WASHINGTON, March 11 (Reuters) - Scientists are marveling over the exquisitely preserved skull of what appears to be the smallest-known bird - tinier than any hummingbird - encased in 99-million-year-old amber and boasting many odd traits including jaws studded with numerous puny teeth.
The skull, measuring about half an inch (14.25 mm) long, belongs to a bird called Oculudentavis khaungraae that lived during the Cretaceous Period in what is now northern Myanmar, the researchers said on Wednesday. None of the rest of the body was preserved, but the researchers estimated that Oculudentavis weighed about an ounce (28 grams) and measured 2 inches (5 cm) long including a hypothetical bony tail.
"I was totally blown away," said paleontologist Jingmai O'Connor of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, describing her reaction upon seeing the fossil. "It's probably the most beautifully preserved Mesozoic bird skull I've ever seen, and it's so weird."
The Mesozoic Era was the age of the dinosaurs.
"I was amazed," added Natural History Museum of Los Angeles County paleontologist and study co-author Luis Chiappe.
O'Connor said Oculudentavis appeared to be smaller than a bee hummingbird, until now considered the world's littlest bird.
Oculudentavis shares few similarities, aside from size, with hummingbirds, which like all modern birds lack teeth and eat nectar. Many Mesozoic birds had teeth, but Oculudentavis possessed the most - about 100, with a conical shape and sharp ridges on the edges. Oculudentavis likely hunted insects. Hummingbirds have long beaks, unlike Oculudentavis.
Birds evolved from small feathered dinosaurs roughly 150 million years ago. Oculudentavis illustrates the almost-incomprehensible size difference among members of the dinosaur lineage, contrasting to contemporaneous South American long-necked, pillar-legged dinosaur Argentinosaurus at perhaps 90 tons and 115 feet (35 meters).
"The size diversity hints at the amazing biology of dinosaurs, capable of sustaining such a diversity of forms," said O'Connor, who led the research published in the journal Nature.
Its eyes resembled those of owls, with the eye bones forming a cone, indicating acute vision, O'Connor said. Unlike birds of prey with forward-facing eyes and binocular vision enabling good depth perception, the eyes in Oculudentavis faced to the sides and bulged out of its head. The small size of the aperture of the eye bones indicates Oculudentavis was active during daytime.
Amber - fossilized tree sap - has preserved numerous small organisms including insects, lizards and frogs.
"Amber is just amazing as a preservational medium," O'Connor said. "If the animal does not decay much before getting entombed in resin, the preservation is phenomenal: All the soft tissues preserved in three dimensions, like a window into an ancient world."
Fossil and skeletal discoveries throughout history
Fossil and skeletal discoveries throughout history
French custom officials present July 6 six of 315 fossilized dinosaur bird eggs seized recently from a container ship from Madagascar and which had transited via the British port of Felixstowe. The fossilized eggs, five or six times larger than an ostrich egg and weigh nearly 12 kg, belong to the flightless bird 'Aepyornis Maximus' species commonly know as 'Elephant Bird'. The eggs have a unit value of 10,000 French francs ($1,560), making the total value of nearly a half million dollars. The shipment of fossilized eggs were destined for a Paris company specialized in collectors in France and northern Europe. Two people are being held for questioning by custom officials.
(Reuters Photographer / Reuters)
Bill Simpson looks inside a fossil of a Tyrannosaurus rex known as "SUE", before removing its forelimb to be used for research at the Field Museum in Chicago, Illinois, U.S., October 6, 2016.
A man cleans a fossil of a mother and baby in Taichung City, Taiwan, April 26, 2016 in this still image taken from video.
(REUTERS/via Reuters TV)
The fossils of the newly-discovered prehistoric pterosaur (front) and a model of its head are displayed at Rio's Federal University Museum in Rio de Janeiro, March 20, 2013. According to Brazilian scientists, the specimen is referred to as Tropeognathus cf. T. mesembrinus, and it is the largest known pterosaur recovered from Gondwana, the name given to the more southerly of the two supercontinents which were part of the Pangaea supercontinent in the past.
