Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. 24/7 Space News .




EARLY EARTH
Were Dinosaurs Destined to Be Big
by Staff Writers
Boulder CO (SPX) Nov 06, 2012


They looked across the "family tree" of dinosaurs and found that some groups, or clades, of dinosaurs do indeed trend larger over time, following Cope's Rule.

In the evolutionary long run, small critters tend to evolve into bigger beasts-at least according to the idea attributed to paleontologist Edward Cope, now known as Cope's Rule. Using the latest advanced statistical modeling methods, a new test of this rule as it applies dinosaurs shows that Cope was right-sometimes.

"For a long time, dinosaurs were thought to be the example of Cope's Rule," says Gene Hunt, curator in the Department of Paleobiology at the National Museum of Natural History (NMNH) in Washington, D.C. Other groups, particularly mammals, also provide plenty of classic examples of the rule, Hunt says.

To see if Cope's rule really applies to dinosaurs, Hunt and colleagues Richard FitzJohn of the University of British Columbia and Matthew Carrano of the NMNH used dinosaur thigh bones (aka femurs) as proxies for animal size. They then used that femur data in their statistical model to look for two things: directional trends in size over time and whether there were any detectable upper limits for body size.

"What we did then was explore how constant a rule is this Cope's Rule trend within dinosaurs," said Hunt.

They looked across the "family tree" of dinosaurs and found that some groups, or clades, of dinosaurs do indeed trend larger over time, following Cope's Rule. Ceratopsids and hadrosaurs, for instance, show more increases in size than decreases over time, according to Hunt. Although birds evolved from theropod dinosaurs, the team excluded them from the study because of the evolutionary pressure birds faced to lighten up and get smaller so they could fly better.

As for the upper limits to size, the results were sometimes yes, sometimes no. The four-legged sauropods (i.e., long-necked, small-headed herbivores) and ornithopod (i.e., iguanodons, ceratopsids) clades showed no indication of upper limits to how large they could evolve. And indeed, these groups contain the largest land animals that ever lived.

Theropods, which include the famous Tyrannosaurus rex, on the other hand, did show what appears to be an upper limit on body size. This may not be particularly surprising, says Hunt, because theropods were bipedal, and there are physical limits to how massive you can get while still being able to move around on two legs.

Hunt, FitzJohn, and Carrano will be presenting the results of their study on the afternoon of Sunday, Nov. 4, at the annual meeting of The Geological Society of America in Charlotte, North Carolina, USA.

As for why Cope's Rule works at all, that is not very well understood, says Hunt.

"It does happen sometimes, but not always," he added. The traditional idea that somehow "bigger is better" because a bigger animal is less likely to be preyed upon is naive, Hunt says. After all, even the biggest animals start out small enough to be preyed upon and spend a long, vulnerable, time getting gigantic

Testing Cope's Rule and the Existence of an Upper Bound for Body Size in Non-Avian Dinosaurs

.


Related Links
Geological Society of America
Explore The Early Earth at TerraDaily.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





EARLY EARTH
New study sheds light on how and when vision evolved
Bristol UK (SPX) Oct 31, 2012
The study, which used computer modelling to provide a detailed picture of how and when opsins evolved, sheds light on the origin of sight in animals, including humans. The evolutionary origins of vision remain hotly debated, partly due to inconsistent reports of phylogenetic relationships among the earliest opsin-possessing animals. Dr Davide Pisani of Bristol's School of Earth Sciences an ... read more


EARLY EARTH
Moon crater yields impact clues

Study: Moon basin formed by giant impact

NASA's LADEE Spacecraft Gets Final Science Instrument Installed

Astrium presents results of its study into automatic landing near the Moon's south pole

EARLY EARTH
Mars Longevity Champ Switching Computers

NASA Rover Finds Clues to Changes in Mars' Atmosphere

Survey Of Matijevic Hill Continues

Preliminary Self-Portrait of Curiosity by Rover's Arm Camera

EARLY EARTH
Voyager observes magnetic field fluctuations in heliosheath

New NASA Online Science Resource Available for Educators and Students

'First' Pakistan astronaut wants to make peace in space

Space daredevil Baumgartner is 'officially retired'

EARLY EARTH
Tiangong 1 Parked And Waiting As Shenzhou 10 Mission Prep Continues

China to launch 11 meteorological satellites by 2020

China makes progress in spaceflight research

Patience for Tiangong

EARLY EARTH
Crew Prepares for Spacewalk After Progress Docks

Crew Preparing for Cargo Ship, Spacewalk

Russian cargo ship docks with ISS: official

Packed Week Ahead for Six-Member Crew

EARLY EARTH
Russian Proton Briz-M Launches Yamal Satellites Into Orbit

SpaceX Transitions to Third Commercial Crew Phase with NASA

Globalstar Birds To Launch On Soyuz Next February

Ariane 5s are readied in parallel for Arianespace's next heavy-lift flights

EARLY EARTH
Physicists confirm first planet discovered in a quadruple star system

Planet-hunt data released to public

New Study Brings a Doubted Exoplanet 'Back from the Dead'

New small satellite will study super-Earths for ESA

EARLY EARTH
ORNL Debuts Titan Supercomputer

UNH Space Scientists to Develop State-of-the-Art Radiation Detector

Samsung muscle versus Apple's 'cool'

1.2 billion smartphones, tablets to sell in 2013: survey




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement