Early angiosperms from the Lower Cretaceous of Jixi, eastern ...

Abstract
Early angiosperms from the Lower Cretaceous of Jixi,
eastern Heilongjiang, China
Ge Sun a , David L.Dilcher b;
a Research Center of Palaeontology, Jilin University, Changchun 130026, PR China
b Florida Museum of Natural History, University of Florida, Gainesville, FL 32611-7800, USA
Received 26 March 2001; received in revised form 18 January 2002; accepted 11 March 2002
Early angiosperms from the Lower Cretaceous Chengzihe Formation exposed near the city of Jixi in Northeast
China are reported here.Ten taxa are presented in this paper including two new genera (Zhengia, Xingxuephyllum),
three new species (Jixia chengzihensis, Zhengia chinensis, Xingxuephyllum jixiense), and three taxa are emended
(Asiatifolium elegans, Jixia pinnatipartita, Shenkuoa caloneura).Also, descriptions of four species are included, Jixia
sp., Xingxueina heilongjangensis, Reproductive A, and Reproductive B.Dating of the fossil angiosperms is based upon
the Hauterivian age of dinoflagellates found in marine sediments conformably underlying the beds from which the
angiosperms were found, and on the biostratigraphic correlation of the Chengzihe Formation to some relevant
equivalents of the neighboring South Primorye, Russia that have alternating marine and non-marine beds.Of special
interest is the diversity of angiosperms found, the small size of the leaves and the associated reproductive material
probably attached to an angiosperm leaf.It consists of an elongate axis that bears small florets arranged helically, the
surface of which is covered with abundant pollen similar to late Valanginian^Hauterivian inaperturate pollen of
Afropollis from Israel.The angiosperms from the Chengzihe Formation of Jixi, China are considered Hauterivian or
Hauterivian^early Barremian in age.ß 2002 Elsevier Science B.V.All rights reserved.
Keywords: early angiosperms; Lower Cretaceous; Jixi; Heilongjiang; China
1. Introduction
One of the major questions in the study of angiosperm
phylogeny and diversi¢cation is what
was the nature of the early angiosperms.This still
remains an unanswered question in spite of the
numerous contributions that have been made in
the past few decades on material from the mid
* Corresponding author.Fax: +1-352-392-2539.
E-mail address: dilcher@£mnh.u£.edu (D.L. Dilcher).
Review of Palaeobotany and Palynology 121 (2002) 91^112
0034-6667 / 02 / $ ^ see front matter ß 2002 Elsevier Science B.V. All rights reserved.
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and upper Lower Cretaceous (Dilcher, 1974,
2000; Hickey and Doyle, 1977; Dilcher and
Crane, 1984; Krassilov, 1982, 1997; Dilcher and
Kovach, 1986; Tao and Zhang, 1990, 1992; Upchurch
and Dilcher, 1990; Nixon et al., 1994;
Hill, 1996; Crepet et al., 2000; Friis et al., 2000;
Mohr and Friis, 2000; Sun et al., 2000).Early
divergence of angiosperms as a group may have
begun as far back as the Triassic but generally
accepted records of the group date from the middle
Early Cretaceous, i.e. about 130 Ma (Crane et
al., 1995; Magallo¤n et al., 1999; Dilcher, 2000).

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G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112
However, a few pollen records from the lower
Lower Cretaceous (e.g. Valanginian) support the
idea that the divergence of the angiosperms could
be earlier (Hughes, 1994; Brenner, 1996).The recent
discovery of early angiosperms (i.e. Archaefructus)
from the western Liaoning, China could
possibly even be traced to the Late Jurassic (Sun
et al., 1998).Nevertheless, the middle Early Cretaceous
appears to be a very important period in
the evolution and development of angiosperms in
the world.Therefore, the recent ¢ndings of angiosperm
megafossils as well as some microfossils
from the early^middle Early Cretaceous Chengzihe
Formation of Jixi, eastern Heilongjiang, China
reported here (Fig.1), are very signi¢cant for
the study of early angiosperms in the world and
particularly in eastern Asia. Sun et al.(1992a) ¢rst
reported the early angiosperm megafossils from
the Chengzihe Formation of Jixi and considered
the age of the angiosperm fossils as Valanginian^
Hauterivian or early Barremian based mainly on
the associated marine dino£agellates in the formation.Later,
Sun and Dilcher (1996, 1997) studied
these early angiosperm leaf remains and particularly
the in£orescence and its pollen grains. He
and Sun (2000) restudied the dino£agellates associated
with the angiosperms of the Chengzihe
Formation, and proposed their new determina-
tions resulting in more precise dating as late Hauterivian
in age.
The early angiosperms from the Chengzihe
Formation of Jixi, China described here all are
dicotyledons with many leaf and reproductive
characters new in the early history of the group
and these are presented so they can be evaluated
as primitive or derived angiosperm characters.At
this locality, abundant fossil ferns and fern allies,
cycadales, bennettitales, ginkgoales, conifers and
caytoniales are associated with the angiosperms,
including Equisetites burejensis, Coniopteris burejensis,
Acanthopteris gothanii, Onychiopsis elongata,
Acropteris sp., Cladophlebis sp., Nilssonia sinensis,
Nilssonia angustissima, Pseudocycas sp.,
Ginkgo sp., Sphenobaiera sp., Elatocladus submanchurica,
Sphenolepis kurriana, Schizolepis sp.and
Sagenopteris sp.(Sun et al., 1992a; Sun, 1995).
2. Material and methods
One important aspect of this investigation is the
validity of the age determination for the fossil
angiosperms described in this paper.The determination
of the age involved a great deal of ¢eld
mapping of the Chengzihe Formation and associated
Muling Formation exposed along the Muling
Fig.1.Geographic position of the locality of the early angiosperms from Jixi of Heilongjiang, China.

