However, others think it came from an Asian elephant, an endangered species.

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Ibers is already looking at ways of growing so-called "energy grasses", such as 4m high Asian elephant grass, in bulk for use as a biofuel.

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He said it was probably more likely they were modern as they were so well-preserved, and could perhaps be part of a cargo of African or Asian elephant tusks.

BBC: The tusks

The video, filmed between 21 January and 15 February last year, showed the Asian elephant chained by one foot and one hind leg in a barn on Bobby Roberts Super Circus in Polebrook.

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NGOs to preserve the Asian elephant.

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One Asian elephant recognized herself.

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Earlier this year, the Victoria and Albert Museum staged an exhibition entitled Maharajah: the Splendour of India's Royal Courts, and the opening tableau featured a full-sized model of an Asian elephant, magnificently bejewelled, ornamented and caparisoned, and surmounted by a gorgeous, glittering, golden howdah.

BBC: No white elephants in this herd