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Zlatkocarpus gen. nov., a new angiosperm reproductive structure with monocolpate-reticulate pollen from the Late Cretaceous (Cenomanian) of the Czech Republic

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A new genus, Zlatkocarpus gen. nov., is described from the Peruc Korycany Formation (Cenomanian) of the Bohemian Cretaceous Basin in the Czech Republic based on inflorescence axis, fruits and pollen. Two species are assigned to the new genus, Zlatkocarpus brnikianus and Z. pragensis. Zlatkocarpus has a compound inflorescence consisting of primary axes bearing semi-decussately arranged spikes. Each spike has helically arranged unicarpellate and unilocular fruits. Each fruit apparently contains a single, orthotropous seed. The stigma is indistinct and sessile at the apex. The fruit wall has distinct globular protrusions (probable resin bodies). The fruits are supported at the base by a small floral cup and a bract. Pollen grains adhering to stigmatic areas and also on other surfaces of the fossil are monocolpate with a long colpus and an open reticulum. The pollen is similar to dispersed pollen broadly referred to the extinct pollen genus Retimonocolpites, but none of dispersed pollen genera are suitable for accommodating the fossils described here.
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Zlatkocarpus
gen. nov., a new angiosperm reproductive structure with
monocolpate-reticulate pollen from the Late Cretaceous (Cenomanian) of
the Czech Republic
JiŘÍ KvaČeka; Else Marie Friisb
a The National Museum, Prague, Czech Republic b The Swedish Museum of Natural History,
Stockholm, Sweden
Online publication date: 18 May 2010
To cite this Article KvaČek, JiŘÍ and Friis, Else Marie(2010) '
Zlatkocarpus
gen. nov., a new angiosperm reproductive
structure with monocolpate-reticulate pollen from the Late Cretaceous (Cenomanian) of the Czech Republic', Grana, 49:
2, 115 — 127
To link to this Article: DOI: 10.1080/00173134.2010.481845
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ISSN 0017-3134 print/ISSN 1651-2049 online © 2010 Collegium Palynologicum Scandinavicum
DOI: 10.1080/00173134.2010.481845
Grana, 2010; 49: 115–127
SGRA
Zlatkocarpus gen. nov., a new angiosperm reproductive structure
with monocolpate-reticulate pollen from the Late Cretaceous
(Cenomanian) of the Czech Republic
Zlatkocarpus, a new Cretaceous angiosperm
JIRÍ KVACEK1 & ELSE MARIE FRIIS2
1The National Museum, Prague, Czech Republic, 2The Swedish Museum of Natural History, Stockholm, Sweden
Abstract
A new genus, Zlatkocarpus gen. nov., is described from the Peruc Korycany Formation (Cenomanian) of the Bohemian
Cretaceous Basin in the Czech Republic based on inflorescence axis, fruits and pollen. Two species are assigned to the new
genus, Zlatkocarpus brnikianus and Z. pragensis. Zlatkocarpus has a compound inflorescence consisting of primary axes bearing
semi-decussately arranged spikes. Each spike has helically arranged unicarpellate and unilocular fruits. Each fruit appar-
ently contains a single, orthotropous seed. The stigma is indistinct and sessile at the apex. The fruit wall has distinct globular
protrusions (probable resin bodies). The fruits are supported at the base by a small floral cup and a bract. Pollen grains
adhering to stigmatic areas and also on other surfaces of the fossil are monocolpate with a long colpus and an open reticulum.
The pollen is similar to dispersed pollen broadly referred to the extinct pollen genus Retimonocolpites, but none of dispersed
pollen genera are suitable for accommodating the fossils described here.
Keywords: basal angiosperms, Chloranthaceae, fossil flowers, inflorescences, infructescences, mesofossils, Myricanthium,
Zlatkocarpus, Retimonocolpites
The Peruc-Korycany Formation from the Bohemian
Cretaceous is rich in angiosperm remains and the
flora, sometimes referred to as the Peruc Flora, is
one of the classical leaf floras that has greatly influ-
enced early ideas on the Cretaceous radiation of
angiosperms. The first major studies of the flora
were those of Velenovský (e.g., 1882, 1883, 1884,
1885a, 1885b, 1889). In more recent years, the flora
has been studied by Zlatko and Jirí Kvacek (e.g.,
Kvacek, Z., 1992; Kvacek, J., 1995, 1998, 1999;
Kvacek & Knobloch, 1997; Kvacek & Eklund,
2003) with the description of many new taxa and
revisions of previously described taxa. Currently,
more than 120 species of angiosperms have been
identified. The fossils are mainly preserved as impres-
sions and compressions in consolidated sediments
and in rare cases show reproductive organs attached
to leafy stems (Velenovský, 1889; Velenovský &
Viniklár, 1926, 1927, 1929, 1931; Kvacek, Z., 1992).
Recently, three-dimensionally preserved mesofossils
were discovered in the Peruc-Korycany Formation.
Combined studies of mesofossils and macrofossils
provide an excellent opportunity to assemble more
complete reconstructions of inflorescence structure
in mid-Cretaceous angiosperms and the plants that
produced the reproductive organs (Eklund &
Kvacek, 1998; Kvacek, J., 2000; Kvacek & Eklund,
2003; Kvacek et al., 2005). These reproductive
structures are small and borne in elongated inflores-
cences/infructescences and include species such as
Mauldinia bohemica Eklund and J. Kvacek (Lau-
raceae), Pragocladus lauroides J. Kvacek and Eklund
(Lauraceae) and several species of Myricanthium.
Myricanthium was first compared to extant members
of Myricaceae (Velenovský, 1889). New studies
show, however, that it is probably not related to
Myricaceae or other eudicots, and that fossils
assigned to the genus are heterogeneous with some
Correspondence: Jirí Kvacek, Department of Palaeontology, National Museum, Václavské nám. 68, 115 79, Praha 1, Prague, Czech Republic.
E-mail: jiri_kvacek@nm.cz
(Received 3 June 2009; accepted 21 March 2010)
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116 J. Kvacek and E. M. FriisJ. Kva M. Friis
species perhaps related to Chloranthaceae (Kvacek
& Eklund, 2003). The heterogeneity of Myricanthium
is also supported by the present study. Unfortu-
nately, the type material for Myricanthium is poorly
preserved, but reinvestigation of M. pragense J. Kvacek
& Eklund shows that it is distinct from the type
material of Myricanthium (type species M. amenta-
ceum Velenovský) and we have therefore included
the species in a new genus, Zlatkocarpus (Z. pra-
gensis). In addition to this species, we have also
recognised another similar species that is here
described as a new species, i.e. Z. brnikensis.
