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10 Mousey Facts About Mussaurus

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.

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Prehistoric Ticks Once Drank Dinosaur Blood, Fossil Evidence Shows
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Ticks plagued the dinosaurs, too, as evidenced by a 99-million-year old parasite preserved inside a hunk of ancient amber. Entomologists who examined the Cretaceous period fossil noticed that the tiny arachnid was latched to a dinosaur feather—the first evidence that the bloodsuckers dined on dinos, according to The New York Times. These findings were recently published in the journal Nature Communications.

Ticks are one of the most common blood-feeding parasites. But experts didn’t know what they ate in prehistoric times, as parasites and their hosts are rarely found together in the fossil record. Scientists assumed they chowed down on early amphibians, reptiles, and mammals, according to NPR. They didn’t have hard evidence until study co-author David Grimaldi, an entomologist at the American Museum of History, and his colleagues spotted the tick while perusing a private collection of Myanmar amber.

A 99-million-year-old tick encased in amber, grasping a dinosaur feather.
Cornupalpatum burmanicum hard tick entangled in a feather. a Photograph of the Burmese amber piece (Bu JZC-F18) showing a semicomplete pennaceous feather. Scale bar, 5 mm. b Detail of the nymphal tick in dorsal view and barbs (inset in a). Scale bar, 1 mm. c Detail of the tick’s capitulum (mouthparts), showing palpi and hypostome with teeth (arrow). Scale bar, 0.1 mm. d Detail of a barb. Scale bar, 0.2 mm. e Drawing of the tick in dorsal view indicating the point of entanglement. Scale bar, 0.2 mm. f Detached barbule pennulum showing hooklets on one of its sides (arrow in a indicates its location but in the opposite side of the amber piece). Scale bar, 0.2 mm
Peñalver et al., Nature Communications

The tick is a nymph, meaning it was in the second stage of its short three-stage life cycle when it died. The dinosaur it fed on was a “nanoraptor,” or a tiny dino that was roughly the size of a hummingbird, Grimaldi told The Times. These creatures lived in tree nests, and sometimes met a sticky end after tumbling from their perches into hunks of gooey resin. But just because the nanoraptor lived in a nest didn’t mean it was a bird: Molecular dating pinpointed the specimen as being at least 25 million years older than modern-day avians.

In addition to ticks, dinosaurs likely also had to deal with another nest pest: skin beetles. Grimaldi’s team located several additional preserved ticks, and two were covered in the insect’s fine hairs. Skin beetles—which are still around today—are scavengers that live in aerial bird homes and consume molted feathers.

“These findings shed light on early tick evolution and ecology, and provide insights into the parasitic relationship between ticks and ancient relatives of birds, which persists today for modern birds,” researchers concluded in a news release.

[h/t The New York Times]

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The Clever Adaptations That Helped Some Animals Become Gigantic
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Imagine a world in which eagle-sized dragonflies buzzed through the air and millipedes as long as kayaks scuttled across Earth. "Ick"-factor aside for bug haters, these creatures aren't the product of a Michael Crichton fever dream. In fact, they actually existed around 300 million years ago, as MinuteEarth host Kate Yoshida explains.

How did the prehistoric ancestors of today’s itty-bitty insects get so huge? Oxygen, and lots of it. Bugs "breathe by sponging up air through their exoskeletons, and the available oxygen can only diffuse so far before getting used up," Yoshida explains. And when an atmospheric spike in the colorless gas occurred, this allowed the critters' bodies to expand to unprecedented dimensions and weights.

But that's just one of the clever adaptations that allowed some creatures to grow enormous. Learn more about these adaptations—including the ingenious evolutionary development that helped the biggest dinosaurs to haul their cumbersome bodies around, and the pair of features that boosted blue whales to triple their size, becoming the largest animals ever on Earth—by watching MinuteEarth's video below.

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