Fossils Indicate That Feathered Creatures Flew Like Chickens

In 1861, researchers found Archeopteryx, a feathered dinosaur, in 150-million-year-old limestone in Solnhofen, Germany. At that time, they were unaware that this fossilized skeleton—and subsequent finds—would provide critical evidence for evolutionary theory, demonstrating that birds indeed descended from dinosaurs.

“They’re maximizing their existence,” remarked Jinmai O’Connor, a paleontologist at Chicago’s open-air museums.

For more than 164 years, scientists have closely examined all available specimens. Thus, one might assume that such well-researched fossil species would yield no further surprises. However, a recent paper published in the journal Nature on Wednesday by Dr. O’Connor and his research team unveiled new details about soft tissues and skeletal structures from a newly identified specimen dubbed the Chicago Archeopteryx. Their findings could offer insights into short flights and clarify how feathered dinosaurs evolved to move from the ground.

Dr. O’Connor noted that for a long time, it has been challenging to understand the flight capabilities and environmental adaptations of Archeopteryx. Many specimens are flattened due to geological processes, which complicates the identification of key skeletal details. While earlier researchers and most modern experts agree the species likely achieved flight, certain anatomical features prompt paleontologists to seek additional data.

The latest specimens acquired by the Field Museum in 2022 and published in 2024 have enabled Dr. O’Connor’s team to begin addressing some of the anatomical uncertainties.

When the fossil arrived at the museum, it was not clearly visible. The specimen matched the color of the surrounding rocks, making most of the soft tissues difficult to discern, according to Dr. O’Connor.

Researchers illuminated the fossils using CT scans and created digital maps of the skeleton to aid in preparing the slab. They also employed special techniques; chemical treatments made soft tissues glow under UV light, helping the team avoid accidentally damaging feathers and skin textures while exposing bones. Such methods weren’t available to fossil preparers in the 1800s.

Unlike other specimens, the bones of the Chicago Archeopteryx are preserved in three dimensions, allowing Dr. O’Connor’s team to closely analyze the skull palate. This revealed the oldest signs of evolutionary trends toward the more flexible skulls of modern birds compared to their ancient counterparts, Dr. O’Connor explained.

In another stroke of fossilization luck, the wings of the specimen were detached from the body and “preserved in detail,” Dr. O’Connor noted. Upon closer examination, the team confirmed that instead of having the previously observed two layers of wing feathers, the Archaeopteryx actually boasts three. In modern birds, this third layer helps connect shorter forearms to the body, creating a continuous lifting surface critical for maintaining flight.

Dr. O’Connor noted that the structure of the wings stands in contrast to other feathered, non-avian dinosaurs, whose long wings remain rigid at the elbows, making them useful but ultimately ineffective for flight.

The absence of a sternum suggests these birds were likely less adept at flying. However, the toe pads found in the Chicago specimen provide additional evidence that these creatures were well-adapted for life on the ground, resembling a Jurassic-era chicken or road runner. They could achieve brief flights if necessary, but generally preferred to sprint.

The newly reported characteristics enhance the current understanding of Archeopteryx and directly support ongoing theories regarding the relationship between the species’ abilities and the origins of flight, according to Michael Pittman, a paleontologist from the University of Hong Kong who was not part of the study.

“This study truly underscores the importance of uncovering new fossils, even in well-known and thoroughly examined specimens,” he stated.

Dr. O’Connor concurred.

“This specimen will keep me engaged for years,” she remarked.