“Wonderchicken” Fossil Reveals Origin of Modern Birds

The oldest fossil of a modern bird yet found, dating from the very end of the Cretaceous, has been identified by an international team of palaeontologists led by researchers from the University of Cambridge.  Sophisticated CT scans (computerised tomography), of a limestone rock, not much bigger than a pack of cards, revealed the exquisitely preserved fossil skull.  Fragments of bone exposed on the rock’s surface suggested that there were more bones buried deep in the rock, but the scientists were not expecting to find the near perfect fossilised skull of a modern bird (neornithine), once the CT scans had been completed.

The bird has been nicknamed “wonderchicken” as its skull shows characteristics found in modern ducks and chickens.  This suggests it is close to the last common ancestor of these types of birds.

A Life Reconstruction of “Wonderchicken” – Asteriornis maastrichtensis

Life reconstruction - Asteriornis maastrichtensis .

Asteriornis maastrichtensis life reconstruction.

Picture Credit: Philip Krzeminski

The fossil comes from a limestone quarry on the Netherlands-Belgium border, making it the first modern bird from the age of dinosaurs to have been found in the northern hemisphere.

Named Asteriornis maastrichtensis, this quail-sized bird (to which it is distantly related), exhibits a previously undocumented combination of galliform-like (landfowl) and anseriform-like (waterfowl) anatomical traits.  Its presence alongside a previously reported Ichthyornis-like bird from the same quarry provides direct evidence of the co-occurrence of crown birds and avialan stem birds.

The Limestone Rock which Contains the Fossil Skull

The lump of limestone ontaining the skull of Asteriornis maastrichtensis.

The limestone containing the skull of Asteriornis maastrichtensis.

Picture Credit: Dr Daniel Field (Cambridge University)

Small Size Could Have Saved Modern Birds from Extinction

Asteriornis was quite small, certainly much smaller than the pterosaurs that it shared the skies with.  The fossil has been dated to 66.8-66.7 million years ago, a few hundred thousand years before the dinosaurs and lots of other animals including many types of bird, died out.

The authors of the scientific paper (published in the journal Nature), speculate that as it was small and it lived by the sea, this way of life, fitting a particular niche in the Late Cretaceous ecosystem, may have helped the ancestors of today’s birds to survive the end-Cretaceous mass extinction event that wiped out the dinosaurs.