In which part of a professional email should you try to be brief, but highly descriptive?

You should try to be brief, but highly descriptive in the part of a professional email known as the subject line.
In the subject line, you shouldn't write too many words, but rather pick out words that convey your message in a few characters. Try to be highly descriptive, so as to show the recipient what you want to tell them in the first couple of words.

The era was mesozoic

According to my researches, the statement   "the factual information allows you to judge how credible the analysis in the source is." is not true. a factual information does not judge any credible analysis because it shows facts that are generally known by everyone.