A recent fossil find fills in a glaring prehistoric bird gap. The Jurassic period claims Archaeopteryx (sometimes called adeinonychosaurian dinosaur), which, despite their feathered wings, appear more dinosaur like. Meanwhile, most Cretaceous avian progenitors appear more birdlike, with short tails ending in a compound bone called a pygostyle.
A team from the Chinese Academy of Sciences report in the journal Nature found a specimen that fits between those proto birds. This finding suggests that the creatures we know as birds — or at least winged creatures that were more bird than dino — emerged 20 million years earlier than previously thought.
Early Bird Fossil Discovery
The team, led by Wang Min, discovered two bird fossils in Jurassic-era rocks in southeast China. Because the rocks in which the fossils were encased date back 149 million years, the fossils show that birds started diversifying away from dinosaurs by the end of the Jurassic period.
It can be difficult to identify where, when, why, and how birds began to differentiate. Bird — or birdlike — fossils from the Jurassic period are relatively rare and often incomplete.
Despite Archaeopteryx’s feathered wings, it closely resembled non-avialan dinosaurs, notably due to its long, reptilian tail, which separates it from both Cretaceous and more modern birds.
Read More: One of the Earliest Birds Ever Discovered Has Rare, Stork-Like Legs
Different Classification
Some paleontologists have questioned whether Archaeopteryx should be considered a bird at all— classifying it as a deinonychosaurian dinosaur, a sister group to birds still considered more dinosaur-like. That reclassification caused some paleontologists to wonder whether real Jurassic birds exist.
The new findings answer that question with a resounding yes.
One of the two fossils, which they named Baminornis zhenghensis, possess bird-like shoulder and pelvic girdles. It also has a short tail. That feature connects it solidly to contemporary birds, because the tail terminates with a compound pygostyle. Although a handlike structure still connects it to dinos, the other features make it more bird than reptile.
Rewriting the Record
This finding rewrites the evolutionary history of birds. "Previously, the oldest record of short-tailed birds is from the Early Cretaceous,” Wang said in a press release. “Baminornis zhenghensis is the sole Jurassic and the oldest short-tailed bird yet discovered, pushing back the appearance of this derived bird feature by nearly 20 million years.”
The second fossil is less complete. Although one feature resembles that of other Cretaceous birds, the poor preservation and lack of bones kept the researchers from classifying it as a new species.
Read More: What Makes Archaeopteryx Fossils the Bizarre Bridge Between Dinos and Birds?
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Before joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.
