Despite the rapid progress in angiosperm palaeobotany
during recent decades, the ecology and life habits of early
angiosperms are still poorly documented. There are several
hypotheses concerning early angiosperm ecology and
According to the traditional view, early angiosperms
were similar to primitive woody magnoliids with evergreen
leaves and large bisexual owers and they inhabited wet
forest understory (Takhtajan 1969, Thorne 1976).
A related view, based on new phylogenetic reconstructions
and data on the morphology and ecophysiology of the most
primitive extant plants, reconstructed early angiosperms
as woody plants, similar to Amborella, which grew in wet,
disturbed forest understory habitats or shady streamside
settings (Field et al. 2004).
Others authors suggested that the early angiosperms
were weedy xeric shrubs or riparian weeds that lived in
open, disturbed habitats in semiarid areas or in disturbed
streamside habitats in mesic environments (Stebbins 1965,
Hickey and Doyle 1977). These hypotheses were based on
arguments that variable conditions might have favored the
evolution of the reproductive and vegetative features of
angiosperms. This is supported by the ndings of the rst
angiosperms in what were semiarid tropical and subtropical
The palaeoherb hypothesis was based on the results of
early phylogenetic analyses which placed angiosperms among
Nymphaeales, Piperaceae, Saururaceae, Aristolochiaceae,
and Chloranthaceae (Taylor and Hickey 1996). It inferred
that the earliest angiosperms were ruderal, fast-growing
herbs or shrubs, growing on sunny, unstable streamsides.
Sun and co-authors suggested an aquatic origin for
angiosperms based of the life habits of Archaefructus and
Sinocarpus (Sun et al. 2002, 2008). Freshwater plants are
among the rst angiosperms reported from the fossil record.
Aquatic angiosperms are also included in the ANITA grade
which is considered to be basal to angiosperms together with
Ceratophyllaceae, Chloranthaceae, and magnoliids (Friis et
FOSSIL IMPRINT • vol. 74 • 2018 • no. 1–2 • pp. 165–178
(formerly ACTA MUSEI NATIONALIS PRAGAE, Series B – Historia Naturalis)
AN ANGIOSPERM DOMINATED HERBACEOUS COMMUNITY FROM THE EARLY –
MIDDLE ALBIAN OF PRIMORYE, FAR EAST OF RUSSIA
LINA GOLOVNEVA1,*, PAVEL ALEKSEEV1, EUGENIA BUGDAEVA2, ELENA VOLYNETS2
1 Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, Russia; e-mail: email@example.com.
2 Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia.
* corresponding author
Golovneva, L., Alekseev, P., Bugdaeva, E., Volynets, E. (2018): An angiosperm dominated herbaceous community from the
early – middle Albian of Primorye, Far East of Russia. – Fossil Imprint, 74(1-2): 165–178, Praha. ISSN 2533-4050 (print), ISSN
Abstract: An extraordinarily well-preserved autochthonous angiosperm herbaceous community is described from the Lower
Cretaceous deposits of the Frentsevka Formation, southern Primorye, Far East of Russia. The locality Bolshoy Kuvshin is situated
on the coast of the Ussuri Bay on the Bolshoy Kuvshin Cape near the town of Bolshoy Kamen. The plant-bearing layer was
determined to be early – middle Albian in age. The angiosperm assemblage includes six species: Achaenocarpites capitellatus
Krassilov et volynets, Ternaricarpites oribundus Krassilov et volynets, Jixia pinnatipartita S.X.Guo et G.sun, Asiatifolium
elegans G.sun, S.X.Guo et shao L.ZhenG and two new undetermined species. The majority of specimens are represented by
fragments of branching stems with attached leaves or fruits or by almost complete plants. Two species (Jixia pinnatipartita and
Asiatifolium elegans) are also in the angiosperm assemblage from the Chengzihe Formation (eastern Heilongjiang, China). The
angiosperm remains are accompanied by the fern Onychiopsis psilotoides which is represented by almost entire young plants.
The plant fossils were buried during a single ooding event and remained very close to their original location. They formed
a pioneer open herbaceous community, consisting of ferns and angiosperms with a predominance of the latter and adapted to
colonize fresh sediments in periodically ooded areas.
Key words: early angiosperms, palaeoecology, Early Cretaceous, Albian, Far East, Russia
Received: March 13, 2018 | Accepted: April 23, 2018 | Issued: August 31, 2018
Unfortunately, most parts of these hypotheses are based
on habits, morphology, and ecology of modern species and
usually cannot be veried with fossil data.
Here we report on new nds from the Albian deposits of
Primorye, Far East of Russia, which allows reconstruction of
the ancient angiosperm dominated herbaceous communities
and their role in the Early Cretaceous vegetation. The fossil
plants were buried in almost autochthonous conditions
during a single ooding event and remained very close to
their original location. The locality of Bolshoy Kuvshin
yielded numerous fern and herbaceous angiosperm remains
with the latter prevailing. The quality of the material is
exceptional and almost complete plants were often found.
