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This is a fascinating story about a dinosaur discovered about 8 miles north of Cañon City Colorado in the Garden Park Fossil Area in 1877 by Oramel Lucas working for Professor E.D. Cope (above picture), famous paleontologist from Philadelphia. The Amphicoelias fragillimus (A. fragillimus) appears to represent the largest land animal ever and that is a story worth telling (actually retelling)!  But,  A. fragillimus is based only the evidence of a single partial vertebrate and the vertebrate has since been lost!      

The discovery in 1877

Oramel and his older brother Ira excavated dinosaur bones in early 1877 that were primarily sauropods, in particular Camarasaurus.  Oramel Lucas began a relationship with Cope, selling him bones at 10 cents a pound. The Amphicoelias fragillimus is one of those discoveries.

Bones were excavated and then shipped to Cope’s home and laboratory on Pine Street in Philadelphia where Cope and his assistant Jacob Geismar did the initial cleaning and preparation.  By 1883, over 150 crates of dinosaur bones were shipped to E.D. Cope and some of this collection was described in publications by Cope.  In late 1877, one or more of those crates contained a partial vertebrate of a dinosaur later to be identified as Amphicoelias fragillimus.

In 1878, Cope initially described the dinosaur in the proceedings of the American Philosophical Society in a report entitled “On the Vertebrata of the Dakota Epoch of Colorado”.  Later in August of 1878 he produced a report and description of Amphicoelias fragillimus within the American Naturalist.  Cope describes the discovery of the vertebrate of Amphicoelias fragillimus as

“The almost entire neural arch of the vertebra of the largest saurian I have yet seen.”

He goes on to include a drawing of what he had discovered and fills in the missing pieces based on his knowledge of other sauropods including what he felt was a possible related species Amphicoelias latus, also discovered in the Cope-Lucas excavation area.


Amphicoelias fragillimus vertebrate drawing by Cope and as modified by Osborn and Mook.

Amphicoelias fragillimus vertebrate drawing by Cope and as modified by Osborn and Mook.

Cope also reported an “immense distal end of femur near small femur” found in the adjacent quarry. Like the vertebrate, this has not been found. It is likely a part of the Amphicoelias.

The Cope Lucas Collections

It was the desire of Cope to see his collection of fossils eventually transferred to the American Museum of Natural History.  The sale and transfer of this massive collection of fossils to the American Museum of Natural History happened in 1902 about five years after Cope’s death in 1897.  This was made possible largely through the efforts of Henry Osborn who was Cope’s personal friend for many years.

In 1921, Henry Fairfield Osborn and Charles Craig Mook completed an amazing 120 page monograph of the Cope-Lucas discoveries in Garden Park entitled “Camarasaurus, Amphicoelias, and other Sauropods of Cope”.   This remarkable monograph describes and illustrates in magnificent detail this remarkable collection and it is a testament to Osborn’s appreciation of Cope.

All the specimens from Canon City were accessioned into the American Museum of Natural History using catalog numbers such as FR 5777 which refers to the Amphicoelias fragillimus which indicates it arrived into the museum collections.

Lucas letters and Cope field notes

John McIntosh had questions about the collection and the initial excavations and noticed that the Osborn-Mook monograph was completed without field notes something clearly noted in the monograph.   It was evident to John that any information on the excavations would be tremendously helpful in answering those questions.

During his research in the American Museum of Natural Histories archives, “Lucas” letters were discovered.  They were discovered 70 years after the monograph was done and had been there all along.   Even more astonishing was the discovery of a small pocket notebook used by Cope during his visit to Garden Park in July 1879.  In it, with the help of O.W. Lucas, Cope had drawn a map of the area, showing not two or three quarries as described in the monograph, but seventeen,”…

Among the entries in the notebook is “III Amphicoelias fragillissimus [sic] from between the two lots” (lots refers to quarries or sites).

Map of the Cope Quarry area by Edward D. Cope.  The approximate location of A. fragillimus is shown on the map.

Map of the Cope Quarry area by Edward D. Cope. The approximate location of A. fragillimus is shown on the map.

Along the path of discovery, questions were being answered but one question was gnawing at John McIntosh.    He was curious about the Amphicoelias fragillimusWhat was its story?  The letters and map did not provide the answer but  they would be helpful.  He turned to a good friend Dr. Kenneth Carpenter to assist.

