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Brachiosaurus

There are some dinosaurs that everybody thinks of when they hear the word “dinosaur”. Among these is a very large sauropod which was the reptilian analog of a giraffe. I am, of course, talking about Brachiosaurus.

Brachiosaurus is one of the more famous dinosaurs. This animal was the iconic “giraffe of the Jurassic”, and for a while it held the record of being the largest dinosaur known. It has been featured in countless books and TV documentaries about dinosaurs, and got a major role in the 1993 movie Jurassic Park. But how much do we really know about it?

Brachiosaurus makes its debut appearance in Jurassic Park (1993).

Considering that Brachiosaurus is one of the more familiar dinosaur names, we actually know surprisingly little about it. This largely has to do with the fact that fossils of this animal are extremely rare. Our total knowledge about this animal’s anatomy comes from bits and pieces of several skeletons that were found here and there across much of the Rocky Mountains within the states of Wyoming, Utah, and Colorado, as well as one location in the extreme westernmost parts of the Oklahoma pan-handle. That’s it.

Map of locations where Brachiosaurus fossils have been found, as of 2020:
1) KU Quarry, Wyoming (KUVP 129724; KUVP 133862; KUVP 142200; KUVP 144767)
2) Freeze-out Hills, Wyoming (one caudal vertebra, undescribed)
3) Reed’s Quarry 13, Wyoming (undescribed specimen)
4) Jensen/Jensen Quarry, Utah (FHPR 17108)
5) Fruita, Colorado (undescribed specimen)
6) Riggs’ Quarry 13, Colorado (FMNH P 25107) (this is the holotype)
7) Dry Mesa Quarry, Colorado (BYU 9462; BYU 12866; BYU 12867; BYU 13023)
8) Potter Creek, Colorado (BYU 4744; USNM 21903)
9) Felch Quarry 1, Garden Park, Colorado (USNM 5730)
10) Kenton Pit 1, Oklahoma (OMNH 01138)

The discovery of Brachiosaurus dates back to the very beginning of the 20th Century. In 1900, a few very large bones were discovered in western Colorado near the small town of Fruita, located only a short distance away from the Utah-Colorado border. There wasn’t much to go on: some vertebrae, one hip bone, one femur, one humerus, and part of the shoulder. Still, the bones were distinctive enough from other sauropod dinosaurs known from the Morrison Formation to warrant classifying it as a new genus. In 1903, the creature was officially named Brachiosaurus altithorax, “arm lizard with a wide chest” by Elmer Riggs.

In 1909, a German paleontological expedition led by Wilhelm von Branca were exploring in the German colony of Tanzania when they discovered some large bones near a site called Tendaguru, meaning “steep hill” in the Mwera language. Excavations revealed that it was a partial skeleton, and similarities were soon observed between these bones and the bones that had been unearthed by Elmer Rigg’s team in Colorado several years earlier. In 1914, these bones were classified as another species of Brachiosaurus, named Brachiosaurus brancai. It helped that there was a lot more of the skeleton in this specimen, and for decades afterwards, the African species of Brachiosaurus served as the model for the North American species. However, beginning in the 1980s, doubts arose whether these animals were, in fact, two species of the same genus. A thorough compare-and-contrast analysis showed that there were actually more differences noted in each bone than similarities. Consequently in 1988, the African species was re-named as Giraffatitan brancai.

Both genera had similarities. Both Brachiosaurus and Giraffatitan were very large animals, both of them belonged to the sauropod group known as “Macronaria”, both of them had necks which could be held vertically or near-vertically rather than the horizontally-oriented necks of many other sauropods, both of them had arms which were longer than their legs (hence Brachiosaurus‘ name) which resulted in high shoulders and the back sloping downwards towards the hips, and the neck was longer than the tail. Now that we have established what they had in common with each other, how different was Brachiosaurus from Giraffatitan? Since neither skeleton is complete, and in fact Brachiosaurus is known from scant remains, it is impossible to do a comprehensive 100% compare-and-contrast analysis of both of their skeletons. However, based upon the remains which we do have, we can draw a few conclusions.

