The avian fossil, found in what is now Madagascar, offers insight into the evolution of the faces of modern birds.
(CN) — A bird from the late Cretaceous period, which resembles something of a buck-toothed toucan with a large scythe-like beak, has provided scientists new insights into the evolution of face and beak shapes of the distant ancestors of modern birds.
An international team of scientists studied a fossil belonging to a previously unknown species of bird from the late Cretaceous period, named Falcatakely. The team of researchers led by Patrick O’Connor, from Ohio University, and Alan H. Turner, from Stony Brook University in New York, published their findings Wednesday in the journal Nature.
The researchers originally discovered the fossil of the crow-sized bird in 2010 in northwestern Madagascar, where the team has worked since the mid-1990s, but it laid in wait until 2017 when a CT scan revealed its significance. The island was a veritable wonderland of biodiversity even 68 million years ago and has distinctive species that evolved in its isolation.
Despite being unusually well preserved, the 3-inch-long fossil is paper-thin in places, which meant researchers couldn’t just cut it out of its rock casing. Instead, they digitally reconstructed a model with the aid of microCT scanning and 3-D printing, allowing them to reveal its detailed anatomical characteristics.
“Falcatakely might generally resemble modern birds with the skin and beak in place — it is the underlying skeletal structure of the face that turns what we know about bird evolutionary anatomy on its head,” O’Connor said in an email. “This one major difference aside, however, we might expect that Falcatakely and other Mesozoic birds would have used complex vocalization, parenting, and any number of other behaviors when interacting with other members of its own species or with the collection of other bizarre animals known to exist during the Late Cretaceous in Madagascar. Whether the fossil record can accurately capture other attributes like these with high fidelity is another matter entirely.”
At first glance the bird’s skull appears similar to many species flying around today, such as the aforementioned toucan. It’s an excellent example of convergent evolution, which can lead to distantly related animals sharing similar features due to common environmental pressures. The internal structure of this bird’s skull is unique to those of modern avians and is not present in any other known Mesozoic examples.
Falcatakely, its name is a combination of Latin and Malagasy words alluding to its small stature and scythe-shaped beak, is known from this single nearly complete skull found in Madagascar. Because of their delicate nature and small size, bird skulls are a rare find in the fossil record, which means scientists are probably under-sampling the Mesozoic diversity of birds.
“Falcatakely made up its face with the same bones and in a similar way as an animal like Velociraptor did,” Turner said in an email. “What is remarkable is that with this ancestral arrangement of bones Falcatakely evolved a beak shape strongly reminiscent of modern birds with high, long upper bills. A beak never before seen in the Mesozoic!”
Birds from the Mesozoic period differ greatly in size, flight adaptations and feather arrangement, but their beak shape and development are typically more constrained. Falcatakely’s beak, however, displays a long and deep rostrum, which sets it apart from other birds from this period.
The beaks of most modern birds are developed in the same way — formed by a single enlarged bone called the premaxilla — while most birds from the dinosaur days have relatively unspecialized snouts formed by a small premaxilla and a large maxilla, such as the Archaeopteryx. Thanks to Falcatakely, the researchers were able to determine that this rule for beak-building was not yet in place during the Late Cretaceous, according to Turner.
“We found that some modern birds like toucans and hornbills evolved very similar sickle-shaped beaks tens of millions of years after Falcatakely,” Ryan Felice, a lecturer at University College London and contributing author of the study, said in a statement. “What is so amazing is that these lineages converged on this same basic anatomy despite being very distantly related.”
Daniel Field, a lecturer in the Department of Earth Sciences at the University of Cambridge who was not involved in the study, said the study shows the variety of skulls seen in modern birds is a kind of “‘re-discovery’ of skull shapes exhibited by long-extinct relatives of birds from the age of dinosaurs.”
“My first reaction was ‘Wow, that’s a crazy fossil,” he said. “The fossil teaches us that the ancient relatives of birds from the age of dinosaurs achieved an even greater degree of anatomical variety than we could have guessed.”