Diatryma, a giant flightless bird often portrayed as a wicked carnivore, may have gently dined on plants.
Michael Warwicker reported on the BBC News, “Giant Eocene bird was ‘gentle herbivore’, study finds.” Here’s how it had been portrayed by artists: “Previous investigations have suggested the giant bird was a carnivorous predator or scavenger.… commonly portrayed as a fierce predator in both scientific works and popular media.” The article includes a typical artist conception of Diatryma snatching up a terrified mammal (see also Encyclopedia Britannica).
Researchers from Washington took another look at its beak, claws and legs and decided it didn’t have the features of a predator. Said one, “A more likely scenario [than being a carnivore] would be a gentle Diatryma that used its beak to harvest foliage, fruits, and seeds from the subtropical forests that it inhabited.”
Why, then, was it assumed to be a big, mean ol’ meat-eater? “Let’s be honest: scary, fierce meat-eaters attract a lot more attention than gentle herbivores.” That may be why it has frequently been thought of as “the bird that replaced dinosaurs as the top predator,” the researcher said.
There were other extinct species called “terror birds” that are still thought to have been predators or scavengers (10/26/2006, 5/19/2007 #6). “The common belief that Diatryma… was likewise a carnivore is more a result of guilt by association than actual anatomical evidence.”
Notice that it was not just artists who got it wrong, but writers of “scientific works.” This is a case study in how scientists see what they expect to see. Instead of a 7-foot tall bird that would have scared human hunters out of their wits, this gentle, overgrown chicken might have made a nice Thanksgiving meal, feeding an extended family of 30 (if you could find an oven big enough).
You can’t tell a lifestyle from just bones. Think of what paleontologists would conclude if they only found the bones of a skunk or porcupine without ever seeing one alive. And even though Diatryma had been thought of as “the bird that replaced dinosaurs as the top predator,” it had nothing to do with dinosaurs. It was more likely a secondarily flightless bird in evolutionary scenarios, or created for its habitat in creationary scenarios. Loss of function is something natural selection is good at. it’s not so great at evolving new complex structures from scratch.