When you think of dinosaurs, you most likely picture roaring T-Rexs or swooping Pterodactyls. However, some suspected that there were many other, more pocket-sized dinos that also roamed the Earth hundreds of millions of years ago, and a tiny skull embedded in amber was initially thought to confirm the existence of "mini- dinosaurs," but this conclusion was later rebutted and reversed by another, dissenting team of scientists.
The new species would have been the first of its kind, as the fossil in which it rested was very weird" as one of the researchers who found it said. The specimen (which is probably a lizard) was discovered in Myanmar — trapped in amber and nearly 100 million years old.
Their findings were published in Nature on Wednesday.
UPDATE July 24, 3:30 PM EDT: Hummingbird-sized dinosaur paper retracted after scientific objections
The original paper claiming a "mini-dinosaur" with more than 100 teeth existed 100 million years ago has since been retracted by the editorial board of the journal Nature, after another group of scientists published their concerns on a preprint website.
The intervening scientists felt that the tiny skull embedded in amber was not a dinosaur, but a lizard — which is different than a dinosaur. While some of the scientists behind the original paper have argued that this error doesn't justify the retraction, others have acknowledged the error, and are moving on.
Mini dinosaur with over 100 teeth
The initially-confirmed dinosaur would have been smaller than our modern-day hummingbird — the smallest living bird. Its head is smaller than a thumbnail. We're talking small, very small.
Regardless of its size, the researchers thought it was most likely a predator, with more than 100 teeth. That's a lot of pearly whites in one small space.
The researchers named the specimen Oculudentavis khaungraae to represent what was thought to be the smallest dinosaur ever discovered. If true, it could have shed light on how small birds evolved from dinosaurs, which were typically larger.
"When I first saw this specimen, it really blew my mind. I literally have never seen anything like this," said Jingmai O'Connor, senior professor at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences in Beijing and a research associate at the Natural History Museum of Los Angeles County.
It's not just its size and teeth that surprised the scientists, but also its eye structure.
In the Oculudentavis, the scleral ring of bones that support the eye is spoon-shaped, which is more in line with how lizard eyes operate, and not other birds. Moreover, their eyes pointed out to the sides instead of directly ahead, which would have restricted the amount of sunlight to enter their eyes. This means that they were most likely daytime hunters and had excellent vision.
Professor O'Connor stated "I just love how natural selection ends up producing such bizarre forms. We are also super lucky this fossil survived to be discovered 99 million years later."
Only the specimen's skull remained in the amber it makes studying the rest of its habits quite tricky.
However, thanks to having been preserved within amber, the specimen is in excellent condition, as if it had been living just yesterday. As co-author of the study, Dr. Luis Chappe from the Natural History Museum of Los Angeles County said "It's lucky this tiny creature was preserved in amber, as such small, fragile animals aren't common in the fossil record."
He continued, sure of the initial results, saying: "This finding is exciting because it gives us a picture of the small animals that lived in a tropical forest during the age of dinosaurs."
Editor's Note: This article has been changed to reflect a retraction by the editorial board of the journal Nature, following a new paper arguing that this specimen was not a dinosaur, after all — but possibly just another lizard. Science is a process of falsification, so we at IE consider this change a part of the larger scientific discussion on the history of life on Earth.