G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112 93
Fig.2.Geological section of the Lower Cretaceous Chengzihe Formation from the Wanrengou to the Muling River Bridge near
Chengzihe of Jixi, Heilongjiang, China.
river of the Chengzihe district, Jixi City, Heilongjiang
Province, China (Fig.2).
Forty-seven beds have been recognized in the
Chengzihe Formation.There is 822 m of sediment
consisting of marine and non-marine alternating
beds of sandstone, shale-siltstone and coals dipping
towards the northwest.There are 34^36 coal
seams that can be found and some of the coal is
mined locally and the sandstone quarried for local
construction material. Sun et al.(1992b) outlined
the stratigraphy of the Jurassic^Cretaceous
boundary sediments in eastern Heilongjiang Province,
China.To the east there was more marine
in£uence and species of the bivalve Buchia are
used to establish the biostratigraphic zones of
the Jurassic and Lower Cretaceous (Sun et al.,
1989, 1992b; Sha, 1992; Sha and Fuersich,
1993).To the west, at Jixi there was less marine
in£uence and dino£agellate fossils are preserved
in several beds as represented by bed 12, which
can be used to establish the age of that portion of
the Chengzihe Formation (Figs.2 and 3).Prepa-

PALBO 2463 19-9-02
Fig.3.Stratigraphic correlations of the Chengzihe Formation of Jixi to its related strata from eastern Asia, Russia, Japan, and North America.
94
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112

G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112 95
rations from bed 12 yielded species such as Canningia
pistica Helby, Kiokansium polypes (Cooks.
et Eis.) Below, Muderongia testudinaria Burger,
Muderongia tetracantha (Gocht.) Alberti, Oligosphaeridium
complex (White) Davey et Williams,
and Palaeoperidium cretaceum Pocock. Sun et al.
(1992b) suggest that the age of the dino£agellate
assemblage from bed 12 is Valanginian^Hauterivian.However,
He and Sun (2000) studied the
dino£agellates from the lower part of the Chengzihe
Formation of Jixi and reported the following
taxa: Odontochitina operculata (O.Wetzel) De£.
et Cooks., Muderongia tetracantha (Gocht.) Alberti,
Batioladinium? exiguum (Alberti) Brideaux,
Gardodinium trabeculosum (Gocht.) Alberti, Palaeoperidium
cretaceum Pocock, Kiokansium sp.,
Escharisphaeridia pocockii (Sarj.) Erkmen et Sarjeant,
Circulodinium asymmetricum (Burger) He et
Sun, Nyktericysta puyangensis Wang et Qiao and
Oligosphaeridium jixiense He et Sun.These two
authors considered the age of marine bed 12
yielding the dino£agellates to be late Hauterivian,
and the age of the lower part of the Chengzihe
Formation to be late Valanginian^late Hauterivian
(He and Sun, 2000).Therefore, we suggest
that the age of the early angiosperms collected
from beds 27^47 in the Chengzihe Formation is
late Hauterivian or late Hauterivian^early Barremian
(Fig.2).
The Chengzihe Formation is conformably overlain
by the coal-bearing Muling Formation.The
two formations correspond to the lower part of
Lipovich Formation and Ussuri Formation, dated
as Barremian^Aptian age.These correlations can
also be extended to the Ussuri Formation, which
is the equivalent of the Older Suchan Formation
from the neighboring Suchan Basin which overlies
the Berriasian^Valanginian marine beds (see Fig.
3 for details of this correlation).Therefore, the
Muling Formation is considered middle^late Barremian
to early Aptian, while the whole Chengzihe
Formation is considered Valanginian (or late
Berriasian) to late Hauterivian (or early Barremian)
in age (Sun et al., 1992a,b, 2000).
Only about 80 specimens of angiosperm megafossils
have been collected from the Chengzihe
Formation by the authors so far, including the
three angiosperm reproductive organs described
here, while specimens of the other plants associated
with the angiosperms number nearly 1000.
That means the early angiosperm megafossils are
rare (about 8%) in the assemblage.This is also the
case when the pollen from these sediments was
examined (Shang, 1997). Brenner and Bicko¡
(1992) and Brenner (1996) also found that early
angiosperm pollen is present at only very low percentages
in the Valanginian^Hauterivian of Israel.
Dilcher and Farley (1988) noted in Cenomanian
age sediments that 63^75% of the megafossils recovered
were angiosperms while only 21^23% of
the miospores recovered were angiosperms.This
demonstrates that angiosperm diversity and abundance
dominate as megafossils long before they
do so in the miospore record.
There are only a few specimens which are compressions
and with cuticle preserved.The preparations
for anatomical study of the reproductive
axis and the cuticles of the angiosperm leaves
were made with Schultze solution for the macerations,
and scanning electron microscopy (SEM)
observations were made with a JAL-3600 SEM.
The surface of the reproductive axis was examined
with Zeiss epi£uorescence and individual pollen
and clusters of pollen grains were studied.
Often extreme oblique light was used to discern
the nature of the leaf margins and the venation
while studying the specimens with a Wild M 500
dissecting microscope.The described specimens
are housed in Nanjing Institute of Geology and
Palaeontology, Academia Sinica, Nanjing, China.
3. Systematics
The following early angiosperm taxa from the
Early Cretaceous Chengzihe Formation of Jixi,
China are described in this paper: Asiatifolium
elegans Sun, Guo et Zheng emend.Sun et Dilcher,
Jixia pinnatipartita Guo et Sun emend.Sun et
Dilcher, Jixia chengzihensis Sun et Dilcher sp.
nov., Jixia sp., Shenkuoa caloneura Sun et Guo
emend.Sun et Dilcher, Zhengia chinensis Sun et
Dilcher gen.et sp.nov., Xingxueina heilongjiangensis
Sun et Dilcher, Xingxuephyllum jixiense
Sun et Dilcher gen.et sp.nov., Reproductive organ
A, Reproductive organ B.

