The fossil hornwort described from Dominican amber is an angiosperm flower

Hornworts (Anthocerotophyta) are a main lineage of land plants but they are exceedingly rare as fossils. The only fossil hornwort described from amber has been interpreted as the best preserved fossil of this group. Reinvestigation of this fossil revealed that this Miocene amber inclusion represents a poorly preserved flower that shows some features of the Caesalpinioideae subfamily of the Fabaceae.     

Vibrational spectroscopy of fossils

Over the last two decades, there has an been increasing interest in applying vibrational spectroscopy in palaeontological research. For example, this chemical analytical technique has been used to elucidate the chemical composition of a wide variety of fossils, including Archaean putative microfossils, stromatolites, chitinozoans, acritarchs, fossil algae, fossil plant cuticles, putative fossil arthropods, conodonts, scolecodonts and dinosaur bones. The insights provided by these data have been equally far ranging: to taxonomically identify a fossil, to determine biogenicity of a putative fossil, to identify preserved biologically synthesized compounds and to elucidate the preservational mechanisms of fossil material. Vibrational spectroscopy has clearly been a useful tool for investigating various palaeontological problems. However, it is also a tool that has been misapplied and misinterpreted, and thus, this review is dedicated to providing a palaeontologist who is new to vibrational spectroscopy with a basic understanding of these techniques, and the types of chemical information that can be obtained. Two example applications of these techniques are discussed in detail, one looking into fossil palynomorph taxonomy and other into the enigmatic Burgess Shale‐type preservation.     

A systematic overview of fossil osmundalean ferns in China: Diversity variation,distribution pattern,and evolutionary implications

The order Osmundales is a unique fern taxon with extensive fossil records in geological past. Diverse osmundalean fossils have been reported from China, ranging in age from the Late Palaeozoic to the Cenozoic. Most of them are based on leaf impressions/compressions, but permineralized rhizomes are also well documented. In this study, we provide a systematic overview on fossil osmundalean ferns in China with special references on diversity variations, distribution patterns, and evolutionary implications. Fossil evidence indicates that this fern lineage first appeared in the Late Palaeozoic in China. The Late Triassic to Middle Jurassic interval was the radiation stage. From the Late Jurassic onward, fossil diversity declined rapidly. Cenozoic osmundalean taxa are represented by the relict species of Osmunda. Geographically, osmundalean fossils are found from both the Northern and Southern phytoprovinces of China, though variations are documented for geographical ranges. The Chinese fossil records cover almost all important stages for the macroevolution of the Osmundales, and contribute to further understanding of evolutionary processes of this peculiar fern lineage.     

Reconstitution d'un « paysage de l'époque houillère » revue à la lumière des découvertes récentes sur les cuticules végétales fossiles

To date, plants with a climbing or scrambling growth habit are widely represented in equatorial forest ecosystems, with a warm and humid climate, with a variety of different species. Although it has been speculated repeatedly that several Late Carboniferous seed ferns applied the same growth strategies as modern vines and /or lianas, only few examples have been substantiated in sufficient details. Most Paleozoic seed ferns are reconstructed as free-growing erect trees. However, these last years, new discoveries about the growth habits of fossil plants have been highlighted on the basis of cuticular material. In this way, different types of climbing organs of seed ferns, reported on pteridosperm cuticles collected from the Stephanian basin of the Blanzy-Montceau (central France), have revolutionized the stereotype of “free-growing erect trees” that we had about these plants. These discoveries demonstrate the potential of cuticular analysis for the reconstruction of growth habits of fossil plants. Moreover they exemplify that climbing and scrambling became common life strategies among Late Carboniferous seed ferns. The increasing proportion of climbing seed ferns in the Stephanian, interpreted as an expression of changing structures of Late Paleozoic coal swamp forests, lead to modify the “classical” reconstructions of the Late Carboniferous landscapes.     

Evidence of polar auxin flow in 375 million-year-old fossil wood

In living woody seed plants (conifers and dicotyledons), when various obstacles such as buds and branches disrupt the axial polar auxin flow, auxin whirlpools are formed that induce the differentiation of circular tracheary elements in the secondary xylem. Identical circular patterns also occur at the same positions in the wood of the 375 million-year-old Upper Devonian fossil progymnosperm Archaeopteris. We propose that this is the earliest clear fossil evidence of polar auxin flow. Such spiral patterns do not occur in the primary xylem of the ca. 390-385 million-year-old Lower Devonian fossil land plants, fossil progymnosperms, Psilotum nudum, living ferns, and current seed plants that we examined. This discovery reveals an exciting potential for plant fossils to provide structural evidence of evolutionarily diagnostic physiological and developmental mechanisms and for the use of a combination of fossil evidence and developmental biology to characterize evolutionary patterns in terms of genetic changes in growth regulation.     

