Of everything we just learned about the life cycle of baby woolly mammoths, one lesson seems to stand out above others: those life cycles were apparently vulnerable to being interrupted by mud.
The two best-preserved woolly mammoth calves yet found still had full skeletons, as well as their muscles, fat, organs, and skin in tact when they were discovered 3,000 miles apart in Siberia. At just one and two months old, Lyuba and Khroma, as they're now called, died from suffocation after inhaling mud.
The mud then covered their bodies, leaving them frozen and preserved for 40,000 years; reindeer herders discovered Lyuba in 2007, while Khroma was found in the permafrost in 2008.
Lyuba with skin…
And what nature hath preserved, no researcher may pull asunder, as the saying goes. The two were mainly missing some hair and nails, and Khroma's tail got bitten off by dogs in the village where she was brought after being excavated. Aside from that, they were in unprecedentedly good shape. For example, Khroma died so suddenly and was preserved so well that she even had clotted blood inside intact blood vessels and undigested milk in the stomach.
There's a lot to learn under the skin, but researchers did not want to immediately start with a necropsy of the mummified bodies. Instead, they were examined from the outsides in, thanks to scanned models that allowed researchers to manipulate and visualize the mammoths' bodies without undue impact.
"These two exquisitely preserved baby mammoths are like two snapshots in time. We can use them to understand how factors like location and age influenced the way mammoths grew into the huge adults that captivate us today," said Zachary T. Calamari of the American Museum of Natural History. Calamari was a co-author of a new study detailing the examination of the mammoth calves, which was published in the Journal of Paleontology .
Conducting minimally invasive examinations wasn't as simple as just sliding a couple of mummies through a CT scanner over lunch. Lyuba was too big for her whole body to be 3D scanned in a hospital, so the researchers made the 3D scan of her body in a scanner designed to find flaws in vehicle transmissions, at Ford Motor Co.'s Nondestructive Evaluation Laboratory in Livonia, Michigan.
Both of the calves' teeth were examined with micro-CT scans at the University of Michigan School of Dentistry, which revealed their ages and that both had been born in the spring. X-rays revealed sediment in their trunks and lungs, indicating how they died. But there's still a lot more to learn from the specimen.
"This is the first time anyone's been able to do a comparative study of the skeletal development of two baby mammoths of known age," said the study's lead author, Daniel Fisher. Fisher is the director of the University of Michigan's Museum of Paleontology.
"This allowed us to document the changes that occur as the mammoth body develops," he said. "And since they are both essentially complete skeletons, they can be thought of as Rosetta Stones that will help us interpret all the isolated baby mammoth bones that show up at other localities.”
Might I suggest they'll be found near some mud?