Thanks everyone! I did consider the half-a-cake-on-end solution and might yet go down that route, but I now just have this idea of a perfect oval shape ready-made. I've lined the bowl by drawing round the base and cutting slits round it, IYSWIM, so it has a neat overlapping lining. Stupidly I didn't check the volume first, so it'll have to come out again.
Now I just have to find someone with a large enough traybake tin...
I wouldn't use the Pyrex. Have you had a look on Pinterest for dinosaur inspiration - I think there are some where they have used a cylindrical cake cut in half then sandwiched together for the body of a lying down dinosaur which looked easy and very effective...
I'm on a mission to make a special dinosaur cake for DS1. It has to feed about 20-24 small children (and stray parents) at a party, so my plan was to make a large traybake (the Swamp), swoosh chocolate buttercream all over it and then lovingly place the Dinosaur on top. Dinosaur will be made in the same cake as the traybake, covered with sugarpaste and plonked into the chocolate buttercream swamp. (hence doing away with impossibility of modelling long neck, etc, in sugarpaste. This beast will have its snout in the mud. )
I was planning to make the body by using a largeish oval pyrex bowl. I know people do bake in pyrex, but what do I need to be aware of? Bowl is approx. 19cm x 12cm at the base and flares to about 23cm x 18cm at the top, though I won't need to use the full depth of the bowl.
Or would it just be easier to make a standard cylindrical cake in a springform and then carve it to shape? <sigh>
If I go the pyrex route, the bowl is lined with greaseproof, but can I use Nigella's chocolate birthday cake recipe (the one where you melt the chocolate and condensed milk and butter together) or is it too heavy to bake in a bowl?
(I'm reasonably experienced at making daft-shaped cakes, but I've never baked in pyrex before.)