From the vault: Fossilized march fly discovered near Colorado’s Douglas Pass |

From the vault: Fossilized march fly discovered near Colorado’s Douglas Pass

Caitlin Row
This march fly, which was discovered near Colorado's Douglas Pass, currently resides at Fruita's Dinosaur Journey Museum. Fully intact fossilzed insect specimens, like this one, are quite rare.
Dinosaur Journey Museum |


WHAT: Dinosaur Journey Museum

WHEN: Daily, 9 a.m. to 5 p.m.

WHERE: 550 Jurassic Court, Fruita

COST: $8.50 for adults, $6.50 for seniors, $5.25 for children and $24.50 for immediate family groups


Editor’s note: “From the vault” features fossils and other dinosaur-related historical artifacts currently stored at Dinosaur Journey Museum in Fruita, Colo.

Fossilized insects are rarely found fully intact. That’s why Fruita’s Dinosaur Journey Museum loves its fossilized march fly, found close to Colorado’s Douglas Pass (near Highway 139, on the way to Utah).

According to Julia McHugh, Dinosaur Journey’s curator of paleontology, the fly was discovered in what’s known as the Parachute Creek Member of the state’s Green River Formation, which dates back to the Eocene Epoch — 34-56 million years ago. The Green River Formation spans Colorado, Utah and Wyoming, and it’s known for its preserved sedimentary layers.

“Fossil insects are very rare, because unlike vertebrates (like us) they have no hard skeletons to leave behind,” McHugh said. “The fragile chitin of their exoskeleton easily decays away, leaving few fossils behind.

“However, when insects are preserved in the rock record, it is normally either in amber (fossil tree sap) or as carbonized impressions between thin layers of shale, like this one. Carbonized fossils can preserve amazing detail in insects. If you look closely at this fossil you can even make out individual segments in the legs and abdomen.”

Currently Dinosaur Journey Museum hosts dozens of fossilized insects, McHugh added, either from the Green River Formation or the Mesa Verde Group (which is a grouping of formations that include the Point Lookout Formation, the Menefee Formation, and the Cliff House Sandstone).

Other insects included in Dinosaur Journey Museum’s collection include trilobites, flies, bees, wasps, spiders, and beetles.

“Most of our insect fossils come from the Green River Formation and were found in the Douglas Pass and Parachute Creek areas, but we have a couple from the Mesa Verde Group (localities are unknown),” McHugh explained. “The fossil fly was collected by Larry Coddington in the early 1990s as part of his master’s thesis.”

To learn more about Fruita’s Dinosaur Journey Museum, visit

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