This hen could peck dinosaurs. Scientists have studied the perfectly preserved Asteriornis skull

Twenty years ago, near the Belgian-Dutch border, Maarten van Dinther found a stone the size of a pack of cigarettes. Inside it was a small, perfectly preserved skull of the oldest direct ancestor of modern birds.

This is a really unique and exciting find, which reveals to us a very poorly understood chapter of bird evolution - says Gerald Mayr, an ornithologist from the Senckenberg Research Institute in Frankfurt.

Asteriornis was a long-legged wading bird that could fly and tens of millions of years ago, during the Cretaceous period, traversed the shores of Europe.

This area was then dotted with smaller chains of islets surrounded by a warm and shallow sea.

An international team of researchers was tasked with examining his skull - which resembles both duck and chicken, which could mean that he was the ancestor of both groups - and fragments of hind legs. The analysis revealed that this particular bird lived on Earth 66.7 million years ago, some 700,000 years before the asteroid impact that led to the end of the dinosaur era. We can therefore suspect that it was a bird that plucked dinosaurs.

It is the only skull of a modern bird discovered so well preserved that lived among dinosaurs such as tyrannosaur or triceratops - says the main author of the study, paleontologist Daniel Field from the University of Cambridge.

Although many birds lived in the time of dinosaurs, most of them belonged to archaic groups such as Enantiornithes , which became extinct together with larger land animals. Contemporary birds, however, developed from the Neornithes group, which appeared at the end of the Cretaceous period.

This particular specimen is the first ideal specimen of the skull of a representative of the Neornithine group from the Cretaceous period - says Jingmai O'Connor, from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.

Construction of the Asteriornis

The Asteriornis resembled the last common ancestor of the order of birds, including ducks and geese (Anseriformes), and of the order, including hens and turkeys (Galliformes). Scientists have long known that these clades separated during the Cretaceous period, and therefore their ancestors must also have existed at that time. Now one of them has been found.

Van Dinther gave the fossils he found to the Natural History Museum in Maastricht. Museum curator and co-author of a new scientific article, John Jagt, sent four small rocks with protruding bones to Field in 2018. After receiving them, Field did not expect anything more than maybe a few broken leg bones. However, due to the fact that late Cretaceous fossils of birds are rare, he decided to use the tomograph to check what else is inside the obtained rocks. To Field's surprise, one of the rocks contained a nearly complete, three-dimensional skull of a modern bird.

This is the first skull of a modern Mesozoic bird and one of the best preserved fossilized bird skulls in general - he adds.

Because most of the oldest fossils of modern birds have been found in the southern hemisphere, some paleontologists have suggested that modern birds originated in the southern supercontinent of Gondwan during the time of the dinosaurs. However, the discovery of Asteriornis in the northern hemisphere undermines this theory.

This hen could peck dinosaurs. Scientists have studied the perfectly preserved Asteriornis skull