Materials and methods
The fossil plants described here were isolated from
sandy mudstone collected in the clay pit near the village
Brník, 60 km east of Prague (49° 58 59 N, 14° 54 56
E – Zlatkocarpus brnikensis) and Hloubetín-Hute, north-
east suburb of Prague (50° 06 34 N, 14° 33 20 E
Z. pragensis) within the Peruc-Korycany Formation
of the Bohemian Cretaceous Basin (sensu Cech et al.,
1980). Palynological data show a late mid-Cenomanian
age for the formation (Pacltová, 1977, 1978).
The Brník section is interpreted as a deep palaeo-
valley filled with fluvial sandstones and mudstones.
It consists of two major parts. The basal part
consists of fine granulated sands and claystones and
represents fluvial sediments of a meandering river
and floodplains. The upper part consists of sand-
stones interpreted as sediments of incised valley fill
of a braided river (Ulicný in Nguyen Tu et al.,
2002). Fossil plants are recorded in the lower part,
which consists of claystone bodies of various thick-
nesses. The fossil bearing claystone is also a resource
for mining. Currently, a number of fern, conifer and
angiosperm leaves have been recorded including
Gleichenia spp., cf. Anemia fremontii Knowlton,
Pagiophyllum sp., lauralean foliage “Eucalyptus
angusta Velenovský, “Aralia formosa Velenovský,
Dicotylophyllum velenovskyi Knobloch, Liriodendropsis
simplex (Newberry) Newberry, and others. Sandstones
of the upper part are usually barren or contain only
poorly preserved leaf impressions.
The material from Prague, Hloubetín-Hute
(Kvacek, J., 1992a, 1992b), was described for the
first time by Kvacek and Eklund (2003). It was
collected from a temporary excavation for the base-
ment of Hotel Pramen in Prague. Unfortunately, the
section was not documented sedimentologically.
Currently, 27 taxa have been recorded including
various ferns assigned to Gleichenia spp., conifers
assigned to “Sequoia heterophylla Velenovský,
Quasisequoia crispa (Velenovský) J. Kvacek, Geinitzia
sp., Brachyphyllum sp., several angiosperm leaf taxa
including Grevilleophyllum constans (Velenovský)
Velenovský, “Eucalyptus angusta Velenovský and
Cocculophyllum cinnamomeum (Velenovský) Velenovský,
Proteophyllum araliopsis Velenovský & Viniklár,
P. productum Velenovský & Viniklár, P. minutum
Velenovský & Vinikr, angiosperm reproductive
structures (Mauldinia bohemica, Pragocladus lauroides
J. Kvacek & Eklund) and several unnamed reproduc-
tive structures (see Kvacek & Eklund, 2003).
Specimens were extracted from the mudstone by
bulk maceration and treated through standard
techniques as described in Eklund and Kvacek
(1998). The material was preliminary examined
using Wild and Olympus binocular microscopes.
More detailed examinations were done using a
scanning electron microscope (Phillips 515 and
Hitachi S-4300). All specimens and preparations are
deposited in the palaeobotanical collections of the
National Museum, Prague (NMP).
Systematic palaeontology
Genus Zlatkocarpus gen. nov.
Derivation of generic name. After Zlatko Kvacek in
recognition of his contribution to our understanding
of the Cretaceous and Tertiary vegetation of the
Bohemian Massif.
Generic diagnosis. Flowers sessile, aggregated in
spikes; each flower supported by a persistent bract
arranged helically along an elongated axis. Flowers
apparently unisexual. Pistillate flowers consisting of
a single carpel surrounded by a floral cup. Stigmatic
area sessile, indistinct. Fruit: a one-seeded berry.
Fruit wall parenchymatous with resin bodies embed-
ded in the tissue under the epidermis. Pollen adher-
ing to the surface of fruits of Retimonocolpites-type,
monocolpate, reticulate-columellate with smooth
muri.
Type species. Zlatkocarpus brnikensis sp. nov.
Other species. Zlatkocarpus pragensis (J. Kvacek &
Eklund) comb. nov.
Figure 1. Zlatkocarpus brnikensis sp. nov. A. Larger fragment of secondary axis with helically arranged fruits, holotype, F 3143. B–E. Details o
f
the holotype: B. Fruit with well pronounced perianth; C. Stigmatic area with adhering pollen; D. Attachments of fruits to secondary axis, note
perianth and small bracts; E. Detail of fruits with well pronounced resin bodies. Scale bars – 1.5 mm (A); 600 μm (B, D, E); 30 μm (C).
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Zlatkocarpus, a new Cretaceous angiosperm 117
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118 J. Kvacek and E. M. FriisJ. Kva M. Friis
Figure 2. Zlatkocarpus brnikensis sp. nov. A–D. Detached fruits: A. With periant in basal part, F 3145; B. With perianth in basal part,
opposite side of (A); C. Fruit from holotype, F 3143; D. With perianth in basal part, F 3147. Scale bars – 600 μm (C); 400 μm (A, B, D).
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Zlatkocarpus, a new Cretaceous angiosperm 119
Zlatkocarpus brnikensis sp. nov.
(Figures 1–3)
Derivation of specific epithet. From the Brník local-
ity, where the fossil was discovered.
Specific diagnosis. Floral cup large, encircling
the basal part of fruit for about one third of the
total length of the fruit. Fruits elliptical in outline
with slightly pointed apex and base. Pollen with
heterogeneous reticulum and distinct colpus margin.
Holotype designated here. NMP F 3143; illustrated
here in Figures 1–3.
Paratypes designated here. NMP F 3144–F 3147.
Type locality. Clay pit near the village of Brník, 60
km east of Prague, Czech Republic (49° 58 59 N,
14° 54 56 E).
Type horizon and age. Peruc Member, Peruc-Kory-
cany Formation, Cenomanian, Late Cretaceous.
Description. All specimens are pistillate, preserved
in the fruiting stage. The most informative specimen
(the holotype, F 3143) is a fragment of a spike, about
6.5 mm long and 2.5 mm wide. It has about 50 fruits
borne in a helical arrangement (Figures 1–3). The
inflorescence axis is about 0.6 mm wide and charac-
terised by transversely aligned wrinkles. Fruits are
densely spaced and born in the axils of small triangu-
lar bracts, spaced at a distance of 0.5–1 mm, each
with a long free tip about 0.12–0.15 mm long. The
other specimens (F 3144–F 3147) are isolated fruits.