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Angiospermae
Dicotyledonae
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112 97
Genus Asiatifolium Sun, Guo et Zheng, 1992
Type: Asiatifolium elegans Sun, Guo et Zheng
emend.Sun et Dilcher
Generic diagnosis: Leaf pinnately compound, rachis
nearly straight.Lea£et oblong to obovate;
apex obtuse to rounded; base cuneate.Margin
entire.Petiole chartaceous.Venation pinnate, brochidodromous;
midvein stout.Secondary veins 5^
8 pairs, nearly opposite.Tertiary and quaternary
veins nearly equal in thickness.Submarginal vein
present.
Asiatifolium elegans Sun, Guo et Zheng emend.
Sun et Dilcher
Plate I, 1^11; Plate III, 8^10; Fig.4A^C
Synonyms:
1992a Asiatifolium elegans Sun, Guo et Zheng; Sun et al., p.
546, pl.I, ¢gs.1^3.
1992a Chengzihella obovata Guo et Sun; Sun et al., p. 546,
pl.I, ¢gs.4^9.
1995 Asiatifolium elegans Sun, Guo et Zheng; Sun, p.429,
pl.141, ¢gs.1^3, text-¢g.9^2, 1^2.
1996 Asiatifolium elegans Sun, Guo et Zheng; Sun and
Dilcher, p.393, pl.1, ¢gs.1^9, text-¢g.1A^B.
Emended description: Leaf pinnately compound,
rachis nearly straight, rachis about 0.6^1.0 mm
in thickness.Lea£et obovate (oblanceolate), usually
1.9^4.8 cm (minimum = 0.7 cm) long by 1.1^
2.0 cm (minimum = 0.3 cm) wide; margin entire;
apex obtuse, often slightly rounded.Leaf lamina
partly asymmetrical, tapering gradually to form a
slight to pronounced asymmetrical base.Petiole
medium length ca. 1.0 cm long by 0.7 mm wide.
Petiolule very short 2.0 mm long by 1.0 mm wide,
appearing to be in£ated.Venation pinnate; midvein
conspicuous with a pronounced taper in
width towards the apex (base 0.5 mm to apex
0.1 mm) and straight to slightly curved. Secondary
veins appear subopposite with branching
more or less irregularly, at 40^50‡ angle from
midvein, secondary veins fork equally in the outer
1/3 of the lamina and may continue to fork two or
three times forming a network that eventually
joins a sub-marginal vein.Few or no intersecondary
veins.The tertiary venation and quaternary
venation often arising at 90‡ angles.Ultimate venation
preserved, appearing to form a closed network
of areole.An evident marginal vein (ca.0.1
mm wide) present just inside of the leaf margin by
about 0.2 mm.
Discussion: The new material (Plate I, 7;Fig.4B)
provides more complete characters of the leaf
which is actually compound, not simple as indicated
in Sun et al.(1992a).The marginal veins,
present just inside the leaf margin by a very short
distance, can be regarded as one of the main characters
of the present species.Regarding the loops
near the margin described by Sun et al.(1992a, p.
546), they seem to be very obscure and would best
be regarded as a sector of the marginal vein.Since
the main characters of Chengzihella obovata (Sun
et al., 1992a, p.546, pl.I, ¢gs.4^9) are consistent
with the present species, the former should be incorporated
into the present species.
Material: More than 20 specimens.
Locality and horizon: Chengzihe of Jixi, Heilongjiang,
China; Chengzihe Formation in the W-B
Section beds Nos.29, 42, 45 and 47.
Plate I.All of the specimens described here are collected from the Lower Cretaceous Chengzihe Formation of Jixi, Heilongjiang,
China, and are housed in Nanjing Institute of Geology and Palaeontology, Academia Sinica, Nanjing, China.
1^11. Asiatifolium elegans Sun, Guo et Zheng emend.Sun et Dilcher.
1, 2.PB16766.1.Bar = 0.5 cm.2.Bar = 1 cm.
3, 10.PB16771.3.Bar = 1 cm.10.Bar = 0.5 cm.
4, 5. PB16772.4.Bar = 1 cm.5.Bar = 0.5 cm.
6.SC10011.Bar = 0.5 cm.
7.SC10013.Bar = 0.5 cm.
8.SC10012.Bar = 0.5 cm.
9.PB16768.Bar = 1 cm.
11.Venation of the leaf and showing the intramarginal vein in detail of 9.Bar = 0.2 cm.

98
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112
Fig.4.Early angiosperms from Lower Cretaceous Chengzihe Formation of Jixi, Heilongjiang, China.(A^C) Asiatifolium elegans
Sun, Guo et Zheng emend.Sun et Dilcher, PB16766, SC10013, PB16768.U1.7, U1.5, U1.5. (D) Jixia pinnatipartita Guo et Sun
emend.Sun et Dilcher, PB16773.U2.(E) Shenkuoa caloneura Sun et Guo emend.Sun et Dilcher, PB16777.U2.(F,I) Jixia
chengzihensis Sun et Dilcher sp.nov., PB16774.U2.(G) Xingxueina heilongjiangensis Sun et Dilcher and Xingxuephyllum jixiense
gen.et sp.nov., SC10025,10026.U2.2. (H) Jixia sp., SC10016. U1.7.

