Modern birds evolved from ground-dwelling ancestor, after asteroid hit

A new study says all modern birds evolved from the same ground-dwelling, common ancestor, after an asteroid slammed into Earth millions of years ago and devastated the planet’s forests.

“Everyone knows an asteroid the size of Manhattan caused a mass extinction 66 million years ago. The composition and distribution of life on Earth today cannot be understood except in light of this cataclysm,” said Yale professor of geology and geophysics Jacques Gauthier, co-author of a study published May 24 in Current Biology. Gauthier is curator of vertebrate paleontology and vertebrate zoology at the Yale Peabody Museum of Natural History.

“Although all the giant dinosaurs disappeared, a few small flying dinosaurs — namely, birds — survived,” Gauthier said. “We propose that widespread destruction of forests following the asteroid impact favored ground-dwelling birds over tree-dwelling birds.”

An international team of researchers from the U.S., England, and Sweden pieced together evidence from the plant fossil record and ecology of ancient and modern birds, in order to conduct the study. The lead author is Daniel Field, of the Milner Centre for Evolution at the University of Bath.

Gauthier said the study’s hypothesis explains the disappearance of the common tree-dwelling birds of the Cretaceous period. “It also explains the fact that although many birds live in trees today, their earliest relatives emerging from the wake of the asteroid impact were long-legged ground dwellers,” he said.

Additional co-authors of the study are Antoine Bercovici of the Smithsonian Institution, Jacob Berv of the Cornell Lab of Ornithology, Regan Dunn of the Field Museum of Natural History, Tyler Lyson of the Denver Museum of Nature and Science, David Fastovsky of the University of Rhode Island, and Vivi Vajda of the Swedish Museum of Natural History.