Looking and acting something like an underwater canister vacuum cleaner, a prehistoric marine reptile apparently used its extremely long neck to sneak up on and suck in unwary fish swimming in murky shoreline waters 230 million years ago.
The creature was discovered two years ago in China and named Dinocephalosaurus orientalis, or “terrible headed lizard from the Orient.” Figuring out what the fossil was and how it lived took the combined skills of the Chinese paleontologist who found it, a Field Museum expert on fossil reptiles who placed it on the evolutionary tree and a University of Chicago expert in biomechanics who has been studying how scallops swim.
The three scientists share authorship of an article in Friday’s edition of the journal Science that introduces Dinocephalosaurus to the scientific literature.
Despite its name, Dinocephalosaurus was not a dinosaur but a protorosaur, a group of carnivorous, lizard-like predatory reptiles. Some protorosaurs lived on land; others, like this one, evolved from an early protorosaur that crawled back into the sea and became a fully aquatic animal.
As an ocean predator, Dinocephalosaurus was probably a pretty diabolical hunter, according to Michael LaBarbera, the University of Chicago professor of organismal biology and anatomy who studied the fossil.
Its 5-foot neck was nearly twice as long as its body, LaBarbera said, but it had a small head, only about five inches long.
“It lived in mucky waters near the shore, where it would be an advantage to have your head and brain out on the end of a long spar,” he said. “A fish swimming there would see something dark coming out of the gloom in the water but wouldn’t be alarmed because it would see that it was about its own size, not a predator.
“It wouldn’t be until it was too late that the fish would realize the thing coming toward it was actually attached to a 5-foot neck that, in turn, was attached to a chunky body, sort of oval shaped like a turtle’s, with flippers like a sea turtle’s.”
The really fiendish touch would have come when the creature opened its reptilian mouth, LaBarbera said.
Not just a neck
Dinocephalosaurus’ long neck was made up of 25 elongated vertebrae, each of which had even longer, delicate cervical rib bones attached. As the reptile stretched and straightened its neck to reach the fish or squid it wanted to eat, the ribs flared out, at least doubling the size of its esophagus.
When the creature opened its toothy mouth, water would rush in, creating an inflow that suctioned in the targeted fish or squid before it could dart away. The creature’s open mouth also swallowed the small pressure wave created by its moving head, eliminating the last possible warning to its prey.
“The teeth on this thing are quite distinctive, fairly slender and kind of needlelike, pointing back into the mouth, ideal for capturing slippery prey like fish and squid,” said LaBarbera. “Once they were down in the esophagus, it would partially open its mouth to expel the water, but the teeth kept the prey caged in.
“It would have been a rather nasty little predator.”
Though protorosaur fossils, both land and marine versions, previously had been found in other parts of the world, Dinocephalosaurus is the first to be found in China.
Chinese paleontologist Chun Li, a professor at Beijing’s Institute of Paleontology and Paleoanthropology, discovered it in 2002 in Triassic limestone formations among the mist-shrouded, sugar-loaf shaped mountains of Guizhou province in southwest China.
The next year he found an almost complete fossil of a Dinocephalosaurus body and a second skull.
China rich in fossils
In the last couple of decades, China has taken a keen interest in its rich deposits of fossil rocks, making it one of the hottest areas in the world for paleontological prospecting. The Beijing institute several years ago began inviting the Field Museum’s Olivier Rieppel to collaborate on analyzing and publishing findings.
Rieppel, an expert on fossil reptiles, periodically goes to China and helps in the initial analysis of new Guizhou fossils. He later does a more thorough analysis in Chicago, figuring out with the help of computers where in the known evolutionary tree of life the creature belongs and its relationship to other animal groups.
“If it’s a new taxon [an animal previously unknown to science], we publish it first in China in a Chinese scientific journal,” said Rieppel. “Chinese scientists also are keen on exposure in Western scientific journals, so I help with that too.”
When Rieppel brought home data on Dinocephalosaurus last spring, he kept wondering about its long neck vertebrae, with their attached ribs.
“The question was,” he said, “what the hell good was this long neck for this animal? What purpose did it serve? Was it an adaptation?
“I just got nowhere with it, so I took it to Michael [LaBarbera] and asked him to take a look.”
Rieppel and LaBarbera both teach evolutionary biology at the University of Chicago. LaBarbera is not a paleontologist, but specializes in studying biomechanics, or how animals physiologically operate. Currently he is studying how scallops swim.
“I like to do my research on things I can eat after I’m done,” jokes LaBarbera.
Not all protorosaurs used their necks like Dinocephalosaurus did, he said. Those living on land certainly wouldn’t have.
“Many marine animals do suction feeding like this, including turtles and salamanders,” LaBarbera said. “So do a lot of fish. If you are a bass fisherman, you know how deeply lodged your plug can be when you catch one because they swallow them so fast.
“This is a reptile, and reptiles have very distensible [expandable] throats, grabbing, killing and swallowing their prey whole.”
From his own experience–he does much of his field work snorkeling in shallow water–LaBarbera also theorizes that, in order to breathe, Dinocephalosaurus had to let its entire neck and body float on the surface to suck air into its lungs.
“If you snorkel,” he said, “you know you can’t use a tube much more than 18 inches long, because your chest can’t expand in water deeper than that. This creature had a neck a meter and a half long [about 5 feet], so it couldn’t just stick its head above the surface and draw air to its lungs that deep in the water.”
Though the Science article lists the Chinese fossil as measuring about 8 feet in length, it probably was much longer because other long-necked protorosaurs have long tails. No tail was recovered with this fossil.