First, it appears that either A) Giraffatitan was larger, or B) Both animals were the exact same length but Giraffatitan was more physically massive. Brachiosaurus is estimated to have reached a length of 70 feet long or thereabouts with a 30 foot neck. By contrast, Giraffatitan may be the same length, but differences in body proportions (which I will describe later) meant that it was bulkier than its North American counterpart. Other estimates state that Giraffatitan exceeded Brachiosaurus in size, measuring 75 to 85 feet long.

Second, the skull shape was different. When most people imagine what the head of a Brachiosaurus looked like, they are actually imagining the head of a Giraffatitan, with its high firefighter-helmet crest. Only one partial skull of a Brachiosaurus has been found near Garden Park, Colorado; it was found in 1883, but it wasn’t identified as belonging to a Brachiosaurus until decades later. Although the skull is not complete, enough of it was preserved to indicate that it was not as tall as the skull of Giraffatitan. It appears to have had a much lower crest, sort of in-between the low curvaceous skull of an Apatosaurus and the tall crested skull of a Giraffatitan.

Skulls of Brachiosaurus altithorax (A) and Giraffatitan brancai (B). Carpenter, Kenneth; Tidwell, Virginia (1998). “Preliminary description of a Brachiosaurus skull from Felch Quarry 1, Garden Park, Colorado”. Modern Geology, volume 23. Page 73 (Pages 69–84).

Third, Brachiosaurus had larger and bulkier shoulders compared to Giraffatitan, despite the fact that Giraffatitan seems on the whole to have been larger and more robustly-built than Brachiosaurus. However, Brachiosaurus might (emphasis on “might”) have had a wider chest than its African counterpart.

Fourth, Brachiosaurus may have had a longer chest compared to Giraffatitan. This cannot be stated with 100% certainty because we have not yet found a complete vertebral column or a complete ribcage of Brachiosaurus which could give us a clear picture of the animal’s body proportions. However, if it is true that Brachiosaurus had a longer torso, it would mean that its back would have had a much gentler slope than its African counterpart.

Fifth, Brachiosaurus might have had a longer tail. Only one tail vertebra of Brachiosaurus has been found so far. However, based upon its features, it has been hypothesized that the tail would have been substantially longer than that of Giraffatitan.

The scarcity of remains hints that Brachiosaurus might have been a rare animal out on the Jurassic plains. Other sauropods such as Camarasaurus were far more common.

Like Camarasaurus, Brachiosaurus was a member of a group of sauropod dinosaurs called the “macronarians”, meaning “the large nostrils”. The skull likely acted as a resonating chamber, able to produce loud low frequency long-range noises, which would be very helpful for communicating over the vast expanses of the Morrison Formation plains. If it is true that Brachiosaurus was rare, or perhaps even a solitary animal by nature, it would still need to communicate with other members of its kind, especially during the mating season. Being able to produce such sound, which could travel over long distances, would help these animals to communicate with each other even if individuals were located miles apart from one another.

Unlike the diplodocid sauropods of the Morrison Formation such as Apatosaurus, Barosaurus, and Diplodocus, Brachiosaurus did not hold its neck in a horizontal position. Instead, it held its neck either vertically or at a diagonal angle. The act of the head sticking far above the ground would minimize the chance that the sounds that it produced would be broken up and dissipated due to ground clutter, such as rocks, trees, and even other dinosaurs. This head attached to a long vertical neck would act like a submarine’s periscope, enabling it to see for long distances, and also enabling other members of its kind to spot it from a long distance away. To make sure that it could be seen from long distances away, it is possible that the head and the neck were very brightly and vividly colored while the rest of the body was comparatively drab. It’s also possible that the head might have sported some type of decoration to further ensure that it could be spotted from miles away by other members of its species – perhaps a frill or a mane of quills or baleen-like bristles. However, color and adornment are only hypothetical conjecture and should not be taken as fact.

