The plant eating dinosaur Azendohsaurus is not actually a dinosaur, only a distant relative, according to a new analysis of A. madagaskarensis based on the entire skull rather than on just the teeth and jaw. Many aspects of Azendohsaurus are far more primitive than previously assumed, which in turn means that its plant-eating adaptations, similar to those of some early dinosaurs, were developed independently.
The new analysis is published in Paleontology.
"Even though this extraordinary ancient reptile looks similar to some plant-eating dinosaurs in some features of the skull and dentition, it is in fact only distantly related to dinosaurs," says John J. Flynn, curator in the Division of Paleontology at the American Museum of Natural History. "With more complete material, we re-assessed features like the down-turned jaw and leaf-shaped teeth found in A. madagaskarensis as convergent with some herbivorous dinosaurs."
The fossil is a member of Archosauromorpha, a group that includes birds and crocodilians but not lizards, snakes, or turtles. The type specimen of the genus Azendohsaurus was a fragmentary set of teeth and jaws found in 1972 near (and named for) a village in Morocco's Atlas Mountains. The fossils on which the current research paper is based was discovered in the late 1990s in southwestern Madagascar. Named A. madagaskarensis, this specimen was uncovered by a team of U.S. and Malagasy paleontologists in a "red bed" that includes multiple individuals that probably perished together. This species was initially published as an early dinosaur in Science over a decade ago, but the completeness of the more recently unearthed and studied fossils has provided the first complete glimpse of what this animal looked like and was related to. A. madagaskarensis was not a dinosaur.
This is a reconstruction of the skull of the new species of Azendohsaurus. On top is a lateral or side view, and on the bottom, a palatal or roof of the mouth view. Note the teeth covering the palate, a highly unusual feature among reptiles, and the downturned front end of the lower jaw, a feature found independently in many herbivorous archosauromorphs.
(Photo Credit: S. Nesbitt)
A. madagaskarensis lived during the period of time that dinosaurs, crocodile relatives, mammals, pterosaurs, turtles, frogs, and lizards were getting their start, and all of the continents were connected as the supercontinent Pangaea. A. madagaskarensis was 2 to 4 meters long and weighed between 20 and 50 kilos (about 44 to110 pounds). A. madagaskarensis was an efficient herbivore—"a veritable four-legged weed-whacker," according to Flynn—with teeth modified for slicing vegetation covering not only its jaws, but also the roof of its mouth. Even though early archosaurs were commonly thought to be primarily carnivorous, A. madagaskarensis shows that traits associated with herbivory were much more widespread across archosaur reptiles.
"Now there are many more cases of herbivorous archosaurs," says André Wyss, professor at the University of California, Santa Barbara. "We are rethinking the evolution of diet and feeding strategies, as well as the broader evolution of the group."
Citation: Flynn et al., 'A new species of Azendohsaurus (Diapsida: Archosauromorpha) from the Triassic Isalo Group of southwestern Madagascar: cranium and mandible, May 2010; doi: 10.1111/j.1475-4983.2010.00954.x
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Order Patterned With Chaos - How Climate Is Predicted For Decades - With Exact Forecasts Only For Days
- Running Sounds May Contain Clues To Injury Prevention
- Is The X(5568) A True Resonance ?
- Russian scientists increase DVD storage capacity million times
- Should Pregnant Women Be Concerned About BPA?
- The Five Stages Of A Dying Theory
- Something is wrong in the Arctic
- "I have not yet unpublished any of your comments here except just now, and all I did was to unpublish..."
- "Okay quick answer, no it is not real. See Debunked: Nibiru will hit Earth on [Insert Date..."
- "Blocking my comments? Cowardly, especially when you are loosing the argument. Again you can find..."
- "Your argument sounds very seductive, although it falls under the category of an appeal to authority..."
- "I just wanted to clarify your statement, When he went into space it was on top of a converted ICBM..."
- The Alzheimer's-Amyloid Hypothesis Confirmed? Not So Fast
- Abortion Rate in U.S. Falls 21% in One Decade
- Child Mummy May Change Timeline for Smallpox
- On Proposed Tanning Bed Ban for Teens, New Study Urges FDA to Act
- Fear Of Dying Got You Down? Retail Therapy Can Help
- It’s Not Brain Surgery, But do you Know What is? Brain Surgery!