As land and sea animals have gotten smaller through the centuries, so has their poop.
What was once teeming woolly-mammoth dung is now relatively dainty cow pies. Giant whale poop has given way to just plain-old, regular-sized whale poop.
Anyone who has ever cleaned Great Dane droppings out of a backyard in the spring is thinking: "Well, thank goodness." But this dearth of dung is a source of modern-day troubles. Less feces means less nutrients moving around the planet via those feces - which means a less fertile growing environment for the world's flora.
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If your tomatoes didn't do well this year, in other words, you might be able to blame the lack of dinosaur dung.
"Large free-ranging animals are much less abundant than they once were. Today, if scientists were to study the role of animals they would find that it is important but small," lead author Chris Doughty told The Washington Post.
"However, in the past, we hypothesize that it would have been at least an order of magnitude larger than today. Essentially, we have replaced wild free-roaming animals with fenced domestic cattle that cannot move nutrients in the same way."
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Specifically, the team was looking at the movement of phosphorous, which is essential for plants to thrive. Giant marine mammals likely transported 750 million pounds from the ocean's bottom to the surface in previous centuries. Today that number is closer to 165 million pounds.
"Phosphorus is a key element in fertilizers and easily accessible phosphate supplies may run out in as little as 50 years," Doughty said in a release. "Restoring populations of animals to their former bounty could help to recycle phosphorus from the sea to land, increasing global stocks of available phosphorus in the future."
While the re-establishment of this nutrient cycle is important, no one anticipates the return of the dinosaur. Hopes lie with the big mammals that still roam the earth.
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"We can (also) imagine a world with relatively abundant whale populations again," he added.