Erwin, Diane , Myers, Jeffrey .
Securidaca-like samaras from the late Eocene Badger's Nose paleoflora, Modoc Co., CA, USA.
Over forty complete to partially-preserved samaras from the latest Eocene (~34 Ma) Badger's Nose (BN) paleoflora of northern California closely resemble samaras of Securidaca (Polygalaceae) and two possibly related fossil genera Deviacer and Paleosecuridaca. The winged fruits are compressions preserved in reddish green shale. Fruits are asymmetrical, nonschizocarpic, lack an attachment scar, and measure 2.5 to 4.1-cm long (N = 24, x = 3.19) and 0.7 to 1.3 cm wide (N = 24, x = 1.05). The wings are broad for most of their length of ≤3.1 cm narrowing proximally near their point of attachment to the ovary. They have a length/width ratio of 3.2, show a rounded apex, and weakly crenulate margin. Wing attachment extends to roughly half of the lower side of the ovary. In the area of backbone-ovary contact, the backbone is straight and parallels the upper surface of the ovary then curves downward, is typically composed of 7-11 (up to 15) distinct, major parallel veins that diverge apically from the ovary and deflect downward with 2-3 main forks. There is anastomosing between forking of the major veins and minor vein reticulation is preserved between the larger veins. Many samaras show a small secondary wing located apically on the backbone, with a form ranging from a simple bump near the middle of the ovary, to a narrow, apically directed protrusion. The narrowly elongate fusiform seed bodies are 0.7-1.1 cm long (N =16, X = 0.9) and 0.15 to 0.3 cm wide (N = 16, X = 0.2), with a length/width ratio of 4.8. Several show remnants of a ~1.0 mm peduncle(?) that flares at its basal point of attachment to the raceme. The seed body surface is smooth and crossed by parallel venation. The BN fruits have been considered similar to Acer negundoides and Deviacer. Because leaves in the BN flora were identified as A. negundoides, it was thought the winged fruits found associated in the same sediments belonged with these leaves. However, the BN leaves are now recognized to be more similar to Rhus or Toxicodendron (Anacardiaceae). Deviacer is a Paleogene genus that was widespread in North America and Eurasia, and thought by some to be the compressed form of the Late Paleocene permineralized genus Paleosecuridaca. Although the BN fruits share features with Deviacer, Paleosecuridaca, and extant Securidaca, there are differences to suggest the BN fruits represent a new related species.
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1 - University Of California, MUSEUM OF PALEONTOLOGY, 1101 Valley Life Sciences Building, Berkeley, CA, 94720-4780, USA
2 - Western Oregon University, Department of Geology, Monmouth, OR, 97361, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Union A/Hyatt
Date: Wednesday, July 11th, 2012
Time: 11:00 AM