Tera and Tyra: Similar Marvels or Different Monsters?

[Orthoceras]

The metric prefix "tera" comes from the Greek word teras or teratos, meaning "marvel, monster", whereas "tyra" in tyrannosaur is derived from tyrant. Tera and tyra seem to have a somewhat similar original meaning, are they perhaps essentially the same?

 

[Bandersnatch]

Seems unlikely. The Greek tyrannos means absolute ruler, not a monster. Associating the monstrous meaning because, arguably, tyrannosaurus was monstrous is putting the cart before the horse - the dinosaur doesn't retroactively affect the meaning of the original word.
Furthermore, the etymonline dictionary lists it as a loanword, whereas teras is native. So unless there was an earlier split from a common root the words should be unrelated and merely superficially similar.