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Picea farjonii sp. nov., scanning electron micrographs of the transition between the leafy shoot and seed cone (PP55921). (A) Detail of distal part of the transition region between leafy shoot and cone showing a rudimentary bract (left arrow, see also (B)) and appressed peg-like leaf bases; note the scar left by abscised rudimentary bract (right arrow, also shown in C). (B) Detail of rudimentary bract in (A), arrow indicates the zone of abscission. (C) Detail of rhomboidal bract abscission scar in (A), note central vascular bundle (central arrow) and two lateral probable resin canals (lateral arrows). (D) Detail of the central vascular bundle from (C). (E) Detail of the proximal part of the transition region between leafy shoot and cone showing broken leaf base (upper arrow) and appressed peg-like leaf bases (lower arrow); note abscission zone (middle arrow). (F) Isolated leaf found attached to the shoot in (A) showing linear, flattened, form and smooth margin (squares indicate the areas shown in detail in (G) and (H)). (G) Detail of the leaf apex in (F) showing an acuminate tip and elongated epidermal cells. (H) Detail of the leaf base in (F) (partially bent) showing a more or less elliptical abscission scar and probable resin canal. (I) Isolated leaf found attached to the shoot in (A) showing two bands of stomata on the putative adaxial surface. (J) Detail of stomata (arrows) showing the stomatal aperture flanked by two sunken guard cells with two lateral and two polar subsidiary cells. Scale bars = 2.5 mm (A), 2 mm (F), 500 m (B, C, E, and I), 100 m (D, G, and H), 50 m (J).
Source publication
Exceptionally well-preserved pinaceous leaves and seed cones are abundant in unconsolidated Early Cretaceous lignites in central Mongolia. These fossils include two seed cones, both of which have helically arranged bract-scale complexes with two winged seeds on the adaxial surface. The larger of the two seed cones, described as Picea farjonii sp. n...
Contexts in source publication
Context 1
... 4N). Seed bod- ies are about one-fifth to one-sixth of the length of the 3. Picea farjonii sp. nov., scanning electron micrographs of bract-scale complexes from the seed cone in Fig. 2E ( 4. Picea farjonii sp. nov., light and scanning electron micrographs of adaxial surface of bract-scale complexes (A-M) and seed (N and O) from the seed cone in Fig. 2E (PP55906). (A) Small, apical bract-scale complex, obovate in outline, showing the emarginate apex of an ovuliferous scale and a single attached seed (arrow); note the shallow cup-like depression caused by the seed body and wing scar on the right half of the ...
Context 2
... single specimen shows the zone of transition be- tween the peduncle of the seed cone and the shoot on which it is borne (Fig. 5). This specimen preserves rudi- mentary bracts, leaf fragments, and peg-like leaf bases with pulvini (Figs. 5A-5E). Leaves are helically arranged on shoots with long grooves and ridges. Three leaves were found attached to the shoot during preparation of the material (Figs. 5E-5J), but the attachment of two of them was not recorded ...
Context 3
... not recorded photographically before the spec- imen disarticulated. These leaves, as well as similar leaves found in close association with the shoot, are linear, flattened, 1.1-4.5 cm long, 0.1-0.7 cm wide (mea- sured at the widest point), and 97-450 m thick (Figs. 5E- 5J). The leaf base is convex. The apex is rounded with a small acuminate tip (Fig. 5G). The leaf margin is ...
Context 4
... long, 19-25 m wide, and arranged in longitudinal files (Figs. 5G and 5J). Sunken stomata occur on most of the leaf surface except at the apex. They are crowded and longitudinally or obliquely oriented. Sto- matal complexes are 54-77 m long, 23-29 m wide, and are composed of two sunken guard cells with two lateral and two polar subsidiary cells ( Fig. 5J; see also Figs. 3M and 3N). The subsidiary cells are rectangular to polyhe- dral in outline. The two polar cells are square in ...
