Early Cretaceous floras in Circum-Pacific region

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Early Cretaceous floras in Circum-Pacific region
Cretaceous Research (1994) 15, 317-332
Early Cretaceous floras in Circum-Pacific Region of China
Cao Zhengyao
Nanjing Institute of Geology and Palaeontology, Academia Sinica, Chi-Ming Ssu, Nanjing 210008, The
People's Republic of China
Received 8 Yanunty 1991 and accepted 15 May 1993
The Early Cretaceous floras in the Circum-Pacific region of China are divided into a southern type
and a northern type. The southern type flora resembles Early Cretaceous floras of Europe and the
Outer Zone of Japan, and is mainly distributed in southeastern China. The northern flora is similar to
those of Siberia and the Inner Zone of Japan, and is widely dispersed in northeast China. Each type
flourished under differing climatic conditions. On the eastern margin of northeast China a mixed
floral type also existed, which is closely related to the Nikan flora of southern Primorye, Russia. The
variations of components in the Early Cretaceous flora of northeast China permit division into early,
middle and late assemblages, which are assigned to the early, middle and late Early Cretaceous,
respectively. The Early Cretaceous flora of southeast China is represented by that of Zhejiang, which
is regarded as early-mid Early Cretaceous in age. The Pingzhou flora of Hong Kong probably belongs
to the Albian, representing the latest of the southern type floras.
KEY WORDS:
Early Cretaceous; floras; Circum-Pacific region; China.
1. Introduction
In the Circum-Pacific region of China Lower Cretaceous plant fossils are
abundant and widely distributed (Figure 1), and may be grouped into a southern
type and a northern type. The southern flora is similar to contemporary floras of
Europe and the Outer Zone of Japan, while the northern flora bears a
resemblance to those of Siberia and the Inner Zone of Japan. The former belongs
to the southern palaeofloristic province, part of Vakhrameev's eastern Asia
Province of the Sino-European Palaeofloristic Realm, including Xizang and
southeast China. The latter belongs to the northern palaeofloristic province which
is assigned to Vakhrameev's Amurland Province of the Canada—Siberian Palaeofloristic Realm, embracing the three provinces of northeast China, the eastern
part of Nei-Monggol and northern Hebei (Vakhrameev, 1964, 1988; Kimura,
1980; Zhou & Li, 1980; Li, 1982; Cao et al., 1982; Chen et al., 1988). A mixed
floral type also existed during the middle—late Early Cretaceous, which comprises
some characteristic forms of both the Siberian and European floras, and closely
resembles the Nikan flora of southern Primorye (Krassilov, 1967). It is found on
the eastern margin of northeast China.
The stratigraphic sequence and correlation of some localities yielding the
principal floras and assemblages are tabulated in Table 1.
The common and important elements of the southern flora are shown in
Figures 2 and 3 and those of the northern flora in Figures 4 and 5.
2. Southeast China
As a whole, the Early Cretaceous floras of southeast China are very similar to the
contemporaneous floras in Xizang of southwest China (Duan et al., 1977; Li
1982), but differ somewhat from those in the specific floral components and
0195-6671/94/030317+ 1 6 508.00/0
© 1994 Academic Press Limited
318
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Figure 1. Map of the Pacific margin of China showing the distribution of Early Cretaceous fossil
megaplant localities. 1-2, Jalainur, Yimin, Dayan (Jalainur Group); 3, Huolinhe (Huolinhe
Formation); 4, Fuxin (Fuxin Formation); 5, Tieling, Changtu (Shahezi and Yincheng Formations); 6, Yincheng (Shahezi and Yincheng Formations); 7, Chiaohe (Moshila Formation); 8-11,
Jixi, Boli, Shuanyashan, Hegang (Chengzihe and Muling Formations); 12, Mishan, Qitaihe
(Dongshan Formation); 13, Dongning (Dongning Formation); 14, Yanbin (Tongfushi and
Dalazi Formations); 15, Xinbin (Nierku Formation); 16, Pingquan ("Jiufotang" Formation); 17,
Beijing Xishan (Tuoli Group); 18, Zhangjiakou (Qingshila Formation); 19-20, Laiyang,
Zhucheng (Laiyang Formation); 21, Sihong (Gacun Formation); 22, Linbin; 23, Huoshan
(Heishidu Formation); 24, Zongyang (Shuanqiao Formation); 25, Nanjing (Yunheshan and
Gacun Formations); 26, SE Hubei (Lingxiang Formation); 27, Tunxi (Yantang Formation);
28-29, W Zhejiang (Shouchang and Laocun Formations); 30, E Zhejiang (Guantou Formation);
31-33, S Zhejiang (Moshishan and Guantou Formations); 34, Zhenghe (Nanyuan Formation);
35, Yunan (Bantou Formation); 36, NE Jiangxi (Xiqi and Zhoujiandian Formations); 37,
Xingguo (Ganzhou Formation); 38, E Guangdong (Goajiping Formation); 39, S Guangdong,
Hong Kong (Baizushan Group, Pingzhou Formation); 40, SE Guangxi (Luoding Group).
