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This is part three of the geology tour for the Life on Earth gallery. We are walking around the timeline and the second case on the floor is the Cambrian. This is the point in the history of the Earth when life went a bit mad really: you had fossils all over the place because animals had started to evolve hard skeletons (things that can be fossilised) and one of the most dominant forms of life at this time were the trilobites.
There are about 50,000 species of trilobite known so far and they lived in all habitats in the sea: from the deep waters up to the beaches and the shallow shelves and also scuttled among reefs in huge abundance. They are related to things like centipedes and horseshoe crabs but there’s nothing really close to them today and, they might look like woodlice, but they’re actually quite distantly related. They died out 250 million years ago but at the time they dominated the oceans.
What you see here is one complete trilobite, sitting on a little rock in the case, and that is resting on top of a large slab which shows various trails and grooves with scratch marks all over them and these are its feeding traces. So what we see here is evidence of these animals scuttling over the floor, digging through the sand to pick out particles of food and occasionally we find evidence of one of these burrows intersecting a worm burrow. You get a huge great curfuffle in the sediment and then the trilobite carries on and the worm doesn’t. So It’s one of these very rare cases where we actually have good evidence for what these animals were eating in the distant past.
There’s a huge diversity of these things, not just in the shapes and the structures the spines on them but also in their life habits.
about 2 years ago
The third section of a tour around the geology on display at Leeds City Museum. Curator Joe Botting takes you around the Life on Earth gallery.