Context 5
... cones of P. farjonii (Figs. 1-6) are much more sim- ilar to those of extant Picea. In both cases the seed cones are solitary and borne on short peduncles that are cov- ered with small, rudimentary bracts (Figs. 2F, 2G, 5A, and 5B). This feature is unique to Picea among living Pinaceae (Farjon 1990(Farjon , 2010. Seed cones of P. farjonii and extant Picea are also similar in size and shape, number of bract- scale complexes, bracts that are tridentate and much shorter than the ovuliferous scales, and bracts that have toothed margins and an abaxial lobe ...
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Premise of the Study
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Methods
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Citations
... The proliferated cupule-bearing structures of Triassic corystosperms likely reflect the form of plants that flourished in favourable growing conditions, as evidenced by the rich and varied Triassic plant assemblages, with many large leaves, in which they occur. In contrast, the much less elaborated reproductive structures of the Early Cretaceous forms, based on the fossil assemblage from the Tevshiin Govi lignite mine, Mongolia, likely reflect the limitations on growth in a depauperate swamp community, with many small leaves (Leslie et al. 2013;Shi et al. 2014Shi et al. , 2016Shi et al. , 2018Shi et al. , 2019Herrera et al. 2015Herrera et al. , 2016Herrera et al. , 2017aHerrera et al. , b, c, 2018Herrera et al. , 2020Herrera et al. , 2021. ...
The group referred to informally as the corystosperms, described initially based on compression fossils from the Triassic of Gondwana, have long been considered critical extinct plants for understanding seed plant phylogeny, the evolution of seed plant reproductive structures and the relationships of angiosperms. Here we describe a new genus and species of corystosperm seed-bearing structure, Jarudia zhoui gen. et sp. nov., based on abundant silicified material collected from the newly discovered chert in the Early Cretaceous Huolinhe Formation of eastern Inner Mongolia, north-eastern China. Jarudia zhoui is a lax seed cone consisting of a flexible central axis bearing deciduous, helically arranged, lateral seed-bearing units. Individual seed-bearing units consist of an elongate bract partially fused to an unbranched cupule stalk that bears a single, reflexed cupule apically. Each cupule is formed by the strongly reflexed cupule stalk and one median and two lateral flaps. The cupule stalk supplied by two vascular bundles and three unvascularized flaps partially enclose two three-angled seeds. Jarudia zhoui bears a striking resemblance to Doylea tetrahedrasperma from the Early Cretaceous of Canada and similar plants from the Early Cretaceous of Mongolia. There are also strong similarities with ovulate structures of Umkomasia from the Triassic of Gondwana in the structure and anatomy of individual cupules, their axial nature, and the architecture of the entire seed-bearing structure that has two orders of branching. New information from Jarudia zhoui, together with information on other corystosperm ovulate organs from the Northern Hemisphere, significantly expands our understanding of this key group of extinct plants, suggests that the cupules of the Early Cretaceous and Triassic corystosperms are homologous, and raises critical questions about the definition and phylogenetic circumscription of the corystosperms, including how Early Cretaceous and Triassic corystosperms are related to each other and to other groups of seed plants, including angiosperms.
... The site represents one of the most important Cretaceous cone sites globally in terms of abundance. Only two other regions are known to have yielded numerous fossils of Pinaceae: Clermont-en-Argonne site in the French Ardennes (Granpré, Albian greensands; Fliche, 1896;Louvel, 1960), and the Dundgovi province in central Mongolia (Aptian-Albian; Herrera et al., 2015Herrera et al., , 2016. Nine species have been described based on the Belgian material, and most of them have been used in multiple comparative and phylogenetic studies of Pinaceae Stockey, 2001, 2002;Gernandt et al., 2008;Smith et al., 2017). ...
Premise of the study:
The expansion of Pinaceae during the Cretaceous is exemplified by the numerous ovulate cone taxa found in Western Europe and North America. The Belgian Wealden facies deposits have delivered hundreds of exceptionally well-preserved yet isolated pinaceous ovulate cones; these cones were placed by convention within form-genera. Ten species have been described in Belgium, representing about 20% of the known fossil record of this period. However, the validity of these taxa is questionable as to their intra- and interspecific variabilities have never been thoroughly studied. Moreover, quantifying the expansion of Pinaceae in terms of morphospace occupation is desirable to reveal the dynamics of this critical radiation.
Methods:
We used linear and geometric morphometry to quantify the shape of the extensive sample of Cretaceous cones of Belgium. These methods were also applied to extant pinaceous species to compare the morphological disparity of Cretaceous assemblages against those of today in selected ecosystems. We used ordination methods (PCA) to visualize morphospace occupation and test for species delineation.
Key results:
We observed that the morphological disparity is not higher in fossil species than in present-day species we sampled. Both morphological approaches confirm that the species Pityostrobus andraei presents high morphological variability. Our resampling tests indicate that ovulate cone morphological variability can be satisfactorily quantified with as few as 15 specimens.
Conclusions:
The results will allow assessing both the variability and the diversity of many fossil assemblages, paving the way for a more robust evaluation of Cretaceous pinaceous diversity. This article is protected by copyright. All rights reserved.
... The obscure Jurassic history of Pinaceae contrasts markedly with its diverse and abundant Early Cretaceous fossil record, which documents remarkable morphological diversity, including the seed cone genera Pseudoaraucaria (Alvin, 1957a(Alvin, , 1957b(Alvin, , 1960(Alvin, , 1988Miller and Robison, 1975), Obirastrobus (Ohsawa and Nishida, 1992), and especially Pityostrobus, a likely polyphyletic genus that includes ≥30 species (e.g., Herrera et al., 2016;Smith et al., 2016). Recent phylogenetic hypotheses suggest that several Early Cretaceous Pityostrobus species may belong to stem lineages of extant abietoids and pinoids (Smith et al., 2016;Gernandt et al., 2018). ...
... A large number of Pityostrobus species have been described based on fossil cones from Early Cretaceous localities, but none shows any indication of a shedder dispersal (e.g., Herrera et al., 2016;Smith et al., 2016;Gernandt et al., 2018;Losada et al., 2018). Most have also been described on the basis of permineralized material, which can be challenging to compare with the abundant lignified specimens on which L. mellonae is based. ...
... Another connection between L. mellonae and abietoids such as Cedrus and Pseudolarix is the well-developed indumentum on the bract-scale complexes. In L. mellonae this covers the entire abaxial side of the ovuliferous scale as well as the distal portion of the adaxial surface, whereas the cones of all other Pinaceae at Tevshiin Govi are glabrous and lack trichome bases in their cuticles (Leslie et al., 2013;Herrera et al., 2016). In L. mellonae, as also in Cedrus and Pseudolarix, the tomentose surface of the cone scale appears to be defined by the shape of the winged seeds ( Figures 6L and 8). ...
Premise:
Seed cones of extant Pinaceae exhibit two mechanisms of seed release. In "flexers" the cone scales remain attached to the central axis, while flexing and separating from each other to release the seeds. In "shedders" scales are shed from the axis, with the seeds either remaining attached to the scale or becoming detached. The early fossil history of Pinaceae from the Jurassic to Early Cretaceous is dominated by flexing seed cones, while the systematic information provided by shedding fossil cones has been overlooked and rarely integrated with data based on compression and permineralized specimens. We describe the earliest and best-documented evidence of a "shedder" seed cone from the Aptian-Albian of Mongolia.
Methods:
Lignite samples from Tevshiin Govi locality were disaggregated in water, washed, and dried in air. Fossils were compared to material of extant Pinaceae using LM and CT scans.
