Not all Saurians have it, and when they do its a space trait. try going on the exchange and look for the every expensive purple BOFFS, although you could get lucky.
Note also that when you view the tooltip for a Saurian or Lethean, the efficient trait is listed at the top with their space abilities, not with the rest of the traits.
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On a more serious note, green, blue and purple Saurians can all ahave it so be sure to check them all and see what's cheaper.