Edward Cope next to his Amphicoelias vertebrate by Dr. Kenneth Carpenter

Edward Cope next to his Amphicoelias vertebrate by Dr. Kenneth Carpenter


Amphicoelias fragillimus vertebrate

Dr. Carpenter began a study of this dinosaur after it was brought to him by John McIntosh in 1998.   This remarkable study was completed and published as “Biggest of the Big” in 2006.

Dr. Carpenter first noted that pretty much all of the very large sauropods such as Argentinosaurus, Seismosaurus (Diplodocus), and Supersaurus, often were found with fragmentary evidence.  He also noted that such dinosaurs are very well known while Amphiceolias fragillimus is rarely noted in paleontology publications.

The holotype (single physical example of an organism) of A. fragillimus consists of a neural arch and spine believed to have been from the last or second to last dorsal (D10 orD9).  It was collected by Oramel and Ira Lucas in 1877 as noted earlier.  The following drawing was developed by Dr. Carpenter completing the vertebrate based on his expertise.


Dorsal vertebrate from Biggest of the Big (reconstructed based on modified Amphicoelias altus)

Dorsal vertebrate from Biggest of the Big (reconstructed by Dr. Kenneth Carpenter and based in part on modified Amphicoelias altus)

Discovery Location

Dr. Carpenter went back to this location in the Garden Park Fossil Area and studied the rock layer in which this specimen would have been excavated.  He discovered that

“the mudstone containing lots (quarries) I-IV is nearly stripped down to the underlying sandstone. The local topography suggests that most of the strata had already been stripped off by the time Lucas made his first dinosaur bone discovery in 1877. Thus, it is probable that most of the Amphicoelias skeleton was destroyed long before the neural spine was found.”

Dr. Carpenter also notes that the probable age which these specimens came from is Tithonian which is at the very end of the Jurassic time period.

Authenticity of the Specimen

Dr. Carpenter noted that although the Amphicoelias fragillimus specimen was missing it had still been assigned the catalog number AMNH (FR) 5777.   He also notes that from the original description “the specimen was apparently missing much of the outer cortical bone and was extremely delicate” noting a Cope quote “much care was requisite to secure its preservation”.  Its delicacy was probably also evident by its name “fragillimus”.

Dr. Carpenter feels that in all likelihood the original specimen simply disintegrated.  For example, a Camarasaurus specimen discovered in the 1970’s in Garden Park by the Denver Museum of Nature and Science simply disintegrated.   In 2012 I was at the Yale Peabody Museum in New Haven Connecticut and took pictures of all the specimens collected by Williston, Mudge, and Felch in 1877 at the Marsh Felch Quarry. Some of that collection was completely fragmented, not surprising considering the time frame it was found.  Some paleontology material found in Garden Park in 1877 was so fragmented that it was simply tossed aside rather than attempting excavation.

When specimens of dinosaurs were being discovered in 1877 preservation techniques were in their infancy.  Hardeners such as “water glass” (sodium silicate) were not in use.  When skeletons in some layers are found and uncovered, the bone can begin to immediately disintegrate without the use of hardeners and preservatives.   The Amphicoelias specimen was excavated from a weathered zone and was most likely in its final stages of decomposing.    Cope likely only drew one side of the specimen in that it may not have been stable enough to turn over. Dr. Carpenter also previously noted the outer (harder) portion of the bone was missing at the time of discovery.

The scientific scrutiny of this specimen which was massive but primarily in relation to size, not authenticity.   I found one group of comments from Darren Naish, the blog entitled Biggest sauropod ever (part II) in regards to the authenticity of the specimen.  I’m paraphrasing from Darren in regards to authenticity and adding comments.

