Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Paleontologists Give Madagascar’s Fiercest Dinosaur a Hand

13.01.2012
66 million years ago, the fearsome, meat-eating dinosaur Majungasaurus crenatissimus prowled the semi-arid lowlands of Madagascar.

Its powerful jaws bristled with bladelike teeth, and its strong legs terminated in formidable claws. Not even its own kin were safe, for given the chance, Majungasaurus was known to engage in cannibalism. Now, a new study published in the Journal of Vertebrate Paleontology shows that there was one part of its dreadful form that was not to be feared: its arms.

First discovered in 1895, Majungasaurus became well known through hundreds of fossils recovered by the joint Mahajanga Basin Project of Stony Brook University and the Université d’Antananarivo between 1993 and 2007. Nearly every structure – from its cranial sinuses to an injury on its tail – has been described in great detail. But the anatomy of Majungasurus’ forelimb has remained a mystery until now.

Lead author Sara Burch, of Stony Brook University, says the arm of Majungasaurus epitomizes the unique forelimb anatomy of abelisaurids, a group of theropod dinosaurs known almost exclusively from southern landmasses collectively known as Gondwana. “The proportions of this limb are unlike anything we see in other theropods. The forearm bones are short, only a quarter of the length of the humerus (upper arm bone), but extremely robust. The wrist bones aren’t even ossified, and the stubby fingers probably lacked claws. The proportions are so strange, it ends up looking like a hand stuck on the end of a humerus.”

Limb reduction is nothing new for theropods; it’s accentuated in the caricature of the mighty Tyrannosaurus rex. Terrifying, to be sure, but with arms too puny to scratch its own face. “Another group of theropods, the alvarezsaurs, go their own odd way with limb reduction,” says co-author Matthew Carrano of the Smithsonian Institution. “These dinosaurs also had very short hands and very short forearms.” And modern-day theropods (those feathered fellows you see flying around) have even lost some digits through evolution. Might one of these scenarios explain the anatomy of Majungasaurus? Not likely, says Burch. “While many theropods have reduced limbs, most retain their normal proportions. We don’t know of any other case where the forearm bones have become more robust in this way. Abelisaurids like Majungasaurus were clearly on a completely different trajectory from the lineage leading to birds.”

With no modern analogs, it’s difficult to speculate on how this stubby forelimb was used. But, says Burch, “grasping is out of the question – there’s no way this animal was doing much manipulation with such a reduced hand. The joint anatomy suggests great mobility at the elbow and wrist, but the individual digits probably could not have moved independently.” The limb may have been used in display, or it may represent an unknown evolutionary path that was cut short by the Cretaceous-Tertiary extinction.

Paleontologist Jonah Choiniere of the American Museum of Natural History, who was not involved with the study, says that the arm of Majungasaurus provides crucial information about theropod evolution. “Until now, most knowledge of the forelimb in abelisaurids has come from two South American species, Carnotaurus sastrei and Aucasaurus garridoi. Thanks to this study, we now know that this morphology was more widespread throughout Gondwana during the Late Cretaceous. What’s more, we now have a solid base for understanding forelimb anatomy in abelisaurids. The next steps are to relate the anatomy to other, more basal theropods and develop robust evolutionary hypotheses for how this bizarre forelimb evolved.”

ABOUT THE SOCIETY OF VERTEBRATE PALEONTOLOGY
Founded in 1940 by thirty-four paleontologists, the Society now has more than 2,300 members representing professionals, students, artists, preparators and others interested in vertebrate paleontology. It is organized exclusively for educational and scientific purposes, with the object of advancing the science of vertebrate paleontology.
The Journal of Vertebrate Paleontology
The Journal of Vertebrate Paleontology (JVP) is the leading journal of professional vertebrate paleontology and the flagship publication of the Society. It was founded in 1980 by Dr. Jiri Zidek and publishes contributions on all aspects of vertebrate paleontology.

For complimentary access to the full article beginning January 13, 2012, visit: http://www.tandfonline.com/loi/ujvp20

The article appears in the Journal of Vertebrate Paleontology 32(1) published by Taylor and Francis.

Citation: S. H. Burch and M. T. Carrano. An articulated pectoral girdle and forelimb of the abelisaurid theropod Majungasaurus crenatissimus from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 32(1).

Journal Web site: Society of Vertebrate Paleontology: http://www.vertpaleo.org

AUTHOR CONTACT INFORMATION

Sarah H. Burch
Department of Anatomical Sciences
Stony Brook University
Stony Brook, New York, U.S.A.
sara.burch@stonybrook.edu
Matthew T. Carrano
Department of Paleobiology
Smithsonian Institution
Washington, District of Columbia, U.S.A.
carranom@si.edu
OTHER SCIENTISTS NOT DIRECTLY INVOLVED WITH THE STUDY
Jonah Choiniere
Division of Paleontology
American Museum of Natural History
New York, NY, U.S.A.
jchoiniere@amnh.org
Kristi Curry Rogers
Biology and Geology Departments
Macalester College
rogersk@macalester.edu
Phone: +1-651-331-6815 (cell)

| Newswise Science News
Further information:
http://www.vertpaleo.org

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

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...

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

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>