Below are a pair of drawings that I made of Brachiosaurus altithorax. I have adorned the top part of the neck with a series of long quills forming a mane, and I also made its head bright red in order to stand out amidst the Morrison landscape. As to the remaining colors of grey with blue stripes, I based this on the Brachiosaurus model made for the Carnegie Collection in the 1980s. The drawings were made with No. 2 pencil, No. 3 pencil, and assorted Crayola and Prismacolor colored pencils.

Brachiosaurus altithorax. © Jason R. Abdale (April 26, 2021).

Keep your pencils sharp, everyone.

Haplocanthosaurus: An Enigmatic Sauropod from the Late Jurassic Period

Introduction

The sauropods are the definitive image of the dinosaur. Almost always, whenever one hears the word “dinosaur”, the image of the long-necked long-tailed four-legged behemoth is what immediately springs to mind. The sauropods were the dominant land herbivores during the Jurassic Period of the Mesozoic Era, and some of our best specimens come from western North America.

In the Rocky Mountains, in the states of Utah, Wyoming, and Colorado lies a massive swath of Jurassic-age rock known as the Morrison Formation. Here are found fossils of some of the most well-known and iconic dinosaur species, names that everyone knows, like Allosaurus, Ceratosaurus, Apatosaurus, Brachiosaurus, Stegosaurus, and Diplodocus. The Morrison Formation was home to a myriad of different species, and not just dinosaurs either. Other prehistoric creatures that have been found in this rock layer include pterosaurs, crocodiles, turtles, lizards, frogs, fish, mammals, and even insects.

While there are a few dinosaur names that stick in people’s memories, the Morrison Formation was home to many dinosaur species. One of them, which is largely unknown by the general public, was a sauropod called Haplocanthosaurus. Part of the reason why this animal doesn’t have the same caché to its name as other Jurassic giants is because it is known from only partial remains, its fossils are extremely rare, and because it is found in the oldest layers of the Morrison Formation, far below the fossil-rich layers of the middle and late strata that have yielded thousands of finds. This article will be an overview of this mysterious and curious, but not quite forgotten, sauropod of the Late Jurassic.

 

Discovery, Localities, and Dating

In the very early 20th Century, the remains of a sauropod dinosaur were found about eight miles north of Cañon City, Colorado, and they were discovered and excavated by one Mr. W. H. Utterback. In early 1903, John Bell Hatcher gave these bones the identification of Haplocanthus priscus, “the ancient simple spine” (1).

However, Hatcher soon learned that the name was already used for a prehistoric fish, and so later that year, he re-classified the dinosaur as Haplocanthosaurus, “simple-spined lizard”:

“Dr. C. R. Eastman has very courteously called my attention to the fact that the generic name Haplocanthus recently proposed by me for a new Sauropod dinosaur from the Jurassic deposits near Canyon City, Colorado, is essentially preoccupied, Agassiz having employed the name Haplocanthus for a genus of fishes. I would therefore propose the name Haplocanthosaurus for this genus of dinosaurs with simple median spines on the anterior dorsals and posterior cervicals” (2).

Later that same year, Hatcher published a lengthy and detailed description of all of the bones assigned to this new genus (3).

In fact, Hatcher was mistaken – the name Haplocanthus wasn’t already occupied after all. According to the rules of the ICZN, the original name would have been the correct one to use, except that nobody had called this creature by that name since its discovery. A proposal was submitted in 1989 to have Haplocanthosaurus as the accepted name of this creature due to its common use and the fact that Haplocanthus was not acknowledged by the paleontological community. The request was approved in 1991, and Haplocanthosaurus became the definite name of this dinosaur genus (4).

