A fossil has been found which shows three young dinosaurs snuggled asleep together.
It was found in a stone block which was taken from the Mongolian desert.
Researchers say they're the first known example of dinosaurs napping in a group.
Lots of animals, such as crows and bats, sleep together for protection and to help keep warm.
Experts think the three dozing dinos must have had a very close bond and were probably related - they might even have been siblings.
The three of them were together like this when they died.
They estimate each one weighed around 45 kilograms which is just a bit more than a German Shepherd dog.
Two of them are in sleeping positions which are like an ostrich or emu with their necks curled back towards their bodies with their arms cradling their heads.
The dinosaurs haven't been named yet but they walked on two legs and had a domed crest on their heads like a cassowary.
They're a type of Oviraptorid - that's a group of dinosaurs with short faces, long necks and toothless beaks which lived during the Cretacious period between 145 million to 65 million years ago!