This locality differs considerably from many other
early angiosperm localities in Primorye and worldwide
which usually contain an allochthonous combination of
different Early Cretaceous plants with an insignicant
admixture of small shrubby or herbaceous angiosperm. It
yielded herbaceous fossils that are usually not preserved
because of their delicate nature. The most autochthonous or
parautochthonous localities with large numbers of herbaceous
angiosperms usually reect an aquatic environment and
occur signicantly later in the geological record (Wang and
Dilcher 2006, Cúneo et al. 2014). Autochthonous localities
with a predominance of herbaceous terrestrial angiosperms
are not known in the Lower Cretaceous and, as far as we
know, neither in younger strata.
The fossils from Bolshoy Kuvshin have the potential to
provide new data on the habits and environment of early
angiosperms, important for understanding their initial
radiation and also for investigation of vegetation structure
and plant interactions in the Early Cretaceous.
In this paper we present a preliminary general description
of the oristic composition and taphonomy of the locality
Bolshoy Kuvshin and discuss in detail its stratigraphical
position and age.
Material and methods
The locality Bolshoy Kuvshin is situated on the coast of
the Ussuri Bay on the Bolshoy Kuvshin Cape in the Bolshoy
Kamen Inlet near the town of Bolshoy Kamen in Primorye
region, Far East of Russia (Text-gs 1, 2).
It was discovered by the geologist A. Oleynikov
and then studied by palaeobotanists V. Krassilov and E.
Volynets (Krassilov and Volynets 2008), who described two
new species of tiny herbaceous angiosperms from there:
Achaenocarpites capitellatus Krassilov et volynets and
Ternaricarpites oribundus Krassilov et volynets.
Fossils come from an outcrop of black shales and
greenish gray tuffaceous sandstones exposed along the
railroad in the base part of the Bolshoy Kuvshin Cape (Text-
g. 3a). A detailed description is given in the stratigraphy
section. The sequence commences and ends with thick
layers of conglomerates. Specimens were found in a layer of
ne-grained sandstone about 15 cm thick which is located
14 m above the lower conglomerate layer (Text-g. 3b). The
coordinates of the site are 43º07.853’N and 132º20.089’E.
The fossiliferous sandstone is massive, without
pronounced bedding planes. The grain size of the sandstone
changes signicantly, but gradually, throughout the layer.
This layer is underlain and overlain by nely laminated
stratied sandstones. The plant remains were buried in the
bedding planes, as well as folded or imbedded obliquely in
the sediment, crossing the bedding planes. It is likely that
this fossil-bearing layer was formed during one catastrophic
Text-fig. 1. Map of Primorye region with early angiosperm
localities near Bolshoy Kamen, Partizansk and Jixi.
Text-fig. 2. Localities of early angiosperms near Bolshoy
A new excavation at this locality was made in summer
2017 by L. Golovneva, P. Alekseev, E. Bugdaeva and E.
Volynets. The fossiliferous layer was uncovered in a square
of about 3 m2. About two hundred specimens were collected.
All specimens are deposited in the palaeobotanical collection
of the Federal Scientic Center of the East Asia Terrestrial
Biodiversity FEB RAS in Vladivostok (former Institute of
Biology and Soil Science), and are given the prex IBSS
The plant fossils are preserved as brownish or dark gray
impressions, yielding no structurally preserved material.
Sometimes it is possible to recognize almost whole plants,
with rhizomes, branching stems, leaves and fruits in organic
connection. Although the preservation does not allow any
study of anatomical details, these fossils provide important
information on the overall habit and ecology of early
The material was studied under a Zeiss Stemi 2000-C
binocular microscope, and photographed using a digital
Nikon Coolpix P7700 camera at low-angle illumination or
In this paper we assign the exposure on the Bolshoy
Kuvshin Cape to the upper part of the Frentsevka Formation
of the Partizansk coal basin. But the stratigraphical
subdivision of the Lower Cretaceous deposits of this area
is debatable. Other authors considered this sequence as
the lower part of the Kangauz Formation (Markevich et al.
2000, Volynets 2005).
Non-marine Cretaceous sediments with subordinate
marine or brackish deposits are widely distributed in
Primorye. There are two big coal basins in the southern part
of this region: the Partizansk (previously Suchan) coal basin
and the Razdolnaya (previously Suifun) coal basin (Text-g.
1). The Partizansk basin is situated along the Partizanskaya
(previously Suchan) River valley, extending from the eastern
coast of the Ussuri Bay to the upper reaches of the Ussuri
River at a distance of about 120 km. The main industrial
deposits are located in the eastern part of the basin, near
Partizansk city. Here the Lower Cretaceous deposits have
been studied most intensively.