  • Cope was very specific about all the discovery details of A. fragillimus. According to his field notes, it was collected in late 1877 by Oramel Lucas … at Garden Park, specifically from quarry III, a site southwest of the hill known today as Cope’s Nipple. The rocks here yielded several other particularly large Morrison Formation dinosaurs (such as Camarasaurus supremus).
    • About 150 crates of bones were shipped to Cope, they are currently housed in the Big Bone Room of the American Museum of Natural History
  • the shipment records discovered by McIntosh show that Oramel Lucas and his brother Ira knew of A. fragillimus and labeled some remains with this name. If it was a hoax, then the Lucas brothers must have been in on it too, which now makes it a conspiracy.
    • historical research into Oramel Lucas establishes a very high level of honesty and integrity
  • The conspiracy would have to extend even further, as an American Museum of Natural History catalogue number, AMNH 5777, was reserved for the A. fragillimus material.
  • The rivalry that existed between Cope and Marsh is also relevant here. As is well known, Marsh enjoyed making a very public fool of Cope when he made a technical error and when he disagreed with Cope, or thought him wrong, Marsh was tediously pedantic in his criticisms.  Marsh never criticized, nor even questioned, the reality of A. fragillimus. Carpenter notes that ‘Marsh is known to have employed spies to keep tabs on what Cope was collecting, and it is quite possible that he had independent confirmation for the immense size of A. fragillimus.
  • Cope’s drawing of A. fragillimus is accurate-looking and elaborate, and his description refers to small detailed features, all of which conform in details with what we know of diplodocoid vertebrae…. the material is documented, in detail, in a proper technical paper. To hoax an entire paper of this sort would be severe science-crime, and there is no indication that Cope was unscrupulous or dastardly, or prepared to stoop this low.
  • It is noteworthy that workers well known for their methodical and conservative approach to sauropod studies (notably John McIntosh) have accepted Cope at his word. Osborn, who succeeded Cope as vertebrate paleontologist for the US Geological Survey and is well known for speaking his mind when he had a problem with something, also never voiced doubts about A. fragillimus.


 Amphicoelias fragillimus Size

Dr. Carpenter analyzed the potential size of the dinosaur and completed a conceptual drawing of the missing parts originally drawn by Cope. Dr. Carpenter later built a full sized model of the Amphicoelias, the only one in existence.  Gregory Paul also took a look at the size.  It is the size that has attracted a rather sizable amount of scientific scrutiny, after all when you are writing about what is probably the largest land animal ever it has a way of initiating conversation!

Dr. Carpenter notes that A. fragillimus was probably a diplodocoid, and thus related to more familiar taxa like Diplodocus and Apatosaurus (rather than the Amphicoelias latus), the major difference being one of size. After careful scientific analysis he concluded that the dinosaur could have been as much as 190 feet in length and as much as 30 feet in height with a mass of 122 tons, dwarfing all other massive sauropods near the end of Jurassic. By comparison, today’s largest animal, the Blue Whale, is only 110 feet long.

In the article entitled “How big was Amphicoelias fragillimus? I mean, really?”   By Mike Taylor February 19, 2010, Mike conducted his own independent evaluation where his estimate was only about 160’ in length and about 80 tons in weight.    Mike’s conclusion at the end indicated that with the limited amount of information to go by (one partial vertebrate) made it difficult to do a highly accurate estimation.

Gregory Paul’s estimate in 1994 was between 130 and 190 feet in length with a mass between 100 and 150 tons.

In regards to the discussion I looked and there are at least 500 various well thought out comments to different blog sites on the subject of size and it can quickly be surmised that this is an open discussion.  This is one that will be answered over time with new discoveries.

Gigantic Dinosaurs.

Gigantic Dinosaurs.


I believe that Amphicoelias was real and was the largest dinosaur yet found to date.  After looking at this topic and learning more about it, I walked away confident that the discovery was real and size estimates are reasonable. I appreciate greater minds than mine who made this realization possible.  I also walked away with an appreciation of the scientific process in the intensity of questions, when a topic comes up like this. There is no one tougher on a scientist than another scientist. 

There are a variety of opinions of exactly how large it was and without more bones being discovered we might not ever know for certainty.  Rather than focusing on “ours was bigger than yours”, what is interesting to me is that something in the Tithonian time period near the end of the Jurassic triggered even larger sauropods such as Supersaurus,  Seismosaurus,  and Amphicoelias fragillimus.  Dinosaurs such as Apatosaurus,  Diplodocus, and Camarasaurus were huge, monstrously huge yet they became even larger near the end of the Jurassic.   Among the other really good work  by Dr. Kenneth Carpenter in “Biggest of the Big” was an analysis of gigantism  

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