In 1954, the Cleveland Museum of Natural History really wanted a large grand dinosaur skeleton to put on display, just like the ones that were on display at the American Museum of Natural History in New York City and the Carnegie Museum in Pittsburgh. So an expedition was sent out west to bring back an attention-grabbing huge dinosaur skeleton. The expedition was led, surprisingly enough, by a college undergraduate student named Edwin Delfs (5).

Their first destination was Dinosaur National Monument, located near the Utah-Colorado border, and they hunted for fossils around that area. Unfortunately, they didn’t find anything. However, the team received a tip from some geology students from Louisiana State University that they ought to check out a site in Garden Park, located near Cañon City, Colorado. (6).

Delfs and his teammates relocated to the suggested location, and on the eastern bank of Four Mile Creek, they hit paydirt. Here were the grandiose fossils that the Cleveland Museum was looking for. However, they couldn’t dig anything up yet. The United States had entered the Atomic Age, and due to the Red Scare of the 1950s, the country was manufacturing hundreds of atomic bombs every year. In order to fuel this doomsday machine, the military needed massive amounts of uranium. Many of the fossils that had been discovered out west during the post-WWII years had been discovered accidentally by people who were prospecting for uranium deposits. Due to all of the uranium deposits in the area, Edwin Delfs first had to file a mining claim on the site before he could dig up any fossils (7).

Over the course of three digging seasons, Delfs and his team chipped away at the stone. Part of the reason why it took so long was due to the extremely hard consistency of the rock that the bones were found in. Another reason was that sudden flash floods would completely flood the excavation site, and unfortunately some of the bones were washed away before they could be saved and prepared. After three years of on-off excavations, the team uncovered a large number of vertebrae and parts of the hip. The specimen, which was substantially bigger than Haplocanthosaurus priscus, was named Haplocanthosaurus delfsi by Dr. Jack McIntosh (who is widely regarded as the greatest sauropod expert EVER) and Dr. Michael Williams who served as the curator of vertebrate paleontology at the Cleveland Museum of Natural History. The jacketed bones were brought back to the Cleveland Museum to be prepared. The skeleton was put on display, and it remains one of the main attractions at the Cleveland Museum of Natural History, where it is affectionately known by the nickname “Happy” (8).

There are currently two species of Haplocanthosaurus known to science: H. priscus and H. delfsi. Both of them are known from comparatively few remains in relation to other late Jurassic sauropods. No complete skeleton has ever been found, and there are numerous bones missing from all known specimens, including the skull; no Haplocanthosaurus skull has ever been found, which makes it difficult to precisely place this species within the dinosaur family tree. So far, we have large chunks of the neck and backbones, a shoulder blade, a few vertebrae from the base of the tail, the hip bones, a few leg bones, and that’s it. Most fossils of this animal have been found in Colorado, but one specimen was found in Montana and was nicknamed “Big Monty”. However, this specimen was found on private property, and it is in the hands of a professional fossil collector and dealer (9).

Fossils of both species of Haplocanthosaurus are found in the early and middle levels of the Morrison Formation, although it is rare within both of those levels. It is completely absent from the late Morrison. It is possible that Haplocanthosaurus lived during the latest part of the Middle Jurassic and therefore straddled the boundary between the Middle and Late divisions. However, there are so few places within North America where Middle Jurassic rocks are exposed, and the number of fossils from those rocks has been aggravatingly miniscule. So, the question of whether or not Haplocanthosaurus was a Middle Jurassic leftover that survived into the earliest parts of the Late Jurassic cannot be answered yet (10).

 

Anatomy

Haplocanthosaurus is distinctive for vertebrae that have only a single dorsal neural spine as opposed to the double-pronged V-shaped dorsal neural spines found in the diplodocid sauropods like Apatosaurus and Diplodocus. It is this anatomical feature that earned it its name “simple-spined lizard”. The neck vertebrae of Haplocanthosaurus have proportionally small centrum disks, high neural arches, a tall dorsal neural spine, and transverse spines that stick out directly sideways. Haplocanthosaurus is also noted for having femur bones that are substantially longer than the shin bones. This hints that Haplocanthosaurus was a very slow-moving animal (11).

