I don't know what mode you are playing on but if you need the keratin to make cement paste for a saddle, i sugges you take a pack of dilophosaurs(5-6) as they can easily kill it

Then if you have tamed one( by *NOT* Shooting it's shell) it's advisable you upgrade the health

They eat berries, advisable the red one

Also... you need to have cement paste for it's saddle