Dinosaurs have lasting fascination for children and adults. They are big, scary and extinct, so we can be terrified by them while knowing we will never meet one. I wanted to be a geologist from when I was young, on the dubious basis that I liked collecting things, but I liked collecting rocks better than other things (I had a horse skull discovered in a pine forest while vomiting from car sickness but I didn't choose being a zoologist). I hoped I might find exciting rocks and fossils in New Zealand; it was a disappointing to discover our dinosaurs have been identified from bone fragments, not whole skeletons, and our trilobites are smaller than a thumbnail.

Jane looking for millimetre-scale trilobites at Cobb Valley (where she subsequently left her brand new Christmas present rock hammer) and the sort of trilobite she'd have liked to find

We have been cycling through La Ruta de Dinosaurios ('dinosaur highway') - both a current phenomenon and a past area through which dinosaurs roamed. Today we went to visit an outcrop with a plethora of dinosaur footprints - where dinosaurs plodded and padded through mud adjacent to a river. Sometimes it was wet and the dinosaurs sank in, sometimes it was dry and they left minimal impressions. Some dinosaurs had claws, some did not. The interpretative text said the dinosaurs with claws were carnivorous...but kiwis have claws. I often wonder about some geological interpretations where there appears to be at least as much imagination as fact...that might be the appeal of dinosaurs – mythical beasts we can create imaginatively. The likelihood of their de-extinction in a Jurassic Park is a good deal less likely than the supposed de-extinction of the dire wolf, and also a very bad idea given we can't manage to stop extinguishing current species.

Notwithstanding my scepticism, the dinosaur footprints had enough of a pull that we walked to see them under a blistering hot sun on our day off biking (it wasn't a very long walk). The attraction we felt was to a place where you can imagine animals walking 120 million years ago; early hominids turned up 6 million years ago, Homo sapiens 315,000 years ago. If the history of the earth since dinosaurs evolved is considered as a year, dinosaurs turned up 1 January and became extinct in the 3rd week of September; Homo sapiens doesn't appear on the scene until December 31st. One of the best things about learning geology is the sense of time it gives you, together with the sense of the insignificance of humans, however significant we like to think we are. Another best thing is how geology allows you to read the way the landscape formed as you cycle/walk/drive through it – reading the book of the rocks.

What I also thought about today was the consciousness of dinosaurs. Humans tend to think we are pretty special because we are conscious – aware of our own existence. We frequently don't attribute this awareness to other organisms, which allows us to do all sorts of things to other organisms which include them becoming extinct. Obviously humans had no bearing on the extinction of dinosaurs, however, as humans expanded across the globe the megafauna in every country became extinct - mammoths, mastodons, giant sloths, moa. Big animals were a great source of food, so good they all got eaten.

However, there's pretty strong evidence that many organisms are conscious, although we still don't have a good or single understanding of what consciousness is. Therefore. I imagine dinosaurs paddling in pools of water by the river on a stinking hot Cretaceous afternoon. There are lots of footprints, so there may have been family groups of dinosaurs with grandparent dinosaurs taking care of the dinokids. Or one dinosaur heading off and the others looking at each other saying, "She knows the way to the river," and following along. It's far easier to move along the river bed than through the dense sub-tropical trees or marshes. Which then led me to thinking about the vast numbers of consciousnesses that have existed in time but no longer – it's bad enough thinking about the mass of individual human consciousnesses when you travel; thinking about consciousness through time is a whole other scale to contemplate.

Should I mail President Trump a geology text book?

Chris & Jane in some more of northern Spain finding dinosaur tracks

1. Chris with the Sierra de la Demanda in the distance (we've already cycled through it)

2. Chris cycling into Villoslava de Cameros - one of many pretty villages. 'De Cameros' refers to the village having been part of the Cameros lordship's territory which extended through a lot of our mountain route.

3. Chris and a big pile of forestry timber – a lot of oak trees are being logged for firewood.

4. Jane in front of the Sajazarra castle

5. Jane cycling in the heather - there's a lot of heather and bare rock above 1600m

6. Dinosaur mural in Enciso

For more pictures of Spain have a look here.