This Bird Kept Its Feathers for 52 Million Years

Eofringillirostrum boudreauxi lived some 52 million years ago — at a time when perching birds were rare. Lance Grande, Field Museum
Fossilized remains of a 52-million-year-old bird
The oddly curving beak may have actually been a boon when it came to cracking open small, hard seeds. Lance Grande, Field Museum

You've probably seen a lot of passerines in your day. In fact, you may have seen one today. Of course, you know them by other names. Like sparrow, or crow, or finch.

But scientists — less-inclined to take flights of etymological fancy — lend them just one broad designation: passerine, or "perching" bird.

And by their account, passerines make up some 6,500 of the 10,000 bird species that bring a colorful chorus to our skies and trees today.

But millions of years ago, you could have gone your whole life without being serenaded by a single bird.

Passerines were incredibly rare — which makes the recent discovery in Wyoming of one that lived 52 million years ago so remarkable. And, as researchers noted in a paper in Current Biology, the bird managed to hold onto its feathers the whole time.

"This particular piece is just exquisite," cooed study author and Field Museum curator Lance Grande in a press release. "It is a complete skeleton with the feathers still attached, which is extremely rare in the fossil record of birds."

Besides the 52-million-year-old perching bird, researchers described a second, similarly rare, passerine found in Germany that likely lived 47 million years ago.

But the Wyoming bird, in all its feathery glory, boasts another fascinating feature: a cartoonishly curved beak that suggests it might have been featured on boxes of cereal for prehistoric children.

"Its beak was very finch-like, extremely similar to species like the American goldfinch for example — short, conical, and tapering to a sharp point," co-author Daniel Ksepka of the Bruce Museum in Connecticut, tells Gizmodo. "The big difference from modern passerines was that it had a reversed fourth toe. The fourth toe pointed backwards, perhaps aiding in grasping or clinging. In modern songbirds, the fourth toe points in the same direction as the other toes. The beak shape suggests it ate small seeds."

It all adds up to what may be the earliest known precursor to modern-day finches and sparrows — except one uniquely suited for the hardscrabble diet of the Early Eocene Age.

"These bills are particularly well-suited for consuming small, hard seeds," Ksepka explains in the release. "Until this discovery, we did not know much about the ecology of early passerines. E. boudreauxi gives us an important look at this."

Dubbed Eofringillirostrum boudreauxiwhich appropriately translates as "dawn finch beak" — the bird was found in the even more appropriately named Fossil Lake, an area that was once a sub-tropical water system teeming with life.

Although the lake has long since dried up, scientists still flock to the area for its trove of well-preserved remains of the distant past from dinosaurs to the poignant tracks of a young woolly mammoth walking alongside an injured parent.

"I've been going to Fossil Lake every year for the last 35 years," Grande notes in the release. "And finding this bird is one of the reasons I keep going back."