G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112 99
Genus Jixia Guo et Sun, 1992
Type: Jixia pinnatipartita Guo et Sun emend.Sun
et Dilcher
Generic diagnosis: Leaf simple, pinnately lobed,
lobes opposite to alternate.Obtuse sinuses extending
to near midvein.Venation pinnate.Midvein
prominent, arched to zigzag.Secondary veins decurrent
along midvein, transversing lamina lobe
near admedial margin.Tertiary and quaternary
veins present.Marginal vein present.
Jixia pinnatipartita Guo et Sun emend. Sun et
Dilcher
Plate II, 1,9;Fig.4D
Synonyms:
1992a Jixia pinnatipartita Guo et Sun; Sun et al., p. 547, pl.
I, ¢gs.10, 12; (non pl.I, ¢g.11).
1992a Rogersia lanceolata Fontaine; Sun et al., p. 543, pl. I,
¢g.15.
1995 Jixia pinnatipartita Guo et Sun; Sun, p.429, pl.141,
¢g.4; text-¢g.9^2, 3.
1996 Jixia pinnatipartita Guo et Sun; Sun and Dilcher, p.
393, pl.1, ¢g.10; text-¢g.1C.
Emended description: Leaf simple, deeply once
pinnately lobed, ca. 1.5^4.5 cm long by 0.6^4.0
cm wide.Margin entire.Apex not preserved;
base narrow cuneate.Petiole incomplete.Lobes
subopposite to alternate, vary in number, form
and size.Basal lobes shorter and appear placed
at an angle of 80‡ to the midvein.Median lobes
narrowly oblong orientated at angles of 60^70‡ to
the midvein, extending free some distance from
the central leaf lamina.Deep obtuse sinuses with
rounded margins extending nearly to the leaf midvein
separate the lobes.Midvein arched, prominent
and giving rise to prominent secondary veins
that arch gradually paralleling the midvein for a
short distance, a signi¢cant portion of the midvein
appears to feed into each secondary vein.The secondary
veins innervate the lobes asymmetrically
transversing the lamina lobe nearer the admedial
lobe margin.Tertiary veins branch at an angle of
75‡ and are often parallel, may branch once near
the leaf margin before joining a marginal vein.
Some tertiary veins extending into narrow lamina
of the lobes depart at an angle of nearly 90‡.
Quaternary venation may branch at nearly right
angles from the tertiary veins forming poorly preserved
areoles.
Discussion: The emended description of the
present species is mainly supplemented by having
the evident marginal vein and the character classi-
¢ed of its tertiary and quaternary venation.One
of the specimens originally described as the
present species (Sun et al., 1992a, p.547, pl.I,
¢g.11) di¡ers from the present species in having
a multi-lobed leaf, and secondary veins arising
opposite or nearly opposite from the midvein.
Therefore, this species of the genus Rogersia originally
described by Fontaine (1889), has been assigned
to a new species described below in detail.
Reviewing the specimen Rogersia lanceolata, originally
described by Sun et al.(1992a, p.543, pl.I,
¢g.15) is actually a segment lobe of the present
species.
Material: 6 specimens.
Locality and horizon: Ibid., in the W-B section
beds Nos.45 and 47.
Jixia chengzihensis Sun et Dilcher sp. nov.
Plate II, 2, 3, 5^8, 10, 11, 13; Fig.4F,I
Synonyms:
1992a Jixia pinnatipartita Guo et Sun; Sun et al., p. 547, pl.
I, ¢g.11.
1995 Jixia chengzihensis Sun et Dilcher; Sun, p.429, p1.
141, ¢gs.5, 7, text-¢g.9^2, 4; [nomen nudum, nomen
invalidum].
1996 Jixia chengzihensis Sun et Dilcher; Sun and Dilcher,
p.393, p1.1, ¢g.11, text-¢g.1D; [nomen invalidum].
Description: Leaf simple, deeply pinnately lobed.
Lobes may have pinnate shallow lobes, usually
1.7^3.2 cm long by ca. 2.0 cm wide. Margin entire.Apex
and base not preserved.Primary lobes
opposite to subopposite, vary in size and shape.
Some lobes preserved are ca. 1.0 cm long by 0.3^
0.4 cm wide at lobe base increasing to 0.7^0.8 cm
wide where secondary lobes are present.One or
two pairs of secondary lobes borne from middle
to apex of the primary lobe.Secondary lobes subopposite
with rounded apex.Midvein of leaf progresses
somewhat zigzag fashion from lobe to
lobe.Midvein prominent, 0.6 mm wide basally
and tapers distally.Secondary veins slightly irregular
that extend into the secondary lobes.Tertiary

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G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112

