Abstract Detail

Paleobotany

Chen, Peirong [1], Del Rio, Cedric [1], Wang, Tengxiang [1], Su, Tao [1].

Fossil capsular valves of Koelreuteria (Sapindaceae) from the Eocene of central Tibetan Plateau and their biogeographic implications.

Koelreuteria, a small genus in Sapindaceae, consists of four extant species. They are discontinuously distributed in East Asia (China, Korea, and Japan) and on the Fiji islands in the South Pacific. Koelreuteria has a wide distribution in Europe, East Asia and western North America during the Paleogene, with the earliest fossil record from the early Eocene (ca. 52 Ma) of western North America. In Asia, that represent the center of diversity of the genus today, the fossil record span from the central to the northeastern Tibetan plateau (TP) and Shandong, Jilin, Yunnan of China. Our aim in this study is to increase the fossil record of Koelreuteria in Asia and to understand their biogeographical dispersal. Here, four capsular valve fossil morphotypes of Koelreuteria were reported from the early Middle Eocene of the Niubao Formation in Jianglang site (4850 m of altitude), Bangor County, central TP, China, namely K. kvacekii, K. lunpolaensis, K. miointegrifoliola and K. aff. allenii. Among them, Koelreuteria kvacekii is a new fossil species, characterized by its widely ovate capsular valves, emarginate to lobed apex and cordate base of the valves, as well as 1–2 suborbicular seeds per locule. Koelreuteria lunpolaensis is clearly distinguished from other species by its emarginate apex, prominent septum and zigzag venation. Koelreuteria miointegrifoliola and K. aff. allenii resemble to modern K. bipinnata-type group of this genus. Fossil evidence of Koelreuteria and other co-occurring plants shows a sub-tropical climate in central Tibet during the Middle Eocene, which was obviously different from present climate in this area. These are the earliest fossil records of Koelreuteria on the TP, and together with previous fossils of the group indicate that the TP might serve as a diversity and diversification center of Koelreuteria during the Paleogene in Asia. They became locally extinct because of the dramatic uplift of the TP after the middle Eocene.

1 - CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan, 666303, China

Keywords:
Capsular valve
 Koelreuteria
Eocene
Tibetan Plateau
biogeography.

Presentation Type: Oral Paper
Session: PL7, Paleobotany: Mesozoic/Cenozoic Paleobotany
Location: /
Date: Thursday, July 22nd, 2021
Time: 1:15 PM(EDT)
Number: PL7004
Abstract ID:369
Candidate for Awards:None