Smaller than the size of the smallest hummingbird alive today, its head was the size of a thumbnail, its jaw full of jagged teeth, and its bulging eyes and lizards. Despite its small stature, the creature was likely a predator.
The researchers said the fossil, called Oculudentavis, represented the smallest dinosaur ever found.
“When I saw this specimen the first time, it really blew my mind. I have literally never seen anything like this,” said Jingmai O’Connor, a senior professor at the Institute of Paleontology and Paleoanthropology of Vertebrates at the Chinese Academy of Sciences in Beijing and a researcher Associate at the Los Angeles County Museum of Natural History.
“There are over 100 teeth present in the jaws. These strange eyes stare off to the side. There is nothing like this alive today.”
While people tend to think of dinosaurs as huge, heavy creatures, this skull and other recent finds in amber suggest that life in dinosaur times was probably more diverse than we think, with many more small dinosaurs and others. creatures that have not yet appeared in the fossil record.
“One of the key messages from this study is that we are probably missing a large part of the dinosaur ecosystem,” said Lars Schmitz, professor of biology at Scripps College in Claremont, California, who along with O’Connor, were the authors. article he published Wednesday in the journal Nature. “We don’t know much about small things in the age of dinosaurs.”
The fossilization of bones in sediments such as clay, silt and sand can crush and destroy the remains of small animals, but amber, which is formed from the resin of coniferous trees, allows its conservation in three dimensions.
“When you have an animal preserved in amber, it looks like it just died yesterday, all the soft tissues in place caught in this little window in ancient times,” O’Connor said.
Beyond our imagination
“I think the diversity of dinosaurs is beyond our imagination. Previously we found a 1 centimeter long dinosaur footprint, which I thought was the minimum length of a dinosaur. Until we found Oculudentavis,” whose name means eye-bird. tooth said Xing
Xing said the piece of amber was purchased in Myanmar by Khaung Ra, Chen Guang’s mother-in-law, director of a museum in southwest China near the Myanmar border dedicated to amber. Khaung Ra, who donated it to the Hupoge Amber Museum for study by scientists, is also honored in the dinosaur’s official full name: Oculudentavis khaungraae.
David Grimaldi, curator of amber at the American Museum of Natural History, said that the rich deposits of amber in Myanmar were formed into larger pieces than elsewhere and are largely mined and traded. As such, he said, they have become a source of many interesting discoveries of ancient plants, insects and fungi, and more recently, dinosaurs.
“This seems like an extremely interesting find, due to the excellent conservation of the fossil and the tiny size of the bird-shaped dinosaur. Look at the teeth and bones of the eyes!” said Grimaldi, who was not involved in the investigation.
Unique traits
The tiny dinosaur’s unique traits shed light on how birds evolved, which descended from dinosaurs, suggesting that they reached their minimum body size much faster than previously thought.
“This process, called miniaturization, commonly occurs in isolated settings, the most famous islands. No wonder 99-million-year-old Burmese amber is believed to come from an ancient island,” O’Connor said.
“Miniaturization is commonly associated with features such as proportionally large teeth and eyes loss. However, since Oculudentavis has more teeth than usual, it shows that evolution doesn’t always follow the rules.”
Other ancient birds such as the winged dinosaur Archeopteryx were much larger. It is not clear from the skull how Oculudentavis relates to early birds and bird-shaped dinosaurs.
Schmitz said there were only a few species of frogs and lizards that were smaller than this Lilliputian dinosaur. “It is really at the lower limit of small [that] a vertebrate can get. “
Unlike hummingbirds, which do not have teeth and feed on nectar, the researchers believe that Oculudentavis would have hunted and feasted on small insects. They think it would have had feathers, although none were preserved in amber.
His eyes were particularly unusual, the study said. The bones in the eye socket would have formed a cone, like the eye bones in owls, suggesting he had sharp eyesight. But her eyes looked to the side instead of the front like an owl. They would also have protruded from its head sideways, which is a type of visual system that no other dinosaur or animal species today uses.
“Normally it retains only small organisms, and if it retains the largest, it is often incomplete and therefore a complete picture is often lost,” he said.
“Even in the case of this discovery of an extremely small dinosaur, it only preserves [the] skull, which sometimes is not enough to infer its systematic position in the dinosaur family tree. In other words, the suggested position for this new species within [the] the dinosaur family is tentative. “
Some scientists have hoped that amber may be a source of genetic material for the creatures trapped inside, such as in the plot of the “Jurassic Park” movie franchise, when scientists extract dinosaur DNA from the blood inside. of insects found in amber. But Xu said this was still unlikely.
“Previously, people thought that amber would be a great source of DNA or protein, but recent studies show that this is probably not the case. But anyway, it often preserves skin, feathers, and other non-skeletal tissues, and … we can get a lot of information [from this]”
O’Connor said the dinosaur skull was “so strange” that it was difficult to discover how it fitted with other known dinosaurs, but said that amber would likely yield equally surprising findings.
“When we think of dinosaurs, we think of these huge skeletons, but paleontology right now is being completely transformed by the discovery of skeletal fossils, vertebrate fossils, preserved in amber.”
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