A new dinosaur with enormously powerful thigh muscles has been discovered in America, it was announced today.
Scientists speculated that the muscles may have been used for kicking during fights over a mate or to ward off predators.
The beast, named Brontomerus mcintoshi, or "thunder-thighs", has been discovered in Utah, USA, and is described in a paper recently published in the journal Acta Palaeontologica Polonica by an international team of scientists from the UK and US.
A member of the long-necked sauropod group of dinosaurs which includes Diplodocus and Brachiosaurus, it lived about 110 million years ago, during the Early Cretaceous Period, and probably had to contend with fierce "raptors" such as Deinonychus and Utahraptor, the researchers said.
The fossilised bones of two specimens - an adult and a juvenile - were rescued from a previously looted and damaged quarry in eastern Utah by researchers from the Sam Noble Museum, at the University of Oklahoma.
Palaeontologists speculate that the larger specimen is the mother of the younger and would have weighed around six tons, about the size of a large elephant, and measured 14 metres in length.
At a third of the size, the smaller specimen would have weighed about 200 kg, the size of a pony, and been 4.5 metres long.
The animal is thought to have had the largest leg muscles of any dinosaur in the sauropod family.
Its species name, mcintoshi, was chosen in honor of John "Jack" McIntosh, a retired physicist at Wesleyan University, Connecticut, and lifelong avocational palaeontologist.
"Brontomerus mcintoshi is a charismatic dinosaur and an exciting discovery for us," said first author Mike Taylor, a researcher in the Department of Earth Sciences at University College London.
"When we recognised the weird shape of the hip, we wondered what its significance might be, but we concluded that kicking was the most likely. The kick would probably have been used when two males fought over a female, but given that the mechanics were all in place it would be bizarre if it wasn't also used in predator defence."
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