Washington, May 21 : Scientists have discovered the first dinosaur tracks on the Arabian Peninsula, which include footprints of the sauropod herd and ornithopod found in Yemen.
Discovered along a Mesozoic coastal mudflat, these dino footprints were found by Anne Schulp of the Maastricht Museum of Natural History in The Netherlands, along with Ohio University paleontologist Nancy Stevens and Mohammed Al-Wosabi of Sana'a University in Yemen.
"No dinosaur trackways had been found in this area previously. It's really a blank spot on the map," said Schulp.
According to researchers, the finding also is an excellent example of dinosaur herding behavior.
The site preserved footprints of 11 small and large sauropods - long-necked, herbivorous dinosaurs that lived in the Jurassic and Cretaceous periods - traveling together at the same speed.
"It's rare to see such a big example of a dinosaur herd, said Schulp. "This is interesting social behavior for reptiles," he added.
One of the dino footprints was spotted by a Yemeni journalist in 2003, about 50 kilometers north of the capital of Sana'a in the village of Madar.
Stevens, Al-Wosabi and Schulp identified it as the footprint of an ornithopod, a large, common plant-eater sometimes referred to as the "cow of the Mesozoic," that walked on its hind legs.
Only a few dinosaur fossils have been reported so far from the Arabian Peninsula, including isolated bones from the Sultanate of Oman, which Schulp has studied, and possible fragments of a long-necked dinosaur from Yemen.
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," said Stevens.
According to Al-Wosabi, the rocks in which the dinosaur tracks are preserved are likely Late Jurassic in age, some 150 million years old.
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.
"This international collaboration provides an exciting new window into evolutionary history from a critically undersampled region," said Stevens.
"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," he added.