Prof. Christian Sidor in his lab at the Burke Museum holding the skull of Saharastega mordiensis, a six-foot long amphibian that lived over 250 million year’s ago.

In the West African country of Niger, the rocks of the Moradi Formation preserve the remains of animals that lived over 250 million years ago during the Permian Period. It was here that recently recruited UW Biology paleontologist, Christian Sidor discovered fossils of two large amphibians never seen before in the modern world. One was crocodile-like in size and appearance, with bony plates along the outside of its body, and lower fangs that protruded through the roof of its long snout. Sidor and his team named the creature Nigerpeton ricqesi, after the country of its origin and a pioneering French paleontologist. The second was named Saharastega moradiensis and was more like a salamander in appearance, but larger:the skull found was from an animal at least six feet long.

Finding the bones of these creatures in Niger has made scientists re-think theories about the types of four-legged animals that lived during the Late Permian and Early Triassic periods, a time when all the continents were fused together to a single land mass called Pangea. Sidor’s research was important to the scientific community because it helps to fill an important gap. Until now, paleontologists commonly believed that animals from this time were able to move freely across the large supercontinent of Pangea. The evidence for this cosmopolitan existence came from dig sites located in China, Russia, and across southern Africa, which were positioned in the northern and southern latitudes of the Earth, even back in the Permian. The glaring omission was data from the central part of the supercontinent, that part straddling the paleo-equator. Sidor explained that dig sites from this time period are rare because very special geographical conditions are required to preserve fossils. The Moradi Formation provides the critical information because its rocks were deposited at the correct time and place (about 10° south of the paleo-equator).

Fossil skull of Saharastega.

Now that these new fossil samples have been found – there are more questions to ask. For one, why were the amphibians and reptiles found in Niger unlike those discovered elsewhere from the Late Permian? Sidor theorizes that climate was a big factor. At the beginning of the Permian huge glaciers dominated the southern hemisphere, but by its end, the Earth went through a massive warming spell, and the glaciers melted back. The center of the super continent, which had been the only place warm enough to support large land-living animals, gave way to a large desert. Sidor theorizes that while some Permian animals were able to migrate along the coastline, the desert-like interior of Pangea was impenetrable. The ancient amphibians and other species may have been isolated by this desert climate and evolved independently for millions of years.

descriptive drawings of Saharastega moradiensis and Nigerpeton ricqesi from Sidor's paper published in Nature, Vol. 434, Apr. 14,2005.

How would amphibians survive in a desert? Sidor explains that the rocks entombing Nigerpeton and Saharastega show evidence of a local oasis. The dig site is located close to rocks that would have formed a local mountain chain during the Permian. Rain falling on these mountains collected into streams that eventually drained into the Moradi area, creating the aquatic habitat for the ancient amphibians to live in.

All of the fossils that Sidor studies today were from species that were killed-off by something catastrophic. Another Biology Professor, Peter Ward, has found rock layers that were teeming with life during the Permian period, but then the next layers of rock are nearly void of all life in the early Triassic period.

“One of the most dramatic and mysterious events in the history of life, the so-called “Great Dying” of animals and plants some 250 million years ago, continues to fascinate and baffle scientists.

Global map of Pangea. Image: Chris Scotese

Of the five or so mass extinctions recorded in Earth’s fossils, this one at the end of the Permian period and the start of the Triassic was the most catastrophic. More than half of the families of living things died out, and as many as 90 to 96 percent of the planet’s marine species were lost. At the same time, perhaps 70 percent of the land’s reptile, amphibian, insect, and plants species went extinct.” - PBS Background for video segment from Evolution: “Extinction!” by geologist Peter Ward.

Today the Sahara desert covers much of Niger with barren rock and scorching sand, creating a landscape not unlike that of Mars. Sidor showed me a photograph of the dig site next to a photograph of Mars – and yes, the photos were practically identical. Prof. Sidor will to return to Niger this November and December to test his climate hypothesis with an international team of geologists and paleontologists. His research has been funded by the National Science Foundation and National Geographic.