Early Cretaceous floras
319
palaeoclirnatic environments indicating that the southern palaeofloristic province
may be further divided into two subprovinces: the Xizang subprovince and the
Southeast Coastal subprovince (Zhou & Li, 1980; Cao et al., 1982; Li, 1982).
The Early Cretaceous flora of Zhejiang may be considered as representative of
the Southeast Coastal subprovince owing to the very complete fossil record there
(Lee, 1948, 1964; Chow & Tsao, 1977, 1979; Cao, 1982, 1987, 1989, 1991;
Wang et al., 1982; Ding et al., 1989). This flora is composed mainly of ferns,
cycadophytes and conifers, with very scarce sphenopsida and ginkgophytes. Of
the Filicales, the Schizaeaceae and Gleicheniaceae are predominant. The main
forms include Gleichenites, Ruffordia, Onychiopsis and Cladophlebis. Weichselia is
also present. Most elements of cycadophytes are Bennettitales, including
Ptilophyllum, Otozarnites, Zamites, Zamiophyllum and Cycadites, but Nilssonia is
scarce. The conifers are dominated by the Cheirolepdiaceae and Cupressaceae,
mostly with scaly leaves, but Podozamites is seen rarely. The flora is similar in
general aspect to the Wealden-type flora of western Europe and to the
contemporaneous floras in the Outer Zone of Japan. However, the presence of
Dictyozamites, which is often seen in the Early Cretaceous floras in the Inner
Zone of Japan (Kimura & Sekido, 1976) and the Far East of Russia (Krassilov,
1967), indicates that the Early Cretaceous flora in Zhejiang has certain affinities
with these. The Early Cretaceous flora in Zhejiang may be divided, in ascending
Table 1. Stratigraphic sequence and correlation of the important localities yielding Early Cretaceous
plants in the Circum-Pacific region of China. Key to symbols: •—insects, M—megaplants,
L3—freshwater molluscs, P—fish, 0—marine fossils.
Stage
Aptian
Pre-Aptian
Albian
—
E. Shandong
SE. Hubei
W, Zhejiang
Qingshan
Leiyang Fm
• •00
L. Volcanic
Lancun Fm
• • 0
Rocks Fm
Lingxiang Fm
• 0
Huangjian Fm
Shouchang Fm
• •00
Moshishan Fm
•
E Zhejiang
U. Volcanic
...-
Fm
Rocks Fm
Hengshan Fm
0
Chaochuan Fm
IN El
Guantou Fm
• •00
/Fangyan Fm
r
W. Fujian
Changling Fm
Nanyuan Fm
• 0
Banton Fm
II 00
Hekou
•0
Jishan Fm
• 1=10
Pingzhou Fm
•.
Hong Kong
N. Hebei
Qingshila
• •00
Fm
W. Beijing
Tuoli
II D
Group
E. Liaoning
Lishugou
For
W. Liaoning
E
Shahai
MO
0
Fm
Chengzihe Fm
lip
Heilongjiang
E. Jilin
Fm
Tujingzi
Lushangfen Fm
••
Nierku Fm
Fuxin
• 0
E
Fm
Muling Fm
Dl
Fm
Xiazhuang Fm
• 0
Dayu
Fm
Sunjiaowan
0
Fm
Dongshan Fm
IMO
Hoshigou Fm
Dongning Fm
•
Xishanping Fm
II 0
Changesi Fm
Tongfushi Fm
•o
Dalazi Fm
00
Nazishan Fm
• 0
Wulin Fm
• 00
Moshila Fm
• •0
Baojiatun Fm
0•0
a
••
320
Z. Cao
order, into three assemblages: Assemblage I, includes plants in the Laocun
Formation; Assemblage II, includes plants in the Shouchang Formation and
Member C of the Moshishan Formation; and Assemblage III, includes plants in
the Guantou Formation (Cao, 1987).