Size measurements are difficult to pin down, because paleontologists currently recognize two species of Haplocanthosautrus: H. delfsi and H. priscus. It appears that Haplocanthosaurus priscus measured only 50 feet long, making it the smallest sauropod yet found in North America, while Haplocanthosaurus delfsi measured 70 feet long. This distinction was not known until 1988. John Foster states that H. priscus likely weighed around 23,000 pounds (10,500 kilograms) while H. delfsi weighed 46,200 pounds (21,000 kilograms). The aforementioned size measurements mean that Haplocanthosaurus priscus was one of the smallest – if not the smallest – sauropod found within the Morrison Formation (12).

 

Phylogeny

Haplocanthosaurus is a bit of an oddball as far as sauropods go because paleontologists haven’t quite made up their minds as to how to classify it. Because Haplocanthosaurus is known only from partial skeletons, deciding where it fits within the sauropod cladogram has proved problematic and aggravating, and paleontologists have repeatedly shuffled this genus around according to their own perceptions.

Due to the shape of its vertebrae, which were unlike those of more advanced sauropods, John Bell Hatcher surmised that Haplocanthosaurus must be a quite primitive. In his initial research paper, he described Haplocanthosaurus as most closely resembling Morosaurus, a name that is now recognized as a junior synonym of Camarasaurus. Since we now classify Camarasaurus as a member of the sauropod group Macronaria, a group which contains species known for having boxy heads and large nostrils, it can be inferred that Hatcher would have placed Haplocanthosaurus in that group as well (13).

Except that Haplocanthosaurus wasn’t included in Macronaria alongside Camarasaurus and Brachiosaurus. It was, instead, included in the family Cetiosauridae. The cetiosaurs were a group of sauropods that are associated with the Middle Jurassic, especially in England, India, and China. One reason why Haplocanthosaurus’ designation as a cetiosaur stuck around for so long was because of the shape and size of the leg bones. Cetiosaurs are characteristic for having femurs that are noticeably longer than their fibulae and tibiae. However, some members of other sauropod groups also have unusually long femurs, so this anatomical feature is not 100% diagnostic towards cetiosaurs (14).

From its discovery until the middle 1990s, the established convention was that Haplocanthosaurus was a cetiosaurid. And then, things began to change. During the middle 1990s, paleontologists began to take a new look at sauropod phylogeny, and many felt that Haplocanthosaurus had been misplaced on the sauropod tree. In 1998, Jeffrey Wilson and Paul Sereno proposed that Haplocanthosaurus might indeed be a primitive member of Macronaria, which is closer to what John B. Hatcher was hinting at in 1903. In 1999, Jose Bonaparte proposed that Haplocanthosaurus was unique enough to warrant a family of its own, which he named Haplocanthosauridae, but this idea was not accepted by the majority of paleontologists. In the early 2000s, it was suspected that Haplocanthosaurus might actually be a very primitive member of the super family Diplodocoidea. A survey conducted in 2005 by Mike Taylor and Darren Naish failed to definitely establish where this genus ought to be placed. John Foster, the author of Jurassic West, postulated in his 2007 book that Haplocanthosaurus was either a cetiosaur or a primitive macronarian. As the 2000s transitioned to the 2010s, the idea that Haplocanthosaurus was likely a primitive diplodocoidean began to gain acceptance within the paleontological community, and this is what most paleontologists now consider Haplocanthosaurus to be (15).

