Did theropods dream of armoured sheep?

I had a 'free' afternoon, having a morning in the office that day and an evening meeting in London.  I cleared it with my boss that I'd take the afternoon out (flexitime) and I made my way to the Natural History Museum to look at the fossil marine reptiles.  Having spent quite some profitable time perusing these, I made sure I had a good look at Sophie, the most complete Stegosaurus ever found and the only one on display in Europe.  She is truly impressive.  After being awed by her size and her plates, the one thing you do notice is that she has a 30cm-ish, small in comparison to her overall size, narrow head (hence the species name S. stenops which highlights this).  On a balcony overlooking the skeleton, the NHM have a clear Perspex model of a Stegosaurus' skull, and this has a coloured model of the brain inside it (right).  The brain is impressively compact - it is tiny.

I remember reading, far longer ago than I would like to admit, that Stegosauruses had two brains - one tiny one in their heads and another one near their pelvises.  Current thought is that the 'second brain' was more probably a glycogen body, so their brains, at well under 100g each, were all they had by way of grey (and while) matter.

Yes, they were predated by theropods, and they defended themselves with their tail spikes (known as Thagomisers, but that's another story).  There is fossil evidence of an injury to an Allosaurus caused by said tail spikes.  But: They were no Einsteins.  They were dim, they probably roamed in herds and they grazed.  A bit like sheep in a way.  Now I like sheep, but it does have to be said that they're not the brightest animals on the planet.

Again, yes, Stegosauruses were thoroughly impressive and this is an amazing specimen; when I look at the photo below, I still feel the awe I felt when I was standing in front of her.  Allosaurus was probably not so impressed.


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