Mars Rovers Just Keep Going

Oct. 17, 2007 -- NASA announced it was extending for the fifth time the mission of Mars space probes Spirit and Opportunity, in their indefatigable exploration of the Red planet.

The two robots touched down three weeks apart on Mars in January 2004 for an expected 90-day mission that instead could stretch out to 2009, the National Aeronautics and Space Administration said on its website.

In September, Opportunity began a perilous descent into the Victoria crater, in Mars' Meridiani Planum region.

On the opposite side of the dusty planet and in the opposite direction, Spirit in early September began climbing onto the Home Plate volcanic plateau where scientists believe the volcanic rock might contain traces of water.

"After more than three-and-a-half years, Spirit and Opportunity are showing some signs of aging, but they are in good health and capable of conducting great science," said John Callas, rover project manager at NASA's Jet Propulsion Laboratory, Pasadena, California.

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The roving probes carry several sophisticated instruments to examine the geology of Mars for information about past environmental conditions.

Opportunity has returned dramatic evidence that its area of Mars stayed wet for an extended period of time long ago, with conditions that could have been suitable for sustaining microbial life, NASA said.

Spirit has found evidence in the region it is exploring that water in some form has altered the mineral composition of some soils and rocks, the space agency added.

To date, Spirit has driven 7.26 kilometers (4.51 miles) and has sent back to Earth more than 102,000 images. Opportunity has driven 11.57 kilometers (7.19 miles) and has returned more than 94,000 images.

T. Rex's Missing 3rd Finger Found

Oct. 17, 2007 — It's bad enough to misplace a finger, much less have it lost for 65 million years. But after decades of searching, paleontologists at Montana's Hell Creek have found the missing third finger of one of Tyrannosaurus rex's undersized "hands."

The finger suggests that T. rex had a powerful wrist and its hands were probably able to hold onto chunks of flesh while the monster's gnarly jaws did all the killing.

The newfound bone is a right metacarpal, equivalent to one of the long bones in the palm of a human hand, explains T. rex investigator Elizibeth Quinlan of Fort Peck Paleontology, Inc., in Fort Peck, Montana. She plans to present the discovery on Oct. 28 at the annual meeting of the Geological Society of America in Denver.

"It's unquestionably the metacarpal," Quinlan told Discovery News. No previous T. rex remains have ever been found with a third metacarpal, despite the fact that the other bones suggested its presence. "There is a notch in the side of the second metacarpal that was just begging to have something fit into it."

The revised anatomy of the hand suggests there was a very strong tendon that attached to second metacarpal, giving the hand a pretty decent grip, she said. Still, the puny limbs were almost certainly not used by T. rex to grapple with prey or kill.

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"We were thinking that T. rex did use its upper appendages not so much in hunting but in feeding," said Quinlan. That means ripping off pieces of flesh from corpses and clutching the stuff to keep it from other hungry predators. "We don't think their table manners were very good."

"I would strongly support (the hand) being used for carrying a piece of meat away," said paleontologist Scott Hartman, science director of the Wyoming Dinosaur Center in Thermopolis. "There is a reason that carrying meat away would be useful."

One reason is that the T. rex head is already so large and heavy that adding the weight of a large slab of meat between its teeth would make it unable to tip back and stand up, Hartman said. Holding meat with the arms, which are lower, avoids that overloaded teeter-totter effect.

Another possibility is that the hands were parenting tools. They would have made it possible for a T. rex to carry yummy slabs of dino flesh to its carnivorous babies, Hartman said.

That said, the new finger bone is not going to cause much change to reconstructions of T. rex, says Hartman. Throughout the evolution of meat-eating dinosaurs there was a trend towards fewer fingers, with the earliest having five fingers and the T. rex having two. This newfound nubbin of a third finger was already on its way out, and did not stick out much, he said.

"In another 10 million years they would have lost (the third finger) completely," said Hartman. Unfortunately for them, however, the age of dinosaurs ended before that could happen.

Related Links:

Fort Peck Paleontology, Inc.

Discovery's Dino Guide

The Fossils of Hell Creek

Building a T. rex skeleton