Abstract Detail

Paleobotany

Liang, Lina [1], Hu, Yi [1], Xiao, Liang [1], Li, Xiangchuan [3].

Fossil fruits, catkins and leaves of Alnus from the early Miocene of Inner Mongolia and its paleoecological implications.

Today, Inner Mongolia of northern China is characterized by a temperate arid continental climate harboring vast steppes and deserts. The geologic section studied here, which is located in Zhuozi County of central Inner Mongolia, is lithologically confined to the Hannuoba Formation, consisting mainly of a suit of gray, black and purple-gray olivine basalt with interbedded brick-red mudstone, gray-white marl and gray shale. The age of the Hannuoba Formation has been interpreted as early Miocene on the basis of K-Ar dating. A large number of arborescent plant fossils, including Alnus unusual pollen, cone-like infructescences, and staminate inflorescences, have been found there. As the sister group to the remaining extant Betulaceae, Alnus, comprises 26 deciduous tree species prevailingly distributed in temperate and subtropical regions of Eurasia and North America. Some species of Alnus extends southwards into the northern part of Africa, the Caribbean, and the Andes of South America. Additionally, 7 species and 1 variety of Alnus are distributed in a large area of China excluding the northwestern interior. Most Chinese species are commonly found in sunny and fertile areas and watersides of eastern and northern China and a few species are found in mid-altitude mountains of southwest China. Among these plants, five species are endemic to China. In comparison with previous investigations on isolated fossil organs, the occurrence featuring multiple organs promotes a better understanding of the systematic position. By comparing macro- and micromorphological characters of the fossil infructescences, staminate inflorescences, winged nutlets and leaves from the early Miocene Hannuoba Formation of Inner Mongolia with those of known extant and fossil species, the present isolated fossils are designated as Alnus zhuoziensis Liang & Li sp nov. based on co-occurrences from the same horizon of different sites. This finding has enriched the fossil record of Alnus in China. The present discovery and co-occurring woody megafossils suggest that a temperate forest existed in central Inner Mongolia during the early Miocene. Later vegetation succession from the past forest to the present-day steppe may be triggered by the global climate cooling and regional aridification since the Miocene.
Keywords: Miocene, Alnus, Hannuoba Formation, Betulaceae, fossil plant

1 - North Gate Of Chang'an University Yanta Campus, Yucai Road, Yanta District, Xi'an City, Shaanxi , Xi'an, 61, 710054, China
2 - North Gate Of Chang'an University Yanta Campus, Yucai Road, Yanta District, Xi'an City, Shaanxi , Xi'an, 61, 710054, China
3 - Chang'an University, School Of Earth Sciences And Resources, 126 Yanta Road, Xi'an, 61, 710054, China

Keywords:
Miocene
Alnus
Hannuoba Formation
Betulaceae
fossil.

Presentation Type: Oral Paper
Number: PB3001
Abstract ID:471
Candidate for Awards:Maynard F. Moseley Award