An American palaeontologist and a team of Egyptians have found the most nearly complete fossilised skeleton of the primitive whale Basilosaurus isis in Egypt's Western Desert, a university spokesman said. Philip Gingerich of the University of Michigan excavated the well-preserved skeleton, which is about 40 million years old, in a desert valley known as Wadi Hitan (the Valley of the Whales) southwest of Cairo, spokesman Karl Bates said. "His feeling is that it's the most complete -- the whole skeleton from stem to stern," said Bates. The skeleton, which is 18 metres (50 feet) long, could throw light on why there are so many fossilised remains of whales and other ancient sea animals in Wadi Hitan and possibly how the extinct animal swam, he said.