A nutritious snack for a Cretaceous beetle.
A dung beetle rolling a prized ball of poop along the desert floor is a picture of success. By procuring a dung ball, a beetle can get a nutritious meal, or provide housing and food for its young. A male can also use the ball to woo females, who are highly impressed by fresh feces.
Today, dung beetles fly around in search of manure piles from large herbivorous mammals, such as elephants and camels. According to a new study published in the journal PLOS ONE, tens of million years ago, before these mammals were around, dung beetles were collecting poop from another source — dinosaurs.
By comparing the DNA of one type of dung beetle to that of 450 other beetle species, a research team led by Nicole Gunter of The Cleveland Museum of Natural History was able to generate a beetle family tree, complete with dates indicating when dung beetles emerged. The new timeline places the origin of dung beetles roughly 30 million years earlier than previously thought, meaning their first major diversifications occurred right in the midst of the age of the dinosaurs.
The precise timing of the rise of the dung beetles coincided with an interesting dietary shift in dinosaurs. Flowering plants were just coming into existence, and their more nutritious and less fibrous foliage might have “resulted in the first palatable dung source for feeding,” said Gunter in a press release.
Dung beetles are known to tunnel through feces when they feed. These trademark signs of tunnelling have been identified in fossilized dinosaur feces, lending further support to the hypothesis that ancient beetles were feeding on dino dung.
Being ecologically tied to dinosaurs meant that their extinction would have had a huge impact on dung beetles. Sure enough, the researchers found that some dung beetle species — likely those that were completely dependent on the dung of dinosaurs — started going extinct around the same time.
Having a broad palate probably helped other dung beetle species survive even after dinosaur dung was off the menu. “We hypothesize that modern dung beetles are descended from species that fed either on the dung of dinosaurs and early mammals, or species already adapted to feeding on Cretaceous mammal dung,” said Gunter.
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