veins poorly preserved, arising from midrib and
secondary veins at wide angles.Quaternary veins
borne at wide angles (up to 90‡) and transverse
leaf lamina to a marginal vein.The 5th order
reticulate venation preserved.Thick marginal
vein forms part of the leaf margin.
Holotype: SC10014, Plate II, 2, 11.
Discussion: The present species is characterized by
secondary lobes, and the secondary veins arising
opposite or nearly opposite from the midvein
which is the major di¡erence between the present
species and Jixia pinnatipartita.
Material: 12 specimens.
Locality and horizon: Ibid., in the W-B section
beds Nos.45 and 47.
Jixia sp.
Plate II, 4,12;Fig.4H
Synonym:
1995 Angiosperm leaf A, Sun, p.429, text-¢g.9^2, 7.
Description: An isolated lobe, more than 3.0 cm
long by 1.0^1.1 cm wide; alternate and oblique
pinnately lobed.Apex and base not preserved.
Lobes nearly asymmetrically triangular in shape,
bluntly acute in apex.Secondary vein thin and
slightly curved.Tertiary veins alternate and narrow,
arising from secondary vein and reaching
each lobe apex.Quaternary and their smaller
veins form areoles.
Discussion: Morphologically, the present isolated
lobe should be attributed to Jixia.The present
species is more or less similar to Jixia pinnatipartita
morphologically, but di¡ers in having triangular
lobes.The present material is also similar to
Jixia chengzihensis, but di¡ers in having alternate
tertiary veins arising from the secondary vein, and
having triangular lobes.
Plate II.
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112 101
Material: 3 specimens.
Locality and horizon: Ibid., in the W-B section
bed No.47.
Genus Shenkuoa Sun et Guo, 1992
Type: Shenkuoa caloneura Sun et Guo
Generic diagnosis: Leaf simple; apex acute, margin
entire.Venation pinnate, brochidodromous.
Midvein prominent.Secondary veins subopposite,
more than 8 pairs, branching profusely.Exmedial
loops of secondary veins along leaf margin.Tertiary
and quaternary veins present.Marginal vein
absent.
Shenkuoa caloneura Sun et Guo emend.Sun et
Dilcher
Plate III, 1^3, ?11; Fig.4E
Synonyms:
1992a Shenkuoa caloneura Sun et Guo; Sun et al., p. 547
pro parte, pl.I, ¢g.13; pl.II, ¢g.1; (non pl.I, ¢g.
14, pl.II, ¢gs.2^6).
1995 Shenkuoa caloneura Sun et Guo; Sun, p.429, pl.141,
¢g.6, text-¢g.9^2, 6.
1996 Shenkuoa caloneura Sun et Guo; Sun and Dilcher, p.
393, pl.1, ¢g.6, text-¢g.12^14.
Emended description: Leaf simple; margin entire;
apex bluntly acute.Midvein given rise to secondary
veins which arch upward then away at angles
of 60^70‡.Intersecondary veins present and
branching profusely.Secondary veins forking
broadly ca.70‡ and profusely toward the leaf
margin.Very weakly brochidodromous interconnections
formed between secondary veins.Exmedial
loops of the secondary veins extending to and
along the leaf margin.No regular loops observed.
Tertiary and quaternary veins usually forming
rectangular or pentagonal areoles.No marginal
vein observed.
1, 9. Jixia pinnatipartita Guo et Sun emend.Sun et Dilcher, PB16773.1.Bar = 0.5 cm.9.Bar = 0.5 cm.
2, 11. Jixia chengzihensis Sun et Dilcher sp. nov., Holotype SC10014. 2. Bar = 0.5 cm. 11. Bar = 0.5 cm.
3, 6. Jixia chengzihensis Sun et Dilcher sp. nov., PB16774. 3. Bar = 0.5 cm. 6. Bar = 0.5 cm.
4, 12. Jixia sp., SC10016. 4. Bar = 0.5 cm. 12. Bar = 0.5 cm.
5, 8. Jixia chengzihensis Sun et Dilcher sp. nov., SC10015. 5. Bar = 0.5 cm. 8. Bar = 0.5 cm.
7. Jixia chengzihensis Sun et Dilcher sp. nov., PB16775. Bar = 0.5 cm.
10. Jixia chengzihensis Sun et Dilcher sp. nov., SC10027. Bar = 0.5 cm.
13. Jixia chengzihensis Sun et Dilcher sp. nov., showing sublobes of 3. Bar = 0.5 mm.

102
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112

Discussion: The present species is characterized by
irregular venation mentioned above.
Material: 2 specimens, including one questionable
in identi¢cation.
Locality and Horizon: Ibid., in the W-B section
bed No.47.
Genus Zhengia Sun et Dilcher gen.nov.
Type: Zhengia chinensis Sun et Dilcher gen.et sp.
nov.
Generic diagnosis: Leaf or lea£et.Margin entire.
Venation pinnate.Secondary veins branching dichotomously
one or two times after going 1/2 distance
to leaf margin.Tertiary and quaternary
veins present.Marginal vein present.Leaves hypostomatic.Stomata
anomocytic; guard cells
sunken; subsidiary cells with collar £ange.
Zhengia chinensis Sun et Dilcher gen. et sp. nov.
Plate IV, 1^7
Synonyms:
1992a Shenkuoa caloneura Sun et Guo; Sun et al., p. 547
pro parte, pl.I, ¢g.14; pl.II, ¢gs.2^6; (non pl.I,
¢g.13; pl.II, ¢g.1).
1996 Zhengia chinensis Sun et Dilcher, p.393, pl.1, ¢g.15;
pl.2, ¢gs.7^9 [nomen nudum, nomen invalidum].
Description: Leaf or lea£et more or less coriaceous,
about 3.5 cm long by 2.4 cm wide; elliptic.
Margin entire.Midvein nearly straight, about 0.5
mm in thickness.Secondary veins arising from
midvein at angles of 60^70‡, and branching dichotomously
one or two times after going 1/2 distance
to the leaf margin.Tertiary and quaternary
veins forming areoles and joining at marginal
vein.Leaves hypostomatic.In upper cuticle, ordinary
epidermal cells irregularly polygonal in form
(average size ca.15U10 Wm), anticlinal walls
nearly straight or slightly sinuous.In lower cu-
Plate III.
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112 103
ticle, stomata elliptic to ovate, anomocytic (average
size ca.30U25 Wm), randomly orientated.
Guard cell sunken and subsidiary cells cutinized
strongly at edges as a collar £ange.Ordinary epidermal
cells irregularly polygonal in form (average
size ca.25 U20 Wm), outer side of periclinal
walls not smooth, but with numerous grooves.
Holotype: SC10023, Plate IV, 1, 3^6.
Etymology: Zhengia, named in honor of Professor
S.L. Zheng of the Shenyang Institute of Geology
and Mineral Resources for his contributions in
the collecting and research work on the Jixi early
angiosperms; chinensis, country in which the
specimen was discovered.
Discussion: The present species is characterized by
coriaceous leaves, and anatomical features mentioned
above.The present material is similar to
Shenkuoa caloneura, but di¡ers in the secondary
veins branching only one or two times, lacking
exmedial looping near the leaf margin, and a presence
of marginal veins.
Material: 6 specimens.
Locality and horizon: Ibid., in the W-B section
bed No.47.
Genus Xingxuephyllum Sun et Dilcher gen. nov.
Type: Xingxuephyllum jixiense Sun et Dilcher gen.
et sp.nov.
Generic diagnosis: Leaf simple.Margin entire.
Midvein prominent.Venation pinnate.Secondary
veins alternate, branching 1/2 to 2/3 distance to
leaf margin.Tertiary and smaller veins present.
Intramarginal vein present.
Xingxuephyllum jixiense Sun et Dilcher gen. et sp.
nov.
Plate V, 1B, 2; Plate III, ?11; Fig.4G
Description: Leaf simple, about 3.5 cm long by
2.0 cm wide (incomplete preservation). Margin
1^3. Shenkuoa caloneura Sun et Guo emend.Sun et Dilcher.3.Showing the irregular venations.PB16777.1.Bar = 0.5 cm.
2.Bar = 0.3 cm.3.Bar = 1 mm.
4, 5. Reproductive organ A, SC10017.4.Bar = 0.33 cm.5.Bar = 1 cm.
6, 7. Reproductive organ B, SC10018.6.Bar = 0.5 cm.7.Bar = 0.33 cm.
8^10. Asiatifolium elegans Sun, Guo et Zheng emend.Sun et Dilcher, SC10019-10021.Bars = 0.5 cm.
11. Shenkuoa caloneura Sun et Guo emend.Sun et Dilcher, SC10022.Bar = 0.5 cm.