Each fruit is encircled by a floral cup, about 0.3–
0.6 mm long (Figures 1A, B, 2A–D). The floral cup
is broadly triangular in abaxial view. In adaxial view it
has an irregular outline with one or two additional
tips (Figure 2B, D). The floral cup is closely adhering
to the fruit and apparently fused to the fruit wall at
least at the base. Epidermal cells are isodiametric,
about 16–25 μm in diameter, and irregularly
arranged. No stomata or trichomes were observed.
The nature of the floral cup is unclear, although its
position suggests that it is a perianth.
Fruits are elliptical in outline with slightly pointed
apex and base, about 0.8–1.2 mm long and 0.45–0.7
mm wide (Figures 1A, B, D, E, 2A–D). The stigmatic
area is sessile and non-protruding, seen as a circular
area of indistinct cells about 0.8–0.1 mm in diameter
(Figure 1B, C, E). The surface of the fruit is irregu-
larly bulging from densely spaced resin bodies embed-
ded in the fruit wall under the epidermis (Figure 1A).
The epidermis consists of distinct, almost isodiamet-
ric, irregularly arranged epidermal cells, about 10–25
μm × 20–50 μm, with convex outer periclinal walls
(Figure 2A, B). The fruits are interpreted as unicar-
pellate. The single seed is apparently orthotropous.
Pollen occurs abundantly on the surface of the
fruits, typically close to the stigmatic area and near
the margin of the floral cup (Figure 1C). Grains
are monocolpate and coarsely reticulate, circular
to broadly elliptical in equatorial outline, with an
equatorial diameter of about 12–18 μm (Figure
3A–F). The colpus is straight and does not reach
the equator. Typically, the grains are folded in the
colpus area and the margin is usually hidden (Fig-
ure 3A, B), but a single specimen shows a distinct
colpus margin (Figure 3D). The reticulum is het-
erogeneous; smaller lumina are about 0.05–0.2 μm
in diameter and larger lumina are up to about 0.4–
0.8 μm in diameter (Figure 3E). Muri are narrow
and low with a flattened to rounded and smooth
profile, about 0.2–3 μm wide; columellae are irreg-
ularly spaced, about 0.3 μm long. Columellae and
reticulum easily detach from the foot layer (Figure
3C, D).
Zlatkocarpus pragensis (J. Kvacek & Eklund) comb.
nov. (Figures 4–6)
Basionym. Myricantheum pragense (Kvacek & Eklund,
2003, p. 1025, figures 4, 5).
Emended diagnosis. As in Kvacek and Eklund (2003)
with the following addition: Floral cup short, about
one fourth of the total length of the fruit, most pro-
nounced adaxially. Pollen with almost homogeneous
reticulum.
Holotype. NMP F 2892 (see Kvacek & Eklund,
2003).
Material. NMP F 2893, F 2895–F 2898, F 3148–
F 3155, F 3461–F 3565.
Type locality. Hloubetín-Hute, north-eastern suburb
of Prague, Czech Republic (50° 06 34 N, 14° 33
20 E).
Type horizon and age. Peruc Member, Peruc-Kory-
cany Formation, Cenomanian, Late Cretaceous.
Description and comments. The type material (holo-
type and paratypes) originally ascribed to Myri-
cantheum pragense by Kvacek and Eklund (2003)
includes remnants of compound inflorescence/
infructescence axes (Figure 4H) as well as isolated
secondary axes (spikelets) with or without attached
floral organs (Figure 4A–C). The spikelets with the
attached floral units and the empty inflorescences/
infructescence fragments are assigned to the same
species based on the characteristic secondary bracts
and rare remnants of fruits in the empty inflores-
cences/infructescence. Additional material includes
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120 J. Kvacek and E. M. FriisJ. Kva M. Friis
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Zlatkocarpus, a new Cretaceous angiosperm 121
axes with a various number of fruitlets attached (F
2547, F 3148, F 3149, F 3151, F 3152, F 3461).
Pollen attached to the stigma surface (Figure 5A,
D, E) is monocolpate and coarsely reticulate, circular
to ellipsoidal in equatorial outline, with an equato-
rial diameter of about 8–10 μm. The reticulum is
almost homogeneous with only a few smaller lumina
(Figure 6A–D). Larger lumina are about 0.1–0.3 μm
in diameter. Muri are narrow and low with slightly
triangular and smooth profile, about 1 μm wide
(Figure 6D). Columellae are about 0.3 μm long and
widely spaced.
Zlatkocarpus pragensis is in general structure very
similar to Z. brnikensis, but the inflorescence/infruct-
escences are more completely preserved showing a
compound organisation with lateral spikelets
arranged in a semi-decussate to helical arrangement
along the main axis (Figure 4H). Zlatkocarpus pragensis
differs mainly by its much smaller floral cup that is
also much more pronounced at the abaxial side than
on the adaxial side (Figure 4G). Fruits are broadly
elliptical to almost circular in outline with an almost
smooth surface and with a thick cuticle (Figure 4D, G).
The stigmatic area is sessile and circular similar to
that in Z. brnikensis.
Discussion
Recognition of the new genus
Zlatkocarpus is based on structurally preserved inflo-
rescence/infructescence axes with attached floral/
fruiting units and adhering monocolpate pollen with
a semitectate-reticulate pollen wall. Muri of the
reticulum are smooth without supratectal ornamen-
tation. Similar dispersed pollen grains are typically
assigned to the pollen genus Retimonocolpites. The
current use of this dispersed pollen genus is very
broad and taxa included in Retimonocolpites clearly
represent a heterogeneous assemblages of lineages with
some species probably related to monocototyledons
and others perhaps related to various basal lineages
of angiosperms (Friis et al., 2010).
Comparison of Zlatkocarpus with extant plants
indicates that this fossil may represent an extinct
lineage of basal angiosperms. It shows some similarity
with Chloranthaceae, but the fossil inflorescences
have distinct helical phyllotaxis in contrast to the
prevailing decussate phyllotaxis of Chloranthaceae.
However, pollen very similar to that of Zlatkocarpus
has been found in unequivocal Araceae (Friis et al.,
2010) and affinity of Zlatkocarpus with early diverging
monocots cannot be excluded.
Fossil inflorescences/infructescences similar in
gross morphology to the fossils described here are
known from several other Early and mid-Cretaceous
floras. They are particularly similar to a variety of
inflorescences/infructescences from the Peruc
flora of the Bohemian Basin generally assigned to
the extinct genus Myricanthium. The type species,
M. amentaceum, was established by Velenovský
(1889) based on compression/impression material
that lacks details on supporting organs or flowers.
