A Trio of Tyrants

The frentic search for North American dinosaur fossils in the late 19th and early 20th centuries can be divided into three phases. First came O.C. Marsh and E.D Cope, whose infamous rivalry resulted in literal trainloads of fossil material and laid the groundwork for our present understanding of dinosaur diversity. Next, teams sponsored by the newly-formed American, Carnegie, and Field museums returned to the same hunting grounds in the western interior to secure display-worthy specimens for their great halls of exhibition. The final phase was smaller in scale but yielded dinosaur specimens so spectacularly complete that most have gone unmatched to this day.

This third fossil rush occurred not in the United States but in Canada, along the cliff-like banks of Alberta’s Red Deer River. Fossil hunting in this region was pioneered in the late 1800s by George Dawson, Joseph Tyrell, and Lawrence Lambe, all working for the Canadian Geological Survey. This success did not go unnoticed by the the American Museum of Natural History’s Department of Vertebrate Paleontology. In 1910, the museum mounted an expedition led by Barnum Brown to the Red Deer River. Rather ingeniously, Brown’s team acquired a pair of 30-foot floating barges, which were used as mobile platforms from which they could excavate the steep river banks. The barges also served as floating campsites and a handy means of transportation in a region without reliable roads.The adventurous Brown was already a media favorite, and the publicity surrounding his Alberta expeditions only increased when the team started bringing back fully articulated and nearly complete dinosaur skeletons (including several with skin impressions).

Under pressure from constituents concerned that the Americans were hauling away so much of their natural heritage, the Canadian government formed its own team of fossil collectors in 1912. The new Canadian Geological Survey team was headed by independent fossil hunter Charles H. Sternberg (a veteran collector who had once worked for Cope) and his sons George, Levi, and Charles Jr. The Canadian and American teams worked in the same region for the next five field seasons. Their rivalry was usually good-natured, but on more than one occasion Brown saw fit to grumble about the Sternbergs’ ethics (never mind that he was the one permanently removing fossils from their country of origin).

Gorgosaurus at AMNH

Three tyrannosaurs mounted in relief at AMNH. Image courtesy of the AMNH Research Library.

All of this is so much preamble for the actual topic of this post – three remarkable Gorgosaurus skeletons* collected near the Red Deer River during the Canadian fossil rush. All three were eventually mounted in relief by AMNH preparator Peter Kaisen, and for a time they were displayed together in the Hall of Fossil Reptiles. These specimens are on the short list of most complete large theropod dinosaurs ever discovered, and in their day they provided researchers an unprecedented look at the physiology of these amazing animals. Nearly a century later, the three mounts are virtually unchanged. Locked behind glass for decades and largely inaccessible to researchers, the mounts themselves are now relics of a fascinating transitional period in the history of dinosaur studies.

*AMNH also recovered a fourth tyrannosaur during this period – Gorgeous George the Daspletosaurus.

As usual, a brief explanation of nomenclature is required. William Matthew and Barnum Brown originally described these specimens as Gorgosaurus, a genus that Dale Russell sank into Albertosaurus in 1970. Most specialists no longer support this synonymization, but the specimens at AMNH are still labeled as Albertosaurus.

Gorgosaurus libratus – USNM 12814

gorgo

A recent photo of USNM 12812 from the ongoing renovation of the national fossil hall. Source

USNM 12814 (originally designated AMNH 5248) was excavated by Brown’s company in 1913 and prepared for display in 1918. Kaisen elected to recreate the death pose in which the Gorgosaurus was found, with its head swept backward over its body. All told, the finished mount included a skull, a complete set of cervical and dorsal vertebrae, complete forelimbs, and a single femur – the pelvis and the rest of the hindlimbs were filled in with casts from other specimens. Since the skeleton was mounted in relief, Kaisen simply painted the tail onto the backdrop.

After at least a dozen years on display at AMNH, the Gorgosaurus was traded to the National Museum of Natural History as part of a complicated deal between the two museums. While surveying fossil collections throughout the United States, Brown realized that a single Barosaurus skeleton from Dinosaur National Monument had been divided among three different institutions. NMNH had the neck and part of one forelimb, the Carnegie Museum had the tail, and the University of Utah had the rest. Between 1929 and 1933, Brown arranged a series of trades in order to unify the Barosaurus at AMNH. The Smithsonian in particular drove a hard bargain – the museum had already invested $3400 in preparing their Barosaurus section, and paleontology staff wanted a good return for their investment. Brown’s initial offer was the fully prepared and mounted Gorgosaurus. Although AMNH valued the field and prep time spent on the fossils at $4573, it was at that point a duplicate specimen taking up valuable space in their increasingly crowded exhibit hall.

