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Abstract Detail


Hermsen, Elizabeth [1].

Seeds of Zanthoxylum (Rutaceae) from the Pliocene Gray Fossil Site, Tennessee, U.S.A.

Gray Fossil Site (in Gray, near Johnson City, Tennessee, U.S.A.) is an early Pliocene fossil locality that yields plant and vertebrate remains preserved in the sediments of an ancient sinkhole lake. The flora of the site includes both microfossils and macrofossils, which overlap only partially in their taxonomic composition. So far, eight angiosperm genera have been described from reproductive macrofossil material, whereas the conifer  Taxodium  has been documented from foliage. Most of the GFS plant macrofossil taxa described so far have primarily Laurasian (North American-European-Asia) fossil and modern distributions, with one genus (Passiflora)  representing an unusual Neotropical component. In this study, I describe  Zanthoxylum  seeds. The seeds are roughly oval in lateral view, small (up to about 5.1 mm long), and slightly compressed. The seed surface is shiny and devoid of wrinkles, ridges, spines, or other protuberances, but is covered by minute circular pits. The large hilum is roughly rectangular to triangular in shape and bordered by a raised lip; it is variable in length relative to the overall length of the seed. The hilum occurs above a raphal crest, which may be distinct or indistinct.  The pitted but otherwise smooth surface of the GFS  Zanthoxylum  seeds is similar to that found on seeds of the modern species  Zanthoxylum americanum, which is native to the eastern United States.  Extant  Zanthoxylum  includes over 200 species and is pantropical in distribution, although  Z. americanum  and some other species occur in temperate regions of the northern hemisphere. Fossil Zanthoxylum seeds are known from North America, Europe, and Asia.  The GFS  Zanthoxylum  species may thus fit both the Laurasian biogeographic pattern and the Neotropical pattern documented from other plant macrofossil taxa found at GFS.

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1 - Paleontological Research Institution, 1259 Trumansburg Road, Ithaca, NY, 14850, United States

North America.

Presentation Type: Oral Paper
Session: PL7, Paleobotany: Mesozoic/Cenozoic Paleobotany
Location: /
Date: Thursday, July 22nd, 2021
Time: 2:15 PM(EDT)
Number: PL7008
Abstract ID:872
Candidate for Awards:None

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