By studying bone cross-sections of dinosaurs that cared for their eggs, such as this oviraptor above, scientists figured out the dinosaurs became parents while still in their teens.

Photograph by Louie Psihoyos/Getty Images

EMAIL NEWSLETTER Photos and News of the Week Get the top photos and news of the week from National Geographic News, plus occasional breaking-news alerts. See Sample >> Please enter a valid email address Thank You! Subscription accepted. An email confirmation will be sent. Privacy Policy MOST VIEWED NEWS Total Solar Eclipse on August 1: Where, How to See It PHOTOS: Rare Mummy Found With Strange Artifacts, Tattoo PHOTOS: Over 100 "Quake Dogs" Get Medical Aid in China NEWS FEEDS      Get our news delivered directly to your desktop—free. How to Use XML or RSS