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© AMNH/M. Ellison

Baby Dinosaurs Took Months to Hatch, Study Finds

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© 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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The T. Rex Fossil That Caused a Scientific Controversy
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In the early 2000s, a team of paleontologists inadvertently set the stage for a years-long scientific saga after they excavated a well-preserved partial Tyrannosaurus rex skeleton from Montana's Hell Creek formation. While transporting the bones, the scientists were forced to break a femur. Pieces from inside the thigh bone fell out, and these fragments were sent to Mary Schweitzer, a paleontologist at North Carolina State University, for dissection and analysis.

Under a microscope, Schweitzer thought she could make out what appeared to be cells and tiny blood vessels inside the pieces, similar to those commonly discovered inside fresh bone. Further analysis revealed what appeared to be animal proteins, which sent Schweitzer reeling. Could she have just discovered soft tissue inside dinosaur leg bone many millions of years old, found in ancient sediments laid down during the Cretaceous period? Or was the soft stuff simply a substance known as biofilm, which would have been formed by microbes after the bone had already fossilized?

Following a seemingly endless series of debates, studies, and papers, Schweitzer's hunch was proven correct. That said, this contentious conclusion wasn't made overnight. To hear the whole saga—and learn what it means for science—watch the recent episode of Stated Clearly below, which was first spotted by website Earth Archives.

[h/t Earth Archives]

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Fossilized Poop Shows Some Herbivorous Dinosaurs Loved a Good Crab Dinner
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Lead author Karen Chin of the University of Colorado Boulder
Courtesy the University of Colorado Boulder

Scientists can learn a lot about the prehistoric world through very, very old poop. Just recently, researchers from the University of Colorado-Boulder and Kent State University studying fossilized dinosaur poop discovered that some herbivores weren't as picky about their diets as we thought. Though they mostly ate plants, large dinosaurs living in Utah 75 million years ago also seem to have eaten prehistoric crustaceans, as Nature News reports.

The new study, published in Scientific Reports, finds that large dinosaurs of the Late Cretaceous period seem to have eaten crabs, along with rotting wood, based on the content of their coprolites (the more scientific term for prehistoric No. 2). The fossilized remains of dinos' bathroom activities were found in the Kaiparowits rock formation in Utah's Grand Staircase-Escalante National Monument, a known hotspot for pristine Late Cretaceous fossils.

"The large size and woody contents" of the poop suggest that they were created by dinosaurs that were well-equipped to process fiber in their diets, as the study puts it, leading the researchers to suggest that the poop came from big herbivores like hadrosaurs, whose remains have been found in the area before.

Close up scientific images of evidence of crustaceans in fossilized poop.
Chin et al., Scientific Reports (2017)

While scientists previously thought that plant-eating dinosaurs like hadrosaurs only ate vegetation, these findings suggest otherwise. "The diet represented by the Kaiparowits coprolites would have provided a woody stew of plant, fungal, and invertebrate tissues," the researchers write, including crabs (Yum). These crustaceans would have provided a big source of calcium for the dinosaurs, and the other invertebrates that no doubt lived in the rotting logs would have provided a good source of protein.

But they probably didn't eat the rotting wood all year, instead munching on dead trees seasonally or during times when other food sources weren’t available. Another hypothesis is that these "ancient fecal producers," as the researchers call them, might have eaten the rotting wood, with its calcium-rich crustaceans and protein-laden invertebrates, during egg production, similar to the feeding patterns of modern birds during breeding season.

Regardless of the reason, these findings could change how we think about what big dinosaurs ate.

[h/t Nature News]

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