Thursday, September 4, 2014

Dreadnoughtus! New Dino May Be Largest Land Animal Ever

From Popular Mechanics:

An international team of paleontologists have just uncovered the coolest dinosaur of this decade, and the biggest fossil ever of a single organism. Meet Dreadnoughtus.

RELATED: Tyrannosaurus Trackways Reveal a Dinosaur's Walk.

By William Herkewitz
Kenneth Lacovara with the right tibia of Dreadnoughtus.
Kenneth Lacovara with the right tibia of Dreadnoughtus
Kenneth Lacovara

September 4, 2014 10:11 AMTEXT SIZE: A . A . A
Move over, Velociraptor and T. rex. Here comes another top-tier dinosaur for the history books.

Today an international team of paleontologistsunveiled the newest Mesozoic badass:Dreadnoughtus schrani. Weighing in at an astonishing 65 tons, standing two stories high at the shoulder, and measuring 85 feet long, this titan is the heaviest dinosaur we've ever (accurately) measured. And its discovery represents the most fossil mass ever found for a single organism—a paleontologist's dream.

"For the [largest] dinosaurs, which we call titanosaurs, finding anything around 20 percent of the fossil is usually considered a home run," says Kenneth Lacovara, the lead Drexel University paleontologist behind the find. "Normally you only find a handful of bones, and the previous record was a 27 percent complete skeleton. With Dreadnoughtus we found 70 percent."

Near-Complete

The reason near-complete finds are so rare is because fossilization requires a quick burial in sediment. As you can imagine, it's an extraordinary occurrence for something as big as a Dreadnoughtus to be buried so quickly. But according to Lacovara, the scientists believe a rapid pair of floods, caused by broken earthen levees in the valley where Dread was found, are behind the impressively complete find. (Sedimentary records in nearby areas back up this idea.)



Lacovara chanced upon Dread during a fossil hunting trip to the Santa Cruz province of southern Argentina in 2005. Two individuals of the same species were found, the biggest of which was composed of 115 massive bones and a single tooth. It took 4 annual trips just to haul the fossil out of the ground, and then another 4 years of cleaning and fossil preparation work to get it ready for study. (Full disclosure: This author spent endless hours in 2010 and 2011 cleaning two of Dred's massive vertebrae. Yes. They are that big.)

According to Jason Poole, a head fossil preparator at Philadelphia's Academy of Natural Sciences and member of the excavation team, "We really started to get a great picture of how lucky we were after that first season. People kept finding all these [fossilized bones] still in their anatomically correct positions over and over again. It was really exciting."

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3D Models and Walking Giants

Lacovara's preliminary research shows that Dread hails from the late Cretaceous Period (about 77 million years ago, close to the end of the age of dinosaurs) and lived in high-altitude and heavily forested valleys. By studying the growth rings in Dread's bones, the paleontologists also discovered, to their astonishment, that despite the creature's enormous size, it was growing steadily up until the day it died.

Although Dread is a contender for the title of largest land animal ever, Lacovara explains that such a claim is actually quite complicated. The current, widely accepted champion is a dinosaur called Argentinosaurus. But Argentinosaurus is only known from a handful of fossils (around 5 percent of its total bones,) so its size and dimensions are roughly estimated. For paleontologists, the gold standard for predicting weight and height involve calculations based on several leg bones. And of the calculable dinosaurs, Dred is number 1.



But what's perhaps the most interesting aspect of this find, Poole says, is that because Dread's fossil is so complete, paleontologists worldwide will now be able to build computer models to answer fundamental but tricky questions about how these massive creatures once roamed the Earth. "And as you understand these creatures' locomotion and ability to move around, you can start answering questions about feeding, their place in the ecosystem, and a whole number of other avenues of research," he says.

Lacovara agrees, and gleefully points to the fact that many of Dread's bones show beautifully persevered scars of muscle attachment, which are already helping direct and constrain their computer models. And while the researchers will return the fossils to Argentina in 2015, they have already taken detailed 3D scans which are free to download online for scientists and the general public. So take a look! The files are formatted so that reverse engineering them for a 3D printer can't be done, but when somebody has hacked a miniature model… please email me.



The tail of Dreadnoughtus schrani. (Left-side view. Neural spines to the left, chevrons to the right.) Credit: Kenneth Lacovara. 

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