Enlarge /. Artist's impression of Falcatakely forsterae.
Given the unusual attention turkeys have received this week, let's talk about dinosaurs. Today's birds are, of course, descendants of the only branch of the dinosaur tree that made it through the mass extinction of the Cretaceous Period. In the days of the dinosaurs, the early birds were slightly different, still retaining teeth and front paws with some more subtle anatomical differences with their modern offspring. A new fossil record reveals an unexpected bird from that period – one with a fat, large toucan-like beak.
The fossil named Falcatakely forsterae comes from late chalk cliffs in Madagascar. Many of the early bird fossils we've discovered so far come from older rocks of the Early Cretaceous Period in China, with the time frame between that point and the End Cretaceous extinction being more of a question mark. The new fossil is a beautifully preserved head of a crow-sized bird with a strikingly long, high and narrow beak.
The early Chinese bird fossils do not show great diversity in beak shape. This is a great contrast to modern day birds, whose wild beak shapes match their many different ecological niches. Pelicans, woodpeckers and parrots have very different diets and require a beak that is adapted to the job. It was believed that enlarged beaks might not be possible until some anatomical shift occurred in the parts of the skull, which meant that the early birds were simply limited. However, the new find shows that this was not entirely true. This species could have inhabited an ecological niche that was empty after extinction – until a modern bird drifted back in much later.
Enlarge /. The fossil (a), the identifications of each structure (b), and the structures arranged in their likely locations (c).
The researchers used 3D imaging to precisely determine the dimensions of each anatomical component. This showed some differences when compared to non-avian theropod dinosaurs or more modern birds. The fossil animal may have a beak shape that resembles some modern birds, but it does so despite the fact that the underlying structure is different.
There are some visible teeth near the tip of the beak and not further back like those of its relatives. And the height of its upper beak is achieved by a very large upper jaw bone (brown in the picture above) where other fossilized species from that period had a thin, more V-shaped bone. Modern birds, on the other hand, have tiny maxillary bones and beaks carried by a large premaxillary bone (green near the tip of the beak in the picture above).
Enlarge /. Skull structure for fossil birds before the Cretaceous Extinction (including this fossil, highlighted in red). Below right is a modern bird (jungle fowl) for comparison.
If there is one weird chalk bird there could be others that add more variety to the chalk collection. The find also raises interesting questions about the evolution of skull structure and beak shape, as modern anatomy did not appear to be required for a large beak of this shape. That takes a simple story and complicates it a little, since the same shape has evolved at different times and in different ways.
And that's good. Surprising fossils are even more fun than the unsurprising ones and further enrich our picture of the past.
Nature, 2020. DOI: 10.1038 / s41586-020-2945-x (About DOIs).