104
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112

entire.Petiole about 4.5 mm long.Midvein distinct,
about 0.4^0.5 mm in thickness; alternating
secondary veins departing midvein at medium to
wide angles, appear to branch 1/2 to 2/3 distance
towards the leaf margin and joining with intramarginal
vein.Tertiary and smaller veins thin,
form a dense network of polygonal areoles.
Holotype: SC10026, Plate V, 1B, 2; Fig.4G.
Etymology: Xingxuephyllum, named in honor of
Professor Xingxue Li of the Nanjing Institute of
Geology and Palaeontology, Academia Sinica for
his contributions to the study of the early angiosperms
from NE China during the 1950s to
1990s; jixiensis, the locality of the new species.
Discussion: The leaf is probably connected organically
with the in£orescence of Xingxueina heilongjiangensis
gen.et sp.nov.(see below).Since the
joint part of the present leaf to the in£orescence is
not well-preserved, the authors will give a new
taxon name to the present leaf.However, names
of the leaf and in£orescence will be combined to
the same taxon when better material showing
clear organic connection mentioned above has
been found.Morphologically, the present leaf is
more or less similar to Shenkuoa, but the latter
has triangular and slightly acute apex which is not
shown in the present species.Moreover, Shenkuoa
is incompletely preserved in its leaf base, which is
di⁄cult to compare to the present species.
Material: 2 specimens.
Locality and horizon: Ibid., in the W-B section
bed No.47.
Genus Xingxueina Sun et Dilcher, 1997
Type: Xingxueina heilongjiangensis Sun et Dilcher
Xingxueina heilongjiangensis Sun et Dilcher
Plate V, 1A, 3^5; Plate VI, 1^6; Fig.4G
Synonyms:
Plate IV.
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112 105
1995 Xingxueina heilongjiangensis Sun et Dilcher; Sun, p.
429, text-¢g.9^2, 8 [nomen invalidum].
1996 Xingxueina heilongjiangensis Sun et Dilcher; Sun and
Dilcher, p.393, pl.2, ¢gs.1^6; text-¢g.1E [nomen
invalidum].
1997 Xingxueina heilongjiangensis Sun et Dilcher; Sun and
Dilcher, p.137, pl.1, ¢gs.1^7; pl.2, ¢gs.1^6; text-
¢g.2.
Description: In£orescence elongate, about 4.2^4.6
mm wide and more than 14 mm long (incomplete
length preserved), consisting of numerous small
£orets borne helically upon an axis.The peduncle
or stock below the position of the £orets is
smooth, slightly bent or arching, 1.2^1.5 mm
wide by 20 mm long borne in the axil of a leaf.
Florets subtended by bracts, 0.8U1.2 mm, £orets
rounded, small, 1.1^1.5 mm in diameter and
crowded helically upon axis.Structure of individual
£oret not understood but pollen in situ have
been found.Pollen nearly circular, 15^20 Wm
in diameter, seemingly inaperturate, exine reticulate
and tectate-columellate, muri more or less
smooth, 0.3 Wm wide, net-like, areoles irregularly
polygonal, about 0.2^1.0 Wm in diameter.
Discussion: The present in£orescence is characterized
by its small size, stout and longer peduncle,
and in situ inaperturate pollen which di¡ers from
those known so far in the world.The present
pollen bears some resemblance to Afropollis
from Israel (Brenner, 1996) but di¡ers in having
smaller areoles and smoother muri on the exine.
Brenner (1996) reported on the oldest known angiosperm
pollen from a core sample taken from
two wells with sediments of late Valanginian to
late Hauterivian age, in Israel (Brenner and Bicko¡,
1992).He reports that the earliest known
angiosperm pollen consist of small, circular, inaperturate
forms with tectate-columellate exine
(Brenner, 1996), however, the pollen is known
1^7. Zhengia chinensis Sun et Dilcher gen.et sp.nov.
1, 2. Showing two incomplete leaves, Holotype SC10023, 10024.1.Bar = 0.5 cm.2.Bar = 0.33 cm.
3^6.Lower cuticle (inside view), SC10023.
3, 6.Stomatal zones, SEM0964, 0965.3.Bar = 30 Wm.6.Bar = 30 Wm.
4, 5.Stomata in detail, SEM0966, 0967.4.Bar = 10 Wm.5.Bar = 10 Wm.
7.Pits and uneven periclinal walls in lower cuticle (outside view), PB16776, SEM0673.Bar = 25 Wm.

