Scientists know little about what growing up in the age of dinosaurs was like, but Mussaurus can help us better explore this intriguing subject. 

1. Its Name Means “Mouse Lizard.”

Was Mussaurus especially rodent-like? No, but babies measuring under 8 inches long have been unearthed, hence the cute-sounding genus name.  

2. It Gets a Cameo in Michael Crichton’s The Lost World.

Early on, one of the novel’s protagonists gingerly picks up a palm-sized Mussaurus. However, for reasons unknown, Spielberg cut this little herbivore from The Lost World: Jurassic Park, his 1997 film adaptation.

3. Mussaurus is Often Mistaken for a Dinosaur Record-Holder.

Mussaurus was originally discovered in 1979 and, at the time, was known only from hatchling remains. Ever since, popular science books have been touting it as the “world’s smallest known dinosaur.” But don’t call Guinness just yet! Paleontologists estimate that average adults would have been over 10 feet long, making Mussaurus far too large to merit this distinction—an assessment vindicated two years ago, when a quartet of grown-up specimens emerged.

Today, the tiniest living dino is the bee hummingbird (Mellisuga helenae), which can comfortably perch on the end of a pencil. But what about those non-avian, extinct varieties? China’s 16-inch Anchiornis huxlei (pictured above) currently takes the cake.

4. Creepy-Crawlies Might Have Been on its Menu.

Paleo-artist Gregory S. Paul believes that, given the shape of their teeth, “small juvenile Mussaurus ... supplemented their diet with insects.” Hey, arthropods are a great source of protein—don’t knock ‘em ‘til you’ve tried ‘em!

5. The Oldest-Known Dinosaur Nest Likely Belonged to a Mussaurus.

In Patagonia’s bountiful fossil beds, seven juveniles were spotted hanging out together next to a pair of decently-preserved eggs. If this actually represents a dinosaurian nesting site, at 215 million years old, it would be the earliest we’ve yet discovered.

6. It Preferred Walking on All Fours.

Mussaurus hatchlings had some relatively long bones in their forelimbs, so the wee beasties most likely got around quadrupedally.     

7. Mussaurus Was Originally Misidentified as a Different Dino.

Remember those mature Mussaurus we brought up earlier? Despite the fact that they lived in Argentina, paleontologists once mistook them for Plateosaurus, a long-necked, stiff-tailed genus known exclusively from Europe (though, in all fairness, those two continents were connected back then as parts of a huge landmass called “Pangaea”).

8. It Had “Extremely Thin” Eggshells.

“You’re a tough egg to crack” … or are you? Mussaurus eggs are notable for having unusually thin shells, compared to most sauropodomorphs (“long-necked” dinos), whose babies had to fight through much thicker casings. Maybe their descendants evolved heftier eggshells as a defense against omelette-savoring predators.

9. Mussaurus Parents Probably Stuck Around.

To many animals, getting abandoned by dads and moms is considered normal. But the fact that partially-grown juvenile Mussaurus have been found near egg fragments might imply some level of parental care. In all probability, the little bundles of joy would have needed it—babies had awkward proportions and were likely rather helpless.

10. Mussaurus Heads Would Have Changed a Lot with Age.

There’s a reason the DMV doesn’t let you use a baby photo on your driver’s license. As people grow, their appearance changes dramatically, and dinosaurs were no different. Relatively speaking, newly-hatched Mussaurus had bigger eyes, shorter snouts, and larger nasal bones than older individuals.