Because Haplocanthosaurus possesses anatomical features found in both sauropod families, it’s possible that it is a transitional species, a “missing link”, between the cetiosaurs of the middle Jurassic and the diplodocids of the late Jurassic. However, proving such a statement is problematic because of the rarity of finds attributed to this genus. Haplocanthosaurus is known from several partial skeletons, but no skull has ever been found. That’s too bad, because a complete skull would probably settle the argument of where this genus fits on the sauropod tree.

Below is a drawing that I made of Haplocanthosaurus. Because no skull has ever been found, I decided to make a sort of half-cetiosaur half-diplodocid design. The short keratinous scutes that run along the middle of its spine are a reference to such spines (longer ones at that) being found in association with diplodocid sauropods; if this was a primitive member of that family, I’m guessing that such spines would be shorter, if it possessed any at all. The tail is somewhat shorter than what you might expect, more in keeping with a cetiosaurid than a diplodocid. The drawing was made on printer paper with a No. 2 pencil.

Haplocanthosaurus delfsi. © Jason R. Abdale. June 21, 2020.

 

Conclusion

Due to the scarcity of remains, theories about Haplocanthosaurus’ appearance and phylogenic relationship to other sauropods are largely conjectural. Museum mounts depicting Haplocanthosaurus, such as the one in Cleveland, are composites of known finds and educated guesswork. In terms of cladistics, the in-vogue assessment is that Haplocanthosaurus is a very archaic member of the super family Diplodocoidea. However, this might change in the future depending on any new finds that are uncovered. All that we can hope for is that we keep looking, and hopefully we’ll be able to uncover some more specimens of this mysterious and intriguing North American dinosaur in the years to come.

 

Source Citations

  1. John Bell Hatcher (February 21, 1903). “A New Sauropod Dinosaur from the Jurassic of Colorado”. Proceedings of the Biological Society of Washington, 16 (1): 1-2).
  2. John Bell Hatcher (1903). “A new name for the dinosaur Haplocanthus Hatcher”. Proceedings of the Biological Society of Washington, 16 (1): 100).
  3. John Bell Hatcher (1903). “Osteology of Haplocanthosaurus, with description of a new species, and remarks on the probable habits of the Sauropoda and the age and origin of the Atlantosaurus beds. Memoirs of the Carnegie Museum, 2: 1–72).
  4. John R. Foster and Mathew J. Wedel (2014). “Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison Formation (Upper Jurassic) near Snowmass, Colorado”. Volumina Jurassica, 12 (2): 197).
  5. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.
  6. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.
  7. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.
  8. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.
  9. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”; “Is Nate Murphy Holding a Dinosaur for Ransom?”.
  10. John Foster, Jurassic West: The Dinosaurs of the Morrison Formation and their World. Indianapolis: Indiana University Press, 2007. Page 200.
  11. John Bell Hatcher (February 21, 1903). “A New Sauropod Dinosaur from the Jurassic of Colorado”. Proceedings of the Biological Society of Washington, 16 (1): 1-2; John Foster, Jurassic West: The Dinosaurs of the Morrison Formation and their World. Indianapolis: Indiana University Press, 2007. Page 200; “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.
  12. John Foster, Jurassic West: The Dinosaurs of the Morrison Formation and their World. Indianapolis: Indiana University Press, 2007. Pages 200-201.
  13. John Bell Hatcher (February 21, 1903). “A New Sauropod Dinosaur from the Jurassic of Colorado”. Proceedings of the Biological Society of Washington, 16 (1): 2.
  14. David Lambert, The Dinosaur Data Book: Facts and Fictions about the World’s Largest Creatures. New York: Avon Books, 1990. Page 65; Don Lessem and Donald F. Glut, The Dinosaur Society Dinosaur Encyclopedia. New York: Random House, Inc., 1993. Page 208; Gregory S. Paul, The Princeton Field Guide to Dinosaurs, 1st Edition. Princeton: Princeton University Press, 2010. Pages 173-177.
  15. Jeffrey A. Wilson and Paul C. Sereno (June 15, 1998). “Early Evolution and Higher-Level Phylogeny of Sauropod Dinosaurs”. Memoir (Society of Vertebrate Paleontology), 5: 1-68; Jose F. Bonaparte (1999). “An armoured sauropod from the Aptian of northern Patagonia, Argentina”. In Proceedings of the Second Gondwanan Dinosaur Symposium, National Science Museum Monographs #15. Y. Tomida, T. H. Rich, and P. Vickers-Rich, eds. Tokyo. Pages 1-12; Mike P. Taylor and Darren Naish (2005). “The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda)”. PaleoBios, 25 (2): 1–7; John Foster, Jurassic West: The Dinosaurs of the Morrison Formation and their World. Indianapolis: Indiana University Press, 2007. Page 188; John A. Whitlock (April 2011). “A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda)”. Zoological Journal of the Linnean Society, 161 (4): 872–915; Emanuel Tschopp, Octávio Mateus, and Roger B. J. Benson (2015). “A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)”. PeerJ. 2015; 3: e857; “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017”.