Later studies have identified structurally preserved
material together with the compression/impression
fossils that clearly demonstrates that Myricanthium-
like fossils from the Bohemian Cretaceous include a
diverse and heterogeneous complex of plants
(Kvacek, Z., 1992; Eklund & Kvacek, 1998; Kvacek
& Eklund, 2003). Currently, three species have been
distinguished. Mauldinia bohemica and Pragocladus lau-
roides both have bisexual and trimerous flowers and
were assigned to the Laurales (Eklund & Kvacek,
1998; Kvacek & Eklund, 2003). Myricanthium pragense
was described for fossils with unisexual and simple
flowers and was tentatively compared with extant
Chloranthaceae (Kvacek & Eklund, 2003).
Because of the poor preservation of the type material
of Myricanthium amentaceum it is unknown whether
this species had unisexual or bisexual flowers and
detailed comparison with the structurally preserved
fossils is not possible. We therefore suggest that the
genus Myricanthium is reserved for inflorescences/
infructescences for which details of floral units and
supporting organs are uncertain and exclude M.
pragense from the genus. Instead a new genus, Zlatko-
carpus, is established for organically preserved inflo-
rescences/infructescences bearing densely packed,
simple floral units supported by small bracts borne hel-
ically along an elongated axis as described here, includ-
ing Z. brnikensis as a new species and Z. pragensis
transferred from Myricanthium. In Z. pragensis, the
spikes are clearly secondary axes from a compound
spike. The secondary axes are borne in a semi-decussate
to helical arrangement. Although the inflorescences of Z.
brnikensis are more fragmentary preserved, the similarity
to Z. pragensis suggests that Z. brnikensis also had
compound inflorescences. Each floral unit con-
sists of a single ovary/fruit encircled by a floral
cup. In Z. brnikensis, the floral cup completely
Figure 3. Zlatkocarpus brnikensis sp. nov. A–F. Pollen grains of Retimonocolpites type: A. Group of pollen grains, holotype, F 3143;
B. Pollen with colpus, F 3147; C. Group of pollen grains, two of them with partly detached reticulum, F 3146; D. Pollen with
colpus and partly detached reticulum, F 3147; E. Detail of exine with heterogenous columellae and smooth muri, holotype, F 3143;
F. Pollen adhering on stigma, holotype, F 3143. Scale bars – 30 μm (A); 12 μm (C); 6 μm (B, D, F); 1.2 μm (E).
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122 J. Kvacek and E. M. FriisJ. Kva M. Friis
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Zlatkocarpus, a new Cretaceous angiosperm 123
encircles the ovary/fruit and is fused to the ovary
wall for most of its length. The most straightforward
interpretation of this structure is that it represents a
perianth of several fused parts that are marked on the
cupule margin as extending tips. A complication in this
interpretation is, however, that the floral cup is more
bract-like in Z. pragensis and does not completely
encircle the ovary/fruit as it does in Z. brnikensis. An
interpretation of the floral cup as a supporting bract
rather than a perianth would imply the floral unit
represents a condensed tertiary axis of a com-
pound inflorescence with small naked flowers.
The spherical bodies, probably resin bodies, pre-
served in the ovary wall and other tissues may be
remains of ethereal oil cells.
We have interpreted the fossil flowers and inflo-
rescences as unisexual and pistillate. Most of the
specimens appear to be preserved in a post-anthetic
stage and the possibility that stamens have been shed
from an originally bisexual flower without leaving any
traces cannot be excluded. However, this alternative
is less likely. None of the specimens has any remains
of filaments or scars from detached stamens. In addi-
tion, the floral cup is fused to the ovary wall for most of
its length in Zlatkocarpus brnikensis and shows no
vascularisation or other evidence for the presence of
stamens.
The individual ovaries/fruits of Zlatkocarpus are
very similar to those of Couperites mauldinensis
Pedersen, Crane, Drinnan & Friis from the Ceno-
manian Mauldin Mountain flora of Maryland,
USA (Pedersen et al., 1991) and Couperites sp.
from the early or mid-Albian Puddledock flora of
Virginia, USA (Friis et al., 1997). In both genera,
fruits are apparently berries with a single seed and
the fruit wall is characterised by abundant resin
bodies embedded in the parenchyma tissue below
the epidermis. Both also have a sessile stigma and
monocolpate reticulate pollen, but ovaries/fruits of
Couperites are distinct in having an elongate,
slightly decurrent stigmatic ridge. Pollen grains
have supratectal ornamentation of minute spines.
Seed structure is well-known for Couperites, anatro-
pous and pendant, while it is less clear, but appar-
ently orthotropous in Zlatkocarpus. Fruits of
Couperites are always found isolated and there is no
information on inflorescences structure for this
fossil.
Comparison with dispersed pollen taxa
Pollen grains broadly similar to those observed on
the stigmatic areas of Zlatkocarpus pragense and Z.
brnikensis are common in dispersed palynological
assemblages from the Early and mid-Cretaceous.
This kind of dispersed grains is typically assigned to
the form genus Retimonocolpites or sometimes to Lili-
acidites. Both genera have been used in a very broad
sense and include a diverse and heterogeneous
assemblage of pollen types that are probably system-
atically widely separated.
The type species for Retimonocolpites, R. dividuus
Pierce, was first described from the Cenomanian of
Minnesota, USA, by using light microscopy (LM)
alone. Thus, no details of micromorphology or
ultrastructure were described or illustrated (Pierce,
1961). The presence of a distinct aperture almost
encircling the grain and dividing it into two halves as
well as a reticulum that occasionally separates from
the main body of the grain were mentioned as defining
characters for the species (Pierce, 1961). Other
features that are probably of systematic importance
such as presence or absence of supratectal ornamenta-
tion and ultrastructure of the pollen wall are
unknown. A study of pollen assigned to R. dividuus
from the Early Cretaceous (Late Albian) of Delaware,
USA, using LM, scanning electron microscopy
(SEM) and transmission electron microscopy
(Walker & Walker, 1984), showed distinct striate
ornamentation of the muri, but that pollen has a
long, extended colpus and may not be identical to
the type.
The type species for Liliacidites, L. kaitangataensis
Couper, was first described from the Late Cretaceous
and Early Tertiary of New Zealand (Couper, 1953).
It is monocolpate, characterised by a distinctly
graded reticulum and muri with beaded supratectal
ornamentation. Liliacidites has often been used as a
repository for other kinds of reticulate pollen, including
grains with a non-graded reticulum and smooth muri.