The stratigraphy of the Lower Cretaceous strata
in the Partizansk basin was studied by Kryshtofovich
(Kryshtofovich 1929, Kryshtofovich and Prynada 1932),
Perepechina (1960), Sharudo (1960), Vereshchagin (1977),
Shtempel’ (1960), Krassilov (1967), Konovalov (Markevich
Text-fig. 3. a – section of the Frentzevka Formation along
the railroad near the Bolshoy Kuvshin Cape; b – the Bolshoy
Table 1. The stratigraphy of the Lower Cretaceous deposits in the Partizansk coal basin.
Partizansk coal basin
Groups Western part
(eastern coast of the Ussuri Bay)
(near Partizansk city)
Romanovka Fm Romanovka Fm
upper Kangauz Fm Kangauz Fm
Unit of black siltstones
Unit of heterogranular sandstones
upper Coal-bearing unit Severosuchan Fm
Valanginian Klyuchi Fm
et al. 2000), Oleynikov (Oleynikov et al. 1990), Likht (1961)
and Markevich (1995).
The coal-bearing deposits are together known as the
Suchan Group, 1,300–1,700 m thick. It lies with erosion and
angular unconformity on the Proterozoic gabbroic rocks or
on the Klyuchi Formation (Tab. 1). This formation records
shallow-marine to nonmarine environments with buchiid
bivalves and plants of the Valanginian age (Markevich et al.
2000). The overlying variegated or red-colored volcaniclastic
deposits make up the Korkino Group (up to 1,500 m), which
is divided into the Kangauz (mostly sandstones) and the
Romanovka (mostly siltstones) formations. This sequence
records the initial phase of the Sikhote-Alin orogenic events.
The coal-bearing deposits of the Suchan Group yielded
numerous fossil plants which were studied by Krassilov
(1967). There are several alternative versions of the
stratigraphic subdivision of the coal-bearing strata of the
Partizansk coal basin. Here we use the scheme proposed
by Likht (1961, 1994) and Krassilov (1967). According to
these authors the Suchan Group consists of the Starosuchan
(Neocomian), Severosuchan (Aptian) and Frentsevka
The upper boundary of the Severosuchan Formation is
marked by the last thick coal layer known as the Velikan
(Giant). The oldest occurrences of angiosperm come from the
bottom of this layer where several Araliaephyllum luciferum
(Krysht.) Golovn. leaves were found (Kryshtofovich 1929,
The Frentsevka Formation includes marine Trigonia
beds, nonmarine black shales and a measure of greenish
gray plant-bearing sandstones and siltstones (Text-g.
4). Trigonia beds usually begin from a bedset (about 30
Text-fig. 4. Schematic sections of the Frentsevka Formation in different areas.
m) of ne-grained grey or greenish-grey heterogranular
sandstones with the remains of trigoniids (Quadratotrigonia
(Transitrigonia) fudsinensis Mirol., Pterotrigonia
hokkaidoana (yeh.), P. pocilliformis (yoK.), Ussuritrigonia
subpyriformis Konov.), following by beach deposits with
fragments of Isognomon sp., Lima sp., Ostrea sp., and
Callista pseudoplana yabe et naGao, representing deposits
of a short-term marine ingression. The age of this assemblage
was estimated as middle Albian (Markevich et al. 2000). It
is overlain by ne-grained sandstones and siltstones with
an admixture of conglomerates and rare thin coal layers.
The thickness of this bedset is 70–80 m. These sediments
include fossil plants Onychiopsis psilotoides (stoKes et
Webb) Ward, Coniopteris burejensis (ZalessKy) seWard,
Cladophlebis frigida (heer) seWard, C. novopokrovskii
Prynada, Polypodites polysorus Pryn., Elatides asiatica
(yoKoyaMa) Krassilov and Athrotaxopsis expansa Fontaine
(Krassilov 1967). The overall thickness varies between 85 to
250 m. The Albian age of this measure was conrmed by the
occurrence of Inoceramus concentricus ParK in the south
part of the Partizansk coal basin from the Vladimirskaya Unit
(Oleynikov et al. 1998) which are considered as deposits
from the same transgression (Markevich et al. 2000).
The black shales measure is 100–150 m thick and consists
of interbedded siltstones and mudstones with beds of ne-
grained sandstones, representing mostly lacustrine deposits.
These sediments yields freshwater molluscs Limnocyrena
anderssoni (Grab.), Campeloma yihsiensis Grab., C.
tani Grab., Viviparus cf. matumotoi suZ., ostracodes and
The overlaying measure is 60–150 m thick and consists
of intercalations of greenish-gray tuffaceous sandstones and
siltstones with an admixture of coarse-grained sandstones
and conglomerates. It yielded fossil plants Onychiopsis
psilotoides, Coniopteris burejensis Podozamites sp., Elatides
asiatica, E. ex gr. curvifolia (dunKer) nath., Elatocladus sp.
and others, including remains of angiosperms, represented
by small Sapindopsis leaves. This sequence begins with
conglomerates (about 1.5–45 m in thickness) which were
interpreted as marking a regional erosion event (Markevich
et al. 2000).
