Wetland megabias: ecological and ecophysiological filtering dominates the fossil record of hot spring floras

Siliceous hot spring deposits form at Earth's surface above terrestrial hydrothermal systems, which create low‐sulphidation epithermal mineral deposits deeper in the crust. Eruption of hot spring waters and precipitation of opal‐A create sinter apron complexes and areas of geothermally influenced wetland. These provide habitat for higher plants that may be preserved in situ, by encrustation of their surfaces and permineralization of tissues, creating T⁰ plant assemblages. In this study, we review the fossil record of hot spring floras from subfossil examples forming in active hot spring areas, via fossil examples from the Cenozoic, Mesozoic and Palaeozoic to the oldest known hot spring flora, the Lower Devonian Rhynie chert. We demonstrate that the well‐known megabias towards wetland plant preservation extends to hot spring floras. We highlight that the record of hot spring floras is dominated by plants preserved in situ by permineralization on geothermally influenced wetlands. Angiosperms (members of the Cyperaceae and Restionaceae) dominate Cenozoic floras. Equisetum and gleicheniaceous ferns colonized Mesozoic (Jurassic) geothermal wetlands and sphenophytes and herbaceous lycophytes late Palaeozoic examples. Evidence of the partitioning of wetland hydrophytic and dryland mesophytic communities, a feature of active geothermal areas, is provided by well‐preserved and well‐exposed fossil sinter apron complexes, which record flooding of dryland environments by thermal waters and decline of local forest ecosystems. Such observations from the fossil record back‐up hypotheses based on active hot springs and vegetation that suggest removal of taphonomic filtering in hot spring environments is accompanied by an increase in ecological and ecophysiological filtering. To this end we also demonstrate that in the hot spring environment, the wetland bias extends beyond broad ecology. We show that ecosystems preserved from the Cenozoic to the Mesozoic provide clear evidence that the dominant plants preserved in situ by hot spring activity are also halophytic, tolerant of high pH and high concentrations of heavy metals. By extension, we hypothesize that this is also the case in Palaeozoic hot spring settings and extended to the early land plant flora of the Rhynie chert.     

A new fossil Cedrus species from the early Miocene of northwestern Turkey and its possible affinities

A new fossil species, Cedrus anatolica n. sp., is described from the early Miocene Hançili Formation of Turkey. All analyses were performed on the thin sections housed at Istanbul University – Cerrahpasa. The new species was interpreted as having the closest affinity with the modern Mediterranean species Cedrus atlantica (Endlicher) Manetti ex Carriere and Cedrus libani Richard. The evolutionary line shows some changes in wood anatomy. From the early Cretaceous to the early Miocene, the pits on the tangential walls of the tracheids gradually decreased, the height of rays increased and the number of epithelial cells in the traumatic resin canals increased slightly. These features are similar in three modern species; other wood anatomical features are also quite stable among the new fossil and modern species.     

An unusual microfungus in a fungal spore from the Lower Devonian Rhynie chert

Abstract: A new fossil microfungus, Kryphiomyces catenulatus gen. et sp. nov., occurs as an endobiotic mycelial thallus in a large spore of a glomeromycotan fungus from the Lower Devonian Rhynie chert. The thallus consists of branched (?pseudo‐)septate hyphae with numerous catenulate swellings. Some hyphal tips produce spherical reproductive structures or propagules. Hyphal morphology in K. catenulatus is reminiscent of that in certain extant Hyphochytridiomycota, Chytridiomycota, and even Ascomycota, but specific diagnostic features that allow assignment of the fossil to modern groups are absent. The discovery of this interfungal association broadens our knowledge about the diversity of microfungi and their intricate associations in early continental ecosystems.     