2.1. Assemblage I
This assemblage is mainly composed of the conifers cf, Sphenolepis sternbergiana
(Dunker) Schenk, S. kurriana (Dunker) Schenk, Cupressinocladus crassirameum
Cao, Brachyphyllum obesum Heer, Pagiophyllum cf. crassifolium (Schenk) Seward,
Pityospermum sp., Elatides? sp., ?Pseudofrenelopsis papillosa (Chow & Tsao),
together with several species of Otozamites and a few ferns.
2.2. Assemblage II
In this assemblage, ferns and cycadophytes predominate, with conifers ranking
next; ginkgophytes and sphenopsida are very rare. The main taxa are Onychiopsis
elongata (Geyler) Yokyama, Gleichenites cf. nordenskioldi (Heer) Seward,
Cladophlebis cf. browniana (Dunker) Seward, Sphenopteris acrodentata Fontaine,
Weichselia reticulata (Stockes & Webb) Fontaine, Ptilophyllum, Dictyozamites,
Zamites, Cycadites, Otozamites, Nilssonia weiiana Cao, Cupressinocladus elegans
(Chow) Chow, Brachyphyllum obesum Heer, Sagenopteris shouchangensis Lee, S.
linanensir Chen. Cladophelbis, Ptilophyllum, Cupressinocladus, Brachyphyllum and
Dictyozamites are most abundant. Specimens probably belonging to Ruffordia and
Pseudofrenelopsis and also present. Owing to the most frequent occurrence and
extensive distribution of Cladophlebis and Ptilophyllum, this assemblage may be
called the Cladophelebis—Ptilophyllum assemblage.
2.3. Assemblage III
This assemblage is composed mainly of ferns and conifers dominated by
Pagiophyllum. Only one species belonging to the Bennettitales has been found.
The important species are Ruffordia goepperti (Dunker) Seward, Onychiopsis
elongata (Geyler) Yokoyama, 0. psilotoides (Stokes & Webb) Ward, Gleichenites
(Ettingshausen) Nathorst,
nipponensis Oishi, Zamiophyllum buchianum
Pseudofrenlopsis parceramosa (Fontaine) Watson, P. papillosa (Chow & Tsao), cf.
Sphenolepis sternbergiana (Dunker) Schenk, Brachyphyllum obesum Heer,
Pagiophyllum obtusior Cao, P. stenopapillae Cao, Cupressinocladus elegans (Chow)
Chow, Podozamites cf. reinii Geyler. This assemblage is named the Ruffordia—
Zamiophyllum assemblage, because these two genera are the characteristic forms.
At the top of Lower Cretaceous in Zhejiang is the Chaochuan Formation,
which is composed of red beds intercalated with volcanic rocks. Plant fossils are
rare: only Pseudofrenelopsis and some coniferous leafy shoots, such as
Pagiophyllum, Cupressinocladus and Podozamites have been found. Angiosperms
are absent.
The famous Bantou flora in western Fujian (Sze, 1945) is composed of cf.
Ruffordia goepperti (Dunker), ?Onychiopsis sp., Cladophelbis dunkeri Schimper,
Sagenopteris yunganensis Sze, Dictyozamites doctyozamioides (Sze), Ptilophyllum
boreale (Heer) Seward, Otozamites cf. klipsteinii (Dunker) Seward, Nilssonia sp.,
Brachyphyllum obesum Heer, Cupressinocladus elegans (Chow) Chow, C. gracilis
(Sze) Chow, C. ?sp., Podozamites? sp. and Sphenobaiera? sp. The Laiyang flora of
eastern Shandong (Chow, 1923; Cao et al., 1982) has almost the same
composition. Fossil plants of the Lingxiang Formation in southeastern Hubei,
which have been described by Meng (1981), include Gleichenites sp., Cladophlebis
Early Cretaceous floras
321
spp. 1, & 2 similar to Cladophelbis dunkeri), Pterophyllum lingxiangense Meng,
Ptilophyllum pecten (Phillips) Morris (?P. arcticum (Heer) Seward), P. sp.,
Lingxiangphyllum princeps Meng, (?Dictyozamites reniformis Oishi), Pseudofrenelopsis parceramosa (Fontaine) Watson, Cupressinocladus elegans (Chow) Chow,
C. obtusirotundus Meng (?C. elegans), Brachyphyllum hubeiense Meng, B. cf.
rhombimamiferum Guo (?B. obesum). These floras are identical in aspect with that in
Zhejiang, in particular to assemblage II, all belong to the early-mid Early Cretaceous.