Results:
Lepidocasus mellonae gen. et sp. nov. is characterized by a seed cone that disarticulated at maturity and shed obovate bract-scale complexes that have a distinctive ribbed surface and an abaxial surface covered with abundant trichomes. The ovuliferous scale has ca. 30-40 resin canals, but only scarce xylem near the attachment to the cone axis. Resin vesicles are present in the seed integument. Phylogenetic analysis places Lepidocasus as sister to extant Cedrus within the abietoid grade.
Conclusions:
The exquisite preservation of the trichomes in L. mellonae raises questions about their potential ecological function in the cones of fossil and living Pinaceae. Lepidocasus mellonae also shows that a shedding dispersal syndrome, a feature that has often been overlooked, evolved early in the history of Pinaceae during the Early Cretaceous.
... . The oldest records of Picea come from the Lower Cretaceous (Valanginian;Cohen et al. 2013) Longarm Formation equivalent on Vancouver Island, British Columbia, Canada and from the Aptian-Albian(Cohen et al. 2013) Tevshiin Govi Formation in central Mongolia(Klymiuk & Stockey 2012;Herrera et al. 2016). The distribution of the genus expanded to West North America, Arctic Canada, Alaska, eastern Russia, and Japan by middle to late Eocene time (LePage 2003b). ...
In this study, we describe the fossil wood flora from the Chattian (late Oligocene) and Aquitanian (early Miocene) deposits that crop out on the Tym River at Kompasky Bor, Russia. Twenty conifer and angiosperm wood taxa are described and a new fossil wood genus Thujopsoxylon gen. nov. and three new species are established: Thujopsoxylon schneiderianum sp. nov.; Piceoxylon nikitinii sp. nov.; and Crataegoxylon sibiricum sp. nov. The Kompasky Bor flora is important because it is the northernmost Chattian macroflora in the West Siberian Plain so far known and provides constraints on the timing and record of plant taxa migrations between Europe and the West Siberian Plain during the late Paleogene and the early Neogene. The fossil wood and macrofossil taxa are compared to European and other West Siberian Plain floras of similar age to understand the spatial and temporal relationships between these floras. The results of this multivariate analysis indicate floristic exchange between Europe and the West Siberian Plain was not prevalent, but much more pronounced between the West Siberian Plain and the Ural Mountains during the Rupelian and Chattian. Furthermore, elements of the polar broad-leaved deciduous forests appear to have occupied northern Europe and extended into the Ural Mountains and, despite the functionality of the lowland corridors between Europe and the West Siberian Plain, floristic exchange was not pronounced until Miocene time when climate became cooler and drier, signaling the onset of the evolution and development of boreal ecosystems in Europe and the West Siberian Plain.
... давно вовлечены в сферу хозяйственных интересов человека [Кулькова и др., 2020а, б;2018;Konôpka et al., 2011, Wiensczyk et al., 2011. Этому во многом способствует удачное сочетание их признаков и свойств [Lindgren et al., 2009;Groot, 2013], а также широкое распространение в северном полушарии Herrera et al., 2016]. Значительные размеры ареала обусловлены экологической пластичностью и высокой резистентностью к негативному влиянию лимитирующих внешних факторов Hamilton, 2016], полиморфизмом и наличием в составе видов большого количества наследственно обусловленных форм [Morgenstern, 1969;Verheggen et al., 1983;Adams et al., 1996;Porth et al., 2015]. ...
