I am about to descend a wire ladder that drops into a recently discovered cave on the small Indian Ocean volcanic island of Rodrigues. My team is studying the ecosystem of the island before human settlement. My partner Julian and Australians Greg and Steve have already gone down the ladder, each vying for the macho achievement of being the pioneer.
Even though I have 15 years' caving experience, ladders still make me uneasy, so it's with shaking knees that I sit on the edge of the hole and transfer my weight on to the rungs. These are small and easy to miss and I am carrying the equipment that the others have forgotten in their haste.
The ladder starts to swing, but I reach the bottom. Greg and Steve are taking photographs of a spectacular stalactite. Julian has seen a bone poking from the cave floor and is picking at it, ineffectually. Smugly, I pass him a trowel and a sample bag, and then switch on the camcorder to record our first find.
I express my opinion that this bone is from a domestic goat. Julian disagrees. He is convinced that it is from a solitaire, an extinct, flightless bird that was found only on Rodrigues.
After about an hour, the Australians are getting thirsty – "Is it beer o'clock yet?" – and we take turns to climb back up.
Beer o'clock gets earlier every day, but first we have to visit the little ramshackle shop on the hillside. With only a pathetic grasp of the local Creole language, we point to what we want. The whole family soon learns to expect us at beer o'clock and there is always a crate of cold Phoenix ready for us. Twelve giant bottles cost about 300 rupees – roughly £6. The Aussies are in heaven.
The bone? Julian was right after all, and my mis-identification is recorded forever on video.
Age of the Dinosaur is at the Natural History Museum until 4 September. The exhibition includes realistic animatronics so that you can come face to face with creatures from the past. Tickets are available from nhm.ac.uk/dinosaur-age.