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International audience; Morphological diagnoses are given for the cricket family Trigonidiidae and its two monophyletic subfamilies, the Trigonidiinae and the Nemobiinae. Owing to their morphological characters, we transfer the extant genus Lissotrachellus Hubbell, 1838 from the Gryllidae: Pentacentrinae to the Trigonidiidae: Nemobiinae. Lissotrachellus was the type genus of Lissotrachelini including also Trigonidomimus Caudell, 1912 and Tohila Hubbell, 1938 which are here transferred to Pentacentrinae incertae sedis. The fossils currently attributed to the Trigonidiidae and its subfamilies are reviewed, in order to facilitate future phylogenetic studies. Few fossils can actually be classified in Nemobiinae or Trigonidiinae, and most are Cenozoic: the oldest nemobiine is the Eocene Baltonemobius fossilis Gorochov, 2010 (37.2–33.9 Ma), while the oldest representatives of the crown group Trigonidiinae date from the Miocene (20.43–13.65). The early Cretaceous Liaonemobius tanae Ren, 1998, originally described in the Trigonidiinae, and currently listed in the Gryllidae, proved an Elcanidae. The mid-Cretaceous Birmaninemobius hirsutus Xu et al., 2020, described in the Nemobiinae, is here transferred to the stem group Trigonidiinae.

One of the two lineages that constitute the crown group Testudines, Pan-Pleurodira, experienced an important radiation during the Early Cretaceous, from the Barremian or earlier. The origin of the two lineages that form the crown Pleurodira (i.e. Pan-Chelidae and Pelomedusoides) is related to this radiation. Pelomedusoides diversified in northern Gondwana in a relatively short period of geological time. The African Aptian fossiliferous region of Gadoufaoua (central Niger) is one of the most interesting fossiliferous areas for the study of the early diversity and evolution of Pelomedusoides, this being where the oldest African identification of the synchronic and sympatric presence of several pleurodiran taxa is recognised. At least two lineages of Pelomedusoides are represented in Gadoufaoua, one being the extinct Araripemydidae. The second lineage had been recognised as related to Pelomedusidae or Podocnemidoidea, both clades representing part of the current biodiversity. A form from Gadoufaoua, hitherto poorly known and preliminarily presented almost 40 years ago, and currently determined as aff. Platycheloides sp., belongs to this second lineage. Its detailed study is performed here. It is defined as Francemys gadoufaouaensis gen. et sp. nov., constituting one of the few nominated pan-pleurodiran taxa (i.e., about a dozen species) currently recognised in the Lower Cretaceous record. It is identified as being closely related to Podocnemidoidea, the clade that groups the common ancestor and all of the descendants of the abundant and diverse extinct bothremydids and extant podocnemidids.

Astragalus, a highly diverse genus of flowering plants with its highest center of diversity in West Asia, is a classic example of rapid species-level radiation and adaptation to a diversity of habitats throughout the world. We examined the historical biogeography of Astragalus using molecular dating and ancestral area reconstruction to understand how past climate changes, geographical patterns and transition in life history have provoked diversification of Astragalus. Our results suggest that Astragalus probably originated during the middle Miocene in West Asia, underwent rapid diversification, subsequently and repeatedly expanded its range in the Mediterranean region, and later to North America through West Europe. This distribution range was also extended toward central and eastern Asia from the Middle Miocene to Pleistocene. Several climatic and geological processes during the Miocene-Pliocene may be implicated in the diversification of the major Astragalus clades. In particular, the annual lineages, which are important elements in the Mediterranean flora of Africa and Europe and in the deserts of southwest to central Asia, have arisen in response to progressing aridity from the late Miocene onwards (between 8.6 Ma and 2.98 Ma). Diversification rate analyses indicate three rapid and recent diversification events, one at c. 11 Ma in the clade that groups most of the Astragalus s.s. (all except the Ophiocarpus sister lineage), one at c. 5 Ma in the crown group of the Hypoglottis clade, including herbaceous annual and perennial species, and the most recent one at c. 3 Ma in the spiny cushion forming Astracantha clade. Our study highlights the complexity of processes and factors shaping diversifications in Astragalus; a complex interaction among climatic modifications providing opportunities for diversification and likely coincident with the evolution of key morphological and physiological adaptations.