Изучали характер и масштаб сезонных изменений пигментного состава хвои разных видов ели (Picea A. Dietr.) в условиях интродукции в Нижегородскую область, выявляли содержание и баланс пластидных пигментов фотосинтеза. Объектами исследования выступали 13 видов ели, относящихся к аборигенам и экзотам: ель европейская (Picea abies (L.) H. Karst.); ель сибирская (Picea obovata Ledeb.); ель Глена (Picea glehnii (F. Schmidt) Mast.); ель белая (Picea glauca (Moench) Voss); ель шероховатая (Picea asperata Masters); ель черная (Picea mariana Mill., Britton, Sterns & Poggenburg); ель колючая форма серебристая (Picea pungens Engelm., f. argentea); ель колючая форма голубая (Picea pungens Engelm., f. glauca Regel); ель сербская (Picea omorika (Pančić) Purk.); ель Энгельмана (Picea engelmannii Parry ex Engelm.); ель колючая (Picea pungens Engelm.); ель аянская (Picea jezoensis (Siebold & Zucc.) Carrière); ель корейская (Picea koraiensis Nakai). Отбор проб осуществлен рендомизированно с соблюдением принципа единственного логического различия. Использовали спектрофотометр СФ-2000. Установлено, что содержание и соотношение пластидных пигментов в хвое динамично в течение года. Определена эффективность влияния фаз сезонного развития растений на характеристики пигментного состава: по содержанию хлорофилла-a – 18,86±0,32%; по содержанию хлорофилла-b – 21,26±0,31%; по сумме хлорофиллов – 16,13±0,33%; по каротиноидам – 37,43±0,25%; по доле хлорофилла-a – 39,74±0,24% и доле хлорофилла-b – 39,74±0,24%. Эффект влияния межвидовых различий по показателям содержания и соотношения разных форм хлорофилла и каротиноидов достоверен и в достаточной мере выравнен при максимуме 23,56±0,91%. При общих тенденциях в сезонной динамике представители рода ель обладают заметной видоспецифичностью пигментного состава.
We studied the nature and scale of seasonal changes in the pigment composition of needles of different spruce species (Picea A. Dietr.) under the conditions of introduction to the Nizhny Novgorod region, and revealed the content and balance of photosynthetic plastid pigments. The objects of the study were 13 species of spruce belonging to aborigines and exotics: Norway spruce (Picea abies (L.) H. Karst.); Siberian spruce (Picea obovata Ledeb.); Glen spruce (Picea glehnii (F. Schmidt) Mast.); white spruce (Picea glauca (Moench) Voss); Dragon spruce (Picea asperata Masters); black spruce (Picea mariana Mill., Britton, Sterns & Poggenburg); silver prickly spruce (Picea pungens Engelm., f. argentea); blue prickly spruce (Picea pungens Engelm., f. glauca Regel); Serbian spruce (Picea omorika (Pančić) Purk.); Engelman spruce (Picea engelmannii Parry ex Engelm.); Blue spruce (Picea pungens engelm.); Ayan spruce (Picea jezoensis (Siebold & Zucc.) carrière); Korean spruce (Picea koraiensis Nakai). Sampling was carried out in a randomized manner, following the principle of a single logical difference. A spectrophotometer SF-2000 was used. It was found that the content and ratio of plastid pigments in conifers is dynamic throughout the year. The effectiveness of the influence of the phases of seasonal plant development on the characteristics of the pigment composition is determined: by the content of chlorophyll-a-18.86±0.32%; by the content of chlorophyll-b-21.26±0.31%; by the sum of chlorophylls-16.13±0.33%; by carotenoids – 37.43±0.25%; by the proportion of chlorophyll-a – 39.74±0.24% and the proportion of chlorophyll-b – 39.74±0.24%. The effect of interspecific differences in the content and ratio of different forms of chlorophyll and carotenoids is significant and sufficiently equalized at a maximum of 23.56±0.91%. With General trends in seasonal dynamics, representatives of the spruce genus have a noticeable species-specific pigment composition.
... The shed parts of the Krassilovia plant are a significant component of the Tevshiin Govi lignite, which shows no evidence of higher energy input and appears to have accumulated largely autochthonously. Growing alongside the Krassilovia plant were a variety of other presumed trees, including taxa related to extant Pinaceae (Schizolepidopsis, Picea, Pityostrobus, [65,86]), Cupressaceae (Elatides, Stutzeliastrobus, Pentakonos, [64,87], and the ginkgophyte Umaltolepis [70], as well as plants that may have been shrubs, such as the corystosperm Umkomasia [31,32]. The absence of lycopods and ferns (as macrofossils, mesofossils, or megaspores), other than the epiphytic filmy fern Hymenophyllum [88], suggests there was little or no herbaceous vegetation. ...