Recently a southern-type florule was discovered in the uppermost part of the
Lower Cretaceous on Pingzhou Isle, Hong Kong (Zhou et al., 1990). This florule
comprises Otozamites sp., Dicotylophyllum sp. and Amesoneuron sp., and seems to
be late Early Cretaceous (Albian)-?early Late Cretaceous in age.
Throughout southeast China, the Lower Cretaceous rocks are mainly composed of continental variegated-red or volcanic beds. The flora is dominated by
representatives of the Schizaeaceae, Gleicheniaceae and Bennettitales, which are
known to occur in tropical or subtropical zones, and also characterized by the
appearance of Weichselia, which is known to have lived in dry habitats. By
contrast, temperature deciduous ginkgophytes are rarely found. Ferns are
characterized by small but thick pinnules with simple veins, which are quite
different from those with large pinnules and complicated veins from the Triassic
and Jurassic. The conifers have scaly leaves closely attached to the stems and the
leaf cuticles are very thick. The leaves of cycadophytes also have a thick cuticle.
These characteristics reflect a rather arid climate.
3. Northeast China
The Early Cretaceous floras of China are generally known as the Ruffordia—
Onychiopsis flora (Sze & Chow, 1962). In northeast China, it has been divided by
Zhou & Li (1980) into early, middle and late assemblages. They are represented
by an Acanthopteris—Nilssonia sinensis assemblage from the Chengzihe Formation,
a plant assemblage of the Muling Formation in the Jixi Basin of eastern
Heilongjiang, and the Shansong flora from the Moshila Formation in the Jaiohe
Basin of eastern Jilin, respectively. The floras of the Dongning Formation
(middle Lower Cretaceous) and the Dongshan, Tongfusi and Dalazi Formations
(the upper Lower Cretaceous) have some characteristic forms of both Siberianand European-type floras, and therefore belong to the mixed type. The flora from
the Nierku Formation of eastern Liaoning is similar (Zheng & Zhang 1989), but
is more closely comparable in aspects to the southern-type flora.
3. 1. Chengzihe assemblage
The plant assemblage of Chengzihe Formation is the richest of the Early
Cretaceous floras of northeast China. It mainly consists of ferns, conifers,
cycadophytes and ginkgophytes. Representatives of the Dicksoniaceae and
ginkgophytes are especially abundant. The ferns include Coniopteris,
Acanthopteris, Gonatosorus, Gleichenites, Onychiopsis, Arctopteris, Adiantopteris,
Eogymnocarpium, Polypodites, Ruffordia, Cladophlebis and Sphenopteris, and the
cycadophytes are represented by Nilssonia, Pterophyllum and Nilssoniopteris. The
ginkgophytes Sphenobaiera and Phoenicopsis occur in addition to abundant
Ginkgoites. The conifers are characterized by having expanded linear or lanceolate
leaves. They are mainly composed of Pinaceae and Elatocladus, with Podozamites
and Lindleycladus frequently seen. Sometimes coniferous leafy shoots with scaly
2
0
ni
Early Cretaceous floras
323
leaves such as Pagiophyllum and Sphenolepis are also found. The age of this
assemblage is thought to be early Early Cretaceous. Recently Sun et al. (1992)
discovered angiospermous megafossils in the top of the Chengzihe Formation in
Jixi and considered its age to be mid Early Cretaceous. Zhou et al. (1980), Zheng
et al. (1980), Zhang & Zhang (1982) and Cao (1992a, b), have documented the
main elements of this assemblage (see Table 2).
