T. Rex Plodded Like an Elephant, Nerve Study Says

The mightyTyrannosaurus rexwas no quick, agile killing machine—the"tyrant king"dinosaur just didn't have the nerves.

Instead, most timesT. rexprobably plodded along like an elephant, according to a new study that estimated the"speed limit"of nerve signals running through the dinosaur's body.

(Related:"T. RexWas Slow-Turning Plodder, Study Suggests.")

When a vertebrate—an animal with a backbone—stubs its toe, electrical signals get carried from the toe to the spinal cord by a nerve, which is made up of bundles of long, fiberlike cells.

Since the researchers couldn't study aT. rex's nerves directly, the team looked at how nerves work in a range of modern animals, from the tiny shrew to midsize dogs and pigs to massiveAsian elephants.

(Related:"'Dinosaur Mummy' Found; Has Intact Skin, Tissue.")

The scientists found that, for all body sizes, nerves have a basic speed limit of about 180 feet (55 meters) a second. That's the fastest a signal can travel from an animal's feet to its spinal cord—the kind of signal that's essential for walking and running.

At that speed limit, big animals such as elephants can't run too fast or they're effectively running blind.

Suppose an elephant steps on a pebble, said study leaderMax Donelanof Simon Fraser University in Burnaby, Canada. If the pachyderm was running fast,"its foot would be nearly off the ground before it could do something in response to that troublesome pebble."

The same goes forT. rex,said study co-authorJohn Hutchinson, an expert on dinosaur movement at the Royal Veterinary College in London.

"Nerves are nerves—in vertebrates anyway,"Hutchinson said."So the principles will apply generally to dinosaurs, too."

T. rexWould Still Have Been Impressive, Exciting

According to the study, there's a trade-off between the number of nerve cells in a bundle and how fast the nerve can transmit a signal.

For a big animal such as an elephant to be as fast as a shrew and still feel every step, the elephant's nerves would have to be 100 feet (30 meters) thick—clearly impossible.

Instead, elephant nerves can either be relatively slow and sensitive or fast and dulled.

As long as a bus and weighing around 6.5 tons, the averageT. rexwould also have needed to move slowly to feel with its feet, according to the study, which appears Wednesday in theProceedings of the Royal Society B.

The idea thatT. rexlumbered like an elephant fits with other studies of the dinosaur's body, including one paper that found thatT. rex's leg muscles would have to have been heftier than its whole body weight for the dinosaur to have been a speed demon.

"To be agile,Tyrannosauruswould need to be both all muscle and all nerve,"Simon Fraser's Donelan said.

(Related:"'Mighty'T. RexMostly Picked Off Youngsters?")

Nonetheless, elephants can occasionally get up to a fast clip, sometimes charging fast enough to catch people. Ditto for big dinosaurs, the Royal Veterinary College's Hutchinson said.

Tyrannosaurus rexwere"by no means slow, sluggish, ponderous, clumsy animals. They still would have been impressive and exciting to see, and capable of surprising feats from time to time."

forNational Geographic News

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Aztec, Maya Were Rubber-Making Masters?

Ancient civilizations in much ofMexicoand Central America were making different grades of rubber 3,000 years before Charles Goodyear"stabilized"the stuff in the mid-19th century, new research suggests.

The Aztec, Olmec, and Maya of Mesoamerica are known to have made rubber using natural latex—a milky, sap-like fluid found in some plants. Mesoamerica extends roughly from central Mexico to Honduras and Nicaragua (regional map).

Ancient rubber makers harvested latex from rubber trees and mixed it with juice from morning glory vines, which contains a chemical that makes the solidified latex less brittle.

(Take aquiz about the ancient Maya.)

By mixing up rubber using different proportions of the two ingredients, researchers at the Massachusetts Institute of Technology found that tweaking the formula led to rubber products with different properties.

Some of the rubber came out more bouncy, suggesting it may have been used to make balls for the legendary Mesoamerican ball games.

As described in ancient Maya texts, ball games often had religious meaning—pitting good against evil. It's thought the ball games sometimes ended in human sacrifice, most famously in ritual decapitation.

(Read about apanel from a royal ball court in Guatemala that's been dubbed a Maya"masterpiece.")

Other latex-to-morning glory proportions created more durable rubber, such as what might have been used in Aztec rubber sandals, which were described by Spanish conquistadors but have never been found by archaeologists.

A 50-50 blend of morning glory juice and latex created rubber with maximum bounciness, while a 75-25 mix of latex and morning glory made the most durable material.

Latex a"Funky White Liquid"

The initial discovery of rubber from latex and morning glory isn't so far-fetched, noted study co-authorMichael Tarkanian, a researcher with MIT's Center for Materials Research in Archaeology and Ethnology.

Morning glory plants tend to grow near rubber trees, and both plants were considered sacred in several Mesoamerican cultures. Morning glory, for example, was also used in religious ceremonies for its hallucinogenic properties.

(Relatedpictures:"Mesoamerican Pyramid Tomb With Human Sacrifices Found.")

To make their re-creations as accurate as possible, Tarkanian and colleague Dorothy Hosler harvested latex from rubber trees and juice from morning glory vines growing in Mexico.

The first challenge was getting the ingredients back to the lab. Latex isn't regulated by U.S. Customs, and so there are no official papers for carrying it into the country, Tarkanian explained,"which is a problem when you're bringing this funky white liquid across the border in Nalgene bottles."

Once safely back in the U.S., the researchers met a new hurdle: The latex needed to be warm.

"The process always worked in Mexico, but not in the air-conditioned labs at MIT,"Tarkanian said. When the mixture was too cold, the molecules simply didn't bond.

Today most rubber is treated through a process called vulcanization, which cooks liquid latex with sulfur to increase strength and elasticity.

Aztec Captains of Industry?

According to Tarkanian, it's no surprise cultures such as the Aztec were making advanced versions of rubber. Despite their common depiction as primitive, violent people, the Aztec had a spirit of scientific inquiry, as shown by their experiments in metallurgy and other industries, he said.

(Related:"Aztec Math Decoded, Reveals Woes of Ancient Tax Time.")

"Their science, engineering, and development skills would have led them to try different combinations"of substances when making rubber, Tarkanian said.

Once the raw ingredients had been mixed, he added, the rubber took about ten minutes to form and another five minutes to harden, giving rubber workers just a few minutes to shape the final product.

Tarkanian and Hosler mostly created sheets of rubber in the lab, but they did make a few rubber balls during one session.

"At the end of the semester, we played the Mesoamerican ball game. The losing team was beheaded,"Tarkanian quipped.

The Mesoamerican-rubber paper will appear in an upcoming issue of the journalLatin American Antiquity.

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