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LETTER doi:10.1038/nature09811
A eudicot from the Early Cretaceous of China
Ge Sun
1,2
, David L. Dilcher
1,2,3
, Hongshan Wang
1,4
& Zhiduan Chen
5
The current molecular systematics of angiosperms
1
recognizes the
basal angiosperms and five major angiosperm lineages: the
Chloranthaceae, the magnoliids, the monocots,
Ceratophyllum
and the eudicots, which consist of the basal eudicots and the core
eudicots
2
. The eudicots form the majority of the angiosperms in the
world today. The flowering plants are of exceptional evolutionary
interest because of their diversity of over 250,000 species and their
abundance as the dominant vegetation in most terrestrial ecosys-
tems, but little is known of their very early history. In this report we
document an early presence of eudicots during the Early Cretaceous
Period. Diagnostic characters of the eudicot fossil
Leefructus
gen.
nov. include simple and deeply trilobate leaves clustered at the
nodes in threes or fours, basal palinactinodromous primary vena-
tion, pinnate secondary venation, and a long axillary reproductive
axis terminating in a flattened receptacle bearing five long, narrow
pseudo-syncarpous carpels. These morphological characters sug-
gest that its affinities are with the Ranunculaceae, a basal eudicot
family. The fossil co-occurs with
Archaefructus sinensis
3
and
Hyrcantha decussata
4
whereas
Archaefructus liaoningensis
5
comes
from more ancient sediments. Multiple radiometric dates of the
Lower Cretaceous Yixian Formation place the bed yielding this
fossil at 122.6–125.8 million years old
6–8
. The earliest fossil records
of eudicots are 127 to 125 million years old, on the basis of pollen
9,10
.
Thus,
Leefructus
gen. nov. suggests that the basal eudicots were
already present and diverse by the latest Barremian and earliest
Aptian.
The evolutionary history of the angiosperms is still being revealed
since their Early Cretaceous or possible earlier origin and their rapid
radiations during the mid-Cretaceous
2,11,12,13
. Here we present a new
fossil plant from the Jehol Biota. The Jehol Biota is preserved mainly in
the Yixian Formation of northeast China (Figs 1 and 2), which has
yielded rich assemblages of animals and plants. Early birds, feathered
dinosaurs, placental mammals and a variety of invertebrate fossils have
been found
14–16
as well as several angiosperms,including Archaefructus
and Hyrcantha
3–5
. The presence of Archaefructus at about 125 Myr
ago
17
clearly documents the presence of basal angiosperms in the
megafossil record of the Early Cretaceous and now we also document
the presence of basal eudicots from the same stratigraphic horizon.
These early angiosperms are followed by diverse and abundant fossils
1
Paleontological Institute of Shenyang Normal University, Shenyang 110034, China.
2
Research Center of Paleontology, Jilin University, Changchun 130026, China.
3
Department of Biology, Indiana
University, Bloomington, Indiana 47405, USA.
4
Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611-7800,USA.
5
State Key Laboratory of Systematic and Evolutionary Botany,
Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
Liaoning
Beipiao
Beijing
Shenyang
50 km
Lingyuan
1
2
N
Figure 1
|
Fossil locations. The map shows the Dawangzhangzi locality in
Lingyuan where the fossil Leefructus mirus gen. et sp. nov. was collected (1) and
the Huangbanjigou locality in Beipiao where Archaefructus liaoningensis was
collected (2). The inset map shows the location of Liaoning Province in
northeast China (star indicates Beijing).
Jiufotang
Formation
Angiosperms Major vertebrates
Manchurochelys manchuensis
Lycoptera muroii
Pterodadyloidea
124.4 ± 1.1 Myr (ref. 6)
122.9 ± 0.3 Myr (ref. 7)
124.4 ± 1.4 Myr (ref. 8)
Leefructus mirus sp. nov.
