"Everything is mixed. Pieces are everywhere, like they've been just kind of thrown all over the asteroid belt," said DeMeo, lead author of a study that appears in this week's journal Nature.
ANALYSIS: NEOWISE is Back in the Asteroid Hunting Business
"It's certainly overturned a lot of traditional thinking," added University of Arizona planetary scientist Dante Lauretta, lead researcher for an upcoming NASA asteroid sample return mission.
"There is still an underlying structure and composition, but there is evidence of mixing and that just makes so much sense to me," he said.
Scientists don't yet know why smaller asteroids buck the trend of their larger siblings, but that it is related to the gravitational elbowing by jostling planets early in the solar system's history.
"What we're leaning toward now is that asteroids, rather than forming in the asteroid belt, formed throughout the entire solar system ... as close (to the sun) as Mercury and as far away as Neptune, and then, through the planetary migration, you scatter them all over the place. What's left is what you see in the asteroid belt today," DeMeo said.