 

Bibliography

Bonaparte Jose F. (1999). “An armoured sauropod from the Aptian of northern Patagonia, Argentina”. In Proceedings of the Second Gondwanan Dinosaur Symposium, National Science Museum Monographs #15. Y. Tomida, T. H. Rich, and P. Vickers-Rich, eds. Tokyo: 1-12.

Foster, John. Jurassic West: The Dinosaurs of the Morrison Formation and their World. Indianapolis: Indiana University Press, 2007.

John R. Foster and Mathew J. Wedel (2014). “Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison

Formation (Upper Jurassic) near Snowmass, Colorado”. Volumina Jurassica, 12 (2): 197–210. https://sauroposeidon.files.wordpress.com/2010/04/foster-and-wedel-2014-haplocanthosaurus-from-snowmass-colorado.pdf.

Hatcher, John Bell (February 21, 1903). “A New Sauropod Dinosaur from the Jurassic of Colorado”. Proceedings of the Biological Society of Washington, 16 (1): 1-2. https://www.biodiversitylibrary.org/page/2345230#page/118/mode/1up.

Hatcher, John Bell (February 21, 1903). “A new name for the dinosaur Haplocanthus Hatcher”. Proceedings of the Biological Society of Washington, 16: 100. https://www.biodiversitylibrary.org/page/2345230#page/118/mode/1up.

Lambert, David. The Dinosaur Data Book: Facts and Fictions about the World’s Largest Creatures. New York: Avon Books, 1990.

Lessem Don; Glut, Donald F. The Dinosaur Society Dinosaur Encyclopedia. New York: Random House, Inc., 1993.

Paul, Gregory S. The Princeton Field Guide to Dinosaurs, 1st Edition. Princeton: Princeton University Press, 2010.

Taylor Mike P.; Naish, Darren (2005). “The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda)”. PaleoBios, 25 (2): 1–7

Tschopp, Emanuel; Mateus, Octávio; Benson, Roger B. J. (2015). “A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)”. PeerJ. 2015; 3: e857. Published online on April 7, 2015. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4393826/.

Whitlock, John A. (April 2011). “A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda)”. Zoological Journal of the Linnean Society, 161 (4): 872–915. Published online on January 12, 2011. https://academic.oup.com/zoolinnean/article/161/4/872/2732063

Wilson Jeffrey A.; Sereno Paul C. (June 15, 1998). “Early Evolution and Higher-Level Phylogeny of Sauropod Dinosaurs”. Memoir (Society of Vertebrate Paleontology), 5: 1-68.

Inverse. “Is Nate Murphy Holding a Dinosaur for Ransom?”, by Jacqueline Ronson (July 5, 2016). https://www.inverse.com/article/17806-sauropod-dinosaur-discovery-montana-fossil-hunter-paleontology-nate-murphy.

