was rather small for a sauropod, not much more than 30 feet (9 m) long. Its head was boxy and topped with a tall bony arch containing the nostrils.

The generic name meaning 'delicate lizard', refers to the nature of the skull, with large openings separated by thin bony struts. The only named species is now known as A. dongpoi, and is named after eleventh-century Chinese poet Su Shi, also known as Su Dongpo, who was born in Sichuan.

The naming of Abrosaurus has been a long and convuluted process. Abrosaurus was discovered in 1984 and was first described in the 1986 Ph.D. thesis of Chinese paleontologist Ouyang Hui, with the specific name "A. gigantorhinus". However, this does not meet ICZN standards of publication, so the species "Abrosaurus gigantorhinus" counts only as a nomen nudum, although it has been used incorrectly in at least one paper (Zhang & Chen, 1996). Ouyang formally described this species in 1989 under the specific epithet A. dongpoensis, but in biological nomenclature, the Latin suffix -ensis is correctly used only to honor localities and the name has since been revised to include the more correct -i suffix, which is used to honor male individuals (Peng & Shu, 1999). Abrosaurus dongpoi is now the accepted name for this taxon.

Abrosaurus was originally described as a camarasaurid sauropod, and while it may not turn out to be a member of that particular family, further research has indicated that it is a basal member of Macronaria, much like Camarasaurus itself. However, the remains of Abrosaurus have not been fully described, making its exact placement in the sauropod family tree difficult to determine (Upchurch et al., 2004).

The holotype, or original specimen, of Abrosaurus is a fossil skull which is nearly complete and very well preserved. A fragmentary skull and a skeleton have also been referred to this taxon but published description is lacking (Zhang & Chen, 1996). All of the material comes from the famous Dashanpu Quarry near Zigong in China, and is housed in the dinosaur museum there. Abrosaurus and at least 4 other species of sauropod are known from the Lower Shaximiao Formation (also called Xiashaximiao) at Dashanpu. These sediments are dated from the Bathonian to Callovian stages of the Middle Jurassic Period, or about 168 to 161 million years ago.

Amphicoelias

Amphicoelias (, meaning "biconcave", from the Greek ἀμφί, amphi: "on both sides", and κοῖλος, koilos: "hollow, concave") is a genus of herbivorous sauropod dinosaur that lived approximately 150 million years ago during the Tithonian (Late Jurassic Period) of what is now Colorado, United States. A herbivore, Amphicoelias was moderately sized at about 25 m (82 ft) long–roughly the same length as Diplodocus, to which it was related. Its hindlimbs were very long and thin, and its forelimbs were proportionally longer than in relatives.

The namesake fossil of the type species Amphicoelias altus, American Museum of Natural History 5764, is uncertain in included material. When described by Edward Drinker Cope shortly after its discovery in 1877, Amphicoelias was noted to include many back vertebrae, a single pubis, and a femur. However, after purchase and cataloging of the material by the AMNH, Henry Fairfield Osborn and Charles Mook described that the specimen had only two vertebrae, a pubis, femur, tooth, scapula, coracoid, ulna and a second femur. The additional material, not mentioned by Cope, was found close in proximity to the holotype and was similar to Diplodocus, a relative of Amphicoelias. Their assignment was questioned by subsequent authors Emanuel Tschopp et al. in an analysis of Diplodocidae.

During the description of Amphicoelias altus in 1877, Cope additionally named A. latus, for a femur and tail vertebrae. Following its description, Osborn and Mook in 1921 reidentified the material as a specimen of Camarasaurus, an assignment followed by other authors who reviewed the material. A year later 1878, Cope named the third species of Amphicoelias, A. fragillimus for a gigantic dorsal vertebra that was subsequently lost. Measuring approximately 2.7 m (8.9 ft) if reconstructed based on Diplodocus, early estimates for the length of the animal in life were between 40 and 60 m (130 and 200 ft) long. Due to the incomplete nature, such lengths–the longest of any known dinosaur and sauropod–were largely ignored. In 2018, Kenneth Carpenter renamed Amphicoelias fragillimus as the new genus Maraapunisaurus, and reclassified it from Diplodocidae to Rebbachisauridae.

Apatosaurus

Apatosaurus (; meaning "deceptive lizard") 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 21–22.8 m (69–75 ft), and an average mass of 16.4–22.4 t (16.1–22.0 long tons; 18.1–24.7 short tons). A few specimens indicate a maximum length of 11–30% greater than average and a mass of 32.7–72.6 t (32.2–71.5 long tons; 36.0–80.0 short tons).