Featherwing beetles, or Ptiliidae (Coleoptera: Staphylinoidea), are characterized by their minute sized-body and peculiar hind wing structures, and include the smallest free-living insects. A half millimeter-long, unsexed adult featherwing beetle from Upper Cretaceous Burmese amber is here described as Kekveus jason gen. et sp. nov. Our observation recovered fine morphological details, such as the fringes of hind wings and pronotal grooves, from the Mesozoic Ptiliidae for the first time. Among Ptiliidae, this is the first nominal extinct genus, the first named representative from Burmese amber, the oldest named fossil, and the first named fossil from the Mesozoic Era. The new taxon is phylogenetically nested deep inside the crown group of Ptiliidae and is hypothesized to belong to the extant tribe Discheramocephalini, as either a member of, a sister to, the clade formed by the genera Skidmorella and Discheramocephalus. Our finding indicates the miniaturization in Ptiliidae can be reliably traced back to at least mid-Cretaceous.

A new species of the Marattialean fern frond Rothwellopteris is proposed for specimens preserving both morphology and anatomy from the Wuchiapingian–Changshingian (late Permian) aged Xuanwei Formation of South China. Fronds are at least bipinnate and bear falcate, pecopteroid pinnules with a thin lamina. The penultimate pinna rachis has a polycyclic vascular system with endarch primary xylem and longer vascular bundles located abaxially in a single radial row, and shorter vascular bundles adaxially arranged in two radial rows, with a vascular bundle sheath of sclerenchyma cells. Ground tissue comprises parenchyma cells and numerous secretory ducts. Features of the new species suggest that it was adapted for mesomorphy, while the previously recognized species Rothwellopteris pecopteroides was adapted for xeromorphy or was a sun-leaf. Like R. pecopteroides, the new species displays a mosaic of morphological and anatomical features characteristic of both the Paleozoic family Psaroniaceae and the extant family Marattiaceae; we interpret it to be a member of the evolutionary stem-group from which stratigraphically younger Marattiaceae evolved. Our findings show that the stem- to crown-group transition within Marattiales commenced before the end of the Permian and that a greater diversity of transitional forms can now be recognized from the late Permian and include the genera Compsopteris, Rothwellopteris, Tietea and Tuvichapteris.

Balaenopteroidae is a diverse superfamily within the mysticetes that consists of numerous recent fossil species. The publication of new taxa has increased, which improves the knowledge about this group. In this work, we name and describe Kennedycetus pericorum from the Late Miocene deposits of the Trinidad Formation in Baja California Sur, Mexico. Our phylogenetic results indicate that this is a step taxon, far from the balaenopterid crown group, that is closely related to Norrisanima miocaena from the Monterey Formation, California. The associated fauna of K. pericorum includes the internal molds of different mollusks attributable to Glycymeridae, Semelidae, and Lucinidae, which indicate a coastal environment of warm waters.

The relatively complete and well preserved shell of a turtle, from the middle Cenomanian of Nazare (Portugal), is studied here. It is recognized as a member of the crown group Pleurodira and, more specifically, of Bothremydidae. Pleurodira are one of the two lineages of modern turtles, their origin being in Gondwana. Pleurodira are very abundant in the uppermost Cretaceous record of Europe. However, this new finding is one of the few occurrences in the lower Upper Cretaceous of Laurasia. A single member of Bothremydidae had so far been identified in Portugal: the late Campanian-early Maastrichtian Rosasia soutoi . It was the only Cretaceous turtle identified in that country both at specific and at generic levels, being exclusive of Portugal. The taxon from Nazare is identified as Algorachelus peregrinus , this form is also present in the contemporaneous beds in Spain, and is the oldest member of Bothremydidae in Laurasia. Algorachelus peregrinus is confirmed here to be a coastal form, which facilitated its spread. The two oldest known bothremydids from Laurasia, the European A. peregrinus and the North American Paiutemys tibert , are compared for the first time. They are recognized as closely related taxa. This study provides new data allowing a more precisely characterization of the oldest so far known dispersal event of Pleurodira in Laurasia, which was performed by an African lineage of Bothremydidae that reached the east coast of the Atlantic Ocean at least in the middle Cenomanian, and the west region of that Ocean at least in the late Cenomanian.

An inclusion in Cretaceous amber from Myanmar is described as a new fossil species in the extant liverwort genus Frullania. The name Frullania pinnata is proposed for the taxon that is characterized by entire underleaves paired with a conspicuous pinnate branching pattern, two distinctive and stable morphological features. Entire underleaves are known in several extant Frullania species but had not previously been documented in Frullania in amber. The combination of morphological characters in this new fossil species is unknown in any crown group lineage of Frullania, and may very well represent a stem lineage element of the genus. This discovery is important because it expands our understanding of the diversity of Frullaniaceae in the Burmese amber forest as well as important ramifications for the phylogenetic reconstruction of extant Frullania lineages.

