Gobi desert reveals modest ancestor of gigantic flying reptiles
It was the start of something big - really big. Scientists have said they have found a fossil from 163 million years ago that is the oldest known ancestor of advanced flying reptiles that culminated in the largest flying creatures in earth's history.
The newly identified Jurassic period creature, a species named Kryptodrakon progenitor unearthed at a Gobi desert site called the Shishugou formation in Xinjiang , had a modest wingspan of 1.3 metres.
But later members of its branch of the flying reptiles known as pterosaurs were truly colossal, including Quetzalcoatlus, whose 10.7-metre wingspan was the same as an F-16 fighter.
The genus name, Kryptodrakon, means "hidden dragon" in honour of the 2000 film Crouching Tiger, Hidden Dragon, that had parts filmed near where it was unearthed. Its species name, progenitor, means ancestral.
Roughly 220 million years ago, pterosaurs became the first flying vertebrates to appear on earth, with birds - first appearing about 150 million years ago - and bats - flying mammals that appeared about 50 million years ago - coming much later.
Pterosaurs arose during the Triassic period not long after their cousins, the dinosaurs, also made their debut. Their wings were supported by an incredibly elongated fourth digit of the hand - the "pinky finger".
The pterosaurs remained largely unchanged for tens of millions of years - with characteristics like long tails and relatively small heads - and none became very big.
But during the later Jurassic period, some developed anatomical changes that heralded the arrival of a new branch called pterodactyloids that eventually replaced the more primitive forms of pterosaurs.
Many of these pterodactyloids had massive, elongated heads topped with huge crests, lost their teeth and grew to huge sizes. Perhaps the defining characteristic of the group is an elongated bone at the base of the fourth finger called the fourth metacarpal, and Kryptodrakon is the oldest known pterosaur with this feature, the researchers said in the journal Current Biology on Thursday.
"In primitive pterosaurs, it is one of the shortest and least variable bones in the wing, but in pterodactyloids it is quite elongated," said Dr Brian Andres, a palaeontologist at the University of South Florida, and one of the researchers.
Kryptodrakon lived right before its fellow pterodactyloids took over the skies. "We can look at his anatomy and see what were the last changes in his body that may be responsible for the success of the group," Andres added.
Another important element of the discovery is the environment where Kryptodrakon lived. This was a river-dominated ecosystem far from the ocean in a region teeming with life, including a fearsome dinosaur predator called Sinraptor and a gigantic plant-eating dinosaur named Mamenchisaurus that boasted one of the longest necks of any creature yet to walk the planet.
George Washington University palaeontologist Dr James Clark said the fact that Kryptodrakon lived in such an ecosystem along with other evidence indicates that advanced pterosaurs - many of which later ruled the skies over seashore ecosystems and fed on fish in the oceans - first evolved far inland.