106
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112

only from dispersed pollen grains.It is signi¢cant
that we have the same pollen type from an in£orescence
in situ which is seemingly attached to a
dicotyledonous leaf.Previously it was thought
that the sulcus of monosulcate angiosperm pollen
were derived from a gymnosperm ancestor which
had monosulcate pollen.However, Brenner proposes
a new model for the evolution of the monosulcate
aperture in angiosperms.He suggests that
the sulcus was developed from within the angiosperm
lineage and that its presence in angiosperms
is entirely an angiosperm feature and not
derived from a non-angiospermous ancestor.The
inaperturate nature of both the pollen mention
here and that described by Brenner may be the
result of the sometimes cryptic nature of apertures
in some angiosperms. Endress (1987) indicates
that in some genera the apertures are often hidden
by reticulate exine ornamentation.The occurrence
of very similar, small, circular, ‘inaperturate’, reticular,
tectate-columellate pollen which Brenner
found as dispersed pollen in Israel, is known
from a megafossil in situ in China.This new material
may provide new characters useful in understanding
the nature of early angiosperms.
The in£orescence consists of a clustering of
small helically arranged £orets borne on a rather
stout axis.Because of the carbonaceous nature of
the preservation and the crowded nature of the
£orets, it is di⁄cult to discern the nature of
each £oret.The parts seem to be very small, forming
£orets 1.0^1.5 mm in diameter. Since the pollen
are derived from the £orets in situ, we assume
that there were anthers in the £orets, but do not
know if the £orets were bisexual or unisexual.
However, it seems most probable that since the
reproductive axis appears to be still attached to
the leaf, in which axis it was borne, and because
Plate V.
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112 107
most all of the £orets are still attached to a common
axis, with no indication of fruit formation,
that the £orets are young or immature.Because
pollen is present and well formed, perhaps the
pollen bearing organs matured before the ovules.
Nevertheless, until we can collect additional material
and make more preparations, we consider
that these £orets were either bisexual or male.
Small bisexual £orets have been described from
the Albian (Friis et al., 1994) and Turonian (Crepet
and Nixon, 1994) sediments in eastern North
America.These £orets are small (2.2 mm), pedicellate,
bear monosulcate pollen and are described
as isolated £orets.The only feature similar between
the fossil £orets of Virginianthus and Xingxueina
is the small size of the £orets.But this is
important because it indicates that several early
angiosperms had £owers that were small, many
of which were crowded upon an individual axis.
Friis et al.(1994) compares Virginianthus with
Calycanthaceae and notes many similarities between
the fossil and several genera of that family,
several of which have small £orets. Crepet and
Nixon (1994) in their review of the fossil £owers
of the Magnoliidae suggest that the angiosperm
ancestral groups probably had small simple £owers
with parts in whorls similar to that known for
the Chloranthaceae, Platanaceae, Buxaceae and
Lauraceae (Friis et al., 1991).Also, Dilcher
(1979) suggested that early angiosperms may
have had small simple £owers.The reproductive
axis appears to be borne in the axil of the leaf of
Xingxuephyllum (Plate V, 1B, Fig.4G).There are
two small carbon fragments of the petiole missing,
but it appears as if the petiole continued to the
slightly enlarged base which is in common with
the base of the reproductive axis.We also considered
a possibility that the two fossils just hap-
1A, 3^5. Xingxueina heilongjiangensis Sun et Dilcher.
1A, 3. In£orescence, SC10025. 1A. Bar = 0.5 cm. 3. Bar = 0.2 cm.
4.Pollen grain from the in£orescence.SEM0775.Bar = 10 Wm.
5.Pollen grains in situ on the surface of the in£orescence as viewed by epi£uorescence microscopy, SC10025.Bar = 80
Wm.
1B, 2. Xingxuephyllum jixiense gen.et sp.nov.Incomplete leaf probably connected organically with the in£orescence,
Holotype SC10026. 1B. Bar = 0.5 cm. 2. Bar = 0.6 cm.

