This is a most recent realease by Australia Post in a series called "fossils." Thes cards were a first day release on the 17th of August 2020 in Lightning Ridge N.S.W. 2834 an area famous for fossiled opal..
Top left card : The Megaraptorid Therepod Dinosaur. "Lightning claw "
Top right card: The Bunya Pinecone.
Bottom left card : Fossilised "Moon Snail"
Bottom right card.: Bunya Pine Tree Queensland .with fossilised wood stamp.