Fossilization of melanosomes via sulfurization

Fossil melanin granules (melanosomes) are an important resource for inferring the evolutionary history of colour and its functions in animals. The taphonomy of melanin and melanosomes, however, is incompletely understood. In particular, the chemical processes responsible for melanosome preservation have not been investigated. As a result, the origins of sulfur‐bearing compounds in fossil melanosomes are difficult to resolve. This has implications for interpretations of original colour in fossils based on potential sulfur‐rich phaeomelanosomes. Here we use pyrolysis gas chromatography mass spectrometry (Py‐GCMS), fourier transform infrared spectroscopy (FTIR) and time of flight secondary ion mass spectrometry (ToF‐SIMS) to assess the mode of preservation of fossil microstructures, confirmed as melanosomes based on the presence of melanin, preserved in frogs from the Late Miocene Libros biota (NE Spain). Our results reveal a high abundance of organosulfur compounds and non‐sulfurized fatty acid methyl esters in both the fossil tissues and host sediment; chemical signatures in the fossil tissues are inconsistent with preservation of phaeomelanin. Our results reflect preservation via the diagenetic incorporation of sulfur, i.e. sulfurization (natural vulcanization), and other polymerization processes. Organosulfur compounds and/or elevated concentrations of sulfur have been reported from melanosomes preserved in various invertebrate and vertebrate fossils and depositional settings, suggesting that preservation through sulfurization is likely to be widespread. Future studies of sulfur‐rich fossil melanosomes require that the geochemistry of the host sediment is tested for evidence of sulfurization in order to constrain interpretations of potential phaeomelanosomes and thus of original integumentary colour in fossils.     

The original colours of fossil beetles

Structural colours, the most intense, reflective and pure colours in nature, are generated when light is scattered by complex nanostructures. Metallic structural colours are widespread among modern insects and can be preserved in their fossil counterparts, but it is unclear whether the colours have been altered during fossilization, and whether the absence of colours is always real. To resolve these issues, we investigated fossil beetles from five Cenozoic biotas. Metallic colours in these specimens are generated by an epicuticular multi-layer reflector; the fidelity of its preservation correlates with that of other key cuticular ultrastructures. Where these other ultrastructures are well preserved in non-metallic fossil specimens, we can infer that the original cuticle lacked a multi-layer reflector; its absence in the fossil is not a preservational artefact. Reconstructions of the original colours of the fossils based on the structure of the multi-layer reflector show that the preserved colours are offset systematically to longer wavelengths; this probably reflects alteration of the refractive index of the epicuticle during fossilization. These findings will allow the former presence, and original hue, of metallic structural colours to be identified in diverse fossil insects, thus providing critical evidence of the evolution of structural colour in this group.     

The Westphalian fossil floras from the Cattybrook Claypit,avon (Great Britain)

Cattybrook Claypit, on the northwest margin ofthe Bristol-Somerset Coalfield, yields an upper Westphalian A (Middle Carboniferous) fossil flora. Most of the fossils are of small plant fragments, transported mainly by winds into floodbasin muds. They represent a variety of plant-types, including pteridosperms, ferns, cordaites, sphenophytes and lycophytes. Of particular interest are finely preserved examples of Lonchopteris, and Corynepteris, which are generally scarce in British floras of this age. Also found at Cattybrook are plant fragments in a crevasse-channel sandstone. These are preserved nearer their original position of growth, and are thus more complete than those found in the floodbasin deposits. They include almost complete fronds of Karinopteris attached to a thick lianatype stem, and large pieces of a Sphenophyllum plant. This is now the best documented late Westphalian A flora in Britain.     

How diverse were ferns in the Baltic amber forest?

