Protorosaurs: Very Long-Necked Pre-Dinosaur Reptiles

[ramonmercado]

Long-necked hunter found in China
The remains of a 230-million-year-old marine reptile with fangs and a long neck have been found in southeast China.
The creature's 1.7m-long neck was almost twice as long as its trunk which measured less than one metre in length.

The creature, Dinocephalosaurus orientalis , is the first reported fully marine member of a diverse group of reptiles called the protorosaurs.

Its discovery is reported in Science magazine by Chun Li, from the Chinese Academy of Sciences, and colleagues.

Protorosaurs were characterised by their long necks and elongated neck vertebrae.

It is possible, say the researchers, that D. orientalis 's small head and stretched neck allowed it to sneak up and lunge at prey before its full profile scared them off.

They also suggest that the animal's specialized neck ribs may have flared outward before an attack, allowing it to swallow the pressure waves created in the water of its shallow-sea habitat.


These waves would otherwise alert the prey to the approaching predator.
Dinocephalosaurus orientalis means "terrible headed lizard from the Orient". The remains were found in 2002 in the Guanling geological formation in China's Guizhou Province.

"This is important research because we have finally explained the functional purpose of this strange, long neck," said Dr Olivier Rieppel, a co-author of the Science paper, from the Field Museum in Chicago, US.

"It allowed an almost perfect strike at prey, which usually consisted of elusive fish and squid."

Scientists say the remains will be compared with similar creatures from the Middle East and Europe to gain insights into protorosaur hunting strategies, evolution and diversity during the Triassic Period.


Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/3686254.stm

Published: 2004/09/24 10:28:43 GMT

© BBC MMIV

 

[ramonmercado]

Pre-Dinosaur Reptile Discovered

Pre-Dinosaur Reptile Discovered -- Long-Necked Hunter

John Roach
for National Geographic News
September 23, 2004

With its body obscured by murky waters, an ancient fanged reptile may have used its long neck to lunge at fish and squid. The scenario is based on analysis of a 230-million-year-old fossil discovered in southeastern China.
The new creature appeared long before the dinosaurs and is named Dinocephalosaurus orientalis, which means "terrible headed lizard from the Orient." It was a protorosaur, part of an order of diverse, predatory reptiles that lived as far back as 280 million years ago.

This nearly complete skeleton (top) of a Middle Triassic marine reptile includes a skull and a hind limb that indicate the animal lived mainly in water. This long-necked sea creature (bottom) lived more than 230 million years ago in present-day southeast China and probably fed on fish and squid.

The ancient reptile had short and broad limbs with relatively few bones in the wrist and ankle joints, an indication that it was more adapted to an aquatic lifestyle than other protorosaurs. (Scientists say living aquatic reptiles may have fewer bones in wrists and ankles than their terrestrial counterparts.)

Dinocephalosaurus also had a relatively stiff neck that was about 5.5 feet (1.7 meters) long. That's nearly twice as long as its trunk, which was three feet (one meter) long. Several thin and flexible rib bones, called cervical ribs, ran along the neck portion of the creature's spine, each bridging several of its 25 neck vertebrae.

"Protorosaurs as a group all have at least somewhat elongated neck vertebrae," said Olivier Rieppel, curator of fossil amphibians and reptiles at the Field Museum in Chicago. Rieppel is co-author of the paper that describes the fossil, which appears in tomorrow's issue of the journal Science.

His past research projects have been funded, in part, by grants from the National Geographic Society's Committee for Research and Exploration.

Stealth Hunter?

For years scientists have struggled to explain the functional significance of the elongated necks common to these reptiles. Analysis of the new fossil by Rieppel and his colleagues offers a solution to the enigma: The feature may have helped protorosaurs hunt.

The mystery surrounding the protorosaurian neck dates back to Tanystropheus longobardicus, a protorosaur from Europe and the Middle East discovered in the 1850s.

Tanystropheus had 12 "grotesquely elongated" neck vertebrae. Scientists could only explain then as a consequence of growth patterns but not as serving any specific purpose, Rieppel said. As in Dinocephalosaurus, cervical ribs in Tanystropheus bridged multiple vertebrae.

After comparing the Dinocephalosaurus fossil to living animals and thinking about how the creature fed in murky coastal waters, Rieppel and his colleagues believe they have discovered a more specific function for the elongated necks.

At the very least, the authors say, the elongated neck would have allowed the reptile to sneak up and lunge at its prey in murky waters close to shore—before the creature's full profile scared off a potential meal.

