Now we need to do a bit of geology.

When the newly-made Earth had cooled down from a big glowing orange blob of lava, life got going on it pretty fast. But for the first two billion years, living creatures were so small you’d have needed a microscope to see they were alive at all.

The creatures were bacteria, and they had the planet to themselves: no plants or animals in sight.

Nowadays bacteria just make things go mucky brown. But these were photosynthesising bacteria. They lived in pools in the bare rock, doing clever things with sunlight, which made the pools go beautiful colours: purple and yellow, and pink, and a lovely sky blue, like you see today in Yellowstone Park.

Now the bacteria may not have looked as if they were doing much, but really they were very busy, churning out an atmosphere and installing air conditioning, to make the planet nice and comfy for animals and plants, and eventually for you and me.

First came plants.

The land began to look less like a paintbox and more like the indoor plants department at the garden centre. There were giant ferns as big as trees, and mosses as big as turnips and runner-beans, plus lots of insects who tried not to get in the way, although there were dragonflies buzzing through the giant ferns as big as crocodiles and probably just as fierce.

With nothing to eat them, the plants did get a bit out-of-hand and, for another billion years, forests grew on top of forests, which had grown on top of forests, eventually making deep deep mushy black bogs which turned into peat.

Then dinosaurs came along and trod the bogs down flat with their big scaly feet and started eating plants like there was no tomorrow.

The plants that remained had spiky triangular leaves, or were poisonous, or both. The dinosaurs didn’t like those and left them on the side of their plate.

Then they started eating each other, which was when T rex really got going. And of course it wasn’t going to stop with T rex, and that’s where the Monstosaurus came in.

Just underfoot in those days was a thick layer of peat from the days of the plants, busy turning into coal. That’s why it’s called the Carboniferous, which is just a fancy word for something which bears coal. Coal is nothing but very very old squashed, toasted peat. (But don’t try making this at home.)

When the Monstosaurus died, it must have fallen over with an awful bump, because the heaviest part crashed through into the Carboniferous peat. So when they got to Boldon Colliery, Dyspepsia found the bones going down into the coal seam. It was no longer a trench they were digging, but a tunnel.

Spookie and Dyspepsia were walking in this tunnel when, all of a sudden, Dyspepsia said, “Spookie, you’re glowing”.

Straightaway Spookie turned and went pop!—through the wall of the tunnel. Then, by the light of her glow, she walked through gallery after gallery, her jaw dropping. For there was the whole tummy and chest cavity of the Monstosaurus, all excavated for them.

Then Spookie stopped glowing and couldn’t get back to Dyspepsia, and when she tried she only bumped her nose. Dyspepsia had to go back and knock on doors and get together a party of ex-miners with pickaxes to come and rescue her.

…to be continued.