These deposits are conformably overlain by the
volcaniclastic Korkino Group. This tuffaceous sequence
contains very few fossil plants (Volynets 2005) and its age
is inferred as late Albian – early Cenomanian mostly on the
basis of its stratigraphical position.
Marine deposits with Trigonia are distributed only
in the eastern part of the Partizansk coal basin. For this
reason some authors did not consider the Frentsevka
Formation as a separate stratigraphical unit. The Trigonia
beds and nonmarine black shales were assigned to the
upper subformation of the Severosuchan Formation, and the
greenish gray plant-bearing sandstones were assigned to the
Kangauz Formation of the Korkino Group (Perepechina et
al. 1958, Sharudo 1960, Markevich et al. 2000).
However, Krassilov (1967) noted that the characteristics
of the terrigenous sediments and composition of plant fossils
in the Trigonia beds and measure of greenish gray plant-
bearing sandstones and siltstones are similar, and interpreted
the conglomerates as marking only local disconformities. In
this article we follow Krassilov’s point of view on the size of
the Frentsevka Formation. Its total thickness near Partizansk
city is about 600 m.
The western part of the Partizansk coal basin, adjacent
to the Ussuri Bay shore is called the Petrovka coal area or
the Petrovka depression. The Cretaceous deposits here were
also assigned to the Suchan and Korkino groups, but they
are less thick and they do not contain industrial coal seams.
The stratigraphical scheme of the Cretaceous deposits of this
area was developed by Perepechina (1960). The deposits of
the Suchan Group are divided into two formations: coal-
bearing and overlaying coal-free formations. The latter was
correlated with the Frentsevka Formation (Krassilov 1967)
and was divided into two units: heterogranular sandstones
and black siltstones (Tab. 1, Text-g. 4). A signicant section
of these units is exposed along the southwestern shore of the
Cape Palets, near the town of Bolshoy Kamen.
The heterogranular sandstone unit is 300 m thick and is
composed mainly of medium- and coarse-grained sandstones
with numerous layers of ne-grained sandstones and
siltstones, as well as layers of gravelites and conglomerates.
There are occasional layers of coal-bearing sediments.
This unit yielded Coniopteris sp., Vargolopteris rossica
Pryn., Ruffordia goeppertii (dunKer) seWard, Lobifolia
novopokrovskii (Pryn.) rassK. et lebedev, Elatides asiatica
(yoKoyaMa) Krassilov, E. ex gr. curvifolia (dunKer) nath.
and Athrotaxopsis expansa Fontaine.
Text-fig. 5. a – unit of black siltstones from the Frentsevka
Formation; b – small fish, scale bar 0.5 cm.
The unit composed of black siltstones is about 100
m thick. It begins and ends with conglomerates 10–30 m
in thickness. Above and below them is interlayering of
sandstones and siltstones. In the middle of this unit there
are 30–40 m of black siltstones with numerous freshwater
invertebrates and small shes (Text-g. 5).
Marine bivalves were not detected in this section in the
Petrovka depression. The layer of black siltstones contains
the same freshwater fauna as the measure of black shales
near the city of Partizansk: Sphaerium, Unio, Mycetopus,
Corbicula, Cyrena, Campeloma, Viviparus (Vereshchagin
1977, Markevich et al. 2000).
The numerous plant fossils occur in all part of the
Frentsevka Formation. In sandstones above lower
conglomerates (Text-g. 6) Krassilov discovered
angiosperms Araliaephyllum (Sassafras) ussuriensis
(Krassilov) Golovn., Artocarpidium sp. and Sapindopsis sp.
In addition to these also Isoetites sp., Pelletieria ussuriensis
(Pryn.) Krassilov, Onychiopsis psilotoides (stoKes et
Webb) Ward, Lobifolia novopokrovskii (Pryn.) rassK. et
lebedev, Cycadites sp., Taeniopteris sp., Elatides asiatica
(yoKoyaMa) Krassilov, E. ex gr. curvifolia (dunKer) nath.,
Athrotaxopsis expansa Fontaine and Brachyphyllum ex gr.
obesum heer were found (Krassilov 1967).
The same section of black siltstones is exposed at the base
of the Bolshoy Kuvshin Cape in the Bolshoy Kamen Inlet
next to the railroad (Text-g. 4). Krassilov (1967) collected
Coniopteris burejensis (ZalessKy) seWard, Onychiopsis
psilotoides (stoKes et Webb) Ward, Cladophlebis
novopokrovskii Pryn., Athrotaxopsis expansa Fontaine
and Elatocladus obtusifolia oishi in sandstones from this
outcrop. Later in this outcrop a new site with herbaceous
angiosperms was found (Krassilov and Volynets 2008).
