The largest dinosaurs of all time had a bad habit of losing their heads. When a titanosaur died, its small skull often wound up far from its massive body, making it hard for paleontologists to track down an animal’s noggin millions of years later.

But now, a complete skull from a newly named species of titanosaur is offering paleontologists a detailed look at how these giants sensed the world around them.

“More than 60 legit titanosaur species have been named to date,” but Sarmientosaurus is only the fourth to have an entire skull, says study co-author Matthew Lamanna, a paleontologist at the Carnegie Museum of Natural History in Pennsylvania.

What’s more, “Sarmientosaurus has probably the most complete and best preserved skull of