It is not common for scientists to dig up a dinosaur jaw—or unearth the remains of fossilized insects. So paleontologists couldn’t believe their luck when they found, in 2010, a 75-million-year-old jawbone of a duck-billed hadrosaur in Dinosaur Provincial Park in Canada’s Alberta province, topped with a 7-centimeter-wide blob of amber with the traces of trees and sap-sucking aphids.
The “remarkable” two-for-one fossil would have been preserved in an incredibly unlikely chain of events, the researchers write today in Scientific Reports. The paleontologists believe that after the Prosaurolophus hadrosaur died—and the flesh had decayed off its jawbone—it washed into a river. There, a blob of sticky resin from either redwood or an araucarian conifer tree also fell. The blob, containing an unlucky aphid, washed up against the bone and was pressed against it by the flow of water, the scientists argue. It was then covered in sediment for tens of millions of years, during which time the resin hardened into amber.
The discovery—the first of its type in North America—carries a cargo of secrets about the dinosaur’s environment. For example, the plant and insect traces inside document what many paleontologists already hypothesized: Some hadrosaurs, which includes the 9-meter-long Prosaurolophus, grazed on conifers near coastal floodplains.