In late 2006, the research team conducted further field work at the Madar site. By taking measurements on the shape and angle of the different digits, they were able to identify the bipedal dinosaur as an ornithopod. The size, shape and spacing of the quadrupedal prints were used to identify the body size, travel speed and other distinguishing features of the animals in the sauropod herd, Stevens said.
The rocks in which the dinosaur tracks are preserved are likely Late Jurassic in age, some 150 million years old, according to Al-Wosabi. The tracks probably went unnoticed for so long, Schulp explained, because they were too big to be spotted by the untrained eye and were partially covered by rubble and debris. "It isn't a surprise that they were overlooked," he said.
Though ornithopods and sauropods overlapped in time, it's a bit unusual to find evidence of such a big ornithopod in the late Jurassic, the researchers noted.
"We really want to learn when did which dinosaurs live where, and why was that?" Schulp said. "How did the distribution change over time, why did one replace another and move from one place to another?"
The researchers agreed that discoveries from Yemen could yield more answers to those questions.
"This international collaboration provides an exciting new window into evolutionary history from a critically undersampled region," said Stevens, an assistant professor in Ohio University's College of Osteopathic Medicine. "These trackways help us to assemble a more detailed picture of what was happening on the southern landmasses. It's exciting to see new paleontological data coming out of Yemen -- and I think there is a lot more to discover."
The Yemen Geological Survey has implemented protective measures to preserve the trackways and to improve their accessibility to tourists, the researchers report.
Partial funding for the research was provided by the Yemen Geological Survey and Ohio University.
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Journal reference:
Schulp AS, Al-Wosabi M, Stevens NJ (2008) First Dinosaur Tracks from the Arabian Peninsula. PLoS One 3(5): e2243. doi:10.1371/journal.pone.0002243 [link]
Adapted from materials provided by Ohio University, via EurekAlert!, a service of AAAS.
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MLA Ohio University (2008, May 21). First Dinosaur Tracks Discovered On Arabian Peninsula. ScienceDaily. Retrieved October 20, 2008, from
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