One of these described by Walker and Walker (1984)
from the Middle-Late Albian of Maryland, USA as
Liliaciditesminutus (=Clavatipollenites minutus Brenner)
is similar to the grains of Zlatkocarpus pragensis, but the
reticulum in Z. pragensis is denser and number of small
lumen is higher.
The pollen grains observed on the surfaces of
Zlatkocarpus have smooth muri and shorter colpi
Figure 4. Zlatkocarpus pragensis (J. Kvacek & Eklund) comb. nov. A. Basal and medial parts of secondary axis with helically arranged
fruits, holotype, F 2892. B. Apical part of empty secondary axis with bracts, F 3155. C–E. Fragments of secondary axis showing
arrangement of fruits and supporting bracts, F 3154: C. Overview; D. Fruit with its bract and perianth; E. Bract and perianth. F. Details
of empty bracts, detail of (B). G. Isolated fruit with well preserved perianth bearing conspicuous epidermal structure, F 3150. H. Basal
part of primary axis with one secondary axis still attached, F 2894. Scale bars – 5 mm (H); 500 μm (A); 400 μm (B); 300 μm (C, F); 200 μm
(E, G); 150 μm (D).
Downloaded At: 13:57 31 January 2011
124 J. Kvacek and E. M. FriisJ. Kva M. Friis
than in Retimonocolpites dividuus and the Bohemian
pollen is clearly distinct from the type species of
Retimonocolpites. Other pollen grains assigned to
Retimonocolpites that have been studied using SEM are
distinguished from the pollen of Zlatkocarpus by differ-
ences in lumen size and shape, length of columellae, or
Figure 5. Zlatkocarpus pragensis (J. Kvacek & Eklund) comb. nov. A–E. Details of the holotype, F 2892 (see Figure 4A): A. Detail of stigma
with adhering pollen; B. Fruit with resin bodies; C. Basal part of secondary axis with attached fruits; D. Retimonocolpites pollen adhering on
stigma; E. Retimonocolpites pollen adhering near to stigma, with elongate outline. Scale bars – 1 mm (C); 400 μm (B); 30 μm (A); 6 μm (D, E).
Downloaded At: 13:57 31 January 2011
Zlatkocarpus, a new Cretaceous angiosperm 125
presence of supratectal ornamentation. Pollen grains
closely similar to those of Zlatkocarpus have also
been found in situ in stamens borne in distinct aroid
inflorescences (Friis et al., 2010).
Systematic position of Zlatkocarpus
The character combination in Zlatkocarpus is
unusual and based on the data currently available, it
is not possible to place the fossils in a modern family
or order. Monocolpate, reticulate pollen is restricted
to non-eudicot angiosperms. The presence of a
heterogeneous reticulum with smaller and larger
lumina in monocolpate pollen has been suggested as
a defining feature for monocotyledons (Walker &
Walker, 1984), and very similar pollen has been
observed in situ in undisputable Araceae flowers
from the Early Cretaceous of Portugal (Friis et al.,
2010). However, if the resin bodies embedded in the
Zlatkocarpus fruit wall represent ethereal oil cells,
affinities with monocotyledons are unlikely. In
monocots, only Acorus has ethereal oil cells, but
Acorus is distinguished from Zlatkocarpus by its
bisexual flowers, much denser arrangement of the
flowers in the inflorescence, and the tectate-perforate
pollen wall. Among other non-eudicot angiosperms
several corresponding features occur in members of
the Chloranthaceae. Ascarina and Hedyosmum have
unisexual flowers borne in compound spikes and
typically are supported by bracts. Flowers are either
naked or have an epigynous, trimerous perianth that
is fused to the ovary for most of its length and only
free at the top of the gynoecium like in the pistillate
flowers of Hedyosmum.
If our interpretation of the floral cup in Zlatokocarpus
as a perigynous perianth is correct, it is comparable
to the perianth of Hedyosmum. The gynoecium in
Chloranthaceae consists of a single carpel with a
Figure 6. Zlatkocarpus pragensis (J. Kvacek & Eklund) comb. nov. A–D. Retimonocolpites pollen, details of F 3155 (Figure 4B): A. Pollen
with colpus, adhering on empty secondary axis; B. Pollen with colpus, adhering on empty secondary axis; C. Pollen with nearly homogenous
reticulum, adhering on empty secondary axis; D. Detail of exine with columellae and smooth muri. Scale bars – 6 μm (A–C); 1.2 μm (D).
Downloaded At: 13:57 31 January 2011
126 J. Kvacek and E. M. FriisJ. Kva M. Friis
single orthotropous ovule. The stigma is sessile.
The phyllotaxis of Chloranthaceae is mostly oppo-
site and decussate, while in Zlatkocarpus only the
secondary spikes are borne in a semi-decussate
arrangement, but floral units are borne in a heli-
cally arrangement. Pollen grains in Chloran-
thaceae are monocolpate-trichotomocolpate in
Ascarina, while the other genera of the family have
more unusual aperture configurations. All have
reticulate pollen grains. Grains with smooth muri
are known in Sarcandra and Chloranthus, but none
of these have monocolpate pollen, while Hedyos-
mum and Ascarina have muri with distinct suprate-
ctal ornamentation.
Simple, unisexual flowers borne in spikes are also
known for some extant members of the Piperales,
but pollen in Piperales is tectate with a continuous,
non-reticulate tectum. Inflorescences in Piperales
are mostly simple spikes, but an exception was
described for the perianthless. Peperomia fraseri
C.DC. has numerous spikes borne along a raceme
(Remizova et al., 2005); it is, however, clearly
distinct from Zlatkocarpus by having bisexual flow-
ers proximally and pistillate flowers distally in the
spikes, a high degree of polymorphism in the struc-
ture of bracts in the same inflorescence, and much
denser secondary branching (Remizova et al.,
2005).
Conclusion
The two new species of Zlatkocarpus described here
add further diversity to the complex of Myrican-
thium-like inflorescences. The organisation of the
inflorescence and flowers is in line with that of many
other Early and mid-Cretaceous angiosperms: flow-
ers are small, often unisexual with few floral parts
and arranged in dense inflorescences. Although the
radiation of eudicot angiosperms was well under way
in the Cenomanian, the diversity of non-eudicot
angiosperms was still much higher in the Cenoma-
nian than later in the Cretaceous and today, and
includes a considerable extinct component. Zlatko-
carpus with its monocolpate pollen clearly belongs to
this non-eudicot component of Cretaceous floras.