NMNH dinosaur specialist Charles Gilmore confided in Brown that he was okay with this trade, but fellow Smithsonian paleontologist Alexander Wetmore wasn’t sold. For years, NMNH staff had been trying to acquire one of the many Moropus specimens AMNH had collected at the Agate Fossil Beds in Nebraska. NMNH had offered a variety of specimens to trade, even sending AMNH a set of brontothere skulls at one point, but AMNH was adamant the Moropus fossils could only be exchanged for cash. Brown really wanted that Barosaurus neck, so in January of 1933, he finally relented and offered the Smithsonian a largely complete Moropus in addition to the Gorgosaurus. Not long after, the Gorgosaurus relief mount found its way into the Hall of Extinct Monsters at NMNH.

Gorgosaurus sp. – AMNH 5458

albertosaurus

A technician (probably Kaisen) adjusts the steel strap holding the femur in place. Source

Brown’s team found their second Gorgosaurus near Steveville, Alberta in 1914. Complete save for the left leg, right arm, and parts of the rib cage and tail, the mount was ready for display in May of 1921. At 24 feet long and 14 feet high, this was by far the largest relief mount at the museum. In fact, it was too big to fit through the workshop doorway in one piece, so Kaisen constructed it in eight sections that were sealed together in the exhibit hall. Each section had its own wooden frame for support, and the bones themselves were held in place with steel straps. The skull, jaw, and left forearm could be removed for individual study. This was unusual for the period (most contemporary fossil mounts were designed to be permanent) and speaks volumes about this specimen’s unique scientific value.

This mount is particularly notable for its awkward running pose. Directly contradicting many narratives of early 20th century paleontology, Matthew and Brown envisioned Gorgosaurus as an animal that “walked and ran much like a gigantic bird.” The AMNH team posed this mount after studying photos of bipedally running lizards, particularly the western tiger lizard*. However, Matthew and Brown noted that the dinosaur’s  limb proportions and range of motion more closely resemble a bird than a lizard, and adjusted the pose accordingly. They also advised a more conservative stride length to compensate for the animal’s considerable weight.

*Matthew and Brown do not provide a scientific name, and the common name “western tiger lizard” doesn’t seem to be used any more. Anyone know what it’s called today?

The final pose was a compromise between the elevated torso of a running lizard and the comparatively tight gait of a bird. It looks more than a little strange, but AMNH 5458 is certainly closer to our present understanding of theropod posture than most mounts of the era. Matthew and Brown’s interpretation of Gorgosaurus turned out to be ahead of its time. Some contemporary researchers, including Lawrence Lambe, declared the running pose to be highly improbable, and virtually all theropod mounts constructed over the next 60 years returned to the tail-dragging posture of the 1915 AMNH Tyrannosaurus.

Gorgosaurus sternbergi” – AMNH 5664

gorgo sternbergi

Gorgosaurus “sternbergi” as it was discovered and originally mounted. Source

The most complete tyrannosaur from the Red Deer River was not collected by the AMNH party, but by the Sternbergs. The elder Charles Sternberg discovered the specimen in 1917, entirely intact save for the left arm and the very end of the tail. In fact, this was the most complete large theropod ever found in North America until it was surpassed by yet another Gorgosaurus, TCM 2001.89.1. Sternberg first attempted to sell the specimen to the British Museum. They weren’t interested, but AMNH was. In 1918, the Department of Vertebrate Paleontology bought the skeleton for $2000, thus completing the tyrannosaur trio.

Matthew and Brown described AMNH 5664 as a new species – Gorgosaurus sternbergi. In their 1921 publication, they describe the skull as longer and shallower than other Gorgosaurus specimens, with rounder orbits. However, Brown and Matthew recognized that these could be juvenile characteristics, noting as well that the unfused pelvic bones were an indication of immaturity. As early as 1970, this specimen was suspected to be a juvenile Gorgosaurus (or Albertosaurus) libratus.