3.2. Muling assemblage
The Muling and Chengzihe Formations yield two successive plant assemblages
included in the Jixi flora. The assemblage of the Muling Formation is more
impoverished than that of the Chengzihe Formation and has different characteristics, although nearly all of the species in it are present in the latter. In the Muling
Formation, ferns form the overwhelming majority of the plant fossils recovered,
cycadophytes, ginkgophytes and conifers become less abundant. Except for a few
persistent forms, the elements that are common in the Chengzihe Formation are
all missing; these include Nilssonia sinensis Yabe & Oishi, Ginkgo huttoni
(Sternberg) Heer, Ginkgoites sibiricus (Heer) Seward, Sphenobaiera cf. longifolia
(Pomel) Florin (?S. qixingensis Zheng & Zhang), Pityocladus, Acanthopteris gothani
Sze is also rarely present. Instead, Asplenium popovii Samylina, Gleichenites?
takeyamae Oishi & Takahasi and Cycadites sulcatus Kryshofovich & Prynada are
recorded. Ruffordia goepperti (Dunker) Seward becomes very common; it is only
occasionally seen in the Chengzihe Formation. This assemblage is regarded as
being mid Early Cretaceous in age (Oishi & Takahasi, 1938; Zhou et al., 1980;
Zhang et al., 1980; Zheng & Zhang, 1982).
3.3. Shansong flora
This flora consists mainly of ferns and conifers with lesser amounts of
cycadophytes and ginkgophytes as well as a very few angiosperms. Among the
ferns, representatives of the Dicksoniaceae are still important but Gleicheniaceae
and Schizaeaceae are missing; the conifers include Pinaceae, Taxodiaceae,
Podozamitaceae and ?Taxales. This is a typical late Early Cretaceous flora of the
Siberian aspect and has been dated as Aptian or Aptian-early Albian (Li et al.,
1986). The flora is listed in Table 3.
In western Liaoning fossil plants from the Fuxin coal-bearing strata have been
studied by many authors (e.g., Sze, 1931; Chen et al., 1980; Zhang, 1980; Chen
et al., 1981; Li, 1981; Zheng & Zhang, 1984, 1986; Shan & Wang, 1985; Shan,
1987; Zhang, 1987). Recently Chen et al. (1988) described in detail fossil plants
Figure 2. Representative early Early Cretaceous fossil plants from Zhejiang and Fujian provinces
(localities 28, 29, 31, 32, 34 in Figure 1). a, Cladophlebis cf. browniana (Dunker) Seward; Jiande,
Shouchang Formation; b, Weichselia reticulata (Stockes & Webb) Fontaine; Huangyan, Moshishan Formation; c, Diayozamites sp., Yongjia, Moshishan Formation; d, Dictyozanntes dicryozamioides (Sze) (repository: Regional Geological Survey Team of Zhejiang); Linan, Shouchang
Formation; e, Zamites sp.; Zhuji Shouchang Formation?; f, Prilophyllum cf. arcticum (Heer)
Seward; Lishui, Shouchang Formation; g, Prilophyllum zhengheense Wang; Zhenghe, Nanyuan
Formation; h, Of ozamites linguifolius Lee; Jiande, Shouchang Formation; 1, Otozamites ef.
klipsteinii (Dunker) Seward (repository: Regional Geological Survey Team of Zhejiang); Qu
Xian, Laocun Formation; j, Cycadites sp. (cf. Pseudocycas steenstrupi (Phillips) Nathrost); Zhuji,
Shouchang Formation; k, Ginkgoites? sp.; Jiande, Shouchang Formation; 1, Solenites vinuateus
(Phillips) Harris (repository: Nanjing Institute of Geology and Mineral Resources); Linan,
Souchang Formation; m, Cupressinocladus elegans (Chow) Chow; Jiande, Shouchang Formation;
n, Cupressinocladus gracilis (Sze) Chow; Zhenghe, Nanyuan Formation; o—p, BrachyphyRum
obesum Heer; Jiande, Caocun Formation; q, Sagenopteris hrtanensis Chen; Linan, Shouchang
Formation; r, Sagenopteris shouchangensis Lee; Jiande, Shouchang Formation. All photographs arc
natural size. The specimens are housed in the Nanjing Institute of Geology and Palaeontology
unless otherwise indicated.
324
C. Zhengyao
Figure 3. Representative plant fossils from the Guantou Formation (?Barremain) of eastern and
southern Zhejiang (localities 30 and 33 in Figure I). a, Equisetites sp.; Linhai; b, Gleichenites
nipponensis Oishi; Linhai; c, Cladophlebis exiliformis (Geyler) Oishi; Linhai; d, Ruffordia goepperri
(Dunker) Seward; Wencheng; e, Onychiopsis psilotoides (Stokes & Webb) Ward; Wencheng; f,
Onychiopsis elongata (Geyler) Yokoyama; Linhai; g, Zamiophyllum buchianum (Ett) Nathorst;
Xinchang; h, Sphenolepis? sp. (x3); Linhai; i, Pseudofrenelopsis parceramosa (Fontaine) Watson;
Xianju; j, cf. Sphenolepis stembergiana (Dunker) Schenk; Xianju; k, Pagiophyllum obtusior Cao;
Xinchang. All photographs are natural size except where noted otherwise. Housed in the Nanjing
Institute of Geology and Palaeontology.