The precise systematic placement of Zlatkocarpus is,
however, unclear. Features of the pollen grains may
suggest affinity with monocotyledons, but organisa-
tion of the flowers and fruit does not allow an unam-
biguous phylogenetic assignment. In flower and fruit
characters, the fossils show particular similarity to
some Chloranthaceae, but Zlatkocarpus is distin-
guished from Chloranthaceae by the spiral phyllo-
taxis of the spikes, and the pollen grains differ in
several respects from those of Chloranthaceae.
Acknowledgements
We thank H. Eklund and Y. Arremo, Stockholm, for
help with SEM photographs of Zlatkocarpus pragensis.
This work was supported by SYNTHESYS (SE-
TAF-1153), the Academy of Sciences of the Czech
Republic (grant no. IAA 304070701), the Ministry
of Culture of the Czech Republic (grant no. MK
00002327201), and the Swedish Natural Science
Research Council.
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... This was later supplemented by studies of associated reproductive structures (Kvaček, 1992). This program was later broadened in more detailed studies of mesofossils (Eklund et al., 1997;Eklund and Kvaček, 1998;Kvaček and Eklund, 2003;Kvaček and Friis, 2010) and Kvaček et al. (2016). ...
... Reproductive structures of early angiosperms are known from many Cretaceous localities (Crane et al., 1989;Dilcher and Crane, 1984;Eklund et al., 1997;Friis et al., 1986Friis et al., , 1994Friis et al., , 1997Friis et al., , 1999Friis et al., , 2000Friis et al., , 2011Kvaček and Friis, 2010;Retallack and Dilcher, 1981;Sun et al., 1998). Their associated foliage is frequently unknown due to taphonomic and preservational issues. ...
... Among Chloranthaceae acuminate teeth argue against a position of A. pecinovense within the Sarcandra-Chloranthus clade, on the other hand tertiary veins running parallel with secondaries argue for its similarity with Ascarina. The presence of Chloranthaceae and related angiosperms in the Peruc Flora is also indicated by finds of reproductive structures (Kvaček and Eklund, 2003;Kvaček and Friis, 2010;Kvaček et al., 2016). Discovery of foliage in association with reproductive structure could specify even more precisely the systematic affinity of the above-described fossils. ...
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... Doyle and Endress (2014) avoided scoring the ovary of Sarcandra and Chloranthus as inferior (or semi-inferior), but this is a question of terminology rather than interpretation; the inferred similarity with Ceratophyllum is more important. A semi-inferior ovary is also found in fossils interpreted as most likely related to extant Chloranthaceae and Ceratophyllum, including Canrightia (one species, Early Barremian to Early Albian of Portugal, Friis and Pedersen, 2011) and Zlatkocarpus (two species, Cenomanian of Czech Republic, Kvaček and Friis, 2010) as well as in an extinct genus of Chloranthaceae, Canrightiopsis (three species, Albian of Portugal Friis et al., 2015). The morphological phylogenetic analysis of Kvaček et al. (2016) placed Canrightia and Zlatkocarpus as two successive sister groups of a clade that includes extant Chloranthaceae as well as Ceratophyllum, with the inferior ovary as an ancestral condition. ...
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... In Clavatipollenites pollen described by Chlonova and Surova (1988) and Archangelsky and Taylor (1993), the supratectal sculpture consists of more pointed elements (nanoechini), while Canrightiopsis differs in having a heterobrochate reticulum like that of its putative extant relatives Sarcandra and Chloranthus. The monosulcate pollen of Zlatkocarpus (Kvaček and Friis 2010) and Canrightia (Friis and Pedersen 2011) differs further in having psilate muri; this supports a phylogenetic position of these mesofossils on the stem lineage of Chloranthaceae, with or without Ceratophyllum (Friis and Pedersen 2011;Doyle andEndress 2014, 2018). Pollen of Late Cretaceous Chloranthistemon species, like that of Sarcandra and Chloranthus, differs still more in aperture condition, with a presumed distal sulcus and a second furrow perpendicular to it at the opposite pole in Chloranthistemon alatus, a spiral aperture resembling the seam of a tennis ball in Chloranthistemon endressii, and six colpi in Chloranthistemon crossmanensis (Crane et al. 1989;Herendeen et al. 1993;Eklund et al. 1997). ...
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Premise of research. Accumulating data from phylogenetic analyses of living taxa and from paleobotany (pollen, leaves, and floral structures) has greatly improved our understanding of the Cretaceous rise to dominance of the angiosperms. Relatives of the near-basal family Chloranthaceae were conspicuous in the Early Cretaceous. These include female flowers and adhering pollen (Asteropollis) that resemble those of the genus Hedyosmum, but male structures with in situ pollen are not well known. Here we focus on the morphology and ultrastructure of pollen from a spike of unistaminate, ebracteate flowers from the Aptian–Albian Catefica locality and its evolutionary implications. Methodology. The coalified mesofossil was isolated from unconsolidated sediment by sieving and was cleaned with HCl, HF, and water. In situ pollen was studied using LM, SEM, and TEM. The phylogenetic relationships of the fossil were evaluated with parsimony analysis of a morphological data set with arrangements of living taxa based on molecular studies. Pivotal results. The pollen aperture is often poorly defined but is most commonly a three-armed sulcus. The exine is reticulate-columellate with a nanoverrucate supratectal sculpture. The nonapertural nexine consists of a thicker foot layer and a thin but continuous endexine that thickens and becomes lamellated under the aperture; the total nexine thickness is less than in most extant Chloranthaceae. Despite some uncertainty due to the thin nexine and similarities between the staminate structure and that of Ceratophyllum, phylogenetic analyses are most consistent with a position attached to the stem lineage of Hedyosmum. Conclusions. The variable but mainly three-armed sulcus of the Catefica fossil may represent an intermediate stage in the transformation from the ancestral simple sulcus of Chloranthaceae to the four- to six-armed sulcus of typical Asteropollis pollen and living Hedyosmum. Dispersed trichotomosulcate pollen with a chloranthaceous exine structure may be indicative of relatives of Hedyosmum, not only Ascarina, as is sometimes assumed.
... These transgressive deposits lie mostly on Triassic rocks, less commonly on Permian or Paleozoic rocks (Mile wicz 1997: 9); their thickness is quite varied, but usually about 100 m (Walaszczyk 2008). Cenomanian palaeofloras are rich and diversified in Bohemia (e.g., Heer 1869;Velenovský 1889;Eklund and Kvaček 1998;Kvaček and Friis 2010;Kvaček et al. 2012;Greguš and Kvaček 2015) and known also in southernmost Lower Silesia (Niebuhr 2019), but no plant fossils have ever been found in Cenomanian strata of the study area. ...
