The fossil of a sea reptile with a neck twice as long as its body is solving the mystery of how some ancient reptiles used their long appendages. According to a report in the current issue of Science, the protorosaur, called Dinocephalosaurus orientalis, swam in a shallow sea in southeast China more than 230 million years ago during the Triassic Period.
Its stiff, 1.7-meter-long neck (about 5.5 feet), topped by a small head with short fangs, may have allowed the creature to sneak up on prey in murky water without being seen.
Dinocephalosaurus on the Hunt
Dinocephalosaurus' specialized neck ribs may have helped the aquatic reptile hunt. As it approached its prey, it expanded its neck to absorb the pressure waves it had made, sucking in the waves, as well as the meal.
"To a fish in murky water, Dinocephalosaurus' head would have initially looked like another animal its own size, but by the time the fish was able to see Dinocephalosaurus' body, it would already have been lunch," said Michael LaBarbera, professor of organismal biology and anatomy at the University of Chicago, in a press release.
The fossil also reveals a special feature of the protorosaur's neck: elongated ribs along the sides may have flared outward before an attack, enabling the animal to swallow the pressure waves it created during its approach.
Fish and some turtles fight pressure waves by rapidly expanding the mouth cavity and sucking prey in.
When Dinocephalosaurus orientalis jabbed its head forward during a hunt, the ribs along its neck would splay outward, increasing the diameter of the esophagus, creating a suction that would swallow the pressure wave created by the lunging head, as well as downing the prey.
"This is important research because we have finally explained the functional purpose of this strange, long neck," said Olivier Rieppel, a co-author of the paper and chair of geology and curator of fossil amphibians and reptiles at Chicago's Field Museum. "It allowed an almost perfect strike at prey, which usually consisted of elusive fish and squid."
The reptile, which, unlike other protorosaurs, lived primarily in the water, has a neck comprised of 25 vertebrae, twice as many as the first protorosaur found in the 1850s. Its extra vertebrae may have made its neck slightly more flexible, according to the researchers.
"Dinocephalosaurus sheds new light on the evolution of protorosaurs and the functional morphology of these long-necked marine reptiles," said Chun Li, lead author and assistant research fellow at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences in Beijing.
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