Smallest known dinosaur found trapped in 99-million-year-old amber

March 12 (UPI) -- Paleontologists have discovered a tiny new species of dinosaur trapped in ancient amber from Myanmar. Scientists estimate the bird-like species is the smallest known dinosaur.

The skull of the new species, which scientists estimate is fully formed, was found inside 99-million-year-old amber. Its size suggests the unusual dinosaur species was roughly the size of a bee hummingbird, the smallest bird on Earth.

"Amber preservation of vertebrates is rare, and this provides us a window into the world of dinosaurs at the lowest end of the body-size spectrum," Lars Schmitz, associate professor of biology at Claremont McKenna College in California, said in a news release. "Its unique anatomical features point to one of the smallest and most ancient birds ever found."

Scientists used high-resolution synchrotron scans, a kind of CT scan, to analyze the skull of the newly named Oculudentavis khaungraae and compare the fossil's features and dimensions to those of other bird-like dinosaurs from the late Cretaceous period.

The size of the bones that supported the dinosaur's eyes suggests it lived a diurnal lifestyle. The bird-like species' eyes share similarities with the eyes of modern lizards. The high-resolution scans also revealed signs of fusion between different skull bones, as well as the presence of teeth, a combination of features never seen in such a small species.

The fossil's discovery, described this week in the journal Nature, suggests the earliest birds and their dino relatives likely evolved miniaturization relatively early on.

"No other group of living birds features species with similarly small crania in adults," Schmitz said. "This discovery shows us that we have only a small glimpse of what tiny vertebrates looked like in the age of the dinosaurs."