Dinosaur Central: Jack Horner and the Museum of the Rockies

The Museum of the Rockies, in Bozeman MT, is one of the biggest science museums in the world. Because it is located near some of the most extensive fossil beds in the US, it has a wonderful collection of skeletons, making it “dinosaur central” for research. Much of what we have learned about dinosaurs in recent years has come from the Museum of the Rockies, and most of that has come from just one person who has been based at the museum—Jack Horner.

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Museum of the Rockies

The Museum of the Rockies was founded in 1957 as part of Montana State University, and was located on the campus in Bozeman MT. It focused largely on the history of the local area, and contained Native American artifacts, historical objects, and the Tinsley Homestead, an original log house built in 1889 and furnished with items ordered from the Sears catalogue.

In the 1970’s, meanwhile, the study of dinosaurs was undergoing a revolution. Until this time, dinosaurs had always been pictured as slow stupid versions of giant reptiles. But in the 1970’s, researchers like John Ostrom and Bob Bakker changed our image of dinosaurs: they were now discovered to be agile and active animals, almost certainly warm-blooded, and very much like birds.

One of the discoveries that changed science’s mind about dinosaur behavior was made by Jack Horner. Horner had been a student at the University of Montana for seven years but never graduated. In 1978 he was doing field work with partner Bob Makela for the Princeton Natural History Museum when he made a remarkable discovery: a large expanse containing a number of round depressions with fossilized eggs in them. The nests belonged to a previously unknown species of duckbill dinosaur, which Horner now named Maiasaura (“good mother lizard”). The find altered the way we thought about dinosaur lifestyles. The expanse of closely-packed nests indicated that the Maiasauras lived together in communal herds and that they nested together in breeding seasons. Horner would excavate the site, now known as “Egg Mountain”, off and on for the next 20 years.

Examination of fossilized embryos inside the eggs showed that the babies were not fully developed when they hatched and had to be protected at birth by an adult. Further, the nests contained layers of trampled eggshell, indicating that the youngsters remained in the nest for a long period of time even after they became mobile, and were cared for by their parents. Slicing the bones open allowed Horner to examine the dinosaur’s growth pattern, and established that Maiasaura had a rapid rate of growth and was likely warm-blooded. It was a very birdlike pattern of behavior.

The find made Horner famous, and he was hired on in 1982 by Montana State University to set up a dinosaur research field project. MSU would become his home base for the next four decades, and a steady stream of finds resulted. One spectacular discovery was a vast field of volcanic ash that had killed and entombed an entire herd of adult Maiasauras, about 60 miles away from the Egg Mountain nesting grounds. By 1986 Horner had been awarded an honorary doctorate in paleontology and a MacArthur foundation grant. He was supervising paleontological digs from Montana to Mongolia, and was making regular TV appearences for National Geographic and the Discovery Channel.

His next big discovery was in 1988, when a rancher in Montana found what turned out to be a partial skeleton of Tyrannosaurus rex, including the skull and the first complete forelimb to be uncovered. Although “Wankel rex” (named after its discoverer) was owned by the US Army Corps of Engineers, the Museum of the Rockies successfully lobbied for the fossil to remain in Montana (most of the previous discoveries were displayed outside the state), and a reconstructed skeleton was displayed at the Museum until 2013, when it was placed on longterm loan to the Smithsonian in Washington DC.

When Michael Crichton was writing his novel Jurassic Park in 1989, he based the book’s protagonist, paleontologist Dr Alan Grant, on Jack Horner. And when Steven Spielberg shot the movie version of “Jurassic Park” in 1993, he took Horner on as a scientific advisor. Horner had already become notorious for his iconoclastic opinion that perhaps T rex had been a scavenger and not the mighty apex predator of popular view. Although Horner never published this hypothesis in a peer-reviewed paper, it became the center of a media frenzy—which Horner viewed as a good way to teach kids how science works.

Meanwhile, in the 2000 and 2001 digging seasons, Horner’s teams uncovered a total of eight separate T rex specimens, which gave the Museum of the Rockies the biggest Tyrannosaurus collection in the world. In 2003, as the summer digging season was reaching its end, one of Horner’s teams was digging out a skeleton of a duckbill named Edmontosaurus. At lunchtime, one of the crew wandered off to sit on a nearby rock ledge—and found a Tyrannosaurus foot bone poking out of a cliff face. When it was excavated, the femur bone was too heavy to lift out, even with a helicopter, so Horner was forced to break the bone into two pieces to carry it away.

It turned out to be a blessing: when the exposed broken surface was examined, the femur revealed a shocking surprise—what appeared to be the remains of soft tissue preserved inside the bone. Back at the Museum of the Rockies lab, team member Mary Schweitzer used acids to dissolve away the petrified stone and expose the tissues. Remarkably, the tissue contained chemical traces indicating that the T rex was a female who had only recently laid eggs. The thigh bone is now on display at the Museum.

Meanwhile, during the 2000 season, Horner also uncovered the skeleton of a baby Triceratops, the first one to be identified. His study of the new fossil, and a re-examination of a number of other horned dinosaurs, led Horner to a controversial conclusion: many of the smaller dinosaur species that have been named and described are actually juveniles of other named species. The baby Triceratops hatched with just a short frill on its neck and tiny nubs for horns. As it grew, Horner concluded, the frill got larger and developed triangular points along its margin while the horns grew upwards (a stage which had been described as a separate species Torosaurus), but as the dinosaur reached adulthood, the edge of the frill got flatter and the horns turned to face out instead of up (the adult Triceratops).

He also detected a growth series in the thick-skulled dinosaur Brachycephalosaurus, with the species Dracorex and Stygimoloch actually being juvenile and subadult stages of the adult. And finally, Horner took on the most popular dinosaur of all, concluding that some of the smaller tyrannosaurid species (such as Nanotyrannus) were actually juveniles of T rex. As many as one-third of all known dinosaur species, Horner asserted, may in fact actually be younger versions of other species. Today the Museum of the Rockies devotes an entire wing to illustrating Horner’s hypothesis, displaying several series of skulls from juvenile to adult.

By 2006 the Museum was looking to expand—it had a huge collection of dinosaur fossils and no good place to display them. So an entire new hall was built, using a $2 million grant from software executive Tom Seibel. And now the Museum of the Rockies exhibits one of the largest displays of dinosaur fossils in the US.

 

 

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