Michael LaBarbera, a study co-author and an organismal biologist at the University of Chicago, suggested a second hunting strategy that employs the neck ribs.

According to LaBarbera, contraction of Dinocephalosaurus's neck muscles would create a rapid straightening of the neck, thrusting the head toward the prey. At the same time the neck ribs would have splayed outward, increasing the volume of the esophagus.

This increased volume is important, according to the researchers. It would have created a suction force that allowed Dinocephalosaurus to swallow the pressure wave that was created as the reptile lunged its head forward through the water.

Pressure waves can serve as a warning signal to prey. Several animals employ strategies to swallow these waves in order to attack more stealthily. Dinocephalosaurus, according to the researchers, was no different.

"Looking back at Tanystropheus, it probably had the same mechanism, but the mechanism was not recognized by scientists," Rieppel said.

Hans-Dieter Sues, the associate director for research and collections at the Smithsonian Institution's National Museum of Natural History in Washington, D.C., voiced caution about this interpretation. His doubts are based on his own examination of Tanystropheus neck vertebrae.

"The cervical ribs of tanystropheid reptiles are very long, spanning multiple vertebrae. I think that, because of these ribs, the neck would have always been held fairly straight, with quite limited side-to-side and even less up-and-down mobility," he said.

Sues, who is a member of the National Geographic Society's Committee for Research and Exploration, added that the neck ribs may have splayed a little; most vertebrates that feed underwater incorporate some suction in capturing prey.

China Find

The lead author of the paper, Chun Li of the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing, discovered Dinocephalosaurus in 2002.

He had been looking for a protorosaurian in southern China for three years, with no luck. Back in a local village after another disappointing day in the field, he was told about some "coarse bones" in limestone a farmer had dug up for use as cement.

"Although the farmer misunderstood the extremely long neck of the monster as its tail, as most people would do, I knew that it was the long-necked protorosaur, which I had searched for for more than three years," Li said.

He added, "I realized that new and different information would be known from this specimen, although I didn't know what … at that moment."

According to Sues, reconstructions of well-preserved protorosaurian neck vertebrae are needed to fully understand the biomechanics of the creatures' elongated necks. Such reconstructions do not yet exist.


http://news.nationalgeographic.com/news/2004/09/0923_040923_protorosaur.html

 

[Anonymous]

I thought that with that Tanystropheus thing they had decided the "neck bones" were not neck bones at all, but the limb bones of something else? Or did they find a more complete one and revise it to the original neck bone theory?

 

[EnolaGaia]

Newly reported research has finally untangled some longstanding mysteries about the extremely long-necked protorosaurian Tanystropheus. For one thing, they determined the fossils collected to date represent two species of different adult sizes who operated in distinct ecological niches.

Scientists Finally Know How an Ancient Reptile Lived With Such an Absurdly Long Neck

Make a crocodile out of taffy. Take its head and tug on it until its neck extends a good few meters from its body. If you squint, this could be what one odd-looking Triassic reptile called Tanystropheus looked like. More or less.

This animal's assortment of ludicrously long fossilized neck bones has confused the heck out of paleontologists for nearly 170 years. By using CT scans to unpack the crushed skulls of the reptiles' remains, researchers finally resolved some nagging questions surrounding this strange animal in August last year.

Specimens of Tanystropheus can reach more than 5 meters (16 feet) in length, with its tail making up roughly a third of its length, and its body maybe a quarter. The rest is all neck. ...

Why this reptile evolved such extended dimensions is a complete mystery. The fact nobody could figure out whether it preferred to be submerged in water or to lumber about on land only made it harder to settle on any conclusions.

Part of its oddness is the shape of the neck bones. Unlike those in a snake or lizard, the cervical vertebrae in Tanystropheus fossils are stretched out like a giraffe's. In fact, when its remains were first uncovered in 1852, the scattered bones were assumed to be the elongated wing bones of a flying pterosaur.

Not all of the individuals we've unearthed are crocodile-sized, either. A number are far smaller, prompting palaeontologists to question whether some of the specimens in their archives belong to juveniles, or represent a completely different species. ...

The growth rings revealed the smaller Tanystropheus bodies did indeed belong to adults, making it fairly clear that what the researchers had on their hands were two separate species.

To distinguish them, the team named the bigger one T. hydroides, after the hydra in Greek mythology. Its smaller cousin kept the original species name of T. longobardicus. ...

FULL STORY: https://www.sciencealert.com/scient...reptile-lived-with-such-an-absurdly-long-neck