What to Name the Oldest Modern Bird Fossil? Wonderchicken

Trilobites Its skull was found in a chunk of rock that went overlooked for nearly two decades. Even paleontology has ugly duckling stories. In 2000, a fossil collector found a chunk of rock about as big as a deck of cards in a limestone quarry in Belgium. Sticking out of it were femur and shin bones the size of twigs that looked like the remains of a miniature chicken dinner.

Eighteen years later, Daniel Field, a paleontologist at the University of Cambridge in England, and Juan Benito, a doctoral student, took a CT scan of the chunk and found a prize within: an almost perfectly preserved ancient bird skull. “It just totally blew our minds,” Dr. Field said. The fossil, described by Dr.

Field and colleagues today in Nature, is between 66. 7 and 66. 8 million years old, making it “the oldest known fossil that’s clearly part of the modern bird family tree,” Dr. Field said.

It’s also the first fossil that resembles a modern bird without any ambiguity found in the northern hemisphere, he said, although at least one expert takes issue with this characterization. Bhart-Anjan S. Bhullar, a paleontologist at Yale who was not involved in the study, said that the fossil is “one of those great discoveries that come up a few times in a lucky lifetime. ” The researchers have given the bird the scientific name Asteriornis maastrichtensis along with a pet name: the Wonderchicken.

Sometime during the Jurassic period, around 165 million years ago, the earliest birds diverged from theropod dinosaurs. Over the next 100 million years, the bird family tree continued to branch out, leading to everything from broad-winged Archaeopteryx to toothy Enantiornithes. When the asteroid hit about 66 million years ago, many of these branches were sheared off.

“Those that survived became the birds we know today.”

Dr. Field noted that modern bird fossils from before the asteroid impact are extremely rare. Examining them can help experts learn about the features that might have allowed modern birds to survive that mass extinction event while other animals, including the dinosaurs, died out. Based on its bones, the Wonderchicken was likely a small, ground-dwelling bird — about the size of a male green-winged teal.