Chicago’s half-finished sauropod

In 2006, the Field Museum of Natural History in Chicago unveiled its newly renovated Evolving Planet exhibit. It’s a slightly exhausting tour of life on Earth from the Precambrian to the present, stuffed to the brim with fossils collected over the Museum’s 120 year history. By far the largest item on display is the mounted skeleton of Apatosaurus (FMNH P25112), which dominates the dinosaur room and marks the midpoint of the exhibit as a whole. I saw the mount last December, and being used to the comparatively puny NMNH Diplodocus, the sheer robustness of this animal was a sight to behold. The gigantic T-beams that support the dorsal vertebral column and pelvic girdle are also pretty impressive, and much more massive than I’ve seen on other sauropod mounts (near as I can tell, these supports have not been moved since the Field Museum moved to its current location in 1921, and the Apatosaurus was not remounted in 2006).

Elmer Riggs was not screwing around when he build a sturdy armature, which is still visible today. Blurry photo by me.

Elmer Riggs was not screwing around when he built a sturdy armature, which is still visible today. Blurry photo by me.

The Chicago Apatosaurus was not always so resplendent, however. At the turn of the 20th century, there was a dramatic rush among large urban museums in the United States to collect and mount the biggest and most spectacular dinosaur that could be found. This fossil craze was primarily motivated by the vanity of the museums’ wealthy benefactors, but proved to be extremely productive for both paleontologists and museums. Mounted dinosaur skeletons sprung up seemingly overnight in cities across the country, making names like “Brontosaurus” and Diplodocus household terms and igniting a wave of interest in museums and natural science. The American Museum of Natural History in New York was the first across the finish line, completing their “Brontosaurus” mount in February of 1905. The Carnegie Museum of Natural History finished their Diplodocus mount in 1907,  alongside casted versions gifted to museums in London, Berlin, Paris, Mexico City and Buenos Aires, among others. The United States National Museum, meanwhile, had inherited much of O.C. Marsh’s vast fossil collection and by 1910, had completed the first-ever mounts of Triceratops, Ceratosaurus and Camptosaurus.

The Field Museum was also in the race, but its efforts were half-hearted from the start. When the Museum administration got word that AMNH and CMNH were planning on finding and displaying sauropods, they sent their paleontologist Elmer Riggs to lead fossil-hunting teams in Utah and elsewhere. Unlike the east coast competitors, however, neither the Field Museum nor its benefactors were willing to put up the necessary funding to properly supply the expeditions. The Chicagoans wanted to match or exceed anything New York did (as Chicagoans often do), but at an institution dominated by anthropologists the funding commitment was not there.

Despite these handicaps, the Field Museum actually managed to collect a more complete and better-preserved sauropod than either AMNH or CMNH. The mounts in New York and Pittsburgh were composites, assembled from several partial skeletons as well as casted or sculpted elements. Riggs’ team, however, had collected a single fully articulated Apatosaurus (labeled FMNH P25112) that was over 50% complete. Unfortunately, this was still only half a dinosaur, and Museum administrators refused to allocate the paleontology department any more funding. An additional field season to find enough sauropod material to complete the mount was off the table, as was purchasing casts from another museum. Nevertheless, Riggs was given the go-ahead to start mounting P25112. Undoubtedly Riggs hoped that once administrators saw how striking the mounted fossils would be (or how stupid the partial skeleton looked), they would pay for the mount to be completed.

Riggs' Apatosaurus mount stood unfinished from 1908-1958. Photo from the Field Museum Library.

Elmer Riggs’ Apatosaurus mount stood unfinished from 1908-1958. Photo from the Field Museum Library.

No such luck. In 1908 the half-sauropod was unveiled to visitors, complete and beautifully preserved from the last cervical vertebra through the proximal half of the tail. Unfortunately, the forelimbs, pectoral girdle, neck and head were all missing, resulting in a teetering, two-legged dinosaur butt that would remain unchanged for another 50 years.

The mount was eventually completed in 1958, after the front half of an Apatosaurus was acquired by Riggs’ successor, Orville Gilpin. At least two generations of visitors have passed through the Field Museum since then. Even so, the half century of half sauropod must have been quite embarassing, and a testament to not taking on projects half-assed.

The completed mount as it stood in the 1970s, Camarasaurus head and all.

The completed mount as it stood in the 1970s, Camarasaurus head and all.


Brinkman, P.D. 2010. The Second Jurassic Dinosaur Rush: Museums and Paleontology in America at the Turn of the 20th Century. Chicago, IL: University of Chicago Press.

Sepkoski, D. 2012. Rereading the Fossil Record: The Growth of Paleobiology as an Evolutionary Discipline. Chicago, IL: University of Chicago Press.


Filed under dinosaurs, field work, FMNH, fossil mounts, history of science, museums, reptiles, sauropods

3 responses to “Chicago’s half-finished sauropod

  1. Those are the Brachiosaurus altithorax holotype dorsals (FMNH P25107) in the cabinet behind the half-an-apatosaur. Above them, the coracoid and one of the ribs of, I assume, the same specimen. Of the two ilia in cabinet to the left, the rightmost (partly hidden by the apatosaur tail) looks like that of Brachiosaurus, too, so I assume that the adjacent sacrum is that of the same individual. No idea where the humerus is, though; nor what that other ilium is.

    • Ben

      Thanks for lending your expertise…I had never looked at those cases closely! Interesting that Riggs would spread the Brachiosaurus around at least three cases on two walls of the room.

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