29 Million-Year-Old Eggs Found in a Prestigious U.S. Monument

Prior discoveries of individual eggs in the area led to misidentification, but this new find sheds light on the true nature of these ancient specimens.

According to CNN, the scans have revealed not only the remarkable age of the eggs but also its probable creator: a grasshopper. The structure of the eggs and the nest closely resemble those of modern grasshopper species, providing a clearer view of the ancient ecosystem and confirming the presence of these insects in that era.

CNN reports that intact egg cases are seldom found, making this find exceptionally rare. As reported in the journal Parks Stewardship Forum, this discovery offers a unique view into the reproductive habits of grasshoppers dating back to the Oligocene Epoch, a period ranging from 33.9 million to 23 million years ago.

In an email to CNN, Lee expressed excitement, stating, “This work is exciting because such exceptional preservation provides unique insights to one of the least understood life stages of insects, particularly in the geologic past.”

This egg pod fossilized in a dynamic environment near a river or stream, yet remained undisturbed and in near-perfect condition.

He stated, “They are the first to be recognized as belonging to orthopterans — grasshoppers and their kin — in the fossil record, which is noteworthy.”

The fossil required no tools for extraction, and Schierup transported it carefully back to the visitor center for further examination.

Dr. Nick Famoso recalled his skepticism about this identification, CNN reveals, noting the curvature of the eggs differed from that of ant eggs and pupae. His suspicion led to further investigation and eventual identification as a grasshopper egg pod.

Famoso explained, “That’s when we discovered that there was this protein layer that was holding everything together.” It was then identified as a subterranean egg pod called an ootheca.

The scans revealed a radial arrangement of the eggs in multiple layers. The mineralization visible in each egg confirmed the fossilization structure, as Famoso described.

He remarked to CNN, “Such large, elliptically curved eggs in a large clutch size (~50 eggs in total) are unknown from any other living groups of insects other than grasshoppers and locusts.”

Famoso added to CNN, “Just being able to see that internal structure and really properly describe what these things look like — that was something that was really exciting for us. There just isn’t anything else like this in the fossil record anywhere that we know of.”

These fossils are significant as they display the earliest example of insects engaging in brood care, a behavior where a parent protects its offspring. Specifically, these ancient bugs carried clusters of eggs on their legs, a method previously unseen in the insect world.

A study published in the journal Proceedings of the Royal Society B: Biological Sciences revealed that the eggs, found in clusters, demonstrate a level of parental care that was not known to exist in insects from such an early period. This revelation provides a new understanding of the evolutionary history of insect behavior.

Among these, 30 specimens were identified as female water bugs, each carrying eggs on their left “mesotibia,” the middle leg of their three legs. 

The eggs were attached to the leg with a stalk, allowing them to jiggle as the insect moved. 

This behavior is similar to that of the earwig, which grooms its eggs to remove harmful mold spores.

Today’s giant water bug carries eggs on its back until they hatch, suggesting a possible evolutionary link between ancient and modern insect parenting strategies.

This level of preservation has allowed scientists to study these ancient creatures in unprecedented detail, as first reported by Live Science.

These eggs measured about 0.04 to 0.05 inches across, a significant size considering the adult water bug was only about 0.5 inches long.

The study notes, “The unoccupied right mesotibia might have been used to maintain balance when swimming and feeding.” 

This finding illustrates the complex relationship between physical adaptations and environmental necessities in the evolution of insect species.

They wrote “To our knowledge, carrying a cluster of eggs on [one] leg is a unique strategy among insects, but is not unusual in aquatic arthropods,” meaning crustaceans. 

The authors of the study explained, “Our finding pushes back the evidence of definitive brooding behavior in insects by almost 38 million years, which are helpful for understanding the evolution and adaptive significance of brood care in insects.”