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Abstract Detail



Paleobotanical Section

Allen, Sarah [1].

Monocotyledonous fossil flowers from the Eocene of the Rocky Mountain region.

Staminate trimerous fossil flowers have been found throughout Eocene strata of the Rocky Mountain region. The majority (34) were discovered at the Blue Rim site of the Bridger Formation in southwestern Wyoming. Additional specimens were recovered from sites in the Green River Formation in both southwestern Wyoming and northwestern Colorado. The differentiated perianth has three small connate triangular sepals in the outer whorl and three distinct elliptical petals in the inner whorl. Sepals are often not visible or preserved, but average 1.4 mm long when present (more frequently on the Green River specimens). Petal length ranges from ~3 to 6 mm, but averages 4.0 mm, while the width ranges from ~1 to 3 mm with an average of 2.1 mm. The androecium consists of six large stamens without (visible) filaments. The elongate anthers are preserved in many orientations indicating they were probably versatile. While the anthers are missing or fragmented on many specimens, they average 4.5 mm long and 0.7 mm wide when preserved. In situ pollen has been successfully extracted from the anthers of a few specimens and viewed by light microscopy and SEM. Pollen ranges from ~23 to 35 µm (average 27.7 µm) in diameter. Grains are globose to boat-shaped with a finely reticulate surface. Recovered grains appear immature as their aperture type is inconsistent and ranges from inaperturate to monosulcate. The flowers resemble those of extant Phoenix (Coryphoid Arecaceae) because of the number of perianth parts and stamens, and the elongate anthers. However, the size of the sepals in the fossil is small in relation to those of extant Phoenix species. The distinctive pinnate fronds and boat-shaped woody seeds of modern Phoenix have never been recovered from these sediments, so these flowers likely represent an extinct type of palm.


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1 - University of Florida, Department of Biology, P.O Box 118525, Gainesville, FL, 32611, USA

Keywords:
Eocene
fossil flower
Wyoming
Colorado
Bridger Formation
Green River Formation
Arecaceae.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PPB005
Abstract ID:685
Candidate for Awards:None


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