Previously unrecognized anatomical features of the cone scales of the enigmatic Early Cretaceous conifer Krassilovia mongolica include the presence of transversely oriented paracytic stomata, which is unusual for all other extinct and extant conifers. Identical stomata are present on co-occurring broad, linear, multiveined leaves assigned to Podozamites harrisii, providing evidence that K. mongolica and P. harrisii are the seed cones and leaves of the same extinct plant. Phylogenetic analyses of the relationships of the reconstructed Krassilovia plant place it in an informal clade that we name the Krassilovia Clade, which also includes Swedenborgia cryptomerioides–Podozamites schenkii, and Cycadocarpidium erdmanni–Podozamites schenkii. All three of these plants have linear leaves that are relatively broad compared to most living conifers, and that are also multiveined with transversely oriented paracytic stomata. We propose that these may be general features of the Krassilovia Clade. Paracytic stomata, and other features of this new group, recall features of extant and fossil Gnetales, raising questions about the phylogenetic homogeneity of the conifer clade similar to those raised by phylogenetic analyses of molecular data.
... Much of the Cretaceous and Paleogene fossil record of Pinaceae is understood from morphogenera, especially the genus Pityostrobus (Smith et al., 2017). Extant genera do not appear until the Early Cretaceous, with ovulate cones of Picea burtonii (Valanginian, Vancouver Island, Canada; Klymiuk and Stockey, 2012) and Picea farjonii (Aptian-Albian, Mongolia; Herrera et al., 2016) and cones and wood of Pinus known from the UK and Nova Scotia, Canada, respectively (Ryberg et al., 2012;Falcon-Lang et al., 2016) and other taxa showing up later. The fossil record of Cupressaceae is rich (Stockey et al., 2005;Taylor et al., 2009) and also extends back at least to the Jurassic with the extinct genus Austrohamia (Early Jurassic of Patagonia, Escapa et al., 2008;and Middle Jurassic of China, Zhang et al., 2012;Dong et al., 2018). ...
Plants are direct recorders of the environmental conditions in which they were growing through their carbon assimilation. Both δ13Cleaf (measured C isotopic composition of the leaf) and Δleaf (isotopic discrimination from δ13Catm by the leaf) values have been proposed to reflect a variety of environmental conditions including MAT, MAP, latitude, elevation, [CO2], and δ13Catm. Herein, we examine three sets of data from gymnosperms with long fossil records as well as selected co-occurring angiosperms to compare responses to potential environmental controls. The first dataset comprises species growing across a wide array of climatic and environmental conditions to examine MAT, MAP, latitude, and elevation. Among those potential environmental factors, none exhibits a strong control on either δ13Cleaf or Δleaf at the family, genus, or species level for either the focal gymnosperms or most of the co-occurring angiosperms. This result holds whether temperature or precipitation are considered annually or seasonally. Plant meta-analyses that have suggested a strong relationship between MAP and δ13Cleaf or Δleaf can instead be interpreted as reflecting constant Δleaf for individual species over their environmental occurrence ranges where individual ecosystems are made up of various species at different points along their individual MAP tolerance. The second dataset comes from an array of species all growing under the same environmental conditions. While differences in δ13Cleaf or Δleaf are small at the family level, at the genus and species level variation is much larger. This suggests that for any paleo-proxy reconstruction, accurate plant identification is critical to selecting the appropriate Δleaf. It also may indicate that there is an evolutionary component to measured Δleaf values, with large differences potentially between early-divergent and derived lineages. The third dataset is derived from herbarium collections of species that span the period of Industrialization (1850-present). During this time period CO2 levels have increased by ~50% and δ13Catm has shifted by >2‰ due to the burning of isotopically more negative fossil fuels. All of the historical records show that plants shifted their δ13Cleaf value, tracking the δ13Catm changes, but they did not change their Δleaf values. This contrasts strongly with some experimental results based on fast-growing herbaceous angiosperms and suggests either that there are fundamental differences between woody and herbaceous plants and/or that gymnosperms respond differently to increased CO2 than angiosperms. Finally, a brief case study is presented that examines how water use efficiency (represented by ci/ca) changed in response to elevated atmospheric CO2 levels in the Eocene to Miocene. Both Thuja and Metasequoia substantially increase their ci/ca ratios during the highest CO2 levels in the Eocene and decreased them in response to falling atmospheric CO2 during the Miocene. This suggests that the compiled Δleaf values described herein can be used to improve a variety of paleo-proxies for atmospheric CO2 levels and for plant responses to changing atmospheric stressors.
