Wasps: Nesting with the dinosaurs

EMORY (US) — Fossil evidence suggests wasps were nesting with dinosaurs as long as 75 million years ago, a new study reports.

Scientists say the discovery at the Two Medicine Formation in northwestern Montana offers clues about the plants that may have been flowering in the area and the climate at the time.

“Insects reproduce quickly, and they’re extremely sensitive to their environments, so they can tell us a lot about prehistoric conditions,” says Anthony Martin, paleontologist at Emory University.

Martin’s study, the first linking wasps and dinosaur nests, appears in the journal Historical Biology.

Co-author David Varricchio, a dinosaur expert from Montana State University, had been studying dinosaur nests in a limestone outcrop at the Two Medicine site, and called in Martin to help analyze fossils that resembled insect pupae.

They correlated the size, shape, and weave-like impressions on the surface of the fossils with those of modern-day wasp cocoons.

They also found the same prehistoric and modern-day correlations in the traces of prehistoric insect burrows and brooding chambers within the assemblage of dinosaur nests.

The Two Medicine Formation consists mostly of sandstone and limestone, deposited by rivers and deltas during the Late Cretaceous. The area is known for its dinosaur eggs and the earthen, ring-shaped remnants of the ground nests that held them.

“Modern insects that use soil for reproduction tend to be relatively picky about where they reproduce,” Martin says. “Bees and wasps like really well-drained soils, for instance, and prefer semi-arid conditions.”

The fossil cocoons litter the ground around the dinosaur-nesting site.

“You can actually use the cocoons as prospector tools if you are looking for dinosaur nests,” says Martin.

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