Early Cretaceous floras
325
Table 2. Principal taxa of the Chengzihe Formation (Lower Cretaceous; eastern Heilongiiang) plant
assemblage.
Equisetales
Equisetites app.
Filicales
Schzaeaceae
Ruffordia goepperti (Dunker)
Gleicheniaceae
Gleichenites cycadina (Schenk)
G. cf. rigida (Neer)
Dicksoniaceae
Coniopteris burejensis (Zalessky)
C. iaportana (Heer)
C. cf. setacea (Prynada)
Acanthopteris gothani Sze
A. acutata (Samylina)
A. alata (Prynada)
A. onychioides (Vassileskaya &
Kara-Mursa)
Gonatosorus kerovae Valthrameev
Pteridaceae
Arctopteris rarinervis Samylina
A. zhengyangensis Zheng
A. ntaculatus Zheng
Adiantopteris sp.
Sinopteridaceac?
Onychiopsis elongate (Geyler)
0. psilowides (Stokes & Webb)
Athyriaceae
Eogyrrowcarpium sitioise (Lee & Yeh)
Polypodiaceae
Polypodites polysorus Prynada
Ferns of unknown affiniry
Cladophlebis argutula (Heer)
C. delicatula Yabe & Oishi
C. lobulata Samylina
Sphenoptetis johnstrupi (Heer)
S. naktongensis Yabe
Nilssoniales
Nilssonia sinensis Yabe & Oishi
N. shuanyanshanensis Zheng
Bennettitales
Prerophyllum cf. propinquum GOppert
P. jixiense Chow & Wang
P. burejense Prynada
P. sensinovianum Heer
Nilssoniopteris prynadae S amylina
N. lixinensis Zheng
N. shuangyashanensis Zheng
Ginkgoales
Ginkgoites ex gr. adiantoides (Unger)
G. manchuricus (Yabe & Oishi)
G. sibiricus (Heer)
Ginkgo digit= (Brongniart)
G. huttoni (Sternberg)
Sphenobaiera cf. pulchella (Heer)
S. gixingensis Zheng
Czekanowskiales
Ixostrobus heeri Prynada
Phoenicopsis angustifolia Heer
Coniferales
Pinaceae
Pityocladus yabei (Toyama & Oishi)
P. ferganensis Turutanova-Ketova
Pityophyllum lindstroemi N athorst
Taxodiaceae
Sphenolepis kurnana Schenk
S. sternbergiana Schenk
Podozamitaceae
cf. Lindleycladus lanceotatus (Lindley
& Hutton)
Conifers of uncertain systematic position
ElatocIadus manchuticus (Yokoyama)
Pagiophyllum shahezium Zhang
Schizolepis heilongjiaregensis Zhang
Gymnosperms of unknown affinity
Taeniopteris beyruchii Schenk
T. mashanensis Chow & Yeh
Carpolithus jidongensis Zheng
from the Fuxin Formation of the Fuxin Basin and equivalent strata in the Tiefa
Basin, and divided the Fuxin flora into an upper assemblage from the upper part
of the Fuxin Formation (the Shuiquan Member) and a lower assemblage from
the lower-middle part of the Fuxin Formation. The former contains 29 species,
many of which are also present in the lower assemblage. According to Shan's
statistics (1987), this assemblage is very similar to the Shansong flora with 17
species being common to both. They are therefore assumed to be roughly
equivalent in age. The lower assemblage resembles the Jixi flora as they contain
many species in common or related, but the conifer species are more diverse.
There are no ferns attributable to Gleichenites, Onychiopsis, Polypodites,
Eogymnocarpium, Gonatosorus and Adiantopteris, but Acrostichopteris has been
found. This is often encountered in the Lower Cretaceous in Europe and North
America. The cycadophytes Ctenis is present but Cycadites sulcatus is missing.
This assemblage is thought to be of early-mid Early Cretaceous age.
