Where did it start? How did it grow complex? Why did it get big? Three moments in Earth’s early history when evolution suddenly, inexplicably turned up the dial.

© Photoillustration by Will Warasila for The New York Times

Flight was probably more widespread in dinosaurs than previously thought. A newly identified species sheds light on how some achieved liftoff.

We asked 100 scientists about unsolved problems in their fields. They sent back provocations — on the origins of life, the possibilities for human progress and much more.

© Photo illustration by Jane Stockdale for The New York Times

"Rex Junior" is a partial but perfectly preserved Tyrannosaurus skeleton found on the Zerbst Ranch in eastern Wyoming. A paleontologist said that the "extraordinary specimen" could rewrite 100 years of knowledge about how the T. rex looked. No photos of the exact specimen yet, but holy moly, paleontology fans!

The largest analysis of bat genomes and fossils suggests that the first bats emerged in Europe roughly 65 million years ago and that echolocation evolved early.

It’s the only example of a dinosaur-era feather found within rock that wasn’t completely flattened through the centuries.

Kent Hups, a high school science teacher in Colorado, discovered a 23-foot trackway of fossilized dinosaur footprints, which offer a glimpse of how the apex predator moved 66 million years ago.

A researcher surveying a San Mateo County creek stumbled upon a preserved Pacific mastodon molar estimated to be at least 10,000 years old.

Meet the earliest known insects. Shaking hands with them will take a while.

Scientists spent over a decade reconstructing the calls of nine species of ancient insects to create the first accurate Jurassic soundscape.

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The Academy of Natural Sciences in Philadelphia, which is affiliated with Drexel University, cited attendance struggles and higher costs in its decision to close.

© Matt Rourke/Associated Press