Although both the Yanliao and Jehol vertebrate assemblages are known for exceptional preservation of feathered dinosaurs, mammals, pterosaurs, lizards, salamanders, and fish, the Early Cretaceous Jehol Biota also contains birds, choristoderes, frogs, and turtles that are currently lacking in the Jurassic Yanliao Biota. The vertebrate assemblages of the Yanliao and Jehol biotas are very distinct from each other, with the salamander Liaoxitriton being the sole unquestionably shared taxon on generic level. Both assemblages contain mainly stem relatives of major clades of extant vertebrates, with all genera and species extinct. Crown group taxa are restricted to some fishes, salamanders, frogs, and turtles. In addition to its much greater taxonomic diversity, the Jehol vertebrate assemblage also shows a greater body size variation among dinosaurs, pterosaurs, and mammals (three major vertebrate groups shared by the two biotas); however, members of these groups are generally small in the Yanliao Biota. The Jehol aquatic vertebrates also show a much greater diversity, characterized by many large-sized forms such as acipenseriforms and choristoderes, possibly indicating growing and more expanded ecological adaptations of the Jehol vertebrates. The relatively greater biodiversity of pterosaurs in the Yanliao Biota as compared to that in the Jehol Biota was due possibly to the lack of birds as a competitor then. Birds in the Jehol Biota had occupied much of the similar ecological niches (forest, lakes etc.) with more sophisticated and refined flight capability. The Yanliao dinosaurs that were dominated by maniraptorans are either paravians or closely related species, possibly indicating that northeastern China could be an origin center of the earliest birds, consistent with the previous hypothesis that this area was probably also the origin and diversification center for many other biological groups. The flourishing time of the Jehol Biota (125 Ma) appears to be coincident with the peak of the destruction of the North China Craton, and the flourishing time of the Yanliao Biota (160 Ma) is coincident with the initiation time of the destruction of the North China Craton or the beginning of the subduction of the Paleo-Pacific plate underneath the Asian continent that resulted a series of tectonic and palaeogeographic and palaeoenvironmental changes, confirming the co-evolution between the two biotas and their geological and palaeoenvironmental background. The frequent volcanic activities during the formation of both the Yanliao and Jehol biotas not only provided much nutrient to the lakes, but also were critical for the exceptional soft tissue preservation of the two lagerstatten. The cold temperature or the fluctuation of temperature during the Middle Jurassic–Late Jurassic transition might be related to the first appearance of feathered dinosaurs and haired pterosaurs. The cold interval during the Early Cretaceous Jehol Biota could possibly partially explain the presence of many feathered dinosaurs including some large-sized theropods.

After the demise of many fish taxa including xenacanth sharks before the Late Triassic, non-marine fish faunas reappeared in Australia the mid-Jurassic in the East Gondwana component of Pangaea with one new chondrichthyan occurring in the Late Jurassic freshwater Talbragar Lagerstatten near Gulgong, New South Wales. The Kimmeridgian Talbragar Fossil Fish Bed unit yields a Jehol-type fauna and flora, with a variety of bony fishes as well as this first-known Jurassic shark in Australasia. The new taxon is based on a partial skeleton lacking a head but with at least partial fins and scales. The latter might be from a hybodontiform or synechodontiform shark or even a crown group neoselachian. From the inferred palaeogeography, this was one of the most southerly living chondrichthyans of the time.

Ottelia Pers. is the second largest genus of the family Hydrocharitaceae, including approximately 23 extant species. The genus exhibits a diversity of both bisexual and unisexual flowers, and complex reproductive system comprising cross-pollinated to cleistogamous flowers. Ottelia has been regarded as a pivotal group to study the evolution of Hydrocharitaceae, but the phylogenic relationships and evolutionary history of the genus remain unresolved. Here, we reconstructed a robust phylogenetic framework for Ottelia using 40 newly assembled complete plastomes. Our results resolved Ottelia as a monophyletic genus consisting of two major clades, which correspond to the main two centers of diversity in Asia and Africa. According to the divergence time estimation analysis, the crown group Ottelia began to diversify around 13.09 Ma during the middle Miocene. The biogeographical analysis indicated the existence of the most recent common ancestor somewhere in Africa/Australasia/Asia. Basing on further insights from the morphological evolution of Ottelia, we hypothesized that the ancestral center of origin was in Africa, from where the range expanded by transoceanic dispersal to South America and Australasia, and further from Australasia to Asia. We suggested that the climatic change and global cooling since the mid-Miocene, such as the development of East Asian monsoon climate and tectonic movement of the Yunnan-Guizhou Plateau (YGP), might have played a crucial role in the evolution of Ottelia in China.

