Published: Fri, March 13, 2020
Sci-tech | By Patricia Wade

Researchers find skull of smallest known dinosaur

Researchers find skull of smallest known dinosaur

And yes, unlike birds living today, many birds from the Mesozoic had teeth.

The tiny creature, named Oculudentavis khaungraae - which means "eye-tooth-bird" - is smaller than a bee hummingbird which, until now, has been considered the smallest bird in the world.

"We know its not an infant from the proportions of the skull (the eye is not proportionately large for its size and the rostrum [beak] is not short), the high degree of fusion between numerous skull bones, and the morphology of certain elements like the maxilla [upper jaw]", O'Connor told Mashable.

The dinosaur's jaw had a surprisingly large number of teeth.

Entombed in amber for almost 100 million years, the creature belonged to the group of dinosaurs that gave rise to modern birds.

Oculudentavis'size isn't the only thing curious about it.

"Animals that become very small have to deal with specific problems, like how to fit all sensory organs into a very small head, or how to maintain body heat", according to lead study author Jingmai O'Connor. During miniaturization, animals normally have lost teeth and enlarged eyes. Called Oculudentavis khaungraae, it was the size of a hummingbird and shared reptilian and bird-like features. In fact, with an estimated 29 or 30 teeth, Oculudentavis has more teeth than any other bird found in the fossil record.

For example, the animal's eye structure surprised the scientists.

Skull of smallest-known bird embedded in 99-million-year-old amber

An artist's rendering of what it may have looked like preying on an insect. The small size of the aperture of the eye bones indicates Oculudentavis was active during daytime. But its eyes faced to the side rather than the front like an owl.

No living animal utilizes such a type of visual system so it is hard to understand how the eyes of Oculudentavis may have functioned. These square-shaped bones help support the eye, but the scleral bones in Oculudentavis are spoon-shaped.

Because the new specimen consists of only a skull, understanding how it is related to birds is unclear. The dinosaur's head is smaller than a thumbnail.

The Mesozoic Era was the age of the dinosaurs.

"To us, the paleontologists, birds are dinosaurs". However, it's very different than modern birds. As a result, like these two groups, Oculudentavis was very likely to have a long tail, like that in non-avian dinosaurs. Khaung Ra, who donated it to the Hupoge Amber Museum so it could be studied by scientists, is also honored in the dinosaur's official full name: Oculudentavis khaungraae.David Grimaldi, a curator for amber at the American Museum of Natural History, said that the rich amber deposits in Myanmar formed in larger chunks than elsewhere and are heavily mined and commercially marketed. Now the amber is kept in a private museum.

"Amber is just awesome as a preservational medium", O'Connor said.

We used to think of dinosaurs as giant lizards, but scientists now believe these creatures were much more bird-like, and some of them were tiny. What's really rare is finding a vertebrate animal preserved in such a fashion - to say nothing of a dinosaur. "Oculusdentavis is by far the smallest and most important specimen", Xing said. "But, anyway, it often preserves skin, feathers and other non-skeletal tissues, and. we can get lots of information [from this]".

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