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© AMNH/M. Ellison

Baby Dinosaurs Took Months to Hatch, Study Finds

© AMNH/M. Ellison
© AMNH/M. Ellison

Getting out of bed in the morning is pretty much the worst. Who wants to leave a cozy, warm bubble and face the cold, harsh light of day? Not us—and apparently not baby dinosaurs, either. Experts say the little tykes may have spent between three and six months curled up in their eggs. The findings were published in the Proceedings of the National Academy of Sciences.

Dinosaur embryos are very rare, which means their journey from fertilized egg to baby thunder-lizard is something of a black box. We do know they had a great deal in common with modern reptiles and with birds, and while both groups lay eggs, the length of their incubation periods vary immensely. Bird babies typically take a few weeks to hatch; reptiles can take months. Because dinosaur eggs were so huge, scientists believed they were probably more bird-like than lizard-like, hatching relatively quickly. It seemed probable that birds inherited their speedy incubation period from their prehistoric ancestors.

To find out for sure, the research team examined fossilized embryos from two dinosaur species: the sheep-sized Protoceratops and the gargantuan Hypacrosaurus, whose eggs were roughly the size of bowling balls. 

The researchers used computed tomography (CT) scanners and microscopes to get a closer look at near-invisible growth lines on the embryos’ teeth. "These are the lines that are laid down when any animal's teeth develops," lead author Gregory Erickson said in statement. "They're kind of like tree rings, but they're put down daily. We could literally count them to see how long each dinosaur had been developing."

© G.M. Erickson

As it turns out, they’d been developing for quite a long time. Little Protoceratops had been in its egg for almost three months; Hypacrosaurus, twice that long.

This long incubation period suggests two things: first, that dinosaurs were closer to modern reptiles than we thought, and second, that those eggs were vulnerable as heck. The longer an embryo sits around in its egg, the more protection and resources it requires, and the slower its development may be once it hatches.

And that sluggish development may have contributed to the dinosaurs’ downfall. The faster a species can mature, develop, and reproduce, the faster it can evolve—a crucial factor in a world buffeted by dramatic climate change like that faced by the dinosaurs.

"We suspect our findings have implications for understanding why dinosaurs went extinct at the end of the Cretaceous period,” Erickson said, “whereas amphibians, birds, mammals, and other reptiles made it through and prospered.”

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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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