Descriptions of two new marine scuticociliates,Pleuronema sinica n. sp. and P. wilberti n. sp. (Ciliophora: Scuticociliatida), from the Yellow Sea,China

Two new marine scuticociliates, Pleuronema sinica n. sp. and P. wilberti n. sp., collected from the sand beach of Qingdao, China, were investigated in vivo and following protargol impregnation. Ciliates of the genus Pleuronema are normally recognizable by their large sail-like paroral membrane although one species, P. grolierei, has shorter cilia in the paroral membrane. Neither of the new forms has the conspicuous paroral membrane in vivo so in this respect they are not typical members of this genus. Pleuronema sinica is characterized by its large, conspicuously flattened body, the possession of only one preoral kinety, the irregular-shaped macronucleus and the rather unusual structure of the oral apparatus. By contrast P. wilberti has a medium-size broad-oval body, six to eight preoral kineties and a highly differentiated membranelle 3 that is five- or six-rowed. An identification key is supplied for the 15 species of Pleuronema for which the infraciliature is known.     

Germination shields in Scutellospora (Glomeromycota: Diversisporales, Gigasporaceae) from the 400 million-year-old Rhynie chert

Glomeromycotan spores from the Lower Devonian Rhynie chert provide the first evidence for germination shields in fossil fungi and demonstrate that this complex mode of germination was in place in some fungi at least 400 million years ago. Moreover, they represent the first direct marker relative to the precise systematic position of an Early Devonian endomycorrhizal fungus. In extant fungi, germination shields occur exclusively in the genus Scutellospora (Glomeromycota: Diversisporales, Gigasporaceae). These structures are regarded as a derived feature within the phylum Glomeromycota, and hence their presence in the Rhynie chert suggests that major diversification within this group of fungi occurred before the Early Devonian.Taxonomical novelties Scutellosporites Dotzler, M. Krings, T.N. Taylor and Agerer Scutellosporites devonicus Dotzler, M. Krings, T.N. Taylor and AgererStürmer 1998     

Teruelia diezii gen. et sp. nov.: an early polysporangiophyte from the Lower Devonian of the Iberian Peninsula

A new basal land plant, Teruelia diezii gen. et sp. nov., is described from the shallow‐water marine deposits of the Lower Devonian (Lochkovian–Pragian) Nogueras Formation of the Iberian Peninsula (north Gondwana palaeocontinent). Teruelia is preserved as a compression fossil and consists of isotomously branched, robust stems terminated in large, fusiform, twisted sporangia. This morphology suggests that Teruelia is very probably equivalent to Aglaophyton, a permineralized early polysporangiophyte known up to now only from the Lower Devonian (early Pragian to ?earliest Emsian) Rhynie Chert in Scotland (Laurussia palaeocontinent), which represents an early terrestrial hot‐spring ecosystem. Accepted phylogenies identify Aglaophyton as sister to vascular plants. Our phylogeny‐based results identify the Aglaophyton/Teruelia biological entity (i.e. Aglaophyton anatomical characters plus Teruelia external morphology) as the most direct vascular plant precursor. It shows that at least one Rhynie Chert type plant had a much wider distribution than previously known and suggests that Aglaophyton was not restricted to hydrothermal environments, unlike other Rhynie Chert plants.     

First evidence of the tooth eruption sequence of the upper jaw in Hyaenodon (Hyaenodontidae,Mammalia) and new information on the ontogenetic development of its dentition

Juvenile material with the main focus on the upper jaw of the fossil predator Hyaenodon was evaluated to study the tooth eruption sequence and to examine the ontogeny of its dentition in detail. The comparison in size of milk to permanent teeth indicates a growth rate of 12–16 % in Hyaenodon. The thin section of a deciduous canine of a North American taxon shows four dental rings. Based on the knowledge of recent carnivores, this implies an age of 3–4 years in the last stage of tooth eruption and thus a long juvenile phase. The mandibles ascertained the most recent established tooth eruption sequence for North American and European species. For the first time ever, juvenile material from Asia is documented and interpreted. This study likewise shows a difference in the sequence of the upper jaw: the first upper premolar erupts before the first upper molar in North American species, whereas the European taxa show an earlier eruption of the first upper molar. This fact further confirms the divergence between the Hyaenodon lineages from North America and Europe.     

