Most of the fossils of the early history of animals is found in the form of teeth. Early placentals, who formed in the north, are accepted as having what are called tribosphenic teeth. These are like a mortar and pestel type teeth. Well a fossil found in Madagasgar (just off the coast of southern Africa) is challenging this theory. It has these tribosphenic teeth but it is dated 25 million years before the previous eldest placental fossil. This is not to mention that the fossil was found in the south, 25 million years before the any found in the north. This would imply that the previous theory for their development has to be turned almost completely around.

     Another fossil find in 1997, called Ausktribosphenos nyktos, by paleontologist Thomas H. Rich of the Museum of Victoria challenges the evolution of placentals. He found tribosphenic teeth in a layer of rock dated 110 million years before the earlist known placental in Australia. Other scientists argue the point with Rich saying that the fossil may be just the misformed teeth of another animal.....even though scientsts themselves develop whole theories based on single oddities.

    University of Oklahoma paleontologist Richard L. Cifelli has come across another intresting placental fossil find in Southern Montana. The fossil called Montanalestes, is dated to around 110 million years ago which is as old as any placental found in Asia. Placentals are thought to have originated in Asia and then afterwards spread into North America but this most recent find suggests that it could have easily spread in the opposite direction as said by the finder, Richard L. Cifelli, "We can no longer just go with this simplistic model that they arose in Asia and then spread into North America, because it could well have happened the other way around.

     In general, I think Mr. Cifelli said it best, "Our evidence is precious little, I think anybody who really stands up for a theory [about mammal origins] strongly is either nuts or thinks way too highly of himself." 

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