The Ediacaran-Cambrian is a time with globally enhanced production of phosphorites. This includes perhaps the two most famous deposits with variable cell and soft tissue phosphatization in microfossils, the Ediacaran Doushantuo Formation, which contains the Weng’an Biota, and the lower Cambrian Kuanchuanpu Formation and equivalents, found in China. A wide range of variables is responsible for phosphatization during this interval, including depositional and geochemical conditions and microbial activity. Degree of microfossil phosphatization is widely dependant upon original cell and tissue types. Microfossils with non-diagenetic morphologies that are iconic for modern crown group metazoans have had the highest level of acceptance for their interpreted phylogenetic affinity. Microfossils with these iconic morphologies are rare from the Weng’an Biota, but relatively common from the Kuanchuanpu Biota. Thus metazoan affinity for Doushantuo microfossils has commonly relied on relatively simple and less-well-known morphologic features of embryonic organisms, for which there is not a concensus on the nature of their phylogenetic signal. Differences in the phosphatized microfossil record between the Weng’an and Kuanchuanpu Biotas are due to the combination of a primary signal reflecting the initiation of the Cambrian explosion, and a secondary signal driven by a multitude of taphonomic processes operating at different levels of effectiveness during deposition of these two units.

A new adephagan beetle embedded in Burmese amber from northern Myanmar is described as Burmapseudomorphus planus gen. et sp. nov. From its broad and flat habitus, the lack of a pronoto-elytral angle, the short and broad head, the short mesoventrite, and the lancet-shaped elongate prosternal process it resembles beetles belonging to the aquatic Dytiscoidea. The metacoxal plates are similar to those of Noteridae. However, pubescent antennal flagellomeres, an anisochaetous protibial antenna cleaner, transversely oriented metepimera, and metacoxae not reaching beyond the lateral margin of the metaventrite identify the fossil as an atypical species of Carabidae. Externally closed procoxal cavities, lacking procoxal rests of the mesoventrite, a narrow mesepimeron not reaching the mesocoxal cavity, and lobate metepimera indicate a placement in a clade comprising Harpalinae and Brachininae. This is supported by analyses of morphological data and a Hennigian character evaluation. The short and transverse head, the streamlined body without pronoto-elytral angle, and the secondarily elongated prosternal process suggest a placement as stem group member of the specialized Pseudomorphini. In contrast to species of the crown group of this lineage, a distinct submento-mental suture is present, ventral cephalic antennal grooves are missing, and the elytra are not truncated posteriorly. The fossil is the first record for Pseudomorphini and documents an origin of this specialized group of Carabidae at least dating back to the Cretaceous. A superficial similarity with the extant migadopine genus Stichonotus (e.g. broad and oval body, apically pointed prosternal process) is the result of convergence.

Two partial skeletons attributable to a single basal turtle taxon (i.e., Testudinata not belonging to the crown group Testudines) are studied here. These specimens come from the lower Albian (Lower Cretaceous) of the lignite coal mine of Santa Maria, in Arino (Teruel Province, Aragon, northeastern Spain). They are identified as belonging to a new member of the clade of terrestrial turtles Helochelydridae, Aragochersis lignitesta gen. et sp. nov. Both specimens represent the most complete skeletons of this lineage so far identified in Europe. The skull and mandible of the new taxon, but also the shell, several vertebrae, and numerous elements of the appendicular skeleton, are preserved. New anatomical information about this relatively poorly known group of basal turtles is provided.

Two specimens of a new species of horseshoe crab, Mesolimulus tafraoutensis sp. nov., are described from the Late Cretaceous (Cenomanian–Turonian) Gara Sbaa Lagerstatte of southeast Morocco. These most likely represent juveniles, as suggested by their small size and possession of a number of characteristics, such as short genal spines, that are characteristic of modern juvenile horseshoe crabs. Despite this, the development of the prosomal keel into a broader cardiac ridge and the scalloped lateral margins of the cardiac lobe clearly place these specimens within Mesolimulus. A further characteristic, the occurrence of only two tubercles on the thoracetron pleural ridges, marks Mesolimulus tafraoutensis sp. nov. as a distinct species. As Mesolimulus resolves phylogenetically as a total group limulid outside of the crown group, the new discovery indicates that stem-lineage limulids persisted into the Cretaceous and co-existed with crown-limulids as they underwent their major radiation.

