Pronoun agreement in number, ambiguous cases

Hey everyone,

One last question before I take my test.

The pronoun must match the antecedent In number. So how would you write this:

The revenue of Goldman is higher than those of its competitors.

Would it just be that of? I just assumed it was those because there are multiple revenues (one for each firm)
(This is from dealbook, which has a sentence that says: "And Goldman’s advisory business is likely to exceed $8 billion in net revenue this year, exceeding by more than one-third those of its nearest competitors, JPMorgan Chase and Morgan Stanley.")

If, indeed, it is that, would this sentwnce work? The revenue of Goldman is higher than its competitors'

This is based on a question from gmatprep about dinosaur metabolism. I'm also curious if "Some scientists contend that many species of dinosaurs had metabolisms more like warm-blooded mammals' than cold-blooded reptiles'" works.

For reference, a mgmat instructor said the following would be NOT ok:

Some scientists contend that the metabolisms of many species of dinosaurs were more more like a warm-blooded mammal’s than a cold-blooded reptile’s.
(And that just sounds wrong).
Thank you!

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