Manchester, Steven R. .
Fruits of Sloanea (Elaeocarpaceae) in the Paleocene of North America and Greenland.
The genus Sloanea, now distributed in tropical and subtropical regions of central and South America, Eastern Asia, Malesia, New Caledonia, Australia, and Madagascar, has distinctive fruits that are easily recognized in the fossil record. Although recently recognized in the Eocene and Oligocene of Europe, the fossil record of Sloanea in North America has received little attention. Sedimentary impressions of the fruits were first described as Carpolithus spinosus by Newberry in 1898 from probable Paleocene strata near the North Fork of the Purgatoire River in southern Colorado and have since been discovered at several Paleocene sites in northern Colorado, Wyoming and Montana, as well as Atanikerdluk, Greenland. The spiny, ovoid fruits are 4- and 5-valved capsules 2.5-3.5 cm in diameter, borne on elongate peduncles that are 2 to 3 times as long as the fruit. A prominent circular disk 5-6 mm in diameter and 1.5 to 2 mm thick surrounds the base of the capsule at the junction with the peduncle. The fruits are ornamented with closely spaced erect spines, 4-5 mm long. Immature fruits (unopened capsules) retain a single persistent style. Most specimens are mature dehisced capsules lacking seeds. The capsules open apically, with valves separating to the lower 1/5 of the fruit. Each valve has a smooth inner lining, with a pronouced median ventral keel representing a septum, indicating that dehiscence was loculicidal. The youngest known North American occurrences are from the Early Eocene Wind River Formation in Wyoming. These fossils, along several occurrences in the Eocene and Oligocene of Europe, indicate that Sloanea was widespread in this part of the Northern Hemisphere during warm intervals of the Tertiary.
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1 - Florida Museum of Natural History, Dickinson Hall, P.O. Box 117800, Gainesville, Florida, 32611, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 1:30 PM