These sediments are conformably overlain by a measure of
tuffaceous sandstones, assigned by Perepechina (1960) to
the Kangauz Formation.
Detailed lithological and facies description of the Early
Cretaceous sediments of the Partizansk coal basin is presented
in the papers by Sharudo (1960) and Golozubov (1997).
Deposits of the Frentsevka Formation reect nonmarine
sedimentation and are represented by alluvial-proluvial,
lacustrine, paludal and coastal facies. The accumulation of
sediments occurred within the lower part of an alluvial valley,
transforming it into a marine bay or estuary. Near the Palets
Cape and the Bolshoy Kuvshin Cape, alluvial-lacustrine
deposits are intercalated with coarse-grained sandstones and
conglomerates, representing deposits of streams owing
down from the upland, located above the position of Ussuri
Bay and the Muravyov-Amursky Peninsula. The Korkino
Group is represented mainly by alluvial facies.
During excavation of the fossiliferous layer in the
Bolshoy Kuvshin locality in 2017 about two hundred plant
fossils were found. Among them remains of angiosperms
predominate (about 90 %). The majority of specimens are
represented by fragments of branching stems with attached
leaves or fruits that belonged to small herbaceous plants.
Several almost complete plants were also found (Text-
The angiosperm assemblage includes six species:
Achaenocarpites capitellatus Krassilov et volynets and
Ternaricarpites oribundus Krassilov et volynets, Jixia
pinnatipartita S.X.Guo et G.sun, Asiatifolium elegans
G.sun, S.X.Guo et shao L.ZhenG and two new species.
Among the angiosperms, remains of Achaenocarpites
capitellatus occur most often. This species was described
by Krassilov and Volynets (2008) based on fragmented
material. The most complete specimen of Achaenocarpites
is represented by a whole plant about 10 cm high with a
straight thin branching stem, several whorls of leaves and
three terminal heads, consisting of numerous achenes
(Text-g. 7a). The leaves are stipulate, ternate, and
pinnatisect. Krassilov compared this species with different
representatives of Ranunculales.
The second most abundant species is Asiatifolium elegans
(Text-gs 7f, 8b, c). Usually this species is represented by
the upper parts of stems with several helically attached and
closely spaced leaves. The leaves are entire-margined, very
diverse both in shape and size. Usually they are oblong,
lanceolate or obovate, with an obtuse to rounded apex and
decurrent base. Venation is pinnate, brochidodromous;
with 5–8 secondary veins. Fructications, associated with
these leaves, have not been detected. This species was rst
described from the Chengziche Formation, exposed near the
city of Jixi in Northeastern China (Sun and Dilcher 2002).
The systematic position of Asiatifolium is uncertain.
Remains of Ternaricarpites oribundus are also
abundant. This species was described by Krassilov and
Volynets (2008). The most complete specimen is represented
by a slender branching axis with several fruits, consisting of
two to ve follicles, most commonly three (Text-g. 9a, b).
The leaves of this plant are unknown. Krassilov believed that
Jixia leaves belonged to the Ternaricarpites plant (Krassilov
and Volynets 2008), but a more detailed study of the material
showed that in fact the leaves were not attached to the stem.
On the basis of morphological characters and comparisons
with other fossils, it appears that Ternaricarpites may also be
related to Ranunculales, such as Achaenocarpites (Krassilov
and Volynets 2008). In addition it has some similarity with
Hyrcantha (Sinocarpus) decussata (lenG et E.M.Friis)
dilcher, G.sun, Q.Ji et H.Q.li from the Barremian to
Aptian Yixian Formation of northeastern China (Leng and
Text-fig. 6. The locality of early angiosperm near the Palets
Text-fig. 7. Plant fossils from Primorye, Partizansk coal basin, Frentsevka Formation, Bolshoy Kuvshin locality, early – middle Albian.
a, c, e – Achaenocarpites capitellatus Krassilov et volynets: a – spec. IBSS 320-132, c – spec. IBSS 320-132, e – spec. IBSS 320-120;
b – Onychiopsis psilotoides (stoKes et Webb) Ward, spec. – IBSS 320-165; d, g – branching infructescence with several follicular fruits:
d – spec. IBSS 320-145, g – IBSS 320-145; f – Asiatifolium elegans G.sun, S.X.Guo et shao L.ZhenG, spec. IBSS 320-75. Scale bar 0.5 cm.
Friis 2003, 2006, Dilcher et al. 2007). The Chinese plant
has similar slender branching stems with terminal fruits
consisting of two – four carpels.