The cervical vertebrae of Apatosaurus are less elongated and more heavily constructed than those of Diplodocus, a diplodocid like Apatosaurus, and the bones of the leg are much stockier despite being longer, implying that Apatosaurus was a more robust animal. The tail was held above the ground during normal locomotion. Apatosaurus had a single claw on each forelimb and three on each hindlimb. The Apatosaurus skull, long thought to be similar to Camarasaurus, is much more similar to that of Diplodocus. Apatosaurus was a generalized browser that likely held its head elevated. To lighten its vertebrae, Apatosaurus had air sacs that made the bones internally full of holes. Like that of other diplodocids, its tail may have been used as a whip to create loud noises.

The skull of Apatosaurus was confused with that of Camarasaurus and Brachiosaurus until 1909, when the holotype of A. louisae was found, and a complete skull just a few meters away from the front of the neck. Henry Fairfield Osborn disagreed with this association, and went on to mount a skeleton of Apatosaurus with a Camarasaurus skull cast. Apatosaurus skeletons were mounted with speculative skull casts until 1970, when McIntosh showed that more robust skulls assigned to Diplodocus were more likely from Apatosaurus.

Apatosaurus is a genus in the family Diplodocidae. It is one of the more basal genera, with only Amphicoelias and possibly a new, unnamed genus more primitive. While the subfamily Apatosaurinae was named in 1929, the group was not used validly until an extensive 2015 study. Only Brontosaurus is also in the subfamily, with the other genera being considered synonyms or reclassified as diplodocines. Brontosaurus has long been considered a junior synonym of Apatosaurus; its only species was reclassified as A. excelsus in 1903. A 2015 study concluded that Brontosaurus is a valid genus of sauropod distinct from Apatosaurus, but not all paleontologists agree with this division. As it existed in North America during the late Jurassic, Apatosaurus would have lived alongside dinosaurs such as Allosaurus, Camarasaurus, Diplodocus, and Stegosaurus.

Aragosaurus

Aragosaurus (meaning "Aragon lizard") was a genus of sauropod dinosaur from the Early Cretaceous period of Galve, province of Teruel, in the autonomous territory of Aragón, Spain.Aragosaurus was a large, quadrupedal plant-eating (herbivorous) dinosaur, which lived during Berriasian, about 145-140 million years ago. It was about 18 metres (59 ft) in length and about 25 tonnes in weight.Like other sauropods, it had a long neck, a long powerful tail, a small head and a bulky body. It was broadly similar to Camarasaurus. It is represented by a partial skeleton, which was found in Spain and was named by Sanz, Buscalioni, Casanovi and Santafe in 1987. The type species is A. ischiaticus. Like Camarasaurus, Aragosaurus probably had a short, compact skull and a moderately long neck. The teeth were large and wide, and would have been useful for slicing through the leaves and branches of tall conifer trees. The forelimbs were only a little shorter than the hind limbs, and the tail was long and muscular.

Brontosaurus

Brontosaurus (; meaning "thunder lizard" from Greek βροντή, brontē "thunder" and σαῦρος, sauros "lizard") is a genus of gigantic quadruped sauropod dinosaurs. Although the type species, B. excelsus, had long been considered a species of the closely related Apatosaurus, researchers proposed in 2015 that Brontosaurus is a genus separate from Apatosaurus and that it contains three species: B. excelsus, B. yahnahpin, and B. parvus.Brontosaurus had a long, thin neck and a small head adapted for a herbivorous lifestyle; a bulky, heavy torso; and a long, whip-like tail. The various species lived during the Late Jurassic epoch in the Morrison Formation of what is now North America, and were extinct by the end of the Jurassic. Adult individuals of Brontosaurus are estimated to have weighed up to 15 tonnes (15 long tons; 17 short tons) and measured up to 22 metres (72 ft) long.

As the archetypal sauropod, Brontosaurus is one of the best-known dinosaurs and has been featured in film, advertising, and postage stamps, as well as many other types of media.

Camarasauridae

Camarasauridae (meaning "chambered lizards") is a family of neosauropod dinosaurs within the clade Macronaria, the sister group to Titanosauriformes. Among sauropods, camarasaurids are small to medium-sized, with relatively short necks. They are visually identifiable by a short skull with large nares, and broad, spatulate teeth filling a thick jaw. Based on cervical vertebrae and cervical rib biomechanics, camarasaurids most likely moved their necks in a vertical, rather than horizontal, sweeping motion, in contrast to most diplodocids. Cladistically, they are defined to be all sauropods more closely related to Camarasaurus supremus than to Saltasaurus loricatus.