Hyrcantha decussata
Archaefructus sinensis
Lycoptera davidi
Peipiaosteus fengningensis
Liaoxiornis delicatus
Jinzhousaurus yangi
129.7 ± 0.5 Myr (ref. 20)
125.2 ± 0.9 Myr (ref. 22),
125.0 ± 0.18 Myr (ref. 21)
126.1 ± 1.7 Myr to
127.4 ± 1.3 Myr (ref. 8)
Archaefructus liaoningensis
Archaefructus eoflora
Peipiaosteus pani
Confuciusornis sanctus
Sinosauropteryx prima
Caudipteryx zoui
Zhangheotherium quinquecuspidens
Jeholosaurus shangyuanensis
Tuchengzi
Formation
I
Lujiatun Bed
II
Jianshangou Bed
Yixian Formation
III
Daxinfangzi Bed
IV
Jingangshan Bed
200–300 m60–100 m200–400 m100–150 m
150–300 m
80–120 m
{
{
V V V
V V V
V V V
V V V
V V
V V V
V V
V V V
V V
V V V
V V
V V
122.1 ± 0.3 Myr (ref. 20)
V V V
V V
V V V
Basalt and andesite
With volcanic breccia (lava)
Shale and
tuff
Tuffaceous
sandstone and tuff
Conglomerate with
volcanic breccia
{
139.0 ± 0.5 Myr (ref. 20),
133.3 ± 2.6 Myr (ref. 17)
Figure 2
|
The ages of the Yixian Formation, showing the fossil angiosperms
and major vertebrates found there. The Yixian Formation is subdivided into
four beds. I, the Lujiatun Bed (about 129.7 Myr old
20
, recently dated as about
133.3 Myr old
17
). II, the Jianshangou Bed (about 125.2 Myr old
22
and 125.0 Myr
old
21
, recently dated as about 127.4–126.1 Myr old
8
. III, the Daxinfangzi Bed
(about 124.4 Myr old
6
and 122.9 Myr old
7
, recently dated as about 124.4Myr
old
8
. IV, the Jingangshan Bed (about 123–122.1Myr old
20
).
31 MARCH 2011 | VOL 471 | NATURE | 625
Macmillan Publishers Limited. All rights reserved
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of all major angiosperm taxa in sediments of the late Aptian and the
Albian ages (112 to 100Myr ago). Much of the record of early angio-
sperm diversity and their subsequent middle to late Albian radiations
come to us from fossils that encompass a complete range of preserved
plant organs such as pollen, mesofossils and megafossils
11,12
. We follow
the Angiosperm Phylogeny Group
18
to classify the fossil.
Angiosperms
Eudicots
Ranunculales (compare Family stem lineage to the Ranunculaceae)
Leefructus
Sun, Dilcher, Wang et Chen, gen. nov.
Leefructus mirus
Sun, Dilcher, Wang et Chen, sp. nov.
Generic diagnosis: The plant consists of a shoot bearing leaves at dis-
tinct nodes. The leaf is simple, petiolate, and deeply trilobate with each
lobe further dissected. Leaves clustered at the nodes in threes or fours are
attached in a tight spiral at each node. Primary venation is basal
palinactinodromous. Secondary venation is pinnate, with secondary
vein branches bracing the leaf sinuses and then producing conspicuous
looping veins near the leaf margin. The long reproductive axis is axillary,
terminating in a flattened receptacle bearing five long, narrow, pseudo-
syncarpous carpels.
Etymology: Lee is given in honour of Shiming Li of Shenyang, China;
fructus for fruiting. The species epithet mirus is from the Latin word
mira, meaning beautiful.
Specific diagnosis: The specific diagnosis is the same as for the generic
diagnosis because of limited material at this time.
Holotype: PISNU-0701 (Fig. 3), deposited in the Paleontological
Institute of Shenyang Normal University, Shenyang, China.
Age and horizon: Early Cretaceous, Daxinfangzi Bed, Yixian
Formation.
