May 3, 2017

New Plant-Eating Dinosaur Was So Big It Had No Predators

Artistic life reconstruction of the dinosaur Galeamopus pabsti.
Carnivores were not the only animals at the top of the Jurassic food chain, suggests a newly described herbivorous dinosaur that avoided predation due to its massive size and “whiplash” tail, which is thought to have cracked like a bullwhip to create sonic booms.

The new species, Galeamopus pabsti, measured well over 66 feet long and weighed more than 15 tons. It lived 150 million years ago and is described in the journal PeerJ.

While healthy adults of this species likely had few or no predators, carnivorous dinosaurs feasted on any of these enormous, meaty animals that had already keeled over.

Emanuel Tschoop, lead author on the study, is a paleontologist at the University of Turin.

“Numerous teeth and tooth marks on the bones of the skeleton show that Allosaurus and Ceratosaurus fed on the carcass, and probably also preyed upon juveniles or sick individuals,” he told Seeker. Both Allosaurus and Ceratosaurus were large carnivorous dinosaurs.

Galeamopus pabsti in its environment in the Late Jurassic of North America. An Allosaurus and two Ceratosaurus are feeding on a carcass of Galeamopus pabsti.
Tschopp and co-author Octávio Mateus of the Universidade Nova de Lisboa and the Museum of Lourinhã in Portugal analyzed the remains of the new dinosaur, which were excavated in 1995 by paleontologist Ben Pabst and his team. Named after Pabst, the dinosaur once lived in what are now Wyoming and Colorado.

“The ecosystem in which G. pabsti lived was a huge alluvial plane, with meandering rivers that flowed from the south-west towards the north and north-east, into a relatively shallow inland sea, which covered parts of what are now Canada and Montana,” Tschopp explained.

The researchers determined that the dinosaur was a diplodocid sauropod, placing it among the most iconic dinosaurs and the longest creatures ever to walk the earth. Members of the family Diplodocidae (meaning “Double Beams”) include Diplodocus and Supersaurus, which may have reached lengths up to 112 feet.

These animals have a reputation for being dullard dinosaurs, since their brains were very small, particularly in relation to the rest of their bodies. The jury, though, is still out on how brain size affected their levels of intelligence.

Paleontologist Emanuel Tschopp and Ben Pabst with the skull of the new species dedicated to Pabst in the Sauriermuseum Aathal: Galeamopus pabsti.
It is suspected that Galeamopus pabsti spent much of its time peacefully feasting on ferns, horse-tails, and other plant materials. Animals on the ground must have mostly seen the tree trunk-like legs of these extremely large dinosaurs.

Another noteworthy feature of the newly described dinosaur is the unusual triangular shape of the part of its neck closest to its head.

“The neck was not a perfect triangle, but it was much wider at the bottom than at the top,” Tschopp said.

A very complete series of neck vertebrae were found with the remains of the dinosaur. It is therefore hoped that these fossils might solve a longstanding mystery over how sauropods held their necks.

Some researchers believe that the necks were mostly held erect, like those of a giraffe, allowing them to reach tall-growing trees and other vegetation. Still other scientists believe that the necks were held in a more horizontal position, permitting the dinosaurs to sweep over large plant food surfaces. Perhaps all of these movements were possible.

Read more at Discovery News

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