In northern Hebei and western Beijing, the fossil plants found in the
Qingshilazi Formation and the lower three formations of the Touli Group (Wang
& Wang, 1979; Chen & Yang, 1982; Wang & Wang, 1984) were named by
326
Z. Cao
Table 3. Principal taxa of the Shansong floral assemblage (late Early Cretaceous) from eastern hilM.
(After Li et al., 1986).
Lycopodiales
Lycopodites muhifurcatus Li et al.
Filicales
Dicksoniaceae
Acanthopteris acutata (Samylina)
4. alata (Prynada)
ConioptenIr vsevoldii E. Lebedev
Pteridaceae
Arctopzeris tschumikanensis E. Lebedev
Sinopteridacae?
Onychiopsis elongara (Geyler)
Adiantaceae
Chiaohoella mirabilis Lee & Yeh
Ch. neozamioides Lee Sc Yeh
Ch. papilioformis Li et al.
Athyriaceae
Fogymnocarpium sinense (Lee & Yeh)
Ferns of unknown affinity
Cladophelebis lobulata Samylina
Cl. delicatula Yabe & Oishi
Raphaelia cretacea (Samylina)
R. denticulata (Samylina)
Sphenopteris sp.
Nilssoniales
Nilssonia sinensis Yabe & Oishi
Ctenis lyrata Lee & Yeh
Ct. burejensis Prynada
Chilinia ctenioides Lee & Yeh
Bennettitales
Nilssoniopteris aniana Li et al.
N. conjugata Li et al.
Ginkgoales
Ginkgo sp. cf. G. sibirica Heer
Czekanowskiales
Czekanowskia? sp.
Phoenicopsis angustifolia Heer
Coniferales
Podozamitaceae
Podozamites sp. 1
P. sp. 2
Pinaceae
Pityocladus robustus Li et al.
Pityolepis? sp.
Piryospermum sp. 1
P. sp. 2
Pityophyllum sp.
Taxodiaceae
Sphenolepis sternbergiana (Dunker)
Taxales?
Torreya? chozezi Lee & Yeh
Phipidiocladus acuminatus Let & Yeh
Ph. jiabellatus Prynada
Ph. mucronatus Lee & Yeh
Conifers of uncertain systematic position
Eladocladus manchterictes (Yokoyama)
E. iwaianus (Oishi)
Brachyphyllum cf. japonicum (Yokoyama)
Gymnospermous seeds of unknown affinity
Samaropsis sp.
Angiosperms of unknown affinity
Vitiphyllum sp.
Phyllites sp.
Wang & Wang (1984) the Acanthopteris gothani assemblage and Otozamites
denticulatus (=Neozamites denticulatus) assemblage. The latter is characterized by
the occurrence of a few Early Cretaceous elements that are also found in western
Europe and North American. Both assemblages are similar to the lower
assemblage of Fuxin flora and the Jixi flora, but contain Acrostichopteris,
Otozamites linguifolius, Dictyozamites, Neozamites and Vitimia, which are not
present or only rarely found in the floras of northeast China. A form that is
typical of the Shansong flora, Chiaohoella, is also present. Acrostichopteris has
otherwise only been recorded from the Taiping Member of the Fuxin Formation
(Chen et al., 1988): Dictyozamites is confined to the Dongning and Dalazi
Formations (Zhang & Xiong, 1983; Zhang, 1986). Otozamites linguifolius, a
characteristic species of the southern flora, has never been reported from other
localities of north and northeast China. Neozamites has been found in the
Shuiquan Member of the Fuxin Formation, and the Dalazi and Dongshan
Formations in the eastern borderland of northeast China, and the Yingcheng
Formation on the margin of the Songliao Basin (Yang & Sun, 1982); Vitimia,
which was erected by Vakhrameev & Kotova (1977) from the Lower Cretaceous
of Transbailkalia in Russia, has not been found elsewhere in China. These two
assemblages are considered to represent two different environments during
almost the same period of time (Wang & Wang, 1984). The fossil plants
occurring in the Xiazhuang Formation (the top part of the Touli Group) at
Xishan, Beijing and the upper part of the Quixiaying Group in Nei-Monggol were
Figure 4. Representative fossil plants from the Chengzihe Formation (early Early Cretaceous,
eastern Heilongjiang: Shuangyashan [a—c, j] and Jixian [d—f, i]) and approximately equivalent
strata. a, Equisetites sp.; b—c, Coniopteris saportana (Heer) Vachrameev (x1.5); d, Conipteris
burejensis (Zalessky) Seward (x1.5); e, Acarnhopten's gothani Sze; f, Acanthopteris onychioides
Zhang; g, Gonatosorus ketovae Vachrameev (Shahezi Formation, Changtu: deposited in the Jilin
Institute of Coal-Field Geology); h, Onyehiopsis elongata (Geyler) Yokoyama (Tuoli Group,
Beijing: deposited in the Wuhan College of Geology); i, Nilssonia sinensis Yabe & Oishi; j,
Elatoeladus manchurieus (Yokoyama) Yabe. All specimens are natural size and housed in the
Nanjing Institute of Geology and Palaeontology except where noted otherwise.
