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Thursday, November 10, 2016

Giant Sloth Coprolite From Nevada: This Poop is Fair to Midden

      An extinct giant sloth once used a spacious cave in Nevada not just as a shelter but also as a huge outhouse, leaving droppings on the cave floor whenever nature called. Now, scientists have analyzed the sloth's mummified dung (which is also known as a midden) and determined what plants the animal ate most frequently, according to new research.




      Chemical analyses of the fossilized poop, known as coprolites, revealed that the ancient sloths primarily ate an orange-flowered perennial shrub known as desert globemallow (Sphaeralcea ambigua),



 a shrub called Mormon tea (Ephedra




and a drought-tolerant plant known as saltbush (Atriplex), said Ryan Haupt, Department of Geology and Geophysics at the U. of Wyoming.




      Scientists have known about the coprolites in southern Nevada's Gypsum Cave since the 1930s. 



      The Shasta ground sloth,  Nothrotheriops shastensis, lived in the cave at different points, from about 36,000 to 11,000 years ago, Haupt said.





      "Radiocarbon dates from the coprolites correlate with periods where the climate was a bit cooler, and since we know that modern tree sloths don't thermoregulate very well, it's possible that these ground sloths were going into the cave to keep warm," Haupt said.


     To complete the analysis, Haupt needed only a few milligrams of each coprolite. After grinding the small samples with a mortar and pestle, he analyzed the specimens for different carbon and nitrogen isotopes.




      Plants that live in dry, hot or otherwise water-stressed environments have evolved strategies to prevent themselves from drying out, such as absorbing sunlight during the day but absorbing carbon dioxide only at night. These strategies also affect the chemical pathways used during photosynthesis, resulting in different ratios of heavy and light stable carbon isotopes in the plants. These ratios work their way up the food chain when animals eat these plants, so by measuring the ratios, Haupt was able to see what plants the sloths chose to eat.




     The analysis fits with the saying, "'You are what you eat,' but down to the atomic level," Haupt said.

      The new results correlate with previous findings that were reached using different methods. For instance, some scientists looked for identifiable plants within the mummified excrement, either under a microscope or based on the plants' DNA, he said. The plants identified in previous studies match the ones Haupt recognized in the isotope analysis.






     But not all species of extinct sloths left behind coprolites, which makes it difficult to compare the diet of the Shasta ground sloth with that of related sloths. Luckily, this molecular analysis, known as stable isotopic analysis, can also be applied to analyses of sloth bones and teeth, "which is pretty neat," Haupt said.




     For instance, the Shasta ground sloth was more of a mixed feeder than other ancient sloths were, including those in the Megatheriidae and Mylodontidae families, Haupt found when he compared the Shasta ground sloth results with already-published values from the bones and teeth of other sloths.




      Timothy Gaudin, a professor at the University of Tennessee at Chattanooga, who was not involved in the study, said the research is encouraging because it requires only a small piece of the coprolite for analysis.




      "In the past, there have been studies on these, but what they've had to do is literally take the coprolites apart, pull all of the little plant parts out and try to identify them one at a time," Gaudin said. "And then you end up with no specimen."






       And so, despite the fact that this happens:





       

       This also happens (My favorite sloth image from Costa Rica with ZoĆ«).





ONWARD!
Steph

"Bombs" atop PVC pipe "missile silos" built by kindergartners on Friday. Sigh.





25 comments:

  1. I envy an individual named for a deadly sin, even if its midden don't inspire gluttony. Are you proud of your fecal erudition?

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  2. When the sloths don't move, we get a pile of crap. Substitute Democrats for sloths.

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    1. By the way, thanks for the cool article, some worthy distractions are needed these days.

      But a clarification for us non-scientists: in the first paragraph you call it mummified dung, which sounds reasonable. But then you call it fossilized poop. I thought a fossil is not the actual material, but a "3d model" cast in minerals that filled the void when the original organic material decayed. As such isn't it impossible to do any fossil analysis other than shape, etc., in a visual inspection?

      I gave dinosaur coprolite as a stocking stuffer years ago, but it seemed pretty rocky to me.

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    2. Yes, it was good to think about real, honest to goodness poop for awhile, eco.

      Great question. It's a matter of time, and yes, replacement. Sloth excrement is actual fossilized poop, though it is much younger than say, dinosaur poop, which often is replaced by agate, jasper, or other rock. Fossils are considered to be anything left behind as evidence of life, so, sensu stricto, your morning poop could be a fossil if pooped out in a drying environment like Nevada.

      Poop. It never gets old. Not!

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    3. Like petrified wood, especially...

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    4. Fair enough. I suppose poop gets a bad name, after all one critter's poop is another critter's meal. And a good thing too, otherwise (after the 6004 years since the planet was Usshered in) we'd be up to our __'s in the stuff.

      Years ago I did a project with composting toilets and according to the manufacturer 90% of poop is water vapor, which jibes pretty well with my memory as a kid of a "new" vs "old" cow chips. So these coprolites must have been impressive indeed, on might even say Charmin'.

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    5. Nothing like a good handful of fossil poop to make you fully appreciate life!

      Sometimes I even wear dinosaur coprolite earrings ;-)!

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    6. And Charmin' was perfect, btw.

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  3. Fitting and timely subject, Word Woman, in the wake a wacky, crappie week.

    LegoScatocologically

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    1. Wacky and crappie, yup!

      Ah, Lego, some scat, oh, logical, singing is just what we need today.











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    2. And a few Hallelujahs. . .

      Sorry, my phone is flaking out today.

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  4. Just learned, via the "Hillary hiking with Margot and Phoebe photo") that Hillary Clinton has a pup, also named Maisie (my Maizie has a 'Z'). If only they had campaigned together. . .(only half kidding; it would have been great to see her out loving her dog!).

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  5. Dormant Supervolcano Underneath Yellowstone Figures Now As Good A Time As Any

    November 11, 2016

    JACKSON, WY — Taking note of the circumstances that were presently transpiring on the surface, the dormant supervolcano located 12 miles beneath Yellowstone National Park reportedly thought to itself Friday that now was probably just as good a time as any. “You know, I’ve gotta do this sooner or later, and frankly, this just feels like a pretty decent time to pull the trigger and go through with this thing, so why not?” the 11,200-cubic-mile magma chamber reportedly told itself, adding that after 630,000 years without a supereruption, and given the week the landmass above it had just endured, the time seemed right to unleash an explosion 1,000 times more powerful than the Mt. St. Helens eruption and blanket much of North America in several feet of fiery ash, immediately killing 90,000 people and setting off a nuclear winter that would slowly annihilate millions more. “It’s been a while, and I mean, I’m more or less due on a geologic time scale, so today seems like a good enough day to me. I might as well just go for it, right?” At press time, the nation’s citizens were breathing an immense sigh of relief as an onrushing wall of superheated gas and volcanic ejecta came hurtling toward them.

    (You can guess where this came from.)

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    1. It's a familiar story to anyone who's worked at Bell Labs. I wonder if John LeCarre would call that big horn antenna "The Pigeon Funnel"?

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  7. New post on "YIMBY: Yes, In My Back Yard: Block Island Wind Farm Begins Operations" is now up.

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  8. One more for this week's theme: It may be almost two centuries old, but it looks like it may our word of the year: kakistocracy.

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    1. Say, could we say NIMBY to DT and export him to Siberia or perhaps Antarctica, please?

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