Deciphering interfungal relationships in the 410-million-yr-old Rhynie chert: Morphology and development of vesicle-colonizing microfungi

The intraradical portion of arbuscular mycorrhizal (AM) fungi comprises mycelium, vesicles, and special physiological interfaces termed arbuscules; sometimes mycorrhizal fungi also produce spores within their hosts. Arbuscules are ephemeral structures that collapse after a few days, while the hyphae and vesicles appear to remain intact for some time after arbuscule senescence (post-arbuscule stage). However, little is known about the fate of mycorrhizal fungi in the post-arbuscule state. The Lower Devonian Rhynie chert yields the oldest fossil evidence of arbuscular mycorrhizas, including multiple specimens of mycorrhizal axes in the post-arbuscule stage. These fossils indicate that many older vesicles of Rhynie chert mycorrhizal fungi are colonized by other microfungi. Three types of fungal remains in vesicles are distinguished based on morphology and development: (1) spheroidal propagules up to 55 μm in diameter extending from short, distal branches of a hypha; (2) spheroidal propagules up to 23 μm in diameter produced within a tenuous mycelium; and (3) thin-walled propagules up to 10 μm in diameter within a hyphal inflation. The abundance of microfungal propagules in vesicles of Rhynie chert mycorrhizal fungi suggests that the mycorrhizal vesicles in some way positively affected the development and reproduction of the intrusive microfungi. Although the systematic affinities of the intrusive microfungi remain unresolved, this discovery is important because it broadens our understanding of the levels of organismal interactions that existed in early non-marine ecosystems.     

Fungal colonization of the rooting system of the early land plant Asteroxylon mackiei from the 407‐Myr‐old Rhynie Chert (Scotland,UK)

Associations between plants and fungi were an important and varied feature of early terrestrial ecosystems, but in most instances their biological functions remain poorly understood. We document a new species of fungus colonizing the rooting system of the early lycopod Asteroxylon mackiei, based on exceptionally well‐preserved fossils from the Rhynie Chert. We investigated historical petrographic thin sections using standard optical microscopy and confocal laser scanning microscopy. P alaeozoosporites renaultii gen. nov., sp. nov. colonized the inner cortex of the plant rooting system. The fungus had an aseptate thallus with isotomous or sympodial branching. The mycelium bore distinctive porate, globose to elongated structures that we interpret as zoosporangia and resting sporangia. Doubts remain over the precise systematic affinity of P. renaultii, which closely resembles chytrids. Whereas most of the Rhynie Chert plants developed symbiotic associations of the mycorrhizal type, it seems that this was not the case for Asteroxylon mackiei, which possessed the most evolved rooting system among the Rhynie Chert plants. We argue that the new root‐borne fungus was probably parasitic. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 201–213.     

Morphology and Phylogeny of the Soil Ciliate Metopus yantaiensis n. sp. (Ciliophora,Metopida), with Identification of the Intracellular Bacteria

The morphology and infraciliature of a new ciliate, Metopus yantaiensis n. sp., discovered in coastal soil of northern China, were investigated. It is distinguished from its congeners by a combination of the following features: nuclear apparatus situated in the preoral dome; 18–21 somatic ciliary rows, of which three extend onto the preoral dome (dome kineties); three to five distinctly elongated caudal cilia, and 21–29 adoral polykinetids. The 18S rRNA genes of this new species and two congeners, Metopus contortus and Metopus hasei, were sequenced and phylogenetically analyzed. The new species is more closely related to M. hasei and the clevelandellids than to other congeners; both the genus Metopus and the order Metopida are not monophyletic. In addition, the digestion‐resistant bacteria in the cytoplasm of M. yantaiensis were identified, using a 16S rRNA gene clone library, sequencing, and fluorescence in situ hybridization. The detected intracellular bacteria are affiliated with Sphingomonadales, Rhizobiales, Rickettsiales (Alphaproteobacteria), Pseudomonas (Gammaproteobacteria), Rhodocyclales (Betaproteobacteria), Clostridiales (Firmicutes), and Flavobacteriales (Bacteroidetes).     

On the Emsian (Lower Devonian) arthropods of the Rhenish Schiefergebirge: 1.Xenarachne, an enigmatic arachnid from Willwerath, Germany

A new fossil arachnid,Xenarachne willwerathensis n. gen., n. sp. is described from the Lower Devonian (upper Lower Emsian) Klerf-beds of Willwerath, Germany. This intriguing fossil has a pedicel and pygidium, indicating that it belongs to the tetrapulmonate arachnids, but cannot be referred with confidence to any particular order. It is placed as Tetrapulmonata incertae sedis, though has similarities to whip spiders (Amblypygi) and spiders (Araneae).Xenarachne could even represent a very early spider, though the Devonian arachnid fauna could have included taxa which did not belong in any currently recognised order.Xenarachne may be an example of just such a fossil.     