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Late Cretaceous plants from the North Sudetic Basin (Lower Silesia, south-western Poland) are reviewed on the basis of megaflora from 17 localities (270 identifiable specimens), mesoflora from two localities, and microflora from four localities. Major sites are Rakowice Małe and Bolesławiec. Eight megafloral assemblages are distinguished (Assemblage 1, Turonian; Assemblages 2, 3, lower–middle Coniacian; Assemblages 4, 5, upper Coniacian?–lower Santonian?; Assemblages 6–8, lower–middle Santonian); the bulk of the palaeoflora is from Assemblages 4–6 and 8. Megaflora consists of 29 taxa (6 ferns, 4 conifers, and 19 angiosperms). Geinitzia reichenbachii is the most common species. Dryophyllum westerhausianum (Richter, 1904) Halamski and Kvaček comb. nov. is a trifoliolate leaf re-interpreted as a representative of Fagales. Three species of Dewalquea are distinguished: Dewalquea haldemiana, Dewalquea insignis, and Dewalquea aff. gelindenensis. Platanites willigeri Halamski and Kvaček sp. nov. is characterised by trifoliolate leaves, the median leaflet of which is ovate, unlobed, with a serrate margin, and cuneate base. Palaeocommunities inferred from the megafossil record include: a back swamp forest dominated by Geinitzia, with abundant ferns; a Dryophyllum-dominated riparian forest; a forest with Dewalquea and Platanites willigeri possibly located in the marginal part of the alluvial plain; dunes with D. haldemiana and Konijnenburgia; a fern savanna with patches of Pinus woodlands. Palynoassemblage A from the Nowogrodziec Member, studied mostly at Rakowice Małe and Żeliszów, consists of 126 taxa, including 105 terrestrial palynomorphs (54 bryophyte, lycophyte, and pteridophyte spores, 16 gymnosperms, 35 angiosperms). The mega- and mesofossil records are dominated by angiosperms; the palynoassemblages are dominated by ferns. Palaeocommunities represented solely by the microfossil record are halophytic (with Frenelopsis and unconfirmed presence of Nypa) and pioneer vegetation. Palaeocommunities are intermediate in general character between those pre-dating the Cretaceous Terrestrial Revolution and modern, angiosperm- dominated vegetation. In comparison to older plant assemblages from contiguous areas laurophylls are much rarer; this might correspond to a real phenomenon of exclusion of lauroids from Santonian riparian forests. The studied assemblage is more similar to younger palaeofloras than to older ones; this might be interpreted as stabilisation of communities after a period of pronounced change related to the rise to dominance of the angiosperms. In contrast to widespread endemism among vertebrates of the European Archipelago, the plant cover consists mostly of species that are widely distributed.
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The vegetation communities of five terrestrial paleoenvironments from the Cretaceous (Cenomanian) Peruc-Korycany Formation of the Bohemian Cretaceous Basin in Czechia. Reconstructions are based on a synthesis of numerous studies of paleobotany, palynology, paleoecology, sedimentology and geochemistry analyses. During the Cenomanian angiosperms were diversified, particularly in alluvial plains, where lauroid and platanoid angiosperms prevailed. continent. This contrasts with BarremianAlbian times when angiosperms occupied only disturbed habitats.
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Background The Chloranthaceae comprise four extant genera (Hedyosmum, Ascarina, Chloranthus and Sarcandra), all with simple flowers. Molecular phylogenetics indicates that the Chloranthaceae diverged very early in angiosperm evolution, although how they are related to eudicots, magnoliids, monocots and Ceratophyllum is uncertain. Fossil pollen similar to that of Ascarina and Hedyosmum has long been recognized in the Early Cretaceous, but over the last four decades evidence of extinct Chloranthaceae based on other types of fossils has expanded dramatically and contributes significantly to understanding the evolution of the family. Scope Studies of fossils from the Cretaceous, especially mesofossils of Early Cretaceous age from Portugal and eastern North America, recognized diverse flowers, fruits, seeds, staminate inflorescences and stamens of extinct chloranthoids. These early chloranthoids include forms related to extant Hedyosmum and also to the Ascarina, Chloranthus and Sarcandra clade. In the Late Cretaceous there are several occurrences of distinctive fossil androecia related to extant Chloranthus. The rich and still expanding Cretaceous record of Chloranthaceae contrasts with a very sparse Cenozoic record, emphasizing that the four extant genera are likely to be relictual, although speciation within the genera might have occurred in relatively recent times. In this study, we describe three new genera of Early Cretaceous chloranthoids and summarize current knowledge on the extinct diversity of the group. Conclusions The evolutionary lineage that includes extant Chloranthaceae is diverse and abundantly represented in Early Cretaceous mesofossil floras that provide some of the earliest evidence of angiosperm reproductive structures. Extinct chloranthoids, some of which are clearly in the Chloranthaceae crown group, fill some of the morphological gaps that currently separate the extant genera, help to illuminate how some of the unusual features of extant Chloranthaceae evolved and suggest that Chloranthaceae are of disproportionate importance for a more refined understanding of ecology and phylogeny of early angiosperm diversification.
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The near-basal angiosperm family Chloranthaceae (with four living genera) is prominently represented in the Early Cretaceous fossil record by pollen and flowers, but its leaves, other vegetative parts and inflorescences are less well known. Here, we report impressions of leaves, stems and inflorescences from the middle–late Albian Escucha Formation of Teruel Province (NE Spain) that help redress this imbalance and bring into clearer focus the morphological and systematic diversity of this key group in the early angiosperm radiation. We used parsimony analysis of a morphological dataset of living and fossil Chloranthaceae to evaluate the position of the fossils on a molecular-based tree of extant taxa. Todziaphyllum elongatum gen. et sp. nov., with festooned semicraspedodromous venation and asymmetrical chloranthoid teeth, is most parsimoniously placed on the stem lineage of the living genus Hedyosmum. Leaves of Alcainea eklundiae gen. et sp. nov., with festooned semicraspedodromous venation and symmetric teeth, occur attached to stems in opposite pairs at swollen nodes with sheathing leaf bases and interpetiolar stipules, along with compound spikes of flowers with a monosymmetric androecium of three stamens, each flower subtended by a bract. This represents the first time that fossil leaves, stems and inflorescences of Chloranthaceae have been found in organic connection. Alcainea may be sister to Sarcandra, Chloranthus or the clade consisting of both genera, like the mesofossil Canrightiopsis. Leaf Type A, with festooned craspedodromous venation and symmetrical teeth, may be related to Ascarina. These observations provide direct evidence for the distinctive vegetative and inflorescence morphology of Chloranthaceae in the Early Cretaceous. They are consistent with the level of diversification inferred from coeval chloranthaceous pollen and floral mesofossils, including lines nested in crown group Chloranthaceae but not in any of living genera, and exhibiting character combinations not retained in living Chloranthaceae.
