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Palm
Modern Guadalupe Palms

FOSSIL FIELD GUIDE

Sabalites
Extinct Fan Palm
Family: Arecaceae

Time
Eocene Epoch

Place
World-wide

In Our Region
Carlsbad, San Diego

Description
Leaves of an extinct fan palm found in Carlsbad, California are similar to those of Sabal palms today, with numerous rays arranged in a fan shape arising from a stout, woody petiole. Occasionally complete fossils have been found with the fanlike leaves and sturdy petiole intact.

Ecology
Members of this family were a common shoreline plant in our area during the Eocene.

The presence of palms in the fossil record is testimony to the former existence of a warm climate, since palms do not tolerate freezing temperatures. Typical examples of a tropical or semi-tropical flora, fan palms have large, thick leaves and grow near ponds, swamps, or lagoons, or in areas of moderate to high rainfall where there is high relative humidity.

Palm leaf impression.
SDSNH catalog no. 110001
Palm leaf impression.

The fossil record of plants in the palm family is very rich and widespread, starting as early as the mid-Cretaceous. Fossil material for palms includes leaves, stems, rhizomes, roots, fruits, seeds and more rarely, flowers or pollen. Some of the earliest records for fossil palm leaves are those of Sabalites. Fruits and seeds from Sabalites have also been discovered.

The related living genus of palms called Sabal contains plants commonly known as palmetto palms or hat palms. This genus consists of 16 species that are found in the coastal areas of the southeastern U.S. and west to Mexico, Bermuda, the Caribbean, Panama, and northern South America. These palms may be found in shady swampy areas, or along the sea coast or tidal flats.

There is evidence that living tapirs are associated with the distribution of palms. After digesting the fruits, tapirs defecate as they move from place to place, and palm seedlings germinate from the tapir dung. It is unknown whether extinct tapirs fulfilled a similar role in the spread of palms such as Sabalites. However, fossil remains of an Eocene tapir have been found locally in strata also containing fossil palm fronds.

Suggested Reading
Tidwell, William D. 1998. Common Fossil Plants of Western North America. Washington, DC: Smithsonian Institution Press.

Harley, Madeline M. 2006. The Palms: A Summary of Records for Arecaceae. Botanical Journal of the Linnaean Society 151(1): 39 - 67.


Text: Margaret Dykens and Lynett Gillette
Photograph: Brad Hollingsworth