Make a full solid from organic model STL file

Hi,

I am an PhD student trying to get a model for my research. I have an skull model (.stl) and I need to transform this file to be able to work with it in solidworks and create some parts from this model and the corresponding assembly. I have tried it, but there are continuos error messages, I could give you more details if you think that you can help me.
I have attached the file so you can determine the feasibility of the job