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Dmitry Bogdanov via Wikimedia Commons // CC BY-SA 3.0
Dmitry Bogdanov via Wikimedia Commons // CC BY-SA 3.0

To Save Their Species, These Prehistoric Animals Mated Early and Died Young

Dmitry Bogdanov via Wikimedia Commons // CC BY-SA 3.0
Dmitry Bogdanov via Wikimedia Commons // CC BY-SA 3.0

For better or worse, every organism is affected by the world around it. Changes in climate or available resources can inspire animal species to relocate, grow bigger or smaller, quit migrating, and even fall down more. Now a group of scientists say a mass extinction event inspired a prehistoric mammal ancestor to condense its lifespan. Their paper was published today in the journal Scientific Reports.

The Lystrosaurus was a charmingly dumpy creature: As you can see in the depiction above it's a bit like a cross between a corgi, a naked mole rat, and an iguana. Therapsids like Lystrosaurus and their cousins the cynodonts roamed the planet 250 million years ago—which was, unfortunately, not a great time to be alive. A series of volcanic eruptions filled the atmosphere with carbon, thereby seriously disrupting the planet’s climate and leading to a mass extinction event. Up to 96 percent of aquatic species were lost, as were around 70 percent of land species. Somehow, through all this, sturdy Lystrosaurus managed to hang on.

Scientists have developed a number of theories on the therapsids' success, including their fondness for underground living, their willingness to travel, and sheer dumb luck. The latest report proposes a new strategy: living fast and dying young.

A team of paleontologists from the U.S. and South Africa examined the tissue microstructure of bones from 103 therapsid specimens. (Bones, like tree rings, are a great way of studying how an individual has aged, and how much.) The specimens represented around 20 million years of evolution, including the periods before, during, and after the mass extinction event.

Image Credit: The Field Museum

The researchers found that, while the therapsids had survived, they’d undergone some major changes. After the event, Lystrosaurus and some of its cousins were quicker to reach maturity, and their lives were much shorter.

“Before the Permo-Triassic extinction, the therapsid Lystrosaurus had a life span of about 13 or 14 years based on the record of growth preserved in their bones,” co-author Ken Angielczyk, of The Field Museum, said in a press statement. “Yet, nearly all of the Lystrosaurus specimens we find from after the extinction are only 2–3 years old. This implies that they must have been breeding when they were still juveniles themselves.”

Post-extinction therapsids had also shrunk. Before the volcanoes, Lystrosaurus was about the size of a little hippopotamus. After, a full-grown animal was closer in size to a large dog—partly because it was so much younger than its ancestors.

How could this have helped? The research team ran computer simulations to model the therapsids’ environment. The simulations revealed that maturing fast and mating young could have increased therapsid species’ chances of survival by as much as 40 percent. The individuals died, but their family lived on.

“With the world currently facing its sixth mass extinction, paleontological research helps us understand the world around us today,” Angielczyk said. “By studying how animals like Lystrosaurus adapted in the face of disaster, we can better predict how looming environmental changes may affect modern species.”

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Big Questions
What's the Difference Between Gophers and Groundhogs?
Gopher or groundhog? (If you chose gopher, you're correct.)
Gopher or groundhog? (If you chose gopher, you're correct.)
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Gophers and groundhogs. Groundhogs and gophers. They're both deceptively cuddly woodland rodents that scurry through underground tunnels and chow down on plants. But whether you're a nature nerd, a Golden Gophers football fan, or planning a pre-spring trip to Punxsutawney, Pennsylvania, you might want to know the difference between groundhogs and gophers.

Despite their similar appearances and burrowing habits, groundhogs and gophers don't have a whole lot in common—they don't even belong to the same family. For example, gophers belong to the family Geomyidae, a group that includes pocket gophers (sometimes referred to as "true" gophers), kangaroo rats, and pocket mice.

Groundhogs, meanwhile, are members of the Sciuridae (meaning shadow-tail) family and belong to the genus Marmota. Marmots are diurnal ground squirrels, Daniel Blumstein, a UCLA biologist and marmot expert, tells Mental Floss. "There are 15 species of marmot, and groundhogs are one of them," he explains.

Science aside, there are plenty of other visible differences between the two animals. Gophers, for example, have hairless tails, protruding yellow or brownish teeth, and fur-lined cheek pockets for storing food—all traits that make them different from groundhogs. The feet of gophers are often pink, while groundhogs have brown or black feet. And while the tiny gopher tends to weigh around two or so pounds, groundhogs can grow to around 13 pounds.

While both types of rodent eat mostly vegetation, gophers prefer roots and tubers (much to the dismay of gardeners trying to plant new specimens), while groundhogs like vegetation and fruits. This means that the former animals rarely emerge from their burrows, while the latter are more commonly seen out and about.

Groundhogs "have burrows underground they use for safety, and they hibernate in their burrows," Blumstein says. "They're active during the day above ground, eating a variety of plants and running back to their burrows to safety. If it's too hot, they'll go back into their burrow. If the weather gets crappy, they'll go back into their burrow during the day as well."

But that doesn't necessarily mean that gophers are the more reclusive of the two, as groundhogs famously hibernate during the winter. Gophers, on the other hand, remain active—and wreck lawns—year-round.

"What's really interesting is if you go to a place where there's gophers, in the spring, what you'll see are what is called eskers," or winding mounds of soil, Blumstein says [PDF]. "Basically, they dig all winter long through the earth, but then they tunnel through snow, and they leave dirt in these snow tunnels."

If all this rodent talk has you now thinking about woodchucks and other woodland creatures, know that groundhogs have plenty of nicknames, including "whistle-pig" and "woodchuck," while the only nicknames for gophers appear to be bitter monikers coined by Wisconsin Badgers fans.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Animals
Watch Christmas Island’s Annual Crab Migration on Google Street View
Google
Google

Every year, the 45 million or so red crabs on the remote Australian territory of Christmas Island migrate en masse from their forest burrows down to the ocean to mate, and so the female crabs can release their eggs into the sea to hatch. The migration starts during the fall, and the number of crabs on the beach often peaks in December. This year, you don’t have to be on Christmas Island to witness the spectacular crustacean event, as New Atlas reports. You can see it on Google Street View.

Watching the sheer density of crabs scuttling across roads, boardwalks, and beaches is a rare visual treat. According to the Google blog, this year’s crabtacular finale is forecasted for December 16, and Parks Australia crab expert Alasdair Grigg will be there with the Street View Trekker to capture it. That is likely to be the day when crab populations on the beaches will be at their peak, giving you the best view of the action.

Crabs scuttle across the forest floor while a man with a Google Street View Trekker walks behind them.
Google

Google Street View is already a repository for a number of armchair travel experiences. You can digitally explore remote locations in Antarctica, recreations of ancient cities, and even the International Space Station. You can essentially see the whole world without ever logging off your computer.

Sadly, because Street View isn’t live, you won’t be able to see the migration as it happens. The image collection won’t be available until sometime in early 2018. But it’ll be worth the wait, we promise. For a sneak preview, watch Parks Australia’s video of the 2012 event here.

[h/t New Atlas]

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