mercoledì 1 luglio 2009

L'antenato dell'elefante? Era grande come un topolino

A 60 million-year-old skull dug up in Morocco has been identified as the earliest form of what is now the earth's largest land mammal. This creature was trunkless, measured less than 2ft (50 cm) from tip to tail and weighed just 9 to 11lbs (4 to 5kg), scientists revealed this week. The mini-jumbo had front incisors which jutted out of its mouth to form the forerunner of the modern tusks. Called Eritherium azzouzorum, it would not have looked much like today's jungle giant yet it was definitely a forerunner of the familiar animal. As only the skull remains, it is hard for the French-based team behind the find to accurately say what the rest of it would have looked like. Analysis of the teeth in the skull proved it was related, however distant, to the modern elephant. It is 10 million years older than other elephant ancestor fossils discovered. But it is an important find because it shows that a new family of modern mammals began to develop a lot sooner after the death of dinosaurs than previously thought. Dinosaurs died out around 65 million years ago and the Eritherium began to evolve - along with some primates and rodents - just five million years later. They would not have stood a chance trying to develop at the same time as dinosaurs because they would not have been able to successfully compete for food, it is thought. So when the big beasts had gone, smaller and more adaptable mammals evolved and have grown since then. It is the forerunner of elephants with trunks which can be directly traced by through mammoths and other ancestors to around 33.7 million years ago, said the researchers. The team from the National Museum of Natural History in Paris says their discovery, around 60 miles east of Casablanca, is significant, particularly the jutting teeth. Lead researcher Emmanuel Gheerbrant said: "This is some kind of precursor of the tusk of the more modern elephant." He said it "was probably no more than 50 centimetres, tip to tail - something like a very large rabbit, size-wise".

(The Telegraph)

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