Description and interpretation: The whole shoot is 16cm long, con-
sisting of a stem with two nodes, each bearing leaves and one fertile
branch. The major stem appears herbaceous (see Fig. 4 for a recon-
struction, and Figs 3 and 5c), robust, multistranded, with a prominent
node, 55 mm long by 2–2.5 mm wide, bearing leaves,fruit and a vegeta-
tive shoot. The leaf scar and leaf attachment at the node appear to be
helical. Three or four leaves are clustered at each node. Proximal leaves
are larger with lateral lobes about 20–35 mm long by 11–12mm wide
and medial lobes are about 35–40 mm long by 15–22 mm wide. Leaves
are simple, estipulate, and deeply trilobate with each lobe further
pinnately lobed with non-glandular lobules gradually decreasing in
Figure 3
|
Holotype specimen of
Leefructus mirus
Sun, Dilcher, Wang et
Chen. The fossil shows multistranded stems, several leaves clustered at two
distinct nodes, three-lobed leaves, and a single reproductive auxiliary shoot.
Scale bar, 1 cm. Photograph by C. T. Li.
Figure 4
|
Reconstruction of
Leefructus mirus
Sun, Dilcher, Wang et Chen.
Diagram by S. Trammel and D.L.D.
a
bc
Figure 5
|
Details of
Leefructus mirus
Sun, Dilcher, Wang et Chen. a,Line
diagram of the leftmost leaf seen in Fig. 3 to show venation. Scale bar, 5 mm.
(Diagram by D.L.D.) b, Enlargement of the fruit in Fig. 3 to show five pseudo-
syncarpous elongate carpels loosely fused and slightly enclosed by a flat
receptacle that has faint oval basal scars (indicated by arrows), and a faint scar
3 mm below the receptacle(indicated by the horizontal arrow). Scalebar, 1 mm.
c, Enlargement of the main axis in Fig. 3 to show the multistranded stem. Scale
bar, 1 mm.
RESEARCH LETTER
626 | NATURE | VOL 471 | 31 MARCH 2011
Macmillan Publishers Limited. All rights reserved
©2011
size distally, resulting in a toothed appearance on the distal leaf margin
(Fig. 5a). The petioles of proximal leaves are elongate, about 37–
40 mm long by 1.3–1.5 mm wide, multistranded and broadly attached
at the node. There may be one abscission scar present at the node. The
petioles of distal leaves are short, 10–15 mm long. Primary venation is
basal palinactinodromous with three major and two minor primary
veins diverging at the extreme base of the leaf lamina from the petiole.
One major primary vein forms the medial vein in each major lobe; each
of the minor secondary veins form sub-marginal veins in the basal
portion of the medial lobes and extend into the basal marginal lobes,
then loop to join superadjacent secondary veins and successive mar-
ginal lobes (Fig. 5a). Secondary venation is pinnate with an irregular
branching pattern. Secondary veins branch and produce conspicuous
looping secondary or tertiary veins near the leaf margin; these branches
form intramarginal veins extending to and fusing with the next distal
secondary veins, or extending into the apex of the lobules but diminish-
ing before reaching the leaf margin. An axillary solitary inflorescence
terminates an elongate pedicle 50 mm long by 0.5mm wide with a faint
scar 1 mm below the receptacle. The fruit (Fig. 5b) is 6mm long by
4 mm wide, pseudo-syncarpous with the basal two-thirds of the five
elongate carpels loosely fused, the carpels sitting on and slightly
enclosed by a flat receptacle. Elongate tips are present on each carpel,
suggestinglong stigmatic tips. The receptacle has several faint oval scars
(Fig. 5b) that may represent scars of deciduous stamens.
The geological age of the Yixian Formation has received consid-
erable attention over the past two decades
19
. The main focus has been
on the two horizons (beds) yielding early angiosperms: (1) the
Daxinfangzi Bed in Lingyuan and (2) the Jianshangou Bed in
Beipiao (Fig. 2).
