The finished frond

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Alan Bowden, curator of Earth Sciences, told us a good few months ago now about a palm frond we'd acquired (more here). Now it's finally on display he tells us about its journey from subtropical Wyoming to the wall of World Museum.
Images from its conservation are on our Flickr page.

a fossiled palm leaf mounted in a large case

The conserved frond in its shiny new case in World Museum

Dinosaurs and their relatives may be on most children’s minds whenever they visit World Museum but there is another new exhibit which is worthy of mention.  This is a fossil leaf.  Not any ordinary leaf but an example of exquisite preservation which has given us a glimpse into a long vanished world.

The story of the greening of the Earth - the flora of our planet and how it has evolved to achieve the wonderful diversity of today - is a bigger story than that of the animals as it contains a record of all the changes that have occurred with our atmosphere and climate, and has the potential of demonstrating where our future lies. 

The newcomer to the museum is a frond of the extinct fan palm Sabalites sp belonging to the family Arecaceae.  This fossil leaf is 50 million years old and was found in Folly Quarry on the Lewis Ranch, near Kemmerer Wyoming, Western Lincoln County, Wyoming, USA. At that time Wyoming was a warm subtropical area with lush and exotic vegetation at the edge of a series of large fresh water lakes which were larger than the Great Lakes Region of Canada.  This is very different from the Wyoming of today, which has a high mountain desert with long winter snows and freezing temperatures.

It was found in a limestone rock known as the Fossil Butte Member of the Green River Formation.  During the Eocene (50 million years ago) this formed as sediment that was being deposited in the fresh water lakes.  A lack of oxygen in the water caused many of the lake’s animals and plants to die, and also stopped bacterial action on the bottom of the lake. This meant that the dead animals and plants which would normally have rotted away were preserved in exceptional detail.  Complete fronds like our specimen are extremely rare.

The fossil shows numerous rays with bifurcating tips branching out from a sturdy woody petiole.  The petiole is well preserved showing a fibrous structure.  The basal attachment of the frond is of an unusual shape which indicates that this specimen may belong to a new, previously un-described, tribe.

The palm frond has spent a year being prepared by members of our conservation team and earth sciences staff. When it arrived it had been crudely covered with an acrylic based paint to ‘enhance detail’ with car body filler to hide cracks. The acrylic, body filler and some rock was very carefully removed to reveal extra details such as the natural colour of the specimen, extensions to the leaves, fragmentary remains of fossil fish beneath the leaf, the fibrous nature of the petiole and unusual features of the basal attachment. The fossil is now displayed on the 4th floor of World Museum and serves as a reminder of climate change over geological timescales.