A Comedy of Dinosaur Errors

Tyrannosaurus rex has been the standard for dinosaur ferocity for more than a century. This dinosaur was the “prize fighter of antiquity,” as the New York Times proclaimed in 1906, but there have been a number of heavyweight challengers for the title of prehistory’s deadliest dinosaur. Among the most recent have been Spinosaurus, Giganotosaurus and Carcharodontosaurus—different sorts of predators that may have out-stretched and out-weighed the tyrant king. In 1941, Natural History ran a feature article on an excavation in the Late Jurassic rock of Oklahoma that turned up the “greatest predator of his time”—a dinosaur “equal in ferocity to Tyrannosaurus rex though he preceded this famous monster by 65 million years.” This was Saurophaganax, a huge predator with a twisted history.

The roughly 150-million-year-old predator was a New Deal dinosaur. According to the article, written by Grace Ernestine Ray, in 1931 cattlemen Pard Collins and Truman Tucker stumbled across some very large bones in the vicinity of Kenton, Oklahoma. They told University of Oklahoma paleontologist J. Willis Stovall about their discovery, and after seeing the bonebed littered with remains of Apatosaurus, Stegosaurus and other classic Morrison Formation dinosaurs, the professor applied to the Works Progress Administration, an agency that put unskilled laborers to work during the Great Depression, for support to excavate the site.

Excavations began in May of 1935 and ran through 1938. The effort did not go smoothly. As paleontologist Dan Chure noted in a review of the project in his dissertation on allosaurids, one of the WPA. policies was that laborers should live in the same county where the work was being done. Since Cimarron County, Oklahoma wasn’t rich in experienced paleontologists and preparators, this meant that the dig was primarily operated by local ranchers and farmhands who may have never even seen a fossil before. Stovall gave the crews a few tips on what to do, but many bones were accidentally destroyed as the workers tried to exhume and prepare them. Worse, no one kept adequate field data, and the uncertainty of the laborers about what was a bone and what was just a concretion led to an extremely high number of “specimens” to come out of the site. The WPA succeeded in that destitute farmers were given plenty of work, but the inexperience of the field hands and the lack of supervision at the site created a terrible mess for anyone hoping to figure out what had happened at that place 150 million years ago.

Not everything was lost. Stovall recognized that some of the bones found at the site, called Pit I, belonged to a carnivorous dinosaur that seemed much bigger than the usual Allosaurus found in strata of the same age. He had a mind to call the creature Saurophagus maximus, for surely it was an enormous “eater of saurians.” That’s about the time that Grace Ray visited the site for her Natural History story. A pair of mistakes further complicated the history of the dinosaur.

On the first page of Ray’s article, “Big For His Day,” there is a photograph of Stovall, his student Wann Langston, Jr. and Langston’s friend William Price poking away at what appears to be an articulated leg of a huge, Allosaurus-like dinosaur still encased in rock. But the photo was staged. Though embarrassed my his part in the faked photo, Langston later explained what happened. The magazine desired a dramatic photo of dinosaur bones coming out of the ground, but there were no bones at the quarry suitable for the story’s opener. Instead, Stovall threw some big theropod bones in his truck with Langston and Price along for the ride. The group picked a place just outside of Norman, Oklahoma, dug a hole in reddish Permian rock (many millions of years older than the Jurassic strata in which the dinosaur was actually found), arranged the bones and posed for the staged snapshot.

Ray’s story was also the first place the dinosaur’s proposed name appeared in print—Stovall’s “Saurophagus” had not yet been given a scientific description when the June 1941 issue of Natural History came out. Some paleontologists thought this publication would be sufficient to officially name the name, thus the journalist Ray, rather than the paleontologist Stovall, would get credit for publishing the moniker. But others disagreed and additionally pointed out that the name Saurophagus had already been given to a type of bird (appropriately, a tyrant flycatcher). The huge dinosaur didn’t have a real name until 1995, when Dan Chure revised the known material and proposed the modified title of Saurophaganax.

(I couldn’t help but be amused by Ray’s reporting, which made the entire pursuit sound better organized than it actually was. In particular, I had to laugh at her closing comments about why Stovall’s monster grew to such a gigantic size: “Despite his strength and power and his technique in terrorizing the enemy, Saurophagus would never have been able to pass the medical test of a military draft board, neither would Mrs. Saurophagus have qualified as a “perfect 36.” They were hopelessly overweight, and it is improbable that any amount of dieting would have remedied the situation. Overactive glands may account for their stupendous size, as in the case of other dinosaurs.” )

But there may be a few more tragic twists to the story before the bones of Saurophaganax can rest. This large dinosaur—estimated to have measured about 43 feet long, comparable to Tyrannosaurus—looked like a pumped-up version of Allosaurus. Maybe that is what Saurophaganax actually was. Allosaurus and Saurophaganax were closely related, lived during the same time, and co-existed with the same dinosaurian fauna. Even though Chure kept Saurophaganax as distinct on the basis of minute characteristics of the vertebrae, other studies have proposed that the dinosaur fell within the expected growth trajectory of Allosaurus. Perhaps the differences between Allosaurus and Saurophaganax are due to size and age. The discovery of a juvenile Saurophaganax would help distinguish the dinosaur as distinct from Allosaurus, but if only giant, Allosaurus-like forms are found then it’s possible that the giant Jurassic predators are Allosaurus that just happened to live long enough to reach greater body sizes. (It’s also worth nothing that Epanterias, a huge Late Jurassic theropod once thought to be unique, is often attributed to Allosaurus.) Recent histological research has indicated that Allosaurus lived fast and died young—possibly before they reached full skeletal maturity—and we would therefore expect exceptionally large specimens to be rare.

If Saurophaganax turns out to be synonymous with Allosaurus, then we will have to revise our understanding of how these widespread Jurassic predators lived and grew up. Such a change might also have some unexpected consequences. For one thing, bones attributed to Saurophaganax have been found in New Mexico and established the reason for the New Mexico Museum of Natural History and Science to put one on display attacking a large sauropod. That sauropod is a particularly large species of Diplodocus, formerly Seismosaurus, and it would be fitting for the predator to also be reassigned to a common, well-known Jurassic genus (though that by itself is not reason for doing so). But there may also be a sticky state symbol problem. Utah selected Allosaurus as its state fossil in 1988, and Oklahoma picked Saurophaganax as its state fossil in 2000. Should Saurophaganax turn out to be Allosaurus in disguise, Oklahoma will have to pick a new dinosaur or stick with the choice and say, “Well, our Allosaurus is bigger than yours, anyway.”

References:

Chure, D., 2000, A new species of Allosaurus from the Morrison Formation of Dinosaur National Monument (Utah-Colorado) and a revision of the theropod family Allosauridae. Ph.D. dissertation, Columbia University, pp. 1-964

Lee, A., & Werning, S. (2008). From the Cover: Sexual maturity in growing dinosaurs does not fit reptilian growth models Proceedings of the National Academy of Sciences, 105 (2), 582-587 DOI: 10.1073/pnas.0708903105

Ray, G. 1961. Big For His Day. Natural History 48, 36-39

Riley Black | | READ MORE

Riley Black is a freelance science writer specializing in evolution, paleontology and natural history who blogs regularly for Scientific American.