YouTube. ExtermCentral. “Haplocanthosaurus: The Ghost of the Morrison Formation by Dr. Cary Woodruff CMNH Dinofest 2017” (November 12, 2017). https://www.youtube.com/watch?v=-NWL7pjrPbI.

Camarasaurus

Camarasaurus, “the chambered lizard”, was a sauropod dinosaur from the Morrison Formation of western North America, dated to the late Jurassic Period about 155 to 145 million years ago. The animal gets its name from the numerous openings within its skull. Camarasaurus belonged to a group of sauropods called the “macronarians” which means “large nostrils”. As such, Camarasaurus was more closely related to Brachiosaurus than to the “diplodocid” sauropods like the eponymous Diplodocus and its relatives.

The Morrison Formation was home to numerous sauropod species, including Apatosaurus, Barosaurus, Brachiosaurus, Diplodocus, and Haplocanthosaurus. Some of these names might be more familiar to the ear. However, in terms of sheer population numbers, Camarasaurus tops the list. More skeletons of Camarasaurus have been found within the Morrison Formation than any other sauropod, and this has led scientists to claim that it was therefore the most common sauropod dinosaur alive during that time.

There are currently three species of Camarasaurus known from the late Jurassic rocks of North America: Camarasaurus grandis, Camarasaurus lentus, and Camarasaurus supremus. Camarasaurus grandis was the oldest of the three, being found in the early and middle stages of the Morrison Formation, about 155-150 MYA. After this appeared Camarasaurus lentus, which is found only within the middle layers of the Morrison; C. grandis and C. lentus co-existed with each other for a time. Finally, both species were replaced by Camarasaurus supremus, the largest of the three species, and it also was alive during the last stages of the Morrison Formation, about 150 -145 MYA. Of these three species, we have more fossils from C. lentus than from the other two.

As far as size goes, Camarasaurus was a tad on the small side for a sauropod. Both Camarasaurus grandis and Camarasaurus lentus measured only 50 feet long. The largest of the three species, Camarasaurus supremus, possibly measured 70 to 75 feet long, but this is only an estimate since no complete adult skeleton of C. supremus has been found yet. Most sources which I have read give a maximum size of 60 feet. However, I ought to state that this might just be an size measurement average between the two numbers seen above, especially since most of these sources do not differentiate between the three separate species but lump all of them together as if they were just one.

Camarasaurus‘ relatively small size (that is, compared with the other larger sauropods that it shared its habitat with) and meaty build likely made it one of the preferred targets for a mob of Allosaurus to take down. The reason why Camarasaurus was the most common species of its kind might be due partly to its smaller-than-average size (smaller stomachs mean more food to go around for everyone, and by extent leads to having larger populations) and partly to its apparently generalist diet. Creatures which have a specialized diet are often hit hard when catastrophes arise, whereas dinosaurs that are more adaptable and flexible in terms of what they eat come out more favorably.

Note: The original drawing that was posted to this article, which was dated to August 5, 2012, was removed because it was anatomically inaccurate and in general was of poor quality. The drawing that you see below is an updated version.

Camarasaurus supremus. © Jason R. Abdale. April 18, 2021.

Many times, you’ll see these dinosaurs illustrated Gregory Paul-style, with thin spindly legs. I decided that the biomechanics of this simply weren’t feasible, and so I gave my animal suitably thicker more elephant-like legs, able to hold up the tens of tons of weight. Also notice that, contrary to other artistic renderings of this species, the neck is NOT held straight vertically upright, but is thrust more forwards in a 45 degree S-shaped curve. In terms of the color pattern, I’ve always imagined Camarasaurus colored in the scheme that you see above, even as a little kid – tan body with broad brown stripes and a somewhat yellowish-tan underbelly. I simply cannot imagine this species colored in any other way. Whether or not Camarasaurus really was colored in this fashion, we’ll probably never know. The two drawings that you see above were made with No. 2 pencil and assorted colored pencils.

Keep your pencils sharp, people.