The issue with being an professional on dinosaur behaviour is that little will be inferred from the fossilised bones of beasts that died tens of millions of years in the past.
For researchers in South Korea, nevertheless, the absence of any residing creatures to watch was merely one other problem to beat. Enter Robopteryx, a robotic that resembles – if one squints and ignores the wheels – the prehistoric, peacock-sized and fan-tailed omnivore, Caudipteryx.
The scientists constructed the machine to check their concepts concerning the origins of birds’ wings and tails. Earlier than the primary feathered flight, some dinosaurs developed feathered forearms and tails, however these have been too weak to get the animals airborne. What drove their evolution remains to be up for debate.
Dinosaur specialists have proposed all method of advantages for small “proto-wings”. They may have labored as insect nets, prevented prey from escaping, allowed for lengthy hops and gliding, and helped heat the animal and its new child offspring.
An alternate speculation is that dinosaurs used their feathered appendages in threatening shows to flush bugs and different prey from their hiding locations. This “flush and pursue” technique, put ahead by the South Korean group, is used with nice impact in the present day within the northern mocking hen and larger roadrunner.
To check their hunch, the scientists put Robopteryx in entrance of unsuspecting grasshoppers and made it carry out completely different wing and tail strikes. These have been designed to imitate shows Caudipteryx might have carried out about 124m years in the past within the early Cretaceous.
“We all the time very fastidiously and slowly positioned the robotic close to a grasshopper with out startling the grasshopper to flee,” mentioned Prof Piotr Jablonski, a behavioural ecologist on the group at Seoul Nationwide College.
Writing in Scientific Studies, the researchers describe how grasshoppers have been extra more likely to scarper when Robopteryx deployed its wings than when it didn’t. In the simplest shows, the robotic swept them again after which swooped them down and forwards. The bugs fled extra usually when the researchers added white patches to the black wings, and when Robopteryx added giant tail feathers to the show, they write.
Some grasshoppers inevitably hopped away as Robopteryx approached, however many would freeze or cover behind a plant stem and alter their place in preparation to flee. “In that scenario, they’re fairly nicely camouflaged and never as simple to identify as throughout a sudden leap,” mentioned Jablonski.
The researchers suspect that flush shows set off historic escape circuitry that’s woven into the insect mind. The defence mechanism units the grasshopper working, however as soon as out within the open, it has a larger probability of changing into the predator’s lunch. If some feathered dinosaurs did hunt on this means, the behaviour might have pushed the evolution of bigger and stiffer feathers, they recommend.
Different scientists, nevertheless, might take some convincing. Jablonski mentioned the group confronted “a number of refusals” from 11 journals earlier than the research was reviewed and accepted for Scientific Studies.
“I’m not so certain about this concept,” mentioned Michael Benton, a professor of vertebrate palaeontology on the College of Bristol. “They’re proper that flight-type feathers originated in dinosaurs after they simply had tiny wings that have been too tiny for powered flight. Nonetheless, these pennaceous feathers are very a lot tailored to make an unbroken wing floor, and the primary feathered dinosaurs might have used them in gliding from spot to identify.
“Folks usually say ‘half a wing is not any use’, however truly half a wing is what many trendy gliding lizards and mammals have and it’s an incredible adaptation for non-powered flight or gliding.”