A strange group of fossil mammals, heretofore only known in South America, has been discovered on the island of Madagascar and in India. The unexpected discoveries were announced in this week's issue of the journal Nature by an international team of researchers. The team was funded by the National Science Foundation (NSF) and led by paleontologist David Krause of the State University of New York at Stony Brook.
The 65-70 million year old mammals, dating from the Late Cretaceous period, were unrelated to any groups living today and are known as gondwanatheres. The discovery of their highly distinctive teeth in such disparate places as South America, Madagascar and India has fundamental implications for plate tectonics, the theory that landmasses move slowly over the face of the earth and were in different places in the past than they are today.
Ironically, though the group of mammals was previously known only to be from Argentina, it was named Gondwanatheria after the supercontinent of Gondwana, which once included all of the landmasses of the southern hemisphere.
"These are major discoveries that go far beyond their obvious significance to paleontologists," says Chris Maples, program director in NSF's division of earth sciences, which funded Krause's work. "Krause and his large-scale, multi-investigator team have provided an excellent example of the contributions that paleontology can make to many areas of geoscience, including tectonic plate positions in Earth's past."
Krause says, "Finding representatives of gondwanatheres on these three now widely separated landmasses suggests to us that they were connected in the Late Cretaceous. A recently proposed geophysical model shows that India and Madagascar were attached to eastern Antarctica well into the Cretaceous while South America was attached to the western end of Antarctica. This discovery supports that hypothesis with totally independent evidence derived from the fossil record."
Significantly, gondwanatheres have not been found in Africa, which lends credence to the research team's conclusion that Africa was relatively isolated during the 35 million years of the Late Cretaceous. "It's not just the mammal evidence that suggests that Africa was off doing its own thing; the dinosaur evidence also indicates a high degree of African endemism during this interval," adds Krause.
Krause has led large-scale NSF-funded paleontological expeditions to Madagascar for three years. Krause's team has discovered a spectacular array of well-preserved and extraordinarily complete skeletal material of crocodiles, birds, dinosaurs and other backboned animals in Madagascar. Despite finding only fragmentary remains of mammals, Krause notes that the mammal specimens "may not be all that spectacular visually, but they're extremely important. Scientific significance, just like beauty, is in the eye of the beholder."
NSF is an independent federal agency responsible for fundamental research in all fields of science and engineering, with an annual budget of about $3.3 billion. NSF funds reach all 50 states, through grants to more than 2,000 universities and institutions nationwide. NSF receives more than 50,000 requests for funding annually, including at least 30,000 new proposals.
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