Sycamore Leaf Fossils Facts

Leaf fossils provide information about ancient climates.

Sycamore trees (Platanus spp.) are prevalent in the fossil record. Scientists have discovered preserved leaves and fruits of Platanus species that date to 115 million years ago. Though ancient, the fossils still resemble the present-day sycamore tree.

Description

The bark of sycamore trees resembles camouflage and has patches of white, brown, gray and yellow wood. Leaves are palmate, lobed and alternate.

Fossil Locations

Fossil records in North America indicate that sycamore trees were abundant along rivers and streams in Colorado, Utah and Wyoming about 63 million years ago. This timing closely follows the extinction of dinosaurs that occurred 65 million years ago.

Historic Climate

Plant fossils provide information about the climate in that region millions of years ago. For example, sycamore trees prefer moisture. So, fossils of this tree in northwestern North America suggest that the climate was once very wet. Fossils of crocodiles in the same region provide evidence for a sub-tropical climate.

Continuous Populations

Fossil records show that sycamore populations were once continuous from Asia to North America to Europe. Scientists suggest that geographic separation occurred tens of millions of years ago. Despite the isolation, the European species, Platanus orientalis, and the North American species, P. occidentalis, can cros- fertilize and produce viable hybrids.

References

• University of California Museum of Paleontology: Localities of the Eocene: The Green River Formation
• Clemson University: November's Specimen of the Month
• UCLA: Speaking the Plane Truth
• "Systematic Botany"; Phylogeny and Historical Biogeography of the Genus Platanus as Inferred From Nuclear and Chloroplast DNA ; Yun Feng et al.; 2005