A team of scientists has just described a new species of dinosaur that would have been trapped in amber for nearly a hundred million years. The animal is one of the smallest dinosaurs known, since its head (including the beak) is only 14 millimeters long.
The authors, who publish their finding in the journal Nature , have named the new species Oculudentavis khaungraae , and it competes in size with the bee hummingbird ( Mellisuga helenae ), one of the world’s smallest living bird species. The specimen was found in an area of Myanmar very tidy in animals that were trapped in amber, a festival for paleontologists, who in recent years have described cockroaches, frogs, snakes, snails and more than a thousand species that are allowing them to recreate in a very detailed way what life was like in a tropical forest a hundred million years ago.
Amber is nothing more than the fossilized resin of ancient conifers, and is an excellent preservation medium that allows today’s scientists to study the characteristics of prehistoric fauna, as it provides a lot of information on soft tissue and skeletal anatomy. In the case of O. khaungraae , researchers have been able to deduce, from the arrangement of the bones found, that this mini dinosaur had a small pupil with daytime activity, similar to the eyes of lizards.
A bird with teeth
Another peculiarity of Oculudentavis is that it has teeth in both the lower and upper jaws, a finding that indicates that this species was predatory and would probably eat insects and other small invertebrates.
The small size of this dinosaur also offers clues to the environment in which it lived. For the authors, it is an example of the so-called ‘insular dwarfism’, an evolutionary process by which animal species undergo a decrease in size to adapt to limited resources.
The modern birds that we know today come from a lineage of dinosaurs that lost weight and acquired other characteristics in an evolutionary process that lasted 50 million years until they reached the well-known Archeopteryx , a genus with intermediate characters between feathered dinosaurs and modern birds that it inhabited the Earth between 150 and 200 million years ago.
The authors of the work, not having the rest of the body, cannot specify in detail the degree of kinship of Oculudentavis with other dinosaurs with bird characteristics. We don’t even know if it could fly. But, as they explain, it is most likely that it belonged to a group of relatively primitive birds, after Archeopteryx and before the Cretaceous birds. In this way, the tiny dinosaur would retain some features, such as teeth, that all modern birds would later lose. The size and morphology of the new species suggest both a body plan and an ecology that was not known until then , and the discovery also highlights the potential of amber deposits to reveal the lower limits on the size of vertebrates.
Referencia: Xing, L., O’Connor, J.K., Schmitz, L. et al. Hummingbird-sized dinosaur from the Cretaceous period of Myanmar. Nature 579, 245–249 (2020).
