Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Four, Three, Two, One . . . Pterosaurs Have Lift Off!

08.01.2009
Pterosaurs have long suffered an identity crisis. Pop culture heedlessly — and wrongly — lumps these extinct flying lizards in with dinosaurs. Even paleontologists assumed that because the creatures flew, they were birdlike in many ways, such as using only two legs to take flight.

Now comes what is believed to be first-time evidence that launching some 500 pounds of reptilian heft into flight required pterosaurs to use four limbs: two were ultra-strong wings which, when folded and balanced on a knuckle, served as front “legs” that helped the creature to walk — and leap.


Illustration by Mark Witton.
A modern-day man and giraffe, drawn to scale, flank the extinct pterosaur known as Hatzegotpteryx. Unlike birds, pterosaurs used four legs to launch themselves into flight, according to new research.

Publishing in Zitteliana, Michael B. Habib, M.S., of the Center for Functional Anatomy and Evolution at the Johns Hopkins University School of Medicine, reports his comparison of bone strength in the limbs of pterosaurs to that of birds and concludes that pterosaurs had much stronger “arms” than legs. The reverse is true of birds.

“We’ve all seen birds take off, so that’s what’s most familiar,” says Habib. “But with pterosaurs, extinct 65 million years and with a fossil history that goes back 250 million years, what’s familiar isn’t relevant.”

A supersized glitch is inherent in the traditional bipedal launch model, Habib notes: “If a creature takes off like a bird, it should only be able to get as big as the biggest bird.”

Birds use legs to launch, wings to flap. They don’t get launch power from wings or flight power from legs. In fact, when a bird is aloft, its legs become payload, or cargo. The muscle on the two back limbs that provides the power to launch must be carried and therefore limits size. Released of that handicap by employing all four legs to launch, giant pterosaurs could fly despite the fact that they were roughly the same size and shape as modern-day giraffes.

“The difference between pterosaurs and birds with regard to critical mechanical properties is very, very large,” Habib says, especially when you’re talking about the big pterosaurs; as the size gets bigger, the difference gets bigger too.”

For example, the wings of these fantastic hairy reptiles, most notably those of Quetzalcoatlus northropi, which spanned to an impressive 35 feet when the creatures were aloft, propelled the creatures into the air during take-offs that Habib describes as leap-frogging long-jumps: “Pterosaurs had long, huge front limbs, so no partner was required. Then, with wings snapping out, off they’d fly.”

Using computer scans to obtain cross-sectional images and geometric data for 155 bird specimens representing 20 species, Habib calculated the strengths of bones in bird limbs and compared these to three species of pterosaurs, the bones strengths of which he calculated using measurements from previously published sources. Structural strength, taking into account length and diameter, among other things, is a measure of how much force a bone can take before it fractures.

Habib also spent time crunching the numbers using the old, bipedal launch model and simply couldn’t find a mathematical solution that would enable the largest of the pterosaurs — using hind legs alone — to launch at all.

“But using all four legs, it takes less than a second to get off of flat ground, no wind, no cliffs,” he said. “This was a good thing to be able to do if you lived in the late Cretaceous period and there were hungry tyrannosaurs wandering around.”

It stands to reason that a large-bodied animal needing to produce lots of power at take-off would use four legs instead of two, Habib says: “We put V8 engines in our biggest, heaviest cars, not V-4s, like the one in my Camry.”

Assumption and convention — rather than reason or data — held sway for centuries, ever since the classical bipedal model of pterosaur take-off was first championed, he notes.

The research was funded by the Jurassic Foundation. Habib, of Johns Hopkins, is the sole author of the paper.

Maryalice Yakutchik | Newswise Science News
Further information:
http://www.hopkinsmedicine.org/fae/
http://www.palmuc.de/zitteliana/
http://www.hopkinsmedicine.org/Press_releases/2009/01_06_08.html

More articles from Life Sciences:

nachricht What happens in the cell nucleus after fertilization
06.12.2016 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Speed data for the brain’s navigation system

06.12.2016 | Health and Medicine

What happens in the cell nucleus after fertilization

06.12.2016 | Life Sciences

IHP presents the fastest silicon-based transistor in the world

05.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>