Long thought to be a simple speck of negative charge, the humble electron may be hiding one more surprise in its depths. The electron was the first fundamental particle discovered. It was the first to have its charge measured, and it inspired the mathematical equation that first hinted at the existence of antimatter, the exotic, oppositely charged counterpart to ordinary matter. Now the electron is poised to go one step further, by helping scientists understand why matter triumphed over antimatter in the early universe. In theory, the Big Bang should have created matter and antimatter in equ... (p. 22)

Pint-sized, two-legged runner from Argentina dates back to the dawn of the dinos, 230 million years ago. (p. 10)

El Niño heated things up even as global temperatures continue to rise in the hottest decade on record. (p. 17)

A detailed X-ray image of a fossil reveals an ancient marine creature’s diet. (p. 14)

Cutting fossil fuel emissions soon would retain enough sea ice habitat for threatened species, scientists say. (p. 5)

A huge shattered moon could have sprayed ice particles around the newborn planet. (p. 10)