Jixia pinnatipartita has simple deeply pinnately lobed
entire-margined leaves (Text-g. 9c). The lobes are thin,
sublinear, usually with additional small lobes and widened
bases, decurrent up and down along the midvein. The leaf
base is truncate or with triangular incision. Venation is
pinnate, craspedodromous. Remains of this species are quite
rare. As with Asiatifolium, this species was rst described
from the Chengziche Formation (Sun and Dilcher 2002).
Fructications, associated with this plant, and its systematics
are not known.
In addition to the previous species, there are two additional
nds that we considered as belonging to new species. One
new species is represented by a swollen curved branching
stem with an axillary bud and three rather large petiolate,
suborbicular to ovate leaves up to 6 cm long, with entire
or crenulate margin and pinnate, brochidodromous venation
(Text-g. 8a). The leaves are thin and often folded, which
indicate an aquatic or semiaquatic habit. This plant closely
resembles well-preserved nymphaeaceous Pluricarpellatia
peltata b.Mohr, bernardes-de-oliveira et D.W.taylor,
described from the Aptian – lower Albian Crato Formation
in Brazil (Mohr et al. 2008).
The other new species is represented by a branching
infructescence with several follicular fruits, consisting of
two-three carpels (Text-g. 7d, g). This plant resembles
Ternaricarpites, but its carpels are bigger, usually in pairs
and basally fused.
Text-fig. 8. Plant fossils from Primorye, Partizansk coal basin, Frentsevka Formation, Bolshoy Kuvshin locality, early – middle
Albian. a – undetermined species, spec. IBSS 320-137; b, c – Asiatifolium elegans G.sun, S.X.Guo et shao L.ZhenG: b – spec. IBSS
320-86, c – spec. IBSS 320-8. Scale bar 0.5 cm.
The angiosperm remains are accompanied by relatively
abundant fern remains (about 10 % of specimens) and
occasional Equisetum rhizomes and scale-leaved conifer
shoots. The conifer component consists of fragmentary
twigs (about 2–5 cm) of Athrotaxopsis expansa Fontaine
and small Sequoia-like shoots. Ferns are represented mostly
by Onychiopsis psilotoides (stoKes et Webb) Ward. The
remains of other ferns are very fragmented. Among them
Ruffordia goeppertii (dunKer) seWard, Teilhardia tenella
(Pryn.) Krassilov and Coniopteris sp. can be recognized.
All these species are represented only by small pieces of
fronds, no more than a few pinnules.
Leaves of Onychiopsis psilotoides, on the contrary, are
usually almost complete. One specimen is represented by
Text-fig. 9. Plant fossils from Primorye, Partizansk coal basin, Frentsevka Formation, Bolshoy Kuvshin locality, early – middle
Albian. a, b – Ternaricarpites floribundus Krassilov et volynets: a – spec. IBSS 320-10, b – spec. IBSS 320-31; c – Jixia pinnatipartita
S.X.Guo et G.sun, spec. IBSS 320-57. Scale bar 0.5 cm.
whole plants, with leaves situated in several different planes
in the sediment (Text-g. 7b). Onychiopsis was widely
distributed in the Early Cretaceous oras of Laurasia. This
fern has leathery pinnules and xeromorphic sporangia,
enclosed in an indehiscent envelope. Both features indicate
water stress in the environment which corresponds to
dwelling in open, sometimes brackish habitats (Friis and
Pedersen 1990). Onychiopsis psilotoides is one of the most
characteristic ferns in all strata of the Partizansk coal basin,
which are mostly nonmarine. Perhaps, this species could
also be a stream-side dweller.
Specimens of Onychiopsis from the Bolshoy Kuvshin
locality differ from specimens of this fern from other
sections in its smaller size. The length of the whole frond
(without stalk) varies from 7 cm up to 30 cm, usually being
about 10–12 cm. Leaves from other sites in the Partizansk
basin usually reach 70–90 cm in length. This implies that
in the Bolshoy Kuvshin predominantly young plants were
The age of the Frentsevka Formation was based mainly
on marine molluscs from Trigonia beds. Konovalov
estimated the age to be middle Albian (Markevich et al.
2000). But in reality the bivalve assemblage includes many
endemic species. Other species with a wider distribution
(Pterotrigonia hokkaidoana, P. pocilliformis, Inoceramus
concentricus) have a rather wide stratigraphical range
during the Albian (Tashiro and Matsuda 1983, Matsukawa
et al. 1997).
Freshwater molluscs, ostracodes and conchostracans
from black shales are in general insufciently studied. At
present they suggest an age range from the Aptian to the
Albian (Markevich et al. 2000).
