In Depth
Asteriornis was a very interesting discovery for followers of bird palaeontology. Living approximately a million years before the end of the Cretaceous, Asteriornis shows skull features that are similar to chickens (galliformes) and ducks (anseriformes). This combination of features shows that in form Asteriornis was very close to the common ancestor of the Neornithes, the group that includes all modern birds. The discovery of Asteriornis has also shown that the early ancestors of modern neornithe birds were not necessarily exclusive to the southern hemisphere as previously suggested given that it is now clear that they were already established in the northern hemisphere at the same time as the south.
Asteriornis is interpreted as belonging within the Neognathae, a sub group of the Neornithes, and being close to the Galloanserae which contains ducks and chickens. The skull of Asteriornis displays features that are similar to both chickens and ducks, which could indicate that Asteriornis is especially close to the ancestral form of both groups. The beak of Asteriornis is shaped in such a way that suggests that Asteriornis would have picked its way along the ground plucking up small invertebrates and perhaps seeds or other plant matter, though the exact diet of Asteriornis is still a subject of speculation. While partially preserved, what parts of the legs that are known support reconstruction of Asteriornis as a ground dwelling bird perhaps similar to a quail or a jungelfowl in ecological niche.
In short Asteriornis may have been a generalist feeder, being able to adapt to a variety of different environments given that its small size meant that Asteriornis would not have had to eat much to live. It may well have been exactly for these reasons that the ancestors of the Neornithes group of birds were able to survive the KT extinction that marks the end of many species. This includes the more primitive birds which by the time of the late Cretaceous may have become overly specialised, making them far more susceptible to the cataclysmic changes of the late Cretaceous. Generalist like the early Neornithes however, were able to hang on long enough to survive and eventually thrive.
Further Reading
- Late Cretaceous neornithine from Europe illuminates the origins of crown birds. - Nature 579:397-401. - D. J. Field, J. Benito, A. Chen, J. W. M. Jagt & D. T. Ksepka - 2020.
