Inner Mongolia, China
OSGF
The fossil chert locality at the Zhahanaoer open-cast coal mine, Jarud Banner, eastern Inner Mongolia, China. At this locality fossil plants are preserved in silica, which infiltrated and petrified the tissues of a mass of jumbled plant parts. The preservation of individual cells within the plant tissues is exquisite, which allows the fossils to be described in great detail and compared to living plants. The most difficult task is to understand which of the many dispersed plant parts were produced by the same kind of fossil plant. These photographs show the field team soon after the discovery of the locality in 2017.
Details of the right hand photograph: Left to right – Qijia Li (Chang’an University, Xi’an), Gongle Shi (Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences), Patrick Herendeen (Chicago Botanic Garden, Glencoe), Hui Jiang (Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences), Fabiany Herrera (Chicago Botanic Garden, Glencoe), Peter Crane (Oak Spring Garden Foundation, Upperville and Yale University), Bole Zhang (Qingdao Research Institute of Geotechnical Prospecting and Surveying, Qingdao). Zhahanaoer Chert, Inner Mongolia, China, ca. 126 million years before present.
Fossil plants from the Zhahanaoer chert locality.
Details: A) Chert slab showing cupules and short shoots (arrows), and abundant wood. B) Transverse section of lycopod showing actino–plectostelic protostele. C) Transverse section of fern petiole showing vasculature of single leaf trace. D) Transverse section of pinaceous needle showing vasculature and two resin canals. E) Longitudinal section of short shoot showing central axis and leaves. F) Transverse section of gymnosperm wood. Scale bars: A=1cm; B=500μm; C=500μm; D=200μm; E=2mm; F=1mm. Zhahanaoer Chert, Inner Mongolia, China, ca. 126 million years before present.
A variety of plant fossils are preserved within blocks of chert at the Zhahanaoer chert locality as revealed by this peeled section (A). Illustrations to the right show only some of the diversity of fossil plants preserved within the chert, which includes stems of club mosses (B), stalks of fern leaves (C) and several kinds of extinct of seed plants, including conifers such as pines (represented by leaves, D), and many short shoots (E) and stems (F) of extinct seed plants.
Fossil cupules and an associated leaf from the Zhahanaoer chert locality.
Details: A) Median longitudinal section of an empty seed-bearing unit. B) Median transverse section of a cupule. The two lateral flaps are fused to the cupule stalk and the median flap is free, together they form the cupule that tightly encloses two triangular seeds. C) Median longitudinal section of cupule showing seed attachment on the tip of the strongly reflexed cupule stalk resulting in the micropyle being oriented toward the base of the cupule stalk. D) Transverse section of a leaf showing eight longitudinal veins. Scale bars, A=1mm; B=1mm; C=1mm; D=100μm. Zhahanaoer Chert, Inner Mongolia, China, ca. 126 million years before present.
Especially common in the Zhahanaoer chert flora are the seed-bearing cupules of an extinct seed plant that is related to flowering plants, but also shows features similar to living Ginkgo. Many cupules are empty and had shed their seeds before being preserved (A). However, many other cupules still have seeds inside: two in each cupule (B), each suspended from a small pad if tissue at the cupule apex (C). It is this extinct plant and its potential relationship to angiosperms that is the focus of the 2021 paper published in Nature. The leaf (D) may be part of the same plant.