Kaisen prepared the relief mount in 1921, this time assisted by Carl Sorenson. The photo above shows the original version of this mount, with the tail projecting straight back from the body. This was how Sternberg discovered the skeleton, and Kaisen wanted to keep the death pose intact. In the 1950s, the tail was “corrected” to make it drag on the ground. Although the display has not been altered since, the revised tail posture is now considered inaccurate. Indeed, the vertebrae apparently had to be angled unnaturally to make the dragging tail work at all.

AMNH 5027 was restored and remounted in 1995.

The Gorgosaurus plaque mounts hide behind Tyrannosaurus rex at AMNH. Photo by the author.

All three Gorgosaurus specimens were first displayed in the cramped quarters of the Hall of Fossil Reptiles (now the Hall of Primitive Mammals) with the rest of the growing AMNH dinosaur collection (USNM 12814 and the tail of AMNH 5664 are barely visible in this photo). 5458 and 5664 moved to the newly opened Great Hall of Dinosaurs in 1922. They flanked the gallery’s rear doorway for 70 years before being moved to the Hall of Saurischian Dinosaurs in 1994. Meanwhile, the Gorgosaurus transferred to the Smithsonian first appeared in the Hall of Extinct Monsters in the 1940s, displayed behind glass on the north wall. It switched to the south side in 1962, and moved about 30 feet up the wall in 1981, where it could only be properly seen from the mezzanine ramp.

Aside from the aforementioned alternation to AMNH 5664’s tail, the Red Deer River Gorgosaurus trio has not been modified since they were first built. This may well change in the not-to-distant future. The NMNH crew is hard at work on a thorough renovation of the national fossil hall, dismantling and restoring all of the classic dinosaur mounts. Meanwhile, the current AMNH paleontology exhibits are now 20 years old, and will soon be due for a similar overhaul. Both institutions will need to decide whether or not to free the Gorgosaurus specimens from their plaster substrate. This would be an extremely difficult process, but not impossible – Phil Fraley Productions recently rebuilt the Carnegie Museum’s Corythosaurus, Dryosaurus, and Camptosaurus as free-standing mounts. Dismantling the relief mounts would give a new generation of scientists access to these important specimens, and it would allow for the skeletons to be given more accurate poses. In addition, a standing Gorgosaurus mount alongside either museum’s Tyrannosaurus rex would be both informative and awesome.

Nevertheless, remaking these mounts would also destroy significant historical context. The carefully restored death pose of USNM 12812 seems like something worth preserving, and the AMNH specimens represent an important transitional period in the history of dinosaur science. In the past, museums have often taken a “science marches on” approach when updating aging displays, but in these mounts might be unique enough in their current form to be left as-is. What do you think?

References

Carr, T.D. (1999). Craniofacial Ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria). Journal of Vertebrate Paleontology 19: 497-520.

Colbert, E.H. (1968). Men and Dinosaurs: The Search in Field and Laboratory. New York, NY: E.P. Dutton & Co., Inc.

Gilmore, C.W. (1946). Notes on Recently Mounted Reptile Fossil Skeletons in the United States National Museum. Proceedings of the United States National Museum Vol. 96 No. 3196.

The Long Road to a Fossil Swap. Digging the Fossil Record, March 19, 2015. http://nmnh.typepad.com/smithsonian_fossils/2015/03/gorgosaurus-and-moropus.html

Matthew, W.D. and Brown, B. (1923). Preliminary Notices of Skeletons and Skulls of Deinodontidae from the Cretaceous of Alberta. American Museum Noviates 89: 1-10.

Russell, D. (1970). Tyrannosaurs from the Late Cretaceous of western Canada. National Museum of Natural Science Publications in Palaeontology 1: 1–34.

3 Comments

Filed under AMNH, dinosaurs, field work, fossil mounts, history of science, museums, NMNH, reptiles, theropods

3 responses to “A Trio of Tyrants

  1. Pingback: PaleoNews #14 | An Odyssey of Time

  2. Dennis Dempsey

    It would be great to see an exhibit on the history of paleontology including historic displays.

  3. Ben

    Hi Dennis, I definitely agree! How cool would it be if (say) AMNH put up a recreation of the historic T. rex mount alongside the updated version?

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