108
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112

pened to fall across one another.If this would be
the case, there should be some indication that one
lays over the top of the other, which, upon close
examination in oblique light, was not the case.
Therefore, we consider that the leaf and the reproductive
axis probably belong together.The
leaf has tertiary and higher venation pattern of
a low order rank that seems to be typical of several
Lower Cretaceous angiosperm leaves.It is
most similar to a generalized Magnoliidae type
leaf. Friis and Endress (1990) suggest that the
extant members of the Magnoliidae exhibit the
most primitive characters of all £owering plant
groups.Some revisions appear to be needed
with the recent hypothesis by Brenner (1996)
and the fossil reproductive structure of Xingxueina
provides many new characters that we hope
will be useful in the overall evaluation of primitive
or early angiosperm characters.
Material: one specimen.
Locality and horizon: Ibid., in the W-B section
bed No.47.
Reproductive organ A
Plate III, 4,5
Description: In£orescence-like in character, oblong
in form, about 2 cm long by 1.1 cm wide.
Axis about 1.5^2.0 mm in thickness, more than
2.5 cm long. The structure of the reproductive
organ not understood, but some fragments look
like the individual reproductive parts preserved in
the specimen.The fragments consist of numerous
disc-like pieces (perhaps seeds or fruits), ca.0.4
mm in diameter.
Material: one specimen.
Locality and horizon: Ibid., in the W-B section
bed No.45.
Reproductive organ B
Plate III, 6,7
Plate VI.
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112 109
Description: In£orescence-like in character, incomplete
in shape, catkin-like, about 3.5 cm
long by ca. 1.2 cm wide. Axis stout, about 1.5
mm wide.Stalk visible more than 5 mm long.
The detailed structure of the reproductive organ
unknown.
Material: one specimen.
Locality and Horizon: Ibid.In the W-B section
bed No.45.
4. Discussion
The early angiosperms from the Chengzihe
Formation of Jixi, China basically are characterized
by their simple, microphyllous, entire leaves
with more or less irregular pinnate and reticulate
venation.Palynologically, the angiosperms have
apparent inaperturate pollen associated with
some dispersed monosulcate types (Shang, 1997).
Based on these characteristics, the Jixi early angiosperms
appear to be early in their development
although they already show some diversity.
The early angiosperm Dicotylophyllum pusillum
Vachr.from the Zazin Formation of the Transbaikalia,
Russia (Vachrameev, 1973, 1991; Krassilov,
1997) is quite similar to Asiatifolium elegans
from the Chengzihe Formation of Jixi, China.
The Russian angiosperm has been considered as
Hauterivian or Hauterivian^Barremian in age by
the Russian authors.In South Primorye of Russia
in the neighboring areas of Jixi, Heilongjiang,
China, there are also some early angiosperms
such as Nyssidium orientale Samylina which is
also considered as Hauterivian or Hauterivian^
Barremian (Samylina, 1968).Thus, it appears
that the Jixi angiosperms described in this paper
represent the early^middle Early Cretaceous level
of the early angiosperm development in Northeast
China and also in northeastern Asian regions.
1^6. Xingxueina heilongjiangensis Sun et Dilcher, SC10025.
1, 2, 6.Showing three pollen grains, SEM0776, 0777, 0779.1.Bar = 10 Wm.2.Bar = 1.5 Wm.6.Bar = 5 Wm.
3, 4.Showing pollen grains borne/attached to periclinal walls of the male parts of the in£orescence (inside view),
SEM0793, 0794.3.Bar = 20 Wm.4.Bar = 10 Wm.
5.Showing some pits and uneven periclinal walls (outside view), SEM0795.Bar = 6 Wm.

110
The early angiosperms of Jixi, China seem to be a
‘link’ in the evolution of early angiosperms which
connects the late Early Cretaceous (Aptian^Albian)
angiosperms in the NE Asian regions such
as those from the Dalazi Formation of NE China
and from the North Suchan Formation of South
Primorye, Russia; to the early Early Cretaceous
or Late Jurassic angiosperms such as those from
the Yixian Formation including Archaefructus,
the earliest known angiosperm reproductive
megafossil material (Sun et al., 1998).
Since the Chengzihe Formation yielding the
early angiosperms consists of marine and non-marine
alternate deposits that can be dated as Hauterivian
or perhaps Valanginian to early Barremian
(Sun et al., 1992b; Sun, 1995), the early
angiosperms can be regarded as index fossils or
standards for biostratigraphic correlations in geological
mapping or prospecting for sedimentary
mineral resources including coal, natural gas or
even oil in Northeastern Asian regions.Moreover,
since the associated plants with the early angiosperms
in the Chengzihe Formation of Jixi are
thermophilous and hygrophilous, in general, and
most of them are coal-forming plants, the Jixi
early angiosperm study should also be helpful in
the reconstruction of paleoclimates, paleogeography
and paleoenvironment in eastern Asia during
the Early Cretaceous.
5. References quoted in Fig. 3
Brenner, 1963; Doyle and Hickey, 1976;
Franks, 1979; Hattin and Siemers, 1978; Kimura,
1975, 1980; Kimura and Ohana, 1990; Krassilov,
1967; Markevich et al., 2000; Retallack and
Dilcher, 1986.
Acknowledgements
G. Sun, D.L. Dilcher / Review of Palaeobotany and Palynology 121 (2002) 91^112
The authors are grateful to the National Natural
Science Foundation of China (NNSFC) for
their support to Projects 39370055, 39779959,
39970050 and to the Chinese Academy of Sciences
(CAS) for their supporting Project KZ952-S1-
426; and to the Florida Museum of Natural His-
tory, and the Becker-Dilcher Endowment Fund of
the Florida Foundation, University of Florida,
and Nanjing Institute of Geology and Palaeontology,
Academia Sinica (NIGPAS) for their kind
support to the present co-operative work.Many
thanks are extended to Profs. Zheng S.L., Piao
T.Y., Shang Y.K. and Mr. Li C.T. for their
help in the ¢eld work; to Drs.G.Brenner,
Wang X.F. and Ouyang S. for their help in the
pollen study; to Mr.T.A.Lott, M.Muller (UF)
and Mao Y.Q. and Li G.J. (NIGPAS) for their
assistance in manuscript preparation, photographing,
illustrations and SEM work.Thanks to Zlatko
Kva›cek and Masamichi Takahashi for their
thoughtful and helpful comments in the review
of this paper.
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