Chicago Museum Unveils the ‘Most Important Fossil Ever Discovered’: the Feathered Dinosaur Archaeopteryx

Archaeopteryx provided the missing link between dinosaurs and the avians of today, serving as critical evidence for Charles Darwin’s theory of evolution

the head, neck and wing of archaeopteryx
Close-up showing the Archaeopteryx fossil’s skull, neck, spine, rib cage and wing bones. The fossil will go on view at Chicago's Field Museum on May 7. Delaney Drummond © Field Museum

Today, some 50 billion birds roam our planet, navigating every continent and environment. With their melodic chirping that awakens people daily and their visits to birdbaths and feeders, birds are a familiar presence in human lives.

But rewind about 150 million years, and Archaeopteryx—widely recognized as the earliest known bird—cut a starkly contrasting image, boasting a snout filled with sharp teeth, wings with claws and a long, bony tail.

Archaeopteryx (meaning “ancient wing” in Greek) was a genus of small, bird-like dinosaurs from the late Jurassic Period that inhabited what is now Europe. Despite the extinct creatures’ differences from today’s birds, they share many similarities with modern avians: a small size, a wishbone and asymmetric feathers, to name a few.

Only a dozen Archaeopteryx fossils have been discovered, most of which are in Europe. But beginning on Tuesday, May 7, Chicago’s Field Museum will make the 13th known Archaeopteryx fossil visible to the public—the first specimen of its kind in a major natural history museum in the Western Hemisphere.

museum and political officials stand in front of the "chicago archaeopteryx" display, with members of the media standing in front
Field Museum paleontologist Jingmai O'Connor shows Chicago Mayor Brandon Johnson and Cook County Board President Toni Preckwinkle the Archaeopteryx fossil slab. Aaron Boorstein

The displayed fossil is accompanied by an animated, holographic projection illustrating how Archaeopteryx would have moved and looked. The fossil will be removed from public view in June in preparation for its permanent exhibition opening this fall.

Archaeopteryx is arguably the most important fossil ever discovered. It transformed how scientists see the world by providing strong support for Darwin’s theory of evolution,” says Julian Siggers, the Field Museum’s president and CEO, in a statement. “This is the Field Museum’s most significant fossil acquisition since SUE the T. rex, and we’re thrilled to be able to study ‘the Chicago Archaeopteryx and to share it with our visitors.”

Unlike SUE, which was named after its discoverer, Sue Hendrickson, the Field Museum’s new fossil is called the Chicago Archaeopteryx, as specimens of the genus are named after the city in which they reside. For example, other Archaeopteryx fossils are named for London, Berlin and Munich. The only other Archaeopteryx in the United States is in Thermopolis, Wyoming.

The Chicago fossil “is, without a doubt, one of the best specimens of this important species that has ever been found,” said Jingmai O’Connor, the Field Museums’s associate curator of fossil reptiles, at a media preview event on Monday.

two feathered birds with long tails and head crests fight over a small lizard
An artist's illustration showing what Archaeopteryx might have looked like in its day. In this image, two Archaeopteryx are fighting over a small lizard. Ville Sinkonnen © Field Museum

When Archaeopteryx was discovered in 1861, it provided a groundbreaking piece of evidence in favor of Charles Darwin’s theory of evolution. Paleontologists view the prehistoric bird-like creature as a transitional fossil, bridging small carnivorous dinosaurs, known as theropods, with modern birds, Live Science’s Joseph Castro writes.

In his 1859 book On the Origin of Species, Darwin noted that the “gravest objection which can be urged against my theory” was the absence of transitional fossils. But the first complete Archaeopteryx specimen provided this “missing link” between birds and dinosaurs—and it was discovered only two years after Darwin published the book.

Archaeopteryx is like the holy grail,” O’Connor said at the media event.

While the Chicago Archaeopteryx is about the size of a homing pigeon, the species could reach up to 20 inches long. A 2018 study found that Archaeopteryx used its wings to fly and moved like modern pheasants, with short bursts of active, flapping flight.

an archaeopteryx fossil spotlighted on a dark background
The Chicago Archaeopteryx fossil slab Delaney Drummond © Field Museum

The Chicago Archaeopteryx was discovered where all other such fossils have been found to date: a deposit in Southern Germany called Solnhofen Limestone. Unearthed by quarry workers in 1990, private collectors held the fossil until Field Museum supporters helped procure it. The fossil reached the museum in August 2022.

“When the specimen arrived, it was still unprepared, meaning that most of the skeleton was obscured by a top layer of rock,” O’Connor says in the statement. “We weren’t sure how complete it was—when we X-rayed the fossil slab and saw that the fossil inside was nearly 100 percent complete, we cheered.”

According to an exhibit label, the museum’s preparators spent 1,300 hours preparing the fossil for display. They “revealed details—like skin imprints and tiny skull bones—that are not preserved in other Archaeopteryx fossils.”

The Field Museum, as well as local and state government officials, are eager for the educational opportunities the fossil offers.

“When this opens permanently this fall, students and teachers will have the unique opportunity to experience the exhibit with a focus on fossil excavation,” Chicago Mayor Brandon Johnson said at the media event.

“We are excited to celebrate this priceless specimen and its significance in further positioning Chicago as a premier destination in the world to explore the natural sciences,” Johnson adds in the statement.

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