First Draft: Mesa County home to early giants of major dinosaur-fossil discoveries

Elmer Riggs’ assistant H.W. Menke standing with a leg bone of the Brachiosaurus discovered on the Redlands near Grand Junction. Photo courtesy of the Field Museum

Elmer Riggs as he appeared later in his life. Photo courtesy of the Field Museum.

The two-thirds complete skeleton of the Apatosaurus that Elmer Riggs discovered south of Fruita, as it appeared at the Field Museum in Chicago in 1909. Photo courtesy of the Field Museum, CSGEO27589.

The Field Museum in Chicago announced Aug. 30 that, beginning early next year, it will display “the biggest dinosaur ever discovered,” Patagotitan mayorum, found in Argentina in 2008.

More than a century ago, the Field Museum began displaying another giant replica of a dinosaur, an Apatosaurus that was uncovered at a site now called Dinosaur Hill, south of the Colorado River near Fruita.

Elmer Riggs, a paleontologist working for the Field Museum at the turn of the last century, spent two seasons working in the Grand Valley — in 1900 and 1901.

He made his first big discovery at the site now called Riggs Hill, near the intersection of South Broadway and South Camp Road on the Redlands. There, he and his assistant, H.W. Menke, recovered the shoulder, ribs, vertebrae and leg bones of a Brachiosaurus.

“This fellow was a record breaker for size for that time,” Riggs told an interviewer during the 1930s. “It was a jim-dandy. I only wish I had the whole skeleton of him.”

A Chicago newspaper of the time bragged that as a result of Riggs’ discovery, the city was home to “the largest land animal that ever lived.” And a Boston newspaper in late 1900 declared the creature that Riggs found “The Monster of All Ages.”

That wasn’t just hyperbole.

“When Riggs named and described Brachiosaurus, it became the new largest dinosaur … and it remained the largest dinosaur for decades,” said William Simpson, fossil vertebrates collections manager for the Field Museum today. “Riggs was always frustrated that Brachiosaurus wasn’t on display more.”

It was his Apatosaurus that received the most prominent display because the skeleton was more complete. That giant fossil has been on continuous display at the Field Museum since December 1908, in two different buildings and in three different exhibit halls, the spokesman said.

Riggs found the Apatosaurus late in the season in 1900. But he didn’t have time or money to excavate it then. Instead, he returned the following year with a crew, and discovered a much more complete skeleton than he had imagined.

But there was no bridge over the Colorado River at Fruita then, so Riggs had to improvise to get the fossils across the river and onto railroad cars to be sent back to the museum in Chicago.

“I went to a lumber dealer and gave him a sketch of a flat boat that was to be 24 feet long and 10 feet wide,” he recalled in that 1930s interview. He planned to use a cable from an old ferry that once crossed the river nearby.

The lumber was delivered, Riggs said, “And I fell to it and in two days I had nailed up that ferry boat.” It took much of that summer to excavate, crate and ship the dinosaur, two-thirds of an entire Apatosaurus.

Riggs’ research took him to Wyoming the following year, and eventually to Argentina. He didn’t return to Mesa County until 1938, when he participated in ceremonies commemorating his earlier discoveries. He dedicated plaques at both Dinosaur Hill and Riggs Hill that year.

Both the Brachiosaurus and the Apatosaurus that Riggs unearthed near Fruita in 1901 were members of a group of long-necked, plant-eating dinosaurs called sauropods. But neither of them was believed to be more than 75 feet long. The Apatosaurus was roughly 72 feet long.

In contrast, Patagotitan mayorum is 122 feet long from nose to tail, according to information provided by the Field Museum. It is part of a group of dinosaurs known as titanosaurs.

New specimens of dinosaurs have been discovered regularly over the past century, and new claimants for the title of the world’s largest land creature have come along frequently.

For a time in the 1970s and 1980s, the title was claimed by a pair of dinosaur fossils discovered at Dry Mesa Quarry on the flanks of the Uncompahgre Plateau near Delta.

Supersaurus and Ultrasaurus — which was later determined to be a large individual of the species Riggs named Brachiosaurus — were the largest dinosaurs found at the time. Ultrasaurus was estimated to be 100 feet long. But it was soon overtaken by discoveries of larger dinosaurs elsewhere on the planet.

At the Field Museum, Riggs’s discoveries were eventually overshadowed by other dinosaurs. One recent creature was not larger, but certainly more fearsome.

Sue, the largest and most complete skeleton of a Tyrannosaurus rex, has been on display in the central hall at the Field Museum since 2000. The giant fossil was discovered on the Cheyenne River Indian Reservation in South Dakota in 1990.

Sue will be disassembled and moved out of the Stanley Field Hall, the central gallery at the entrance to the museum, beginning next February. The cast of Patagotitan mayorum will take up residence there.

But Sue won’t disappear. She will be reassembled in another exhibit hall in the museum called “Evolving Planet,” and will be placed in context with other dinosaurs.

Equally important, the dinosaurs and other fossils discovered by Elmer Riggs, in western Colorado and on other expeditions, also remain at the museum, some of them very visible.

The Apatosaurus is also in the Evolving Planet display area now.

A plastic replica of a Brachiosaurus skeleton, based on Riggs’s incomplete fossil discovered on the Redlands, stands outside the Field Museum. Inside, in addition to Apatosaurus, are bones of some of the many other fossils and dinosaurs and early mammals that Riggs discovered.

Information from The Field Museum in Chicago, the Museums of Western Colorado and Bob Silbernagel’s book, “Dinosaur Stalkers: Tracking Dinosaur Discoveries of Western Colorado and Eastern Utah.” More information about the Field Museum can be found at

Bob Silbernagel’s email is .(JavaScript must be enabled to view this email address).


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