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The exploration of the origin and diversification of angiosperms has entered an exciting new era. Fresh insights and new results are rapidly accumulating from paleobotany and a wide spectrum of botanical disciplines, and an increasing number of phylogenetic models for seed plant and angiosperm relationships are being developed. Current phylogenetic hypotheses broadly support previous views that the most basal angiosperm taxa fall within a grade of organization corresponding to the subclass Magnoliidae; however, there are divergent views on the resolution of relationships within the magnoliid grade. In part, discrepancies among the results from different analyses reflect difficulties in the polarization of critical reproductive characters, which arise because of the substantial morphological gap between angiosperms and other seed plants and the absence of important angiosperm features (e.g., carpel) in their closest seed plant relatives. These problems are also compounded by the extreme floral diversity among extant Magnoliidae, which ranges from the minute and naked, unisexual, unistaminate/unicarpellate flowers of Hedyosmum (Chloranthaceae) to the large bisexual and multipartite flowers of Magnolia (Magnoliaceae).
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In the last decade significant new information has been gained about the early evolution of flowering plants through studies of Early Cretaceous angiosperm pollen and the pollen of living primitive flowering plants. Although most recent palynological studies of extant primitive angiosperms have used both scanning and transmission electron microscopy, few ultrastructural studies of early fossil angiosperm pollen grains exist. This paper represents an attempt to remedy this situation. Thirteen different types of Lower Cretaceous angiosperm pollen grains from the Potomac Group of eastern North America and the Fredericksburgian of Oklahoma were examined ultrastructurally, including Clavatipollenites hughesii, two aff. Clavatipollenites species, Asteropollis asteroides, Stephanocolpites fredericksburgensis, Retimonocolpites dividuus, R. peroreticulatus, two aff. Retimonocolpites species, Stellatopollis barghoornii, and three species of Liliacidites. These grains were investigated using a technique that we have developed for working with single fossil pollen grains by which we are able to undertake combined light, scanning electron, and transmission electron microscopy of the same pollen grain. This technique is invaluable for the evolutionary study of small, light-microscopically similar, dispersed fossil pollen grains, such as those that constitute the bulk of the earliest known part of the fossil record of the flowering plants, and provides a much improved means of delimiting Early Cretaceous angiosperm pollen form genera such as Clavatipollenites, Retimonocolpites, and Liliacidites. Our study also reveals that a close similarity exists between some Early Cretaceous angiosperm pollen and pollen produced by certain living primitive angiosperms. Clavatipollenites hughesii, Asteropollis asteroides, and Stephanocolpites fredericksburgensis exhibit varying degrees of similarity at the ultrastructural level respectively to pollen of the extant angiosperm genera Ascarina, Hedyosmum, and Chloranthus, all three of which belong to the modern family Chloranthaceae. Pollen described under the form genus Liliacidites possesses many features that are restricted to pollen of living monocotyledons, while Retimonocolpites possesses certain monocotyledonous palynological features, but to a lesser extent. Large monosulcate pollen grains with distinctive crotonoid sculpturing described as Stellatopollis barghoornii have no counterpart among the pollen of extant angiosperms. The question of the origin and early evolution of the angiosperms is dealt with in the second part of the paper, and the fossil pollen record of early flowering plants is considered in light of what is known about pollen evolution in living primitive angiosperms. Analysis of the taxonomic distribution of characters of living primitive angiosperms suggests that angiosperm pollen is primitively monosulcate, boat-shaped, large- to medium-sized, psilate or at best only weakly sculptured, noninterstitiate to interstitiate-granular, atectate, and without endexine. This type of pollen is found today only in the otherwise primitive angiosperm families Magnoliaceae, Degeneriaceae, and Annonaceae. It is concluded that Clavatipollenites and other currently known types of Early Cretaceous angiosperm pollen grains represent relatively advanced primitive angiosperm pollen that is already too specialized to reveal anything about the earliest evolution (or the origin) of the flowering plants. Finally, what can be deduced about the origin and early evolution of flowering plants from fossil and living primitive angiosperms is considered. The conclusion is drawn that the ancestory of the angiosperms must be sought in the pteridosperms or in a derivative group. A 5-stage model of early angiosperm evolution is proposed, based on the early (Barremian to Middle Cenomanian) fossil pollen record of the flowering plants and the inferred phylogenetic relationships of living primitive angiosperms. From an original, pre-Barremian basal complex of entomophilous flowering plants, whose living descendants include such angiosperms as the Magnoliales, Laurales, and Winterales, we envision evolution of a major line of anemophilous and apetalous angiosperms in the Barremian-Aptian, the descendants of which include advanced magnoliid angiosperms, such as the Chloranthaceae, as well as related primitive hamamelidid angiosperms, such as the Trochodendrales, Cercidiphyllales, and Hamamelidales. The evolution of wind-pollination so early within the angiosperms may have been connected with the increasing aridity (and possible decline in insect pollinators) that occurred soon after the earliest appearance of Clavatipollenites-type pollen in the Barremian of Africa and South America, when major splitting of West Gondwana was taking place. The majority of dicots, including the subclasses Dilleniidae, Rosidae, and Asteridae, appear to be derived from this early group of entomophilous-derived anemophilous angiosperms, and, thus, most of the dicots probably represent flowering plants that have secondarily returned to entomophily.
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Nilsonia holyi Kvacek et Knobloch, sp. nov. is described as a new entire-margined cycadophyte foliage species from the Cenomanian of the Bohemian Massif. It displays entire-margined lamina, a typical emarginate apex, simple secondary veins and a characteristic arrangement of stomata. N. holyi is compared with N. bohemica Velenovsky, N. orientalis Heer, N. tenuinervis Seward, N. thomasii Harris and other entire-margined Nilsonia species, New occurrences of N. bohemica are reported from the localities Jetrichovice and Velke Opatovice. Width of leaf lamina is suggested as a good morphological character for Nilsonia bohemica leaf impressions. (C) 1997 Elsevier Science B.V.