EPOD - a service of USRA
The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.
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
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