in Jurassic and Cretaceous Stratigraphy

Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321
Ginkgoales and Czekanowskiales from the Middle Jurassic in Western
Junggar Basin of Xinjing, China
Yuyan Miao 1 , Ge Sun 2,3 , Chuntian Li 3 , Yuejun Chen 3
1. Beijing Museum of Natural History, Beijing, China (E-mail: myyzzh@126.com)
2. Shenyang Normal University, Shenyang, China
3. Jilin University, Changchun, China
Middle Jurassic strata are well exposed in western
Junggar Basin of Xinjiang, yielding abundant fossils
of Ginkgoales and Czekanowskiales (Miao, 2009).
The earliest known study of the Middle Jurassic plants
from the Junggar Basin was made by A.C. Seward in
1911, in which the taxa Ginkgo obrutschewii Seward
and Raphaelia diamensis Seward were first reported
(Seward, 1911). Since 2001, the authors have carried
out a new-cyclic study of the Middle Jurassic flora
from the Xishanyao Formation of the western Junggar
Basin, and over 50 species of 26 genera have been
identified, including horsetails, ferns, seed ferns, ben-
nettitales, ginkgoales, czekanowskiales, conifers, etc.
Generally, the flora is represented by the assemblage
of Coniopteris-Phoenicopsis, implying a warm-tem-
perate and some humid climate favorable for the coal-
forming in large scale during the early Middle Jurassic
time (Seward, 1911; Zhou, 1995; Miao, 2003; Sun et
al., 2004; Miao, 2005; Sun et al., 2006; Zhou, 2003).
At present, the authors have collected about 400
pieces of specimens of Ginkgoales and Czekanow-
skiales preserved in compression or impression from
the Xishanyao Fm. of the Baiyang River valley of
northwestern Junggar Basin and the Manas River
valley of the southwestern Junggar Basin. The well-
preserved cuticle material brings a favor to the anato-
mic study of the fossil plant taxonomy.
The taxa of Ginkgoales consist of Ginkgo obrut-
schewi Seward,G. cf. sibirica Heer,G. coriacea
Florin,Baiera furcata (L. et H.) Harris et Millington,
Sphenobaiera junggarensis Sun, Miao et Chen,S. cf.
huangi (Sze) Hsü,Desmiophyllum sp., Stenorachis cf.
lepida (Heer) Seward, etc. Among them Sphenobaiera
junggarensis was first reported in the Junggar Basin in
2006 (Sun et al., 2006). The cuticular characters of
Sphenobaiera junggarensis indicate some new data for
reconstruction of the paleoclimate of the Junggar
Basin.
The taxa of Czekanowskiales include Czekanow-
skia rigida Heer,C. cf. setacea Heer,Phoenicopsis (P.)
angustifolia Heer,P. speciosa Heer,Leptostrobus laxi-
flora Heer,and Ixostrobus sp. The cuticle study of
Phoenicopsis helps us in the taxonomy of this genus,
while the reproductive organs Leptostrobus and Ixo-
strobus bring us more fresh knowledge on the
evolution of Czekanowskiales.
Since Ginkgoales and Czekanowskiales both are
deciduous in nature, their abundance in the strata from
the Junggar Basin implies a warm-temperate and some
humid paleoclimate with seasonal changes during the
Middle Jurassic (Miao, 2005; Zhou, 2003; Deng,
2007).
Key words: Ginkgoales; Czekanowskiales;
Middle Jurassic; Junggar Basin
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