Palaeontologists now think dinosaurs were more like birds than we thought, with chickens their nearest living descendants.

The groups also roughly correspond to time periods, although most if not all of these groups still have living descendants.

It was a large species with distinctive features suggesting that it represents an extinct lineage with no living descendants.

They believed they could combine and rearrange the genetic material from these living descendants into a recreation of the extinct horse.

He sired a total of 2,250 foals, and as of 2003, was estimated to have in excess of 55,000 living descendants.