A new species of Baiera from the Early Cretaceous Jehol Biota of southeastern Jilin,China

The Early Cretaceous Yingzuilazi Formation is exposed in the Baishan Basin, Baishan region of the southeastern Jilin Province, China. So far, no reports on fossil plants from this formation have been published. During recent field excursions, abundant faunal remains belonging to the Early Cretaceous Lycoptera–Ephemeropsis–Eosestheria assemblage of the Jehol Biota and numerous fossil plants were collected from the lacustrine beds of the lower part of this formation. A new species of Ginkgoales from this formation, Baiera baishanensis n. sp., is described based upon the leaf morphology and epidermal characters. This is the first report about fossil plants from the Yinzuilazi Formation, the easternmost distribution area of the Jehol Biota. The discovery of the new species extends significantly the stratigraphic and geographic distribution of Baiera in the Early Cretaceous Jehol Biota as well as the Eurasia. It also shows that Baiera was a common member of Ginkgophytes once lived in the Early Cretaceous deciduous forest of Northeast China. The new species also improves our knowledge on understanding the leaf morphology, epidermal features, and diversity of Baiera during the Early Cretaceous. Analysis of the epidermal characters of the new species and other associated plants reveals that the plants grew in a warm and humid climate in the temperate zone. The presence of some deciduous plants, including gingkgoaleans, czekanowskialeans, and some conifers, demonstrates a climate with seasonal fluctuations and precipitation.     

Hassiella monospora gen. et sp. nov., a microfungus from the 400 million year old Rhynie chert

A new microfungus, Hassiella monospora gen. et sp. nov., consisting of coenocytic hyphae is associated with degraded plant material in the Early Devonian silicified Rhynie chert ecosystem. Some hyphae produce small bulb-like projections that subsequently develop into spherical, thick-walled and highly ornamented reproductive structures. Mature reproductive structures are characterized by a prominent, funnel-shaped appendage that is interpreted as an amphigynous antheridium. When combined, these features are suggestive of the oogonia/oosporangia in certain extant members of the Peronosporomycetes (Oomycota).     

The late Eocene hyracodontid perissodactyl Ardynia from Saint Jacques,Inner Mongolia,China and its implications for the potential Eocene–Oligocene boundary

Saint Jacques is a classic Oligocene fossil locality in China, which was first investigated by P. Teilhard de Chardin and E. Licent in 1923. All the fossil mammals previously reported from the area are Oligocene in age. Here we report some new material of the hyracodontid Ardynia from two lower horizons in the Saint Jacques area. These new specimens represent two species: Ardynia praecoxMatthew and Granger, 1923 and A. ordosensis n. sp. A right lower jaw of Ardynia praecox with complete i1-c shows that i2 is the largest. The new species, Ardynia ordosensis, is characterized by a moderately hypsodont M1 with a pillar-like “crista” and the metaloph connecting the ectoloph distal to the metacone, characters that are more similar to those of A. altidentata than to any other species in Ardynia. The stratum bearing Ergilian Ardynia extends the deposits at Saint Jacques down to the upper Eocene. In combination with early Oligocene microfossils from the strata overlying the upper Eocene Ardynia-bearing layers, it is reasonable to conclude that the Saint Jacques section may bracket, or likely document, the Eocene–Oligocene transition.     