... The lignites at Tevshiin Govi locality contain diverse, abundant and exquisitely preserved plant fossils, including fertile and sterile fronds of the filmy fern Hymenophyllum iwatsukii F. Herrera et al. (Hymenophyllaceae) (Herrera et al. 2017a), leaves of Podozamites (Presl) Braun, Pseudotorellia Florin (Shi et al. 2018) and seed-bearing structures of Umkomasia and Umaltolepis Krassilov (Herrera et al. 2017b). Also important in the Tevshiin Govi assemblages are abundant conifer leaves as well as seed cones and seeds of Cupressaceae (Shi et al. 2014;Herrera et al. 2016b), probable stem group and crown group Pinaceae (Leslie et al. 2013;Herrera et al. 2016a), and the putative voltzian conifer Krassilovia F. Herrera, G. Shi, A. B. Leslie, Knopf, Ichinnorov, Takahashi, P. R. Crane & Herend (Herrera et al. 2015). ...
... They can be: (1) simple, linear, often needle-like and with a single vein, e.g. leaves of unequivocal Pinaceae (Herrera et al. 2016a) There is strong evidence from stomatal and cuticular structure that Podozamites harrisii is the leaf of Krassilovia mongolica (Herrera et al. in progress) and there is also good evidence that Pseudotorellia resinosa is the leaf of Umaltolepis mongoliensis F. Herrera, G. Shi, Ichinnorov, Takahashi, Bugdaeva, Herend. & P. R. Crane (Herrera et al. 2017b;Shi et al. 2018). ...
New discoveries of corystosperm seed-bearing structures from the Tevshiin Govi locality, Mongolia, which is of Early Cretaceous (Aptian–Albian) age, show that the individual seed-bearing units of Umkomasia mongolica were borne in a cone, as also documented for the very similar reproductive units of Doylea tetrahedrasperma. New material from the Tevshiin Govi locality also documents two additional species of Umkomasia–U. corniculata sp. nov. and U. trilobata sp. nov.–that most likely grew in a different environment to U. mongolica. The occurrence of three different Umkomasia species in the Early Cretaceous of Mongolia, together with other records from the Early Cretaceous of the Northern Hemisphere, indicate that previous concepts of corystosperms, based mainly on material from the Southern Hemisphere, need to be revised. The consistent reproductive architecture of the seed-bearing structures in all three corystosperm species, with a bract subtending a variously modified axis bearing ovules, is similar to the situation in Ginkgo and conifers. These underappreciated architectural commonalities among the reproductive structures of major groups of seed plants are likely significant for a deeper understanding of seed plant evolution and require further exploration. © 2019, © The Trustees of the Natural History Museum, London 2019. All rights reserved.