The Daxinfangzi Bed of the Yixian Formation in Lingyuan is an
important horizon for early angiosperms, including Archaefructus
sinensis,Hyrcantha decussata and Leefructus mirus gen. et sp. nov.
This bed has been dated as 122.9 60.3 Myr old
7
, 124.4 61.4 Myr old
8
and 124. 4 61.1Myr old
6
. We consider the Daxinfangzi Bed to range in
age from 122.6 to 125.8 Myr. The lowest volcanic beds of the Lujiatun
Bed have been dated at 133.3 62.6 Myr (ref. 17) and 129.7 60.5
Myr (ref. 20). The Jiufotang Formation, which conformably overlies
the Yixian Formation, was dated as 122.1 60.3 Myr ol d
17,20
(Fig. 2).
These dates indicate that the entire Yixian Formation ranges in age from
121.8 to 135.9 Myr, lasting a total of about 7 to 14Myr (refs 17 and 20).
The Jianshangou Bed in Beipiao is also an important horizon for
the age of early angiosperms including Archaefructus liaoningensis and
A. eoflora. Since 2001 this bed is dated as 125.0 60.18 Myr old
21
or
125.2 60.9 Myr old
22
, which is close to the Barremian–Aptian boundary.
Recently, further dating using both
40
Ar/
39
Ar and U–Pb methods yielded
ages of 127.4 61.3 to 126.1 61.7 Myr (ref. 8). According to these radio-
metric dates, the age of the Jianshangou Bed can be considered to range
from 124.3 to 128.7 Myr.
Wang et al.
23
have examined basal eudicot phylogeny and evolution
with a large generic and species sampling including all seven families of
Ranunculales (105 taxa including 42 new sequences, 129 genera of
Ranunculales and 99 genera of Ranunculaceae) using both a 65-
character morphological data set and molecular data from four genomic
regions—the plastids rbcL,matK,trnL-F and nuclear ribosomal 26S
ribosomal DNA. They present their results using both maximum
parsimony and Bayesian inference, which give strong support for the
monophyletic nature of three main clades, the family Eupteleaceae (two
species), the family Papaveraceae (750 species) and the core Ranunculales,
the latter consisting of the five families Circaeasteraceae (two species),
Lardizabalaceae (50 species), Menispermaceae (450), Berberidaceae
(650 species)and Ranunculaceae (2,000 species). The numberof species
in these families is very uneven, but the combination of molecular and
morphological character states resulted in well-resolved cladograms
23
.
The morphological characters of Leefructus mirus gen. et sp. nov. are
well preserved. These characters include multistranded and possible
herbaceous upright stems, several leaves clustered at two distinct nodes,
three-lobed leaves with the lobe margins further lobed and a unique
venation pattern. The fossil leaves resemble the venation patterns and
forms of Delphinium leaves, typical of the Ranunculaceae. The fossil
shoot has a simple reproductive auxiliary long pedicle terminating in a
collection of five basally fused follicles sitting on a flattened receptacle
(Figs 3–5), which appears to have several small scars around its base.
Several genera of the Ranunculaceae have two to five multilobed leaves
and carpels borne on flattened receptacles at the ends of long axillary
pedicles. The small circular scars on the receptacle may represent
attachment scars of stamens (Fig. 5b). Because many of the fossil char-
acters occur in extant genera of the Ranunculaceae, we suggest the fossil
Leefructus mirus gen. et sp. nov. to be an extinct taxon along the stem
lineage of this extant family.
The term eudicot was proposed in 1991 as a ‘‘putatively monophy-
letic group’’ using tricolpate pollen to define the clade
9
. This clade was
recognized at the Barremian–Aptian boundary from sediments in
Gabon
24
and from the early Albian of the Potomac Group in North
America
25
. Hughes
10
recognized tricolpate pollen from Bed 35 at the
base of the Vectis Formation that Hughes considered to be ‘‘Phase 4’’,
which is at the Barremian–Aptian boundary. This current understand-
ing of the fossil record places the earliest fossils of the eudicots at this
Barremian–Aptian boundary age of about 125 Myr. The distribution
of this pollen type from cores taken off the coast of Gabon and from
England suggests that eudicot plants were already distributed widely
by about 125 Myr ago and probably had an earlier origin.
