Hadrosaurs would have run cross country in dino high school

Brett Smith for redOrbit.com – Your Universe Online

In the struggle to survive against big meat-eating dinosaurs like Tyrannosaurus rex, some smaller dinosaurs evolved the ability to sprint, while others developed long-distance running abilities.

The duck-billed hadrosaur fell into the latter category, according to a report from the University of Alberta. The physiology of the herbivore allowed it to outrun T. rex, but only over longer distances. The legendary predator was a faster sprinter.

Published by Indiana University Press, the report describes how hadrosaurs’ large tail muscles (caudofemoralis) affected their running abilities.

Using data from the 3-D modeling of modern reptiles, researchers know T. rex could sprint fast because “the physical distance the muscle has to contract to swing the leg through a single arc is very, very short,” report author W. Scott Persons, a paleontologist from the University of Alberta in Canada, told Scientific American.

In contrast, hadrosaur’s caudofemoralis muscles were attached much farther down on the femur. This made its muscle contractions longer and its strides slower, meaning it wasn’t quick, but could travel greater distances.

The study is based on 75-million-year-old fossils of two hadrosaurs from Alberta, one of an adolescent and one of an adult.  The comparison between the hadrodaurs and T. rex is relevant not just because of their potential predator/prey relationship, but also because their physical make-ups are quite similar.

A new species of hadrosaur

Hadrosaurs include a range of duck-billed dinosaurs and one particularly unique hadrosaur was just discovered, according to a report published in September. The 30-foot-long, 8,500-pound Rhinorex condrupus was particularly unique for its enormous “King Nose,” which its scientific name roughly translates to. The massive proboscis is different from the bony crest that appears atop the skulls of most other hadrosaurs.

“The purpose of such a big nose is still a mystery. If this dinosaur is anything like its relatives then it likely did not have a super sense of smell; but maybe the nose was used as a means of attracting mates, recognizing members of its species, or even as a large attachment for a plant-smashing beak. We are already sniffing out answers to these questions,” said study author Terry Gates, a paleontologist from NC State.

The big-nosed dinosaur was first found in Utah during the 1990s, but it wasn’t until researchers recently began reconstructing the skull that they realized just how unique this animal was. Closely related to other hadrosaurs like Parasaurolophus and Edmontosaurus, Rhinorex is the sole complete hadrosaur fossil from central Utah.

“We’ve found other hadrosaurs from the same time period but located about 200 miles farther south that are adapted to a different environment,” Gates said. “This discovery gives us a geographic snapshot of the Cretaceous, and helps us place contemporary species in their correct time and place. Rhinorex also helps us further fill in the hadrosaur family tree.”

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