Diverse temperate forest types and a high atmospheric humidity have recently been suggested for the Eocene source area of Baltic amber. However, ferns are astonishingly rare as inclusions in this amber, which is in contrast to other seed‐free land plants, fungi, and lichens. Moreover, the identities of some of the few described putative fern taxa are dubious, and some fossils were even assigned to the Paleozoic seed fern genera Alethopteris, Pecopteris and to the form genus Sphenopteris containing Paleozoic and Mesozoic fern‐like leaf fossils. Here, we review previously described fern inclusions from Baltic amber and identify further fern‐like leaf inclusions as belonging to the extant angiosperm genus Comptonia (sweet ferns, Myricaceae). We conclude that only one taxon, Matonia striata (Matoniaceae), can with confidence be identified as a Polypodiopsida representative. Although “Pecopteris” humboldtiana is so far only known as sterile foliage, its leaf morphology strongly suggests that also this taxon belongs to the Polypodiopsida rather than to any other tracheophyte lineage. We propose accommodating “Pecopteris” humboldtiana in the new genus Berendtiopteris. “Alethopteris” serrata and “Sphenopteris” phyllocladoides are not to be regarded as evidence of ferns from Baltic amber. Reinvestigation of the holotypes of these two taxa did not reveal to which tracheophyte lineages these fossils belong. We suggest that the scarcity of fern remains from Baltic amber may reflect both a relatively low fern diversity in the source area of the fossil resin, and an absence or rarity of epiphytic and climbing ferns as observed in modern temperate forest ecosystems.     

中国东北中生代时期的传粉昆虫与虫媒植物

昆虫与植物的相互作用在昆虫与植物协同进化和发展中起着至关重要的作用。化石记录中发现了昆虫取食花粉、授粉滴、访问中生代裸子植物具胚珠的繁殖器官等多方面的昆虫化石证据。20世纪90年代以来,研究和报道了大量采自中国东北地区保存良好的昆虫与植物化石。例如发表于Science上的2篇具有长喙的双翅目和长翅目昆虫化石文章,暗示着它们很可能参与各种裸子植物的授粉。在本篇文章中,作者回顾了已报道的中国东北晚中生代时期的昆虫化石,并把它们与授粉或访"花"相联系。另外,作者对采自同一层位的同时代的植物化石进行了初步研究并介绍了可能涉及到与昆虫相互作用的代表性植物。今后将进一步深入研究,以期在化石中找到昆虫授粉和访花的直接证据。     

An Early Permian plant assemblage from the Taiyuan Formation of northern China with compression/impression and permineralized preservation

A small but diverse fossil flora is described from the Early Permian Taiyuan Formation occurring at the Yangshuling mine in Pingquan district of Hebei Province, northern China. Fossils occur as compression/impressions within mudrocks and fine-grained sandstones and also as carbonate permineralizations within volcaniclastic tuffs. All are fragmentary and contain lycopsids, sphenopsids, ferns and seed plants, and include several new species. In the compression assemblage sphenopsid and pteridosperm foliage accounts for the majority of the fossils recognised with only a few other kinds of plant organs present. In contrast, the permineralized assemblage is dominated by cordaitaleans with a composition similar to that occurring in coal-ball assemblages elsewhere in the Taiyuan Formation. From the taxonomic synthesis presented it is apparent that the Yangshuling permineralized assemblage contains many of the plant taxa diagnostic of the northern realm of the Early Permian Cathaysian flora, and preserves a representative sample of the wetland coal-swamp vegetation of this time. The permineralized assemblage at Yangshuling represents the first example of anatomically preserved plants from volcaniclastic lithologies from the Palaeozoic of China, raising the possibility of similarly preserved plant-fossil assemblages elsewhere in the Cathaysian realm.     

川西昌台地区上三叠统勉戈组的双壳类Pergamidia-Halobia群落特征及古环境分析

川西昌台地区上三叠统勉戈组上部为一套直接覆盖在流纹质火山岩之上的板岩,该板岩富集双壳类化石。化石保存完整,以食悬浮物质的外栖足丝型双壳类动物为主．根据优势属和常见属可建立一群落,即Pergamidia—Halobia群落。以根隆剖面为例．该群落的发展可分为3个阶段：第一阶段,群落中只出现了Halobia和Parapergamidia两个属．具有个体较小、数量较少的特点;第二阶段．群落中出现了12个属,以底栖双壳类Pergamidia为优势分子．Halobia仍是常见属,该时期群落具有个体较大、数量较多的特点;第三阶段。该时期群落组成分子相对第二阶段发生衰退,只剩下3个属,其中Halobia是常见属。岩石地层特征表明,该化石群落所在层位的沉积环境为火山活动末期的较深水环境。地球化学特征表明化石群落所在层位的岩石具有热水沉积的特点：常量元素的三元投点落人热水区域内及其附近;锰的含量较高;微量元素Si／Ba比值均小于1;铅、锌、钡、铷等金属元素含量明显高于地壳含量。综合分析表明．流纹质火山活动后期的热水活动是导致Pergamidia-Halobia群落发展的外界因素。     

