The materials used for the making of models are attuned to the purpose intented. In general the models consist entirely of plastic. Large models are reinforced by glass fibres so that we can reach a high stability with the lowest possible weight. The advantage of plastic is its large degree of insensitivity against climate changes and the fact that damages due to insect bites are not to be feared. Thus models can be exposed in outdoor areas as well as under uncontrolled conditions.
Unfortunately we don’t know exactly. Starting from skeletons finds, science takes pains to reconstruct the habitus of the animals. Skeleton finds however, are seldom complete and all characteristics of the animal cannot be deduced from them.
The hedgehog is a good example for that.
Let us suppose that we don’t know any hedgehog at all, but we have found the skeleton of one. The bones would be marvellously preserved, but everything else, e.g. skin and spines would be missing. We examine the skeleton and compare it with other known animals; thus we find out that this is a mammal walking on four legs, with the dentition of an insectivore. To get a better picture now, a model of what the animal may have looked like alive should be made.
We then assemble the skeleton, muscles and sinews are made as we think they may have been. Most of the mammals have skin and hair, our hedgehog might also have that because we don’t have any evidence that for it being any different.
What would our reconstructed hedgehog look like without spines?