Exceptionally preserved fossil biotas provide crucial data on early animal evolution. Fossil anatomy allows for reconstruction of the animal stem lineages, informing the stepwise process of crown group character acquisition. However, a confounding factor to these evolutionary analyses is information loss during fossil formation. Here we identify that the Ordovician Fezouata Shale has a clear taphonomic difference when compared to the Cambrian Burgess Shale and Chengjiang Biota. In the Fezouata Shale, soft cellular structures are most commonly associated with partially mineralized and sclerotized tissues, which may be protecting the soft tissue. Also, entirely soft non-cuticularized organisms are absent from the Fezouata Shale. Conversely, the Cambrian sites commonly preserve entirely soft cellular bodies and a higher diversity of tissue types per genus. The Burgess and Chengjiang biotas are remarkably similar, preserving near identical proportions of average tissue types per genus. However, the Burgess shale has almost double the proportion of genera that are entirely soft as compared to the Chengjiang Biota, indicating that the classic Burgess Shale was the acme for soft tissue preservation. Constraining these biases aids the differentiation of evolutionary and taphonomic absences, which is vital to incorporating anatomical data into a coherent framework of character acquisition during the earliest evolution of animals.

The Lower Devonian Rhynie Chert is justly famous for the clear glimpse it offers of early terrestrial ecosystems. Seven species of stem and crown group vascular plants have been described from Rhynie, many preserved in growth position, as well as 14 species of invertebrate animals, all arthropods save for a single nematode population. While these shed welcome light on early tracheophytes and land animals, modern terrestrial ecosystems additionally contain a diversity of microscopic organisms that are key to ecosystem function, including fungi, protists and bacteria. Fungi ranging from mycorrhizae to saprophytes are well preserved in Rhynie rocks (and references therein), and oomycetes are also present. Both green algae (charophytes) and cyanobacteria have also been locally documented locally. To date, however, heterotrophic protists have not been observed in Rhynie cherts, even though such organisms contribute importantly to carbon, nitrogen and silica cycling in modern terrestrial communities. Here we report the first occurrence of heterotrophic protists in the Rhynie ecosystem, specifically a population of testate microfossils interpreted as arcellinid amoebozoans. These new fossils expand the ecological dimensions of the Rhynie biota and support the hypothesis that arcellinids transitioned from marine through freshwater environments to colonize soil ecosystems in synchrony with early vascular plants.

A new skeleton of the Early Eocene stem group mousebird Masillacolius brevidactylus is described, which for the first time provides information on the skull morphology of this unusual coliiform species. Notably, the mandible exhibits long, blade-like retroarticular processes, which were previously only known from two distantly related taxa of stem group Coliiformes. An assessment of the evolutionary significance of these structures depends on the phylogenetic interrelationships of stem group Coliiformes, which remain poorly resolved. Proceeding from recent phylogenies, the new fossil strengthens the supposition that these processes are plesiomorphic for a coliiform subclade, which also includes the extant species, and that they were secondarily reduced in crown group Coliiformes. In this case, the stem species of the clade including extant mousebirds would have exhibited feeding specializations that were lost in the evolutionary lineage leading to the extant species. Alternatively, these processes may constitute an apomorphy of a clade including Masillacolius and the Early Eocene North American Chascacocolius. In the new Masillacolius fossil a large seed is preserved, which was most likely ingested by the bird. It therefore adds another specimen to the list of coliiform fossils with seeds as stomach or gut contents and documents a long evolutionary history of frugivory in coliiform birds. This contradicts a recent proposal that birds did not play an important role as seed dispersers in the early Cenozoic.

Crown-group salamander Kiyatriton leshchinskiyi , from the Lower Cretaceous (Aptian–Albian) Ilek Formation of the Shestakovo locality in Western Siberia, Russia, was the first “lissamphibian” discovered from the Mesozoic of Russia and it is the only Early Cretaceous salamander from Asia which was found outside China. In this paper a detailed redescription of type and newly collected material on Kiyatriton leshchinskiyi , consisting fragmentary cranial and postcranial bones is presented. The structure of the atlas, trunk vertebrae and femur suggest that Kiyatriton leshchinskiyi may be a member of the Cryptobranchoidea.

