Cretaceous Bird Fossil: Researchers Use 3D Technologies to Reveal Beak Developments

An international team of researchers led by Ohio University (OU) Heritage College of Osteopathic Medicine Professor Patrick O’Connor announced the discovery of a Late Cretaceous crow-sized stem bird from Madagascar with a long and deep beak morphology that was previously unknown among Mesozoic birds and is superficially similar to modern birds, like toucans. A reconstruction of the new bird named Falcatakely highlights evolutionary changes in face and beak shape. To unravel the anatomy of the stem bird, researchers used high-resolution microcomputed tomography (microCT) and extensive digital modeling to virtually dissect individual bones from the rock it is embedded in, as well as enlarged 3D printing of the digital models to reconstruct the skull and compare it with other species.

Found in northwestern Madagascar, the specimen, which belongs to an extinct group of birds called Enantiornithines, survived more than 66 million years, meaning it dates from the end of the Cretaceous period. Described in a new paper published in the journal Nature, the finding is essential for refining hypotheses that relate to the morphological evolution and diversification of early birds, which according to the authors remains relatively incomplete owing to a paucity of new fossil discoveries.

Artwork by paleontologist Mark Witton capturing the biology and environment of Falcatakely, and the process of its microCT dissection. Image courtesy of Mark Witton/Ohio University

Very few early birds are known from the entire Cretaceous period of Afro-Madagascar. Bird skeletons are rare in the fossil record because of their lightweight bones and small size, and bird skulls are an even rarer find, described Ohio University News. Falcatakely is the second Cretaceous bird species discovered in Madagascar by the National Science Foundation-funded team, stating in the study that this latest specimen expands knowledge of realized cranial shape disparity within the Enantiornithine evolution and Mesozoic birds as a whole.

“As the face began to emerge from the rock, we knew that it was something very special, if not entirely unique,” described O’Connor, Professor of Anatomy and Neuroscience at OU and lead author of the study. “Mesozoic birds with such high, long faces are completely unknown, with Falcatakely providing a great opportunity to reconsider ideas around head and beak evolution in the lineage leading to modern birds.”

Study Co-authors Joseph Groenke (left) and Dr. Patrick O’Connor (right). Image courtesy of Ohio University

The delicate specimen remains partially embedded in rock due to the complex array of lightly built bones that make up the skull. Although quite small – with an estimated skull length of only 8.5 cm – the unique preservation reveals many important details and unique developments of the beak, like a complex series of grooves on the bones making up the side of the face indicating that the animal hosted an expansive keratinous covering, or beak, in life.

Since O’Connor and his colleagues couldn’t remove the individual bones of Falcatakely from the rock for study, the research team generated a life reconstruction of the specimen using a microCT scan and digital reconstruction. Initial scanning was made possible by New York’s Stony Brook University Department of Radiology, followed by the use of the microCT scanner at the OU Edison Biotechnology Institute. To facilitate study and reconstruction of the specimen, some polygon files were exported as STL files and printed at three times their natural size using a Stratasys Objet350 Connex 3D prototyper that is housed at the OU Innovation Center. In charge of the 3D printing process was Laboratory Director Misako Hata, who oversees operations for the Biotechnology Research and Development Facility and the 3D Printer Lab, and has vast experience in 3D printing.

Study Co-author and Laboratory Coordinator in OU Heritage College of Osteopathic Medicine, Joseph Groenke, said that “a project like this bridges disciplines ranging from comparative anatomy, paleontology, and engineering/materials science. Our partnership with the Ohio University Innovation Center was a key part of this process. Being able to see each of the bones as a prototype replica formed the basis for understanding the specimen and also in reconstructing it.”

As the research progressed, it was quickly apparent to the experts that the bones making up the face in Falcatakely are organized quite unlike those of any dinosaur, avian or nonavian, despite having a face superficially similar to several modern bird groups alive today. O’Connor described that Falcatakely might generally resemble any number of modern birds with the skin and beak in place, yet its underlying facial skeletal structure breaks with what scientists know about bird evolutionary anatomy.

The reconstruction of Falcatakely that was generated using microCT reveals a nearly complete right lacrimal. While the digitally reconstructed palate unveils a substantial level of detail not typically observable in Mesozoic early birds. Alan Turner, study Co-author and Associate Professor of Anatomical Sciences at Stony Brook University, indicated that the extinct group of Enantiornithines birds, to which Falcatakely belongs, represent the first great diversification of early birds, occupying ecosystems alongside their non-avian relatives such as Tyrannosaurus and Velociraptor (a Turkey-sized feathered theropod unlike the Jurassic Park deadly version of the raptor). “Unlike the first birds, such as Archaeopteryx, with long tails and primitive features in the skull, enantiornithines like Falcatakely would have looked relatively modern,” indicated Turner.

“The more we learn about Cretaceous-age animals, plants, and ecosystems in what is now Madagascar, the more we see its unique biotic signature extends far back into the past and is not merely reflective of the island ecosystem in recent times,” said O’Connor. “The discovery of Falcatakely underscores that much of the deep history of the Earth is still shrouded in mystery, particularly from those parts of the planet that have been relatively less explored.”

Artist reconstruction of the Late Cretaceous enantiornithine bird Falcatakely. Image courtesy of Mark Witton/Ohio University

Paleontologists have been turning to 3D scanning and 3D printing digital reconstruction technologies for years to advance their research by replicating, recreating, and studying fossils and functional morphologies. Early researchers used molds and casts to share fossil replicas with other investigators and the public. Today, experts can render virtual files tangible by transforming scans into 3D printed structures. For example, Dutch conservators are using 3D printers to create pieces that can fill in the final gaps of a dinosaur skull, the famous Triceratops skull No. 21, which Yale University’s Peabody Museum of Natural History traded to the Delft University Geological Museum in the 1950s; or Canada’s Royal Tyrrell Museum paleontologists, who use 3D printing to replicate fragile fossils, bringing the study of our geologic past closer to what it may have looked like.