Late Pliocene diversity and distribution of Drynaria(Polypodiaceae) in western Yunnan explained by forest vegetation and humid climates

The palaeodiversity of flowering plants in Yunnan has been extensively interpreted from both a molecular and fossil perspective. However, for cryptogamic plants such as ferns, the palaeodiversity remains poorly known. In this study, we describe a new ferny fossil taxon, Drynaria lanpingensis sp. nov. Huang,Su et Zhou(Polypodiaceae), from the late Pliocene of northwestern Yunnan based on fragmentary frond and pinna with in situ spores. The frond is pinnatifid and the pinnae are entirely margined. The sori are arranged in one row on each side of the primary vein. The spores have a semicircular to bean-shaped equatorial view and a tuberculate surface. Taken together with previously described fossils, there are now representatives of three known fossil taxa of Drynaria from the late Pliocene of western Yunnan.These finds suggest that Drynaria diversity was considerable in the region at that time. As Drynaria is a shade-tolerant plant, growing preferably in wet conditions in the understory of forests, its extensive existence may indicate forest vegetation and humid climates in western Yunnan during the late Pliocene.This is in line with results from floristic investigations and palaeoclimatic reconstructions based on fossil floras.     

A new microinvertebrate with features of mites and tardigrades in Dominican amber

From time to time, small, fragile, previously unknown fossil invertebrates are found in specialized habitats. Occasionally, as in the present case, a fragment of the original habitat that existed millions of years ago is also preserved. The present article describes a previously unknown microinvertebrate in Dominican amber that cannot be placed in any group of extant invertebrates. Placed in a new family, genus, and species, the fossil shares characters with both tardigrades and mites, but clearly belongs to neither group. The several hundred fossil individuals preserved in the amber shared their moist, warm habitat with pseudoscorpions, nematodes, fungi, and protozoa. The large number of fossils provided additional evidence of their biology, including their reproductive behavior, developmental stages, and food. While there is no extant group that can accommodate these fossils, and we have no knowledge of any extant descendants, this discovery shows that unique lineages of minute invertebrates were surviving in the mid‐Tertiary.     

Cambrian anemones with preserved soft tissue from the Chengjiang biota, China

The group Cnidaria includes 'jellyfish', soft-bodied anemone and anemone-like forms and calcified corals. These diploblastic organisms have a fossil record extending back to the earliest metazoans of the Neoproterozoic; however certain cnidarians of the subclass Zoantharia, characterized by soft-bodied anemone-like forms, are absent or poorly represented in the fossil record. Despite the paucity of fossils, it is thought that calcification by soft anemone-like animals was responsible for producing the skeleton that allowed the preservation of the first corals. We report discovery of an abundant assemblage of in situ soft-bodied polyps with tissues. They are preserved in exquisite detail and come from the well-known Lower Cambrian Chengjiang biota of Yunnan, China. The soft-bodied polyps display a simple anatomy that is comparable to some extant anemones of the order Actinaria. The new fossils are assigned to Archisaccophyllia kunmingensis n. gen. et n. sp. Their simple and conservative form suggests that these fossils may represent some kind of ancestral rootstock. The preserved life assemblage provides a unique snapshot of Lower Cambrian anemone life and provides clues for relationships with extant actiniarians as well as calcified corals.     

Unlocking the early fossil record of the arthropod central nervous system

Extant panarthropods (euarthropods, onychophorans and tardigrades) are hallmarked by stunning morphological and taxonomic diversity, but their central nervous systems (CNS) are relatively conserved. The timing of divergences of the ground pattern CNS organization of the major panarthropod clades has been poorly constrained because of a scarcity of data from their early fossil record. Although the CNS has been documented in three-dimensional detail in insects from Cenozoic ambers, it is widely assumed that these tissues are too prone to decay to withstand other styles of fossilization or geologically older preservation. However, Cambrian Burgess Shale-type compressions have emerged as sources of fossilized brains and nerve cords. CNS in these Cambrian fossils are preserved as carbon films or as iron oxides/hydroxides after pyrite in association with carbon. Experiments with carcasses compacted in fine-grained sediment depict preservation of neural tissue for a more prolonged temporal window than anticipated by decay experiments in other media. CNS and compound eye characters in exceptionally preserved Cambrian fossils predict divergences of the mandibulate and chelicerate ground patterns by Cambrian Stage 3 (ca 518 Ma), a dating that is compatible with molecular estimates for these splits.     

