Opalized Fossil of a Cycad Cone

January 06, 2023


Mila_cycad (003)

Photographer: Mila Zinkova   

Summary Author: Mila Zinkova  

Shown above is an opalized cycad cone fossil (31 x 11 x 9 mm) that was found in Lighting Ridge, Australia. Fossil cycads, dating from the Mesozoic, have been uncovered on every continent. These very ancient group of seed plants are thought to be a sister group to all other living seed plants.

Most fossil cycads are called cycadeoids and are classified scientifically in the order Bennettitales. During the Jurassic, cycads and their kin, along with conifers and ginkgos, dominated the plant kingdom. They remain extant and are commonly referred to as living fossils.

On occasion, cycad fossils are opalized. If a cavity in a rocky surface resulted when a living organism, such as a shell or pinecone, was buried in sand or clay and then rotted away, an opalized cast or fossil replica may form of the object that was buried. Click here to see a video of this fossil, which also includes clips of a modern cycad.


Lighting Ridge, Australia Coordinates: -29.4278, 147.9790

Related Links:

Fossil Cycadeoid