But these deposits contain a rich plant assemblage
including ferns, gingoaleans, cycadophytes, czekanowski-
aleans, conifers and angiosperms. Krassilov (1967) noted
that plant assemblages from all formations of the Partizansk
coal basin have a similar composition and differ mainly in
the quantitative ratio between species. The most abundant
species in the Frentsevka Formation are Onychiopsis
psilotoides (stoKes et Webb) Ward, Cladophlebis frigida
(heer) seWard, Elatides asiatica (yoKoyaMa) Krassilov,
Athrotaxopsis expansa Fontaine, Coniopteris burejensis
(ZalessKy) seWard, Cladophlebis frigida (heer) seWard,
Lobifolia novopokrovskii (Pryn.) rassK. et lebedev,
Polypodites polysorus Pryn. Elatides asiatica (yoKoyaMa)
Krassilov, Elatocladus ex gr. curvifolia (dunKer) nath.
and Athrotaxopsis expansa Fontaine. All these species have
a wide distribution in the Early Cretaceous.
Volynets (2005, 2006) developed a very detailed
stratigraphical sequence of the oristic assemblages for
the Partizansk, Razdolnaya and Alchan coal basins. She
distinguished two successive assemblages dated from
middle to late Albian in the deposits of the Frentsevka
Formation. Unfortunately these assemblages were not
compared with any accurately dated assemblages in other
regions. Therefore they are not of use for age determination
of the Bolshoy Kuvshin locality.
Plants having the greatest biostratigraphic signicance
are early angiosperms. In the mid-Cretaceous angiosperms
were already quite numerous and the majority of species
were characterized by a narrow stratigraphical range.
Unfortunately, many species were endemic which thus
prevents any correlation with different basins.
In addition to herbaceous plants from the Bolshoy
Kuvshin locality, three species of angiosperms were recorded
from the Frentsevka Formation: Araliaephyllum (Sassafras)
ussuriensis (Krassilov) Golovn., Artocarpidium sp.,
Sapindopsis cf. angusta (heer) seWard et V.conWay.
In the extensively studied sequence of the Potomac
Group in the eastern United States, Araliaephyllum and
Sapindopsis were recorded in the deposits referred to the
lower part of the pollen Zone II-B (locality Bank near
Brook). The age of this locality was determined as early to
middle Albian (Doyle and Hickey 1976) or as middle to late
Albian (Hochuli et al. 2006, Doyle and Upchurch 2014).
In Zone I (Aptian to earliest Albian) only simple unlobed
leaves with predominantly pinnate venation were recovered.
From Zone II-C (latest Albian-Cenomanian) large platanoid
leaves became abundant in channel and levee facies (Doyle
and Upchurch 2014). In accordance with these data, the age
of the Frentsevka Formation should be estimated as middle
Albian, possibly including the beginning of late Albian.
However, the Bolshoy Kuvshin assemblage includes
two species, in common with the ora of the Chengzihe
Formation, including in Jixi Group: Jixia pinnatipartita and
Asiatifolium elegans. The angiosperms from the Chengzihe
Formation were initially considered to be Hauterivian
– early Barremian in age (Sun and Dilcher 2002). More
recently reinvestigation of Aucellina bivalves from the Jixi
group indicated a younger age, from the Barremian to Albian
(Gu et al. 1997). The Chengzihe Formation is dominated
by nonmarine coal-bearing deposits that intercalated with
several marine beds. It contains plant megafossils, ostracodes,
shes, reptiles, abundant bivalves and dinoagellates (Sha et
al. 2003). Nowadays the Chengzihe Formation is considered
to be mainly Aptian but lower marine beds perhaps extends
downward into the Barremian. The overlying Muling
Formation is composed of nonmarine coal-bearing deposits
intercalated rarely with brackish sediments. It is dominated
by grey and greenish-grey ne-grained sandstones and
siltstones interbedded with mudstones, tuffs and coal beds.
The fossils recovered from the Muling Formation (brackish
bivalves and dinoagellate assemblage) suggest an Aptian –
early Albian age (Sha et al. 2003).
Angiosperms were collected from the middle and upper
part of the Chengzihe Formation and are expected to be
Aptian in age. Until the present time, early angiosperms
were considered as a rapidly evolving group whose species
have the narrow stratigraphical ranges. The difference in
age of the same species from Primorye and Heilongjiang
implies that Jixia pinnatipartita and Asiatifolium elegans
had wider stratigraphical ranges, maybe from Aptian to
early – middle (late?) Albian, or that the age determinations
were not accurate enough and additional stratigraphical
investigations are necessary. Perhaps, an early Albian age
could be a possibility for both plant assemblages.
Overall, we accept an early – middle Albian age for early
angiosperms from the Frentsevka Formation.
Deposits of the Frentsevka Formation near the Bolshoy
Kuvshin Cape are represented by alluvial-lacustrine
oodplain facies intercalated with coarse-grained sandstones
and conglomerates, representing deposits of braided rivers
owing down from the upland where is now located the
Ussuri Bay (Sharudo 1960).
