The skull of a hummingbird-size dinosaur from 99 million years ago during the Cretaceous Period has been discovered in a piece of amber. The tiny dinosaur has been named Oculudentavis khaungraae – by combining the Latin words “oculus” (eye), “dentes” (teeth), and “aves” (bird) for the first name, followed by the last name which is in reference to Khaung Ra who donated it. The piece of amber was initially discovered in a mine in Myanmar back in 2016 and was eventually donated to the Hupoge Amber Museum in China by Ra who had purchased the specimen.
The specimen weighs only 0.07 ounces which is equivalent to a couple of dollar bills. In fact, it measured just one-sixth of the size of the tiniest known early fossil bird meaning that it was the smallest known dinosaur during the Mesozoic Era (252 million to 66 million years ago).
Even though it was incredibly small, the Oculudentavis khaungraae had around a hundred very sharp teeth. Jingmai O’Connor, who is a senior professor of vertebrate paleontology at the Chinese Academy of Sciences as well as the co-lead researcher of the study (which can be read in full here), explained to Live Science, “It has more teeth than any other Mesozoic [dinosaur-age] bird that we know of,” adding that there were even teeth located underneath its eye at the back of the jaw “which suggests that the animal could really open its mouth really, really wide.” He went on to say that it was so small that the only thing it was probably able to eat was insects. Additionally, he noted the unusual sockets for the teeth by stating that “the teeth are fused into the skull, which is highly unusual for a dinosaur, including birds.”
Since the Oculudentavis khaungraae lived on an island arc, that might be the reason why some creatures were much smaller according to a theory suggesting that they “miniaturize” when they live on islands that are isolated. It may also be the reason why it developed some strange features like the bones around its eyes being in the shape of a spoon and potentially bulging out (similar to a lizard’s eyes). Another interesting fact is that its eyes were located on the sides of its head and they had small pupils suggesting that it hunted during the daytime. A picture of the Oculudentavis khaungraae skull preserved in amber can be seen here.
Many people in the science world have reacted to this incredible discovery. Darla Zelenitsky, who is an assistant professor of dinosaur paleobiology at the University of Calgary, told Live Science that the find is “truly astonishing” and that “This discovery is a stark reminder that ancient birds, and even non-bird dinosaurs potentially, may have evolved to diminutive sizes, but are unknown because they are too small to preserve in the fossil record under ordinary circumstances.”
Sara Burch, who is an assistant professor of biology (specializing in birds and meat-eating theropod dinosaurs) at the State University of New York College at Geneseo, weighed in by stating that the Oculudentavis khaungraae “provides a fascinating look at miniaturization in an early bird,” adding that “This new specimen is the size of a hummingbird, but exhibits some unique and unexpected adaptations that suggest that it was quite different ecologically.” “Specimens like this give us the opportunity to learn more about what is biologically possible at very small body sizes.”