Albuquerque Dig Yields Bones of a Dinosaur Dubbed ‘Earthshaker’

Nine bones from what may have been the world’s largest dinosaur--an 80-ton, 100-foot-long behemoth--have been excavated from a site near Albuquerque by David Gillette, a paleontologist with the New Mexico Museum of Natural History.

“It’s one helluva big dinosaur,” said paleontologist Nicholas Hotten III of the Smithsonian Institution.

The bones were originally discovered in 1980 by retired music teacher Arthur Loy of Albuquerque, who was out hiking, but Gillette was not able to excavate them until last year. The site is about 60 miles northwest of Albuqerque. Gillette delayed announcement of the discovery until Friday because “we didn’t want to say anything until we were sure what we had.”

Gillette has so far recovered eight articulated--connected--bones from a 10-foot section of the middle of the dinosaur’s tail and a thighbone from the upper part of the hind leg.

Estimate of Size

Extrapolating from these bones, Gillette estimated that the new dinosaur--which he called seismosaurus or “earthshaker”--was probably 100 to 120 feet long, 18 feet high at the shoulder, and 15 feet high at the hip. He estimated that it weighed at least 80 tons.

“Ours appears to be the longest dinosaur ever discovered, and a good case could be built for it being the largest ever known,” Gillette said in a telephone interview.

In comparison, a bull elephant weighs about 7 1/2 tons and a blue whale about 100 tons.

The bones were isolated from the 150-million-year-old Morrison Formation, which spreads through New Mexico, Colorado and Utah. The largest previously known dinosaurs, called supersaurus and ultrasaurus, were also isolated from the Morrison Formation by paleontologist James A. Jensen, who has since retired from Brigham Young University.

‘Nothing Outrageous’

“That formation has been very productive of real big dinosaurs,” Hotten said, “so there is nothing outrageous about Gillette’s discovery.”

Supersaurus was about 100 feet long and 25 feet high at the shoulder, and weighed 60 to 70 tons.

Seismosaurus, like supersaurus and the similarly sized diplodocus, is a member of the sauropod family of dinosaurs characterized by long, graceful necks, a bulky body, and a long tail. Sinclair Oil Co. has used a stylized picture of a sauropod as its trademark.

The sauropods were plant eaters whose long necks allowed them to graze on the tops of the coniferous forests that covered much of the Earth during the Jurassic period during which the Morrison Formation originated.

Later Than the Others

Gillette believes that seismosaurus came later in the Jurassic than the other large dinosaurs because its bones were found higher in the Morrison Formation, indicating that they were buried more recently.

He and other paleontologists agree that the sauropods existed in large numbers for only a relatively brief period. Bones from another large family of dinosaurs, the titanosauridae, have been dated from near the end of the Cretaceous period--about 65 million years ago, shortly before dinosaurs became extinct.

“One member of the titanosauridae--alamosaurus-- seems to have been a giant, but no one has a real good feel for its size,” Gillette said.

“It appears that there was a gradual diminishing of abundance and diversity of sauropods during the Jurassic,” Gillette added. “That diminishment correlates with the diminishing dominance of the coniferous forest and its replacement by flowering plants . . . which supported mostly smaller dinosaurs.

‘Were Crowded Out’

“I don’t think it’s any great mystery about the sauropods’ becoming extinct. They just lost out on living space and food--they were crowded out.”

Gillette hopes to learn a lot more about seismosaurus. “We have a lot more bone in the ground and we’re going to continue these excavations sometime in the next month or so,” he said.