To all spanish speaking people, or skilled at speaking spanish.?

You should not write it in English and then translate, and you especially shouldn't have someone else translate it. You should think of the Spanish you have learned so far and use what you know, making it simple. You can always look up words you don't know like "dinosaurs". Your teacher wants to see your grasp of the language and ability to write something in Spanish and may also be able to tell if you got help on it if it appears to be above your level of Spanish. Plus you are not gaining anything by having someone else translate it. What about when you get a test on the imperfect?