From Living the Scientific Life blog in the USA:
In the past few years, China has become famous for the number and quality of bird fossils from the Early Cretaceous that have been discovered there.
This week, another such discovery has been reported by an international team of Chinese, American and Japanese scientists.
The bird that made these tracks was named Shandongornipes muxiai in honor of the teen-aged daughter, Muxia Li, of team member, Rihui Li, a geologist at the Qingdao Institute of Marine Geology.
“It is a huge surprise to find evidence of a roadrunner-like species darting around beneath the feet of Cretaceous dinosaurs,” said Martin Lockley of the Dinosaur Tracks Museum, University of Colorado at Denver, and senior author of the study.
These ancient birds and feathered dinosaurs have changed our understanding of bird origins and evolution.
But it is not known whether representatives of contemporary bird groups existed 130 million years ago.
“Whether or not there were any representatives of modern bird groups in the Cretaceous is currently the subject of a lot of debate,” said Jerry Harris of Dixie State College of Utah.
He was invited to join the Shandongornipes research team because of his expertise on Chinese bird fossils.
“But as research progresses, we are finding more and more evidence that some Cretaceous birds were very similar, though not identical, to modern birds.
Shandongornipes is another surprising, but very welcome, example,” Harris added.
“If the tracks had been found in very recent deposits in North America, we would have assumed they were made by the well-known roadrunner,” said Lockley.
“But finding them in the Cretaceous of China, long before even the nearest relatives of roadrunners had evolved, makes us call them ‘roadrunner-like’.”
Organisms that live in similar ecosystems and have similar natural histories often evolve matching anatomical structures — a phenomenon known as convergent evolution.
For example, dolphins (mammals), sharks (fish), and the now-extinct ichthyosaurs (reptiles) all evolved analogous body shapes because that shape is ideal for rapid swimming.
Similarly, the bird that made the Shandongornipes tracks probably converged on a roadrunner-like body shape and likely exhibited similar behaviors.
Our modern roadrunner, Geococcyx, is a species of cuckoo and, like all cuckoos, has two forward-pointing and two backward-pointing toes, a condition known as zygodactyly that is also evident in Shandongornipes tracks.