Acaulosporoid glomeromycotan spores with a germination shield from the 400-million-year-old Rhynie chert

Scutellosporites devonicus from the Early Devonian Rhynie chert is the only fossil glomeromycotan spore taxon known to produce a germination shield. This paper describes a second type of glomeromycotan spore with a germination shield from the Rhynie chert. In contrast to S. devonicus, however, these spores are acaulosporoid and develop laterally in the neck of the sporiferous saccule. Germination shield morphology varies, from plate-like with single or double lobes to tongue-shaped structures usually with infolded margins that are distally fringed or palmate. Spore walls are complex and appear to be constructed of at least three wall groups, the outermost of which includes the remains of the saccule. The complement of features displayed by the fossils suggests a relationship with the extant genera Ambispora, Otospora, Acaulospora or Archaeospora, but which of these is the closest extant relative cannot be determined. The acaulosporoid spores from the Rhynie chert document that this spore type was in existence already ∼400 mya, and thus contribute to a more complete understanding of the evolutionary history of the Glomeromycota. This discovery pushes back the evolutionary origin of all main glomeromycotan groups, revealing that they had evolved before rooted land plants had emerged.     

A new species of Microraptor from the Jehol Biota of northeastern China

Herein we describe a new species of Microraptor from northeastern China that provides new information on the characteristics of the genus and anatomical details suggesting a gliding behaviour. Although specimens of Microraptor have been known for at least a decade, the completeness of the new fossil provides additional morphology that highlights the uniqueness of this taxon. The new specimen, Microraptor hanqingi, is the key to understanding the evolutionary significance of hindlimb wings. A four-winged structure present on an organism sharing an evolutionary lineage leading to modern birds implies that gliding was a stage in the development of avian flight. M. hanqingi represents the largest known microraptorian from China with a total length of approximately 1 m, and was closely-related to the venomous form, Sinornithosaurus.     

An enigmatic, solifuge-like fossil arachnid from the Lower Carboniferous of Kamienna Göra (Intra-Sudetic Basin), Poland

A new arachnid (Chelicerata: Arachnida) from the Lower Carboniferous (Upper Viséan) Szczawno Formation of Kamienna Göra, Poland, is described asSchneidarachne saganii n. gen. et n. sp. Early Carboniferous arachnids are generally rare and this new fossil cannot be easily assigned to any of the known arachnid Orders. It shares a number of features with some members of the arachnid order Solifugae (camel spiders, sun spiders): namely large, forward-projecting, chelate chelicerae with dentate fixed and free fingers, a distinct median sulcus on the carapace and an interrupted ridge of tubercles on the dorsal opisthosoma set into a loosely-defïned median field. However, it lacks unequivocal autapomorphies of Solifugae. This fossil may be one of a growing number of stem-group Palaeozoic arachnids which lack the füll set of diagnostic characters seen in crown-group members of the various orders. Thus,Schneidarachne saganii could represent a basai member of the lineage leading up to modem solifuges.     

A new Permian gnetalean cone as fossil evidence for supporting current molecular phylogeny

• Background and aims The order Gnetales has been the central focus of controversy in seed plant phylogeny. Traditional treatment of morphology supports the anthophyte hypothesis with Gnetales sister to angiosperms but current molecular data reject this hypothesis. A new fossil gnetalean cone, Palaeognetaleana auspicia gen. et sp. nov., is reported from the Upper Permian in North China, and its phylogenic implications are considered.• Methods Samples of cones from the upper part of the Upper Permian redbeds of Baode section, northwestern Shanxi Province, China, were examined.• Key results The cone is characterized by its unusual nature of reproduction that combines features of post-Triassic gnetaleans and some of the Palaeozoic conifers. It is made up of a number of imbricate axillary units, each simply formed by an ovule and a subtending bract, which may be comparable with the axillary seed-scale complex of some of the Palaeozoic conifer cones. The cone exhibits at least a partially bisexual character that appears to have pollen sacs with monosulcate ribbed pollen grains and sessile, asymmetric, and radiospermic ovules. The ovule has an integument of three envelopes: an outer one of pointed scales; a middle sclerified one; and an inner cuticle that extends upward into a micropyle with an oblique tip.• Conclusions The new Permian cone has unequivocal affinity with the Gnetales. The fossil has considerably extended the divergence time of the Gnetales from 140 (210?) back to 270 myr ago and, therefore, provides the first significant fossil evidence to support the current conclusion based on molecular data of seed plants, i.e. monophyletic gymnosperms, comprising the Gnetales are closely related to conifers.Key words: Palaeognetaleana auspicia (gen. et sp. nov.), Gnetales, bisexual fossil cone, phylogeny of seed plants, radiation of gymnosperms, molecular data, Late Permian, North China