This unusual bird superpower dates back to the extinction of the dinosaurs

The ibis and kiwi are relentless diggers, probing the sand and soil for worms and other buried prey. Sandpipers can also be seen along the shore poking around at small creatures with their beaks. These birds have long been thought to use trial and error to find their prey.

But the scientists then discovered something much stranger: Their beaks are threaded with cells that can sense vibrations passing through the ground. Some birds can directly sense the movements of their distant career, while others pick up waves bouncing off buried shells – echolocating like a dolphin or bat, in essence, across the earth.

There is another odd detail in this story of unusual bird senses: Ostriches and Emus, birds that certainly don’t hunt this way, have beaks with a similar interior structure. They are honeycomb with pits for these cells, although the cells themselves are absent. Now, scientists in a study published Wednesday in Proceedings of the Royal Society B report that the ancestors of prehistoric birds dating almost as far back as dinosaurs were likely able to detect vibrations with their beaks.

The birds that use this remote sensing today are not closely related to each other, said Carla du Toit, a graduate student at the University of Cape Town in South Africa and author of the article. It made her and her co-authors curious about when exactly this ability evolved and whether ostriches, which are close relatives of kiwis, had an ancestor who used this sensory ability.

“We took a look to see if we could find any early bird fossils from this group,” Ms. du Toit said. “And we are very lucky.” There are very well preserved bird fossils called lithornithids dating from just after the event that led to the extinction of non-avian dinosaurs.

They first had to collect data on the beaks of more than 50 species of birds so that they could tell how similar or different fossil birds were to modern birds. The team recorded the number of holes in the beak bone and the size of the beak and head, important details because birds that dig for food have a characteristic shape.

Then they took a look at the lithornithids. And indeed, the ancient beaks and head structure were extremely similar to the beaks of kiwis, ibises, and sandpipers, much closer than any other bird in the study.

“It looks like they have this organ and they were able to use the sense of touch from a distance to probe and locate their prey as well, which is really cool, because it just shows that it’s really old,” said Mrs. du Toit.

This means that the ancestors of ostriches and emus lost the ability sometime after the lithornithids’ life, leaving them only traces in their bone structure of this lost talent. They also lack the enlarged brain regions that kiwis, ibises, and shorebirds dedicate to processing sensory information from the beak.

Ms du Toit and her colleagues are currently studying the ibis hadeda, a South African bird that uses remote sensing, to see how far it can detect hidden objects – possibly buried up to 20cm below the surface.