The first appearance and evolution of the crown group Cetacea – Mysticeti (baleen whales) and Odontoceti (toothed whales and dolphins) – from archaeocete ancestors corresponds with major climatic and oceanographic changes shortly before the Eocene–Oligocene boundary (ca. 34.0 Ma). These environmental changes impacted marine productivity and may have sparked the evolution of the distinct bulk-feeding strategy used by mysticete whales today. The movements and feeding habits of living cetaceans can be tracked using the isotopic composition of the structural carbonate within bioapatite of their bones and teeth, which records latitudinal gradients in marine δ13C and δ18O values. Here, we exploit this relationship to determine the past movements and feeding habits of late-surviving archaeocetes (kekenodontids) and early odontocetes and mysticetes sampled from Oligocene fossil sites in the USA (latitude: ~ 30°N) and New Zealand (latitude: ~ 50°S). Bioapatite δ13C and δ18O values for fossilized tooth enamel and bullae from fossil cetaceans were surprisingly similar to those for living cetaceans, which indicates that the feeding habits of these species and the isotopic composition of Oligocene seawater (ca. 28 Ma) were very close to present-day conditions. Values for toothed mysticetes and odontocetes match expectations based on cetacean species feeding at these latitudes today, suggesting these individuals were residents that foraged in close proximity to where their fossils were discovered. In contrast, the extremely low δ13C and δ18O values for some edentulous mysticetes from New Zealand are more similar to values observed in extant mysticetes that seasonally migrate to high latitudes, where they bulk-feed on lipid-rich zooplankton. Enamel δ13C values for kekenodontids showed the greatest range and overlapped with both edentulous mysticetes and resident species; these differences correlate most strongly with tooth type and may reflect an ontogenetic shift in diet associated with the transition from nursing to marine prey. When combined with evidence of increasing morphological disparity, fossil bioapatite δ13C and δ18O values support interpretations that the Oligocene was an interval of heightened taxonomic and ecological diversification within Cetacea.

A new turtle taxon, Camerochelys vilanovai gen. et sp. nov., from Hauterivian–Barremian levels of the eastern Cameros Basin (La Rioja, Iberian Range, Spain), is proposed here. Elements of the shell corresponding to five individuals are assigned to it. Camerochelys vilanovai is a turtle with a low, oval and longer than wide shell. It is diagnosed by a combination of characters that includes, among others, the presence of an ornamentation pattern, restricted to the medial area of the vertebral scutes, and composed of thin, numerous and poorly developed radiating striations; shallow nuchal notch; short, and more than four times wider than long cervical scute; five vertebral scutes, all of them substantially wider than long, the second and third ones being more than two times wider than long, and the fourth one two times wider than long; sagittal contact of the last pair of costal plates; presence of inframarginal scutes; absence of mesoplastra. Camerochelys vilanovai is identified as a member of Pan-Cryptodira not assigned to Eurysternidae, to the clade including representatives of Paracyptodira and Plesiochelyidae, or to the crown group Cryptodira. This new taxon could be a representative of Xinjiangchelyidae, a clade belonging to the stem group of Cryptodira, and identified in the Asian and European record. The description of this new taxon further increases the known diversity of turtles in the Early Cretaceous of the Iberian Range, a region where members of several clades of the stem group of Testudines, Pan-Pleurodira and Pan-Cryptodira have been previously identified.

Cyclestheria hislopi is thought to be the only extant species of Cyclestherida. It is the sister taxon of all Cladocera and displays morphological characteristics intermediate of Spinicaudata and Cladocera. Using one mitochondrial (COI) and two nuclear (EF1α and 28S rRNA) markers, we tested the hypothesis that C. hislopi represents a single circumtropic species. South American (French Guiana), Asian (India, Indonesia, Singapore) and several Australian populations were included in our investigation. Phylogenetic and genetic distance analyses revealed remarkable intercontinental genetic differentiation (uncorrected p-distances COI>13%, EF1α>3% and 28S>4%). Each continent was found to have at least one distinct Cyclestheria species, with Australia boasting four distinct main lineages which may be attributed to two to three species. The divergence of these species (constituting crown group Cyclestherida) was, on the basis of phylogenetic analyses of COI and EF1α combined with molecular clock estimates using several fossