I'm studying english watching a netflix drama "Emily in Paris".
I don't understand that mean of "expensive dinosaur" in a conversation.
Emily is working for Savoir as marketing company.
Olivia Thompon in Duree's CMO. (Duree is a cosmetic company)
Duree was used to be a client of Savior.
Olivia wanted to hire Emily as an influencer to promote Duree products.
Emily declined an offer and suggested that work with Savoir to Olivia.
Olivia said "I fired your agency. They're a very expensive dinosaur"
Is it an idiom? Could you let me know how to understand it?