Cathetosaurus

Cathetosaurus is a dinosaur sauropod genus that contains one species: Cathetosaurus lewisi that was thought to be within the genus Camarasaurus. The holotype specimen was originally described by James Jensen and is now in the Brigham Young University collection.

Como Bluff

Como Bluff is a long ridge extending east-west, located between the towns of Rock River and Medicine Bow, Wyoming. The ridge is an anticline, formed as a result of compressional geological folding. Three geological formations, the Sundance, the Morrison, and the Cloverly Formations, containing fossil remains from the Late Jurassic of the Mesozoic Era are exposed. Nineteenth century paleontologists discovered many well-preserved specimens of dinosaurs, as well as mammals, turtles, crocodilians, and fish from the Morrison Formation. Because of this, Como Bluff is considered to be one of the major sites for the early discovery of dinosaur remains. Among the species discovered is the only known specimen of Coelurus. Significant discoveries were made in 22 different areas scattered along the entire length of the ridge. It is included on the National Register of Historic Places as well as the National Natural Landmark list.

Europasaurus

Europasaurus is a basal macronarian sauropod, a form of quadrupedal herbivorous dinosaur. It lived during the Late Jurassic (middle Kimmeridgian, about 154 million years ago) of northern Germany, and has been identified as an example of insular dwarfism resulting from the isolation of a sauropod population on an island within the Lower Saxony basin.

Galve, Teruel

Galve is a municipality located in the province of Teruel, Aragon, Spain. According to the 2006 census (INE), the municipality has a population of 145 inhabitants. There is an important paleontological site.

Garden Park, Colorado

Garden Park is a paleontological site in Fremont County, Colorado, known for its Jurassic dinosaurs and the role the specimens played in the infamous Bone Wars of the late 19th century. Located 10 km (6.2 mi) north of Cañon City, the name originates from the area providing vegetables to the miners at nearby Cripple Creek in the 19th century. Garden Park proper is a triangular valley surrounded by cliffs on the southeast and southwest and by mountains to the north; however, the name is also refers to the dinosaur sites on top and along the cliffs. The dinosaur sites now form the Garden Park Paleontological Resource Area, which is overseen by the Bureau of Land Management.

Lourinhasaurus

Lourinhasaurus (meaning "Lourinhã lizard") was an herbivorous sauropod dinosaur genus dating from Late Jurassic strata of Estremadura, Portugal.

Macronaria

Macronaria is a clade of the "suborder" (more likely an unranked clade than a suborder) Sauropodomorpha. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence macro- meaning large, and –naria meaning nose). Fossil evidence suggests that macronarian dinosaurs lived from the Late Jurassic (Kimmeridgian) through the Late Cretaceous (Maastrichtian). Macronarians have been found globally, including discoveries in Argentina, the United States, Portugal, China, and Tanzania. Like other sauropods, they are known to have inhabited primarily terrestrial areas, and little evidence exists to suggest that they spent much time in coastal environments. Macronarians are diagnosed through their distinct characters on their skulls, as well as appendicular and vertebral characters. Macronaria is composed of several subclades and families notably including Camarasauridae and Titanosauriformes, among several others. Titanosauriforms are particularly well known for being some of the largest terrestrial animals to ever exist.

Macronaria was described by Wilson and Sereno who proposed the new subdivisions among the clade Neosauropoda. Previously, this clade was thought to have Brachiosaurus and Camarasauridae forming one sister group, and Titanosauroidea and Diplodocoidea forming another. This proposed shift with Macronaria placed Diplodocoidea as an outgroup to the new clade Macronaria, under which all other neosauropods would fall.

Moabosaurus

Moabosaurus (meaning "Moab reptile") is a genus of turiasaurian sauropod dinosaur from the Early Cretaceous Cedar Mountain Formation of Utah, United States.

Neosauropoda

Neosauropoda is a clade within Dinosauria, coined in 1986 by Argentine paleontologist José Bonaparte and currently described as Saltasaurus loricatus, Diplodocus longus, and all animals directly descended from their most recent common ancestor. The group is composed of two subgroups: Diplodocoidea and Macronaria. Arising in the early Jurassic and persisting until the Cretaceous-Paleogene extinction event, Neosauropoda contains the majority of sauropod genera, including genera such as Apatosaurus, Brachiosaurus, and Diplodocus. It also includes giants such as Argentinosaurus, Patagotitan and Sauroposeidon, and its members remain the largest land animals ever to have lived.When Bonaparte first coined the term Neosauropoda in 1986, he described the clade as comprising “end-Jurassic” sauropods. While Neosauropoda does appear to have originated at the end of the Jurassic period, it also includes members through the end of the Cretaceous. Neosauropoda is currently delineated by specific shared, derived characteristics rather than the time period in which its members lived. The group was further refined by Upchurch, Sereno, and Wilson, who have identified thirteen synapomorphies shared among neosauropods. As Neosauropoda is a subgroup of Sauropoda, all members also display basic sauropod traits such as large size, long necks, and columnar legs.

