By Dr. Becker
Just as all dogs descended from the gray wolf, it’s thought that all birds share one common ancestor: a bird that lived in South America about 95 million years ago. This is a departure from previous estimates, which put birds’ common ancestor as living 170 million years ago.
The new, much younger, descendent is described in a new study in the journal Science Advances.1 The authors wrote:2
“Modern birds (Neornithes) are the most diverse group of terrestrial vertebrates in terms of their species richness and global distribution, yet we still have a poor understanding of their large-scale evolutionary history.”
Using DNA sequences of “clock-like” genes from modern bird families, and combining them with 130 fossil birds, the researchers were able to come up with a new timeline for the evolution of birds, including when they became widely diversified.
Modern Birds’ Ancestor ‘Looked Like a Bird, Not Like a Dinosaur’
Dinosaurs were still roaming Earth 95 million years ago when modern birds’ common ancestor was alive. However, the bird was not a dinosaur, nor did it look like one, according to the study. “This ancestor would have looked like a bird,” the study’s co-author said, and may also have been able to fly.3
There were many flying birds around in the Late Cretaceous period, but only one survived long enough to give flight to modern-day birds; the rest of the period’s bird species went extinct. The identity of the ancient bird is unknown, but the researchers revealed that it lived undisturbed for about 25 million years.
Then, about 66 million years ago (and before the mass extinction event that made dinosaurs disappear), rapid diversification occurred.
The diversification, in which new species began to evolve from the original common ancestor, occurred during a cooling trend on Earth and was also likely influenced by plate tectonics, during which areas of land may have been connected or disconnected, influencing travel routes.
It’s thought the ancient birds took two main routes as they left South America and continued to diversify along the way:
- A trans-Antarctic interchange that resulted in birds reaching Australia and Zealandia (New Zealand)
- A North American Gateway, helped along by an inter-American land bridge, that allowed the birds to reach North America, Africa, Asia and Europe
Birds May Have Gotten Their Sharp Hearing From a 245 Million-Year-Old Reptile
There are many mysteries surrounding birds, including how they came to develop such a sharp sense of hearing. Owls, for example, can locate prey in the dark, solely by hearing them move. Yet, they have no visible outer ear, which is used for amplifying sounds in humans.4
Using a fossil of Euparkeria, however, researchers may have discovered where birds got their excellent hearing. Euparkeria was an ancient reptile that was about 2 feet long and walked upright on two legs.
The reptile, which is thought to be a close relative of birds, dinosaurs and crocodiles, lived some 245 million years ago.
Researchers from the Federal University of Santa Catarina, Brazil used a CT scan to get a glimpse into the reptile’s inner ear, which revealed several characteristics that would have led to phenomenal hearing.5 Among them:
- An unusually long cochlea, which would have extended hearing range
- Special regions for pressure relief
- An ability to detect airborne sounds
Study author Gabriela Sobral, Ph.D., told the Daily Mail:6
“It is very exciting we can dig so deep into the palaeobiology of an extinct animal just by looking at the anatomy of its inner ear … Euparkeria has many transitional characteristics that can help us better understand how the highly speciali[z]ed ear of birds came into being.”
Ancient Hummingbird-Sized Wings Found Fossilized in Amber
Adding to the recent discoveries about ancient birds was a pair of tiny bird wings found fossilized in amber. The wings, thought to be about 99 million years old, were found in Burma and exquisitely preserved — even the hair, bones and feathers were intact and the colors still visible.7
The wings belonged to a bird of the group Enantiornithes, probably a hatchling. Similar in appearance to modern-day birds, the ancient species also had claws on their wings.8 Also of note, the birds were thought to hatch nearly fully developed, unlike modern-day birds.
As more discoveries are made, both due to scientific advances and fossil records, it’s likely we’ll learn even more about the fascinating ancient history of birds, as well as gain new insight into the modern feathered friends living among us.