in Jurassic and Cretaceous Stratigraphy

Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321
In Situ Spores of Two Dipteridaceous Ferns from the Jurassic of China
and Their Evolutionary Implications
Yongdong Wang 1 , Hong Zhang 2 , Gaetan Guignard 3 , Ning Tian 1 , Zikun Jiang 1
1. Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, P. R. China
(E-mail:ydwang@nigpas.ac.cn)
2. Institute of Coal Geology, Xi’an Branch, China Coal Research Institute (CCRI), Xi’an 710054, China
3. Université de Lyon, F-69622, Lyon, France; Université de Lyon 1, Villeurbanne; CNRS, UMR5125, Paléoenvironments et
Paléobiosphère, France
The Dipteridaceae is a representative lepto-
sporangiate fern family with a single extant genus
Dipteris, and is currently restricted to Indo-Malaysian
region. During the Mesozoic, the family was globally
distributed with more up to 6 genera and 60 species.
They form a significant element of many Northern
Hemisphere Mesozoic floras, from Middle Triassic to
Early Cretaceous. Among them, Dictyophyllum and
Hausmannia are two representative genera of the
family. So far only four species of Dictyophyllum have
been described for their in situ spores from the Triassic
and Jurassic. All of the previously described species of
Hausmannia are based on compression/impression
fossils, and little is known about the fertile structures
including sporangia and in situ spores of this genus. In
this note the in situ spores of two dipteridaceous ferns
Dictyophyllum and Hausmannia from the Jurassic of
China are reported based on recent studies on the
material from western Hubei and Inner Mongolia,
China.
Fig.1 Frond, fertile pinnae and in situ spores of
Dictyophyllum nilssonii (Brongniart) Goeppert from the Lower
Jurassic Hsiangchi Formation in Western Hubei, China (after
Guignard et al., 2009)
Well-preserved compression specimens of Dictyo-
238
phyllum nilssonii (Brongniart) Goeppert were investi-
gated from the Lower Jurassic Hsiangchi Formation in
Western Hubei, Southern China. The reproductive
characters including sporangia and in situ spores are
examined using LM and SEM (Guignard, Wang et al.,
2009). The sporangia are rounded with oblique annulus,
each being 300-450 µm in diameter. Each sporangium
produces 220-280 trilete spores that are triangular to
subtriangular in outline with smooth exines as well as
interradial thickenings along the laesura in proximal
surface (Fig.1). The in situ spores are average 40 µm in
diameter and comparable to the dispersed trilete spore
genus Dictyophyllidites.
Fig.2 Lamina, sporangia and in situ spores of Hausmannia
sinensis Wang and Zhang from the Middle Jurassic of Inner
Mongol (Inner Mongolia), Northern China (After Wang and
Zhang, 2009)
A new species of Hausmannia (H. sinensis Wang
and Zhang) was reported from the Middle Jurassic of
Nei Mongol (Inner Mongolia), Northern China based
on exceptionally well-preserved fertile specimens, in-
cluding sori, sporangia, annuli as well as in situ spores
(Wang and Zhang, 2009). Laminae are broadly
fan-shaped with almost entire margin. Primary and
lateral veins dichotomously branch to form square or
polygonal meshes. Each ultimate mesh bears one to two
circular sori of 0.4 mm in diameter. The sori are