Small shelly fossils and trace fossils near the Precambrian-Cambrian boundary in the Yukon Territory, Canada

In the past an ‘explosion’ in diversity and abundance of small shelly fossils and of trace fossils has served to mark the base of the Cambrian. However, no evidence has been presented to prove that the ‘explosions’ of the two groups were synchronous. We describe small shelly fossils and trace fossils from the same phosphatic limestone beds that indicate that the two events were separate in time. The small shelly fossils are Anabarites trisulcatus, Hyolithellus cf. H. isiticus, Microcornus? sp., Protohertzina anabarica, P. unguliformis, P. sp. A, Pseudorthotheca sp. A, Rushtonia? sp. A, four types of tuberculate plates and one type of reticulate plate. These fossils represent a restricted, ‘pre-explosion’ fauna and are assigned to the Anabarites-Circotheca-Protohertzina Assemblage Zone, an uppermost Precambrian zone in the Meishucun Stage, Yunnan Province, China. A point at the top of this zone has received strong international endorsement for future designation as the base of the Cambrian. Associated with the small shelly fossils are the trace fossils Cruziana sp. A, Cruziana? sp. B, Rusophycus sp. A, Palaeophycus rubdark and arthropod scratch marks. If found in isolation, this trace fossil assemblage would be considered as post-Precambrian because it includes large, highly organized arthropod traces that are traditionally accepted as occurring above the trace fossil ‘explosion’. We therefore conclude that the trace fossil ‘explosion’ predates the small shelly fossil ‘explosion’. If the proposed location of the base of the Cambrian in Yunnan is accepted, the small shelly fossil ‘explosion’ concept and its relationship to the boundary would not be greatly modified. The trace fossil ‘explosion’, however, would no longer indicate the base of the Cambrian and the ranges of some trace fossils would be extended into the Precambrian.     

Ediacaran microbial colonies

Enigmatic discoidal fossils are common in Neoproterozoic sedimentary sequences and in the stratigraphic record pre-date the first appearance of diverse Ediacaran fossil assemblages. Termed 'medusoids', these Neoproterozoic discoidal fossils have generally been interpreted as coelenterate-grade organisms implying a radially symmetrical body plan for ancestral eumetazoans. Analysis of exceptionally preserved discoidal fossils from the White Sea area, however, indicates that most of these discoidal forms represent colonial microbes. Localized pyritization, for example, reveals the presence of a conspicuous filamentous substructure in Ediacaria , whereas concentric rings, radial sectors and central structures in Cyclomedusa and Paliella compare directly with Recent microbial colonies growing in a nutritionally heterogeneous environment. At least some Ediacaran discoids can be compared with extant concentric ring-shaped microbial colonies that grow in hypersaline microbial mats. Insofar as most of the remaining record of Ediacaran discoids can be attributed to the holdfast structures of non-radiate modular organisms, there is no support from the fossil record for identifying a radiate ancestry for the Metazoa.     

The role of experiments in investigating the taphonomy of exceptional preservation

In the last 20 years, much taphonomic experimentation has focused on the interpretation of exceptionally preserved fossils. Decay experiments have been used to interpret the features preserved in soft‐bodied fossils and to determine the sequence of character loss and its impact on phylogenetic position. Experiments on the impact of microbial communities on decay and mineralization have started to illuminate the processes involved in the fossilization of soft tissues, including embryos. The role of decay in promoting authigenic mineralization has been used to investigate the formation of Ediacaran macrofossils and concretions. Maturation experiments have shown how the constituents of animals and plants are transformed over time to a macromolecular material that converges on a similar stable composition. Other maturation experiments have explained how structural colours in fossils are altered from the original. A major area requiring investigation is the role of specific types of microbes in decay and their impact on sediment and pore water chemistry, as well as the environmental controls that determine their presence and level of activity. Microbial activity has received less attention than other factors in attempts to explain why the occurrence and nature of exceptional preservation varies in time and space through the fossil record.