The plant-bearing layer is about 15 cm thick and
represented by ne-grained non-stratied sandstone. This
layer is underlain and overlain by nely laminated sandstones
and siltstones. Most likely, the latter were deposited on the
oodplain as a result of the activity of small, meandering
channels. The plant remains are often folded, rolled and cross
bedding planes. It is likely that this fossil-bearing layer was
formed during one single catastrophic ooding event. The
locality contains numerous remains of diverse herbaceous
angiosperms with an admixture of the fern Onychiopsis
psilotoides. Many specimens are represented by almost
complete plants or big fragments with attached leaves and
fruits. Plants were small (10–30 cm high) and very delicate.
Their complete preservation in rather coarse sediment
indicates the absence of water transport. They were deposited
very close to their original location. Thus, this locality can
be considered as autochthonous, reecting the vegetation
which grew near to the burial place. We interpret this
vegetation as an open herbaceous community, consisting of
ferns and angiosperms with a predominance of the latter. This
community occupied low at plains between river channels.
Conifers and other woody plants were perhaps excluded from
this environment by periodic ood events, low drainage,
and by the unstable groundwater level. In the plant-bearing
layer conifers are represented mostly by very rare, small
(2–5 cm) shoots of Athrotaxopsis expansa. These remains
are considered as an allochthonous admixture in this locality,
as well as the small rare fragments of the ferns Ruffordia
goeppertii, Teilhardia tenella and Coniopteris sp. In several
meters below the plant-bearing layer there is leaf mat in the
sandstone, consisting exclusively of Athrotaxopsis expansa
twigs and cones. Possibly this plant can have formed thickets
on levees and other elevated parts of a oodplain.
The fern Onychiopsis psilotoides is represented by
almost complete, but small young plants. This implies
that the fern-angiosperm herbaceous community was a
pioneer, reecting the early succession stage and adapted
to colonize fresh sediments in periodically ooded areas.
Powerful oods, bearing abundant sediments or migration
of channels can periodically destroy pioneer communities.
Krassilov suggested that herbaceous angiosperms could
also colonize fresh ash fallouts (Krassilov and Volynets
2008). Reconstruction of such an angiosperm herbaceous
community is shown in Text-g. 10.
The locality Bolshoy Kamen, containing abundant
remains of several herbaceous angiosperm species, is
signicantly different from other early – middle Albian
angiosperm sites, where the angiosperm can be diverse
and well-preserved, but their remains occur rarely and
Text-fig. 10. Reconstruction of environment with herbaceous angiosperms from deposits of the Frentsevka Formation.
The preservation of complete herbaceous angiosperm,
ferns and gnetaleans is typical for the Aptian – early Albian
Crato Formation in Brazil (Mohr and Friis 2000, Mohr et
al. 2015), and for the Aptian Yixian Formation in Northeast
China (Sun and Dilcher 1997, Sun et al. 1998, Leng and
Friis 2003, Dilcher et al. 2007, Sun et al. 2008, Yang et al.
In the Yixian Formation herbaceous plant fossils occur
in nely laminated lacustrine tuffaceous siltstones together
with diverse invertebrate lake fauna and shes (Pan et al.
The Crato plattenkalk limestones were also formed by
a large freshwater or brakish-water lake. It was suggested
that periodic torrent rainfall could have washed down into
the water almost complete plants which grew not far from
the lake shore (Mohr et al. 2015). Angiosperms constituted
a minor scattered element of the nearshore vegetation (Mohr
and Friis 2000). It is interesting that many herbaceous
remains from the Crato Formation are represented by young
plants, documenting their early growth stages (Rydin et
al. 2003). It is possible that these plants also could have
inhabited periodically disturbed places along streams or lake
An authochthonous plant assemblage from the riparian
deposits was described from the Bajo Grande locality,
coming from the lower Aptian Anteatro de Tico Formation,
Argentina (Cladera et al. 2007). This assemblage includes
the liverwort Ricciopsis gradensis cladera et al., ferns
Adiantopteris tripinnata cladera et al., and undetermined
Schizaeaceae, and the gnetophyte Ephedra verticillata
cladera et al. Taphonomical studies suggest that these
plants grew and were buried near the levee. This locality
documents an open fern herbaceous vegetation with
gnetaleans, but unfortunately without angiosperms.
Our data support Hickey and Doyle’s (1977)
interpretation of early angiosperms as riparian weeds. They
also show that early angiosperm preferred open wet fern
communities, inhabited periodically ooded river valleys
and coastal plains. Such environments were favorable for
appearance of different aquatic and semiaquatic life forms,
which are so numerous among the early angiosperms.
The present study was carried out within the
framework of the institutional research project (no.
AAAA-A18-118030690081-1) of the Komarov Botanical
Institute of the Russian Academy of Sciences and was
supported by the Russian Foundation for Basic Research
(project 16-04-01411). We would like to thank A. Herman
and other anonymous reviewers for their helpful comments
during preparation of the manuscript.
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