... Th e abundance of fossil specimens of H . iwatsukii in the lignite fl oras and the exquisite preservation also suggest little long distance transport from the place of growth. Th e Tevshiin Govi and Tugrug fl oras were dominated by conifers and other gymnosperms, some of them deciduous, including conifers such as Krassilovia ( Herrera et al., 2015 ;Shi et al., 2017 ), Schizolepidopsis , Picea , and Pityostrobus in Pinaceae ( Leslie et al., 2013 ;Herrera et al., 2016 ), Elatides , Stutzeliastrobus , and Pentakonos in Cupressaceae ( Shi et al., 2014 ;Herrera et al., 2017b ), the putative ginkgophyte plant Umaltolepis ( Herrera et al., 2017a ), as well as the corystosperm Umkomasia . Th e authors hypothesize that H . iwatsukii was an epiphyte on one or more of these woody plants. ...
Premise of the study:
Hymenophyllaceae ("filmy ferns") are a widely distributed group of predominantly tropical, epiphytic ferns that also include some temperate and terrestrial species. Hymenophyllaceae are one of the earliest-diverging lineages within leptosporangiate ferns, but their fossil record is sparse, most likely because of their low fossilization potential and commonly poor preservation of their delicate, membranaceous fronds. A new species of unequivocal fossil Hymenophyllaceae, Hymenophyllum iwatsukii sp. nov., is described from the Early Cretaceous of Mongolia based on abundant and exceptionally well-preserved material.
Methods:
Bulk lignite samples collected from Tevshiin Govi and Tugrug localities in Mongolia, were disaggregated in water, cleaned with hydrochloric and hydrofluoric acids, washed, and dried in air. Fossils were examined and compared to material of extant Hymenophyllaceae using LM and SEM.
Key results:
The fossil fern specimens are assigned to the Hymenophyllaceae based on their membranaceous laminae with marginal sori that have sessile to short-stalked sporangia with oblique, complete annuli, and trilete, tetrahedral-globose spores. Within the family, the fossil material is assigned to the extant genus Hymenophyllum on the basis of bivalvate indusia and short, included receptacles.
Conclusions:
Hymenophyllum iwatsukii was likely an epiphyte based on the sedimentary environment in which the fossils are preserved, the associated fossil flora, and the growth habit of extant species of Hymenophyllum. The new fossil species underlines the extent to which morphological characters in Hymenophyllum have been conserved despite significant tectonic, climatic, ecological, and floristic changes since the Early Cretaceous.
... Other than the tiny leaves of a probable epiphytic or climbing fern, the flora is devoid of pinnately compound leaves. In all cases the leaves in the fossil assemblage are needle-like (Schizolepidopsis, Picea) (16,17), scale-like (Stutzeliastrobus) (19), or simple and parallel-veined (Podozamites, both species of Pseudotorellia) (9). ...
The origins of the five groups of living seed plants, including the
single relictual species Ginkgo biloba, are poorly understood, in large
part because of very imperfect knowledge of extinct seed plant diversity.
Here we describe well-preserved material from the Early
Cretaceous of Mongolia of the previously enigmatic Mesozoic seed
plant reproductive structure Umaltolepis, which has been presumed
to be a ginkgophyte. Abundant new material shows that Umaltolepis
is a seed-bearing cupule that was borne on a stalk at the tip of a
short shoot. Each cupule is umbrella-like with a central column that
bears a thick, resinous, four-lobed outer covering, which opens from
below. Four, pendulous, winged seeds are attached to the upper part
of the column and are enclosed by the cupule. Evidence from morphology,
anatomy, and field association suggests that the short
shoots bore simple, elongate Pseudotorellia leaves that have similar
venation and resin ducts to leaves of living Ginkgo. Umaltolepis
seed-bearing structures are very different from those of Ginkgo
but very similar to fossils described previously as Vladimaria. Umaltolepis
and Vladimaria do not closely resemble the seed-bearing
structures of any living or extinct plant, but are comparable in some
respects to those of certain Peltaspermales and Umkomasiales
(corystosperms). Vegetative similarities of the Umaltolepis plant to
Ginkgo, and reproductive similarities to extinct peltasperms and
corystosperms, support previous ideas that Ginkgo may be the last
survivor of a once highly diverse group of extinct plants, several of
which exhibited various degrees of ovule enclosure.