The early fossil record of basal eudicot evolution is incomplete, so
each fossil that can be placed in this clade provides new and important
information about early angiosperms. Previous fossil angiosperms
reported from the Yixian Formation include Archaefructus and
Hyrcantha
3–5
. It is possible that Hyrcantha could also be considered
within the stem lineage of the Ranunculaceae
4,26
,andArchaefructus is
considered to be basal to all angiosperms
3,26
.
Molecular studies during the past decade have helped to push the
age of the first angiosperms earlier than the Early Cretaceous
27–30
. The
basalmost ANITA (Amborella,Nymphaea,Illicium,Trimenia and
Austrobaileya) grade must have existed before mesangiosperms (mag-
noliids, Chloranthaceae, Ceratorpyllum, monocots and eudicots). The
presence of the megafossils, Leefructus mirus gen. et sp. nov. and
Hyrcantha decussata
4,26
, which also has possible Ranunculales/
Ranunculaceae affinities, documents eudicot evolution early in angio-
sperm history. Both the fossil record and molecular data suggest the
early presence of basal eudicots, which encourages us to consider
seriously the probable pre-Cretaceous evolution of the angiosperms.
METHODS SUMMARY
Leefructus mirus gen. et sp. nov. was collected from the Daxinfangzi Bed (previ-
ously known as Dawangzhangzi Bed) of the middle part of the Yixian Formation
exposed in Dawangzhangzi Village (41u09996199 N, 119u16929899 E) about
15 km south of Lingyuan City in western Liaoning Province (Figs 1 and 2).
Lithologically the Daxinfangzi bed is mainly composed of yellowish grey and grey
sandstone intercalated with grey silt stone and tuffaceous silt and fine-grained
sandstone. The Daxinfangzi bed is dated as 122.6–125.8 Myr old
6–8,14,17
.Leefructus
mirus gen. et sp. nov. is preserved as an impression in the intercalated yellowish
grey siltstone. Only one part of the impression was collected and studied. On the
same slab, Leefructus mirus gen. et sp. nov. co-occurs with the fish, Lycoptera
davidi Sauvage. Several small samples were removed from the same slab and
macerated in hopes of finding pollen, spores or cuticular material but we had
no success. Small dark pigmented flakes were removed and examined with the
scanning electron microscope for organic remains. These were found to consist of
iron-stained matrix and no original organic material is preserved.
Received 14 April 2010; accepted 6 January 2011.
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Acknowledgements We acknowledge the support of the Key Lab of Evolution of Past
Life and Environment in Northeast Asia, Ministry of Education, China, and Project
‘‘111’’ of China, NSFC project number 40842002, and the President Special Fund of
Shenyang Normal University to carry out this research project during 2008–2009.
Many thanksto S. M. Li and L. X. Wang for their help in collectingthe fossil specimen. We
thank Y. Duan, C. T. Li, Y. S. Liu, D. M .Jarzen, T. Lott, S. Trammel and W. Wang for their
assistance in analysis, computer work, photography and artwork. We also thank P. and
D. Soltis, K. Nixon, M. Moore and J. Doyle for suggestions.
Author Contributions G.S.and D.L.D. designed the research plan. G.S., D.L.D.,H.W. and
Z.C. performed analysis. G.S., D.L.D. and H.W. wrote the manuscript. All authors
discussed and commented on the manuscript.
Author Information Reprints and permissions information is available at
www.nature.com/reprints. The authors declare no competing financial interests.
Readers are welcome to comment on the online version of this article at
www.nature.com/nature. Correspondence and requests for materials should be
addressed to G.S. (sunge@synu.edu.cn) and D.L.D. (dilcher@indiana.edu).
RESEARCH LETTER
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