The fragmentary remains of the Kryptodrakon progenitor. REUTERS/Illustration by Brian Andres/Outline by Peter Wellnhofer/
It was the start of something big - really big.
Scientists today said they have found a fossil from 163
million years ago that represents the oldest known example of
a lineage of advanced flying reptiles that later would
culminate in the largest flying creatures in Earth's history.
The newly identified Jurassic period creature, a species
named Kryptodrakon progenitor that was unearthed in the Gobi
desert in northwestern China, was modest in size, with a
wingspan of perhaps 1.3m.
But later members of its branch of the flying reptiles known
as pterosaurs were truly colossal, including Quetzalcoatlus,
whose wingspan of about 10m was roughly the same as that of
an F-16 fighter.
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 - appearing
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 later
during the 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
elongation in the bone at the base of the fourth finger
called the fourth metacarpal, and Kryptodrakon is the oldest
known pterosaur to have this advance, the researchers said.
"In primitive pterosaurs, it is one of the shortest and least
variable bones in the wing, but in pterodactyloids it is
quite elongated," said Brian Andres, a paleontologist at the
University of South Florida, and one of the researchers.
Kryptodrakon lived right before its fellow pterodactyloids
began to take over the ancient 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
Another important element of the discovery is the environment
that Kryptodrakon called home.
It lived in 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 ever to walk the planet.
George Washington University paleontologist James Clark said
the fact that Kryptodrakon lived in such an ecosystem along
with other evidence indicates that the advanced pterosaurs -
many of which later ruled the skies over seashore ecosystems
and fed on fish in the oceans - actually first evolved far
inland in a terrestrial environment.
The origin of the pterodactyloids had been a little bit of a
quandary, with their fossil record not extending back in time
as much as some scientists had expected. Kryptodrakon is
about five million years older than any other known member of
the advanced pterosaur lineage, the researchers said.
"This is filling in that time gap," Clark said.
Its genus name, Kryptodrakon, means "hidden dragon" in honor
of the 2000 film "Crouching Tiger, Hidden Dragon," that had
parts filmed near where it was unearthed. Its species name,
progenitor, means ancestral.
The research was published in the journal Current