Abstract Detail

Systematics

Manchester, Steven R [1], PIGG, KATHLEEN [2], DeVore, Melanie [3], Zlatko, Kvacek [4], Dillhoff, Rick [5].

Extinct character combinations in Trochodendraceae from the Eocene of Washington and British Colombia.

The Trochodendraceae, which are today confined to two monotypic Asian genera, were more widespread geographically in the fossil record with occurrences in the Paleogene of western North America, and in the Miocene of Iceland, Japan, Kamchatka and western North America. A fully articulated branch bearing leaves, axillary buds, as well as an infructescence documents another extinct representative of Trochodendraceae from the Eocene of Republic, Washington. The elongate, pointed terminal buds, and leaves with stout petioles, thick lamina, a single primary vein and pinnate secondary veins, serrate margin with glandular teeth, and anomocytic stomata, resemble those of extant Trochodendron. However, micro CT scanning of the infructescence, still partly imbedded in the shale, reveals a combination of characters found separately today in Tetracentron (four persistent styles) and Trochodendron (pedicellate fruits with a nectariferous pad beneath each style). The numerous stamen scars observed in modern and Miocene fruits of Trochodendron do not occur in this fossil, indicating another similarity with Tetracentron which has only 4 stamens. The fruits are capsules, with styles that persist on the lateral margins as in the two modern genera. The persistent styles are basally recurved, but then reflex to curve toward the fruit apex, in contrast to the strictly recurved styles of modern Tetracentron and Trochodendron. The physical connections documented in this specimen provide important clues for reassembling other dispersed trochodendraceous plant remains that co-occurred with this one in the Okanagan Highlands. The same species of dispersed infructescence occurs also at McAbee, British Colombia. In addition to the infructescence characterized above, there are several specimens of a similar kind infructescence from Republic bearing sessile 4- to 5-styled fruits. While the architecture of those fruits closely resembles that of the fruits described above the fruits are smaller and sessile; hence we infer that they may represent Tetracentron, which was earlier documented in the flora based on by its distinctive leaves, Tetracentron hopkinsii Pigg, Dillhoff, DeVore, & Wehr. A few inflorescences from Republic and infructescences from McAbee, bear pedicellate fruits with greater numbers of styles, and appear to represent true Trochodendron, namely T. drachukii Pigg, Dillhoff, DeVore, & Wehr and may be inferred to correspond with the palmately veined leaves of Trochodendron nastae Pigg, Wehr and Ickert-Bond, indicating that at least three different trochodendraceous plants coexisted in the Eocene Okanagan Highlands.

1 - University Of Florida, Florida Museum Of Natural History, PO BOX 117800, Gainesville, FL, 32611, USA
2 - Arizona State University, SCHOOL OF LIFE SCIENCES FACULTY & ADMIN, BOX 874501, Tempe, AZ, 85287-4501, USA
3 - Dept Of Biology & Env. Science, GC & SU Campus Box 81, MILLEDGEVILLE, GA, 31061-0001, USA
4 - Charles University, Faculty of Science, Institute of Geology and Palaeontology, Albertov 6,, Prague, kvacek@natur.cuni.cz, Czech Republic
5 - 1307 212TH AVE NE, SAMMAMISH, WA, 98074, USA

Keywords:
Paleobotany
Eocene
fossil
Trochodendraceae.

Presentation Type: Oral Paper
Session: 14, Systematics I: Basal Dicots, Monocots & Rosids
Location: Sundance 1/Omni Hotel
Date: Monday, June 26th, 2017
Time: 3:45 PM
Number: 14010
Abstract ID:488
Candidate for Awards:None