Petulia was a walrus at the Marineland zoo in California. Ben Burtt used her vocalizations as a basis for Chewbacca's voice, alongside those of the bears Pooh and Tarik.
A blog post by Tim Veekhoven and Mark Newbold on StarWars.com, "Drawing from the Present: Familiar Creatures in a Galaxy Far, Far Away," mentions that Ponda Baba's voice was based on that of a walrus, although they were unsure if he too was voiced by Petula.
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- "Chewbacca: How to Work the Wookiee Look" — Star Wars Insider 201