328
Z. Cao
designated by Wang & Wang (1984) as a primitive angiospermous assemblage
and dated as late Early Cretaceous.
3.4. Mixed floras
The Tongfusi and Dalazi Formations in the Yanji Basin of eastern Jilin, which
consist mainly of variegated coarse-grained sediments intercalated with paper
shale or oil shales, contain plant assemblage that is quite different from the
Shansong flora. Except for Acanthopteris, Coniopteris, Onychiopsis, Ginkgoites,
Pityocladus, Elatocladus (E. iwaianus) and primitive angiosperms of Vitiphyllumtype which are common to both, the Dalazi flora also yields Ruffordia,
Acrostichopteris, Gleichenites, Otozamites, Zamiophyllum, Elatides (E. curvifolia),
Frenelopsis, Pseudofrenelopsis, Suturovagina and Cupressinocladus (Oishi, 1941;
Chow & Tsao, 1977; Zhang et al., 1980; Zhou et al., 1980; Zhang, 1986), which
are mostly believed to be characteristic forms of the Sino-European Palaeofloristic Realm. The plant assemblage of the Dongshan Formation, which consists
mainly of pyroclastic rocks intercalated with sandstones and shales in eastern
Heilongjiang (Zheng & Zhang, 1983; Cao, 1984), is essentially similar to those of
the Tongfusi and Dalazi Formations, all being close to the Nikan flora of
southern Primorye, Russia (Krassilov, 1967). According to Zheng & Zhang
(1983), more than half of the species from the Dongshan Formation are common
to, or similar to those of the Nikan flora.
The Dongning Formation in the Dongning basin which connects with the
Suifen Basin of southern Primorye has been correlated with the Muling
Formation of the Jixi basin. It contains a flora of rather different aspect from that
of the Muling Formation. According to Oishi (1935) and Zhang & Xiong (1983),
it has about 18 species in common or related to those of the Lipovitz Formation
of the Nikan Group, among them Nathorstia, Dictyozamites and Sagenopteris
which are rarely seen in coeval floras of northeast China, hence emphasizing the
closeness of the relationship.
In northeast China, most Lower Cretaceous coal-bearing deposits are rich in
fossil plants, reflecting a climate favourable for their growth. The presence of
ferns with thin laminae and deciduous gymnosperms such as ginkgophytes and
Pityocladus indicate a warm, humid temperate-subtropical climate. However,
from the beginning of the middle Early Cretaceous, ginkgophytes gradually
declined and the elements of Sino-European Palaeofloristic Realm increased,
probably implying that the floras were influenced to varying degrees by the warm
and arid climate dominant in southern Eurasia. The Dongning, Dongshan and
Dalazi floras flourished in a climate similar to that indicated by many "Wealden"
floras.
Figure 5. Representative fossil plants from the Chcngzihe Formation (eastern Heilongjiang: Jixi
[a—b], Suibin [d], Jixian [e] and Shuangyashan [f—i]) and approximately equivalent strata. a,
Glekhennes cycadina (Schenk) Prynada; b, Sphenopteris johnstrupi Heer; c, Ginkgoites sibiricus
(Hccr) Seward (Fuxin Formation, Fuxin); d, Sphenobaiera cf. pulchella (Heer) Florin; e,
Ixostrobus heeri Prynada; f, Ginkgoites manchuricus (Yabe & Oishi) Cao; g, Phoenicopsis sp.; h,
Pityocladus yabei (Toyama & Oishi) Chang; i, cf. Lindleyeladus lanceolatus (Lindley & Hutton)
Harris. All photographs are natural size. The specimens are housed in the Nanjing Institute of
Geology and Palaeontology except a, b and h, which are held by the Shenyang Institute of
Geology, and c which is in the collection of the China University of Geology.
Early Cretaceous floras
329
330
Z. Cao
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