BOZEMAN, MONT.--A Bozeman, Mont., woman took particular notice of recent news that scientists had found a rare dinosaur embryo in the Patagonia region of Argentina.
Frankie Jackson, a research associate in the Museum of the Rockies and earth sciences department at Montana State University-Bozeman, is one of six scientists who described the discovery in the Nov. 19 issue of the journal Nature.
Photographs from the expedition appear in the December issue of National Geographic.
The Nature paper tells of rare embryos from a dinosaur nesting site covered with thousands of eggs over about one square mile. Jackson helped confirm that the fossilized embryos belong to sauropods--huge plant-eating dinosaurs like Apatosaurus, which used to be called Brontosaurus.
"I think this is a very exciting discovery. Extremely important," said Museum of the Rockies paleontologist Jack Horner.
Dinosaur embryos are rare, he said. Only six others have been found throughout the world.
"The exciting thing about this is we finally have identifiable embryonic remains inside an egg," said Jackson.
Scientists have identified sauropod eggs based on bones found in the same sediments as the eggs, but that method hasn't been accurate, she added.
It's also the first embryo retrieved from the Southern Hemisphere and the first to contain fossilized skin from baby dinosaurs.
Jackson was not on the expedition last spring that initially discovered the 70 million- to 90-million-year-old egg site. Scientists from the American Museum of Natural History in New York and Argentina's Museo Municipal Carmen Funes found the nesting ground where thousands of dinosaurs may have gathered to lay their eggs.
American Museum paleontologist Luis Chiappe contacted Jackson after learning from a colleague that she studies fossilized egg shells. Chiappe asked her to join the project and describe the eggs found in Argentina.
Jackson looked at thin sections of shell fragments under two microscopes. One is a powerful scanning electron microscope in the university's Image and Chemical Analysis Laboratory, which funded her project.
Jackson saw a bumpy surface, straight pores and distinctive shell "units" reaching from the inside to the outside of the shell. She could also see horizontal growth lines in the shell that look like tree rings. Those growth lines, as well as the general appearance of the shell, told her the sample was "minimally altered," she said.
"The preservation in these eggs is pretty amazing," she said.
Her initial microscopic analysis proved the eggs belonged to dinosaurs rather than to birds or crocodiles. Other evidence--such as the embryos and teeth found at the site--confirmed that the animals were sauropods. As a result, Jackson said, the new research conclusively links the egg to a particular type of dinosaur.
The American Museum of Natural History has asked Jackson to join the expedition's return trip to South America in March. She'll be in charge of data collection at the field site.
"There seems to be an incredible amount of material," she said. "They didn't do a lot of collecting [last year] because the discovery came at the end of the field season."
Jackson has several other egg research projects under way, and last year she co wrote a Nature article on the evolution of dinosaur reproductive traits. She's also taught geology and paleontology at the Museum of the Rockies field school near Choteau, Mont., for 10 years.
"It's mostly my experience at Egg Mountain that got me involved in the expedition to South America this spring," Jackson said.
She first visited Egg Mountain 11 years ago with her son and his two cousins. The experience changed her life, Jackson said. The geology, more than the dinosaurs, captivated her interest.
She signed on the same summer as a camp cook and later earned a degree from the University of Montana. Currently she does research in the MSU earth sciences department and at the Museum of the Rockies.
Journal
Nature