Patagosaurus

Patagosaurus (meaning "Patagonia lizard") is an extinct genus of eusauropodan dinosaur from the Middle Jurassic of Patagonia, Argentina. It was first found in deposits of the Cañadón Asfalto Formation, which date to around 165 to 161 million years ago. Although originally twelve specimens were assigned to the taxon, at least one of them may belong to a different genus. Patagosaurus probably lived alongside genera as Piatnitzkysaurus, Condorraptor, and Volkheimeria.

Since Patagosaurus is known from many specimens, including at least one juvenile, its anatomy and growth are fairly well understood. Both ages exhibit the typical features of a sauropod, a long neck, small head, a long tail, and being quadrupedal. The juvenile exhibits features different from the adult in regions like the mandible, pectoral girdle, pelvis and hindlimb, although overall their anatomy is quite similar. The many known specimens help fill in gaps in the anatomy of the genus, such as the forelimb and skull. Parts of the skeleton, like the pectoral girdle, tibia, and pubis are more robust, while others, like the forelimb and ischium, are more gracile. The material of Patagosaurus is similar to closely related taxa like Cetiosaurus and Volkheimeria, more primitive genera such as Barapasaurus and Amygdalodon, and more derived sauropods like Diplodocus and Camarasaurus.

Ruyangosaurus

Ruyangosaurus (Ruyang County lizard) is a genus of titanosauriform sauropod dinosaur recovered from the Early Cretaceous Haoling Formation of China. The type species is R. giganteus, described in 2009 by Lü Junchang et al. Along with Huanghetitan and Daxiatitan, Ruyangosaurus is among the largest dinosaurs discovered in Cretaceous Asia.

Sauropoda

Sauropoda ( or ), or the sauropods (; sauro- + -pod, "lizard-footed"), are a clade of saurischian ("lizard-hipped") dinosaurs. They had very long necks, long tails, small heads (relative to the rest of their body), and four thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land. Well-known genera include Brachiosaurus, Diplodocus, Apatosaurus, Brontosaurus, and Mamenchisaurus.Sauropods first appeared in the late Triassic Period, where they somewhat resembled the closely related (and possibly ancestral) group "Prosauropoda". By the Late Jurassic (150 million years ago), sauropods had become widespread (especially the diplodocids and brachiosaurids). By the Late Cretaceous, those groups had mainly been replaced by the titanosaurs, which had a near-global distribution. However, as with all other non-avian dinosaurs alive at the time, the titanosaurs died out in the Cretaceous–Paleogene extinction event. Fossilised remains of sauropods have been found on every continent, including Antarctica.The name Sauropoda was coined by O.C. Marsh in 1878, and is derived from Greek, meaning "lizard foot". Sauropods are one of the most recognizable groups of dinosaurs, and have become a fixture in popular culture due to their impressive size.

Complete sauropod fossil finds are rare. Many species, especially the largest, are known only from isolated and disarticulated bones. Many near-complete specimens lack heads, tail tips and limbs.

Wyoming Dinosaur Center

The Wyoming Dinosaur Center is located in Thermopolis, Wyoming and is one of the few dinosaur museums in the world to have excavation sites within driving distance. The museum displays the Thermopolis Specimen of Archaeopteryx, which is the only real specimen of this genus on display outside of Europe.

Fifteen minutes from the museum are their many dig sites. Located on the Warm Springs Ranch, more than 10,000 bones have been discovered and excavated, most of which are either on display or stored just down the hill at the museum.

One of the most notable fossil assemblies on the property is from the "Something Interesting" or SI excavation site. This site presents the rare occurrence of both dinosaur trace fossils and body fossils including footprints of many Sauropods and Allosaurus as well as skeletal remains from Camarasaurus, Diplodocus, and Apatosaurus - three of the sauropods most common in the area during the Late Jurassic. Most of the bones belong to a juvenile (30 foot long) Camarasaurus that was scavenged by many Allosaurs. This is known based on the presence of both teeth and claw marks on many of the bones present as well as an abundance of shed Allosaur teeth (more than 100) found among the bone debris. Research conducted by Debra Jennings back in 2006, determined that the bones were accumulated in the past when the site was part of a shallow alkaline lake. There are in fact at least two separate layers of bone bearing material created as the lake expanded and shrank with changes in the environment over time.(Jennings 2006).

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