Dr. Martin Pickford displays a sub-complete skull of a fossil ape found in Karamoja region, northeast of Uganda's capital Kampala, during a news conference in Kampala August 2, 2011. Ugandan and French scientists have discovered a fossil of a skull of a tree-climbing ape from about 20 million years ago in Uganda's Karamoja region, the team said on Tuesday.
Gerald McSorley holds up a Jurassic fossil, clearly showing four prefectly preserved vertebrae, complete with spinal cord and blood vessels, which he found on the shores of Loch Ness, at his home in Stirling in Scotland, July 16, 2003. Though experts have stressed that the find is not related to the original Loch Ness monster - the remains of the plesiosaur (a long-necked, carnivorous sea reptile) are around 150 million years old and Loch Ness did not exist until the last Ice Age around 12,000 years ago - they say the find is evidence that the 35-foot-long creature once existed in the area.
(REUTERS/Jeff J Mitchell)
Gustavo Lara, Director of Culture of the town of Roque Perez, holds part of a femur bone of a glyptodont, a kind of large armadillo, at an excavation site on the outskirts of Roque Perez, some 84 miles south of Buenos Aires, May 6, 2009. Fossil bones of nine glossopteris, a glyptodont, the nearly complete skeleton of a megatherium and a head of a stegomastodon dating from the Pleistocene, the epoch from 1.8 million to 10,000 years ago, were found by paleontologists in the sediments of the Salado River due to a drought that has been affecting the area for months, local media reported.
Chilean paleontologist Consuelo Huidobro looks on at a mastodon's fossilized remains at the rural Padre Hurtado municipality near Santiago March 24, 2011. The remains of the mastodon were discovered on the banks of the Mapocho river during the construction of a water treatment plant, local media reported. It is believed that mastodons inhabited earth some 15,000 years ago.
An unearthed mastodon's fossilized remains are pictured at the rural Padre Hurtado municipality near Santiago March 11, 2011. The remains of the mastodon were discovered on the banks of the Mapocho river during the construction of a water treatment plant, local media reported. It is believed that mastodons inhabited earth some 15,000 years ago. Picture taken March 11, 2011.
Brazilian paleontologist Alexander Kellner shows the fossils and a model of the newly-discovered prehistoric pterosaur to journalists during its presentation at Rio's Federal University Museum in Rio de Janeiro, March 20, 2013. According to Brazilian scientists, the specimen is referred to as Tropeognathus cf. T. mesembrinus, and it is the largest known pterosaur fossils recovered from Gondwana, the name given to the more southerly of the two supercontinents which were part of the Pangaea supercontinent in the past.
Visitors look at the skeleton of an Apatosaurus named "Einstein" displayed at the Lewis hall in Fundidora park in Monterrey, northern Mexico, September 23, 2009. Einstein, a 75 foot, 4.5 tonne skeleton of an Apatosaurus, was found in 2005 in Dana Quarry, Wyoming, United States, and is the first major dinosaur whose skull has been found intact. With 85 percent of its skeleton being original, the exhibit is considered the most complete and articulated Apatosaurus known in the world, according to the organizers.
A detailed view of the hands or claws of Trix the female T-Rex exhibition at the Naturalis or Natural History Museum of Leiden on October 17, 2016 in Leiden, Netherlands. The skeleton of Tyrannosaurus rex was excavated in 2013 in Montana, USA, by Naturalis Biodiversity Center. The fossil is part of the Naturalis collection and is more than 80% of the bone volume present. All essential and high volume bones are in place. This places Trix in the top 3 ranking of the most complete Tyrannosaurus rex skeletons in the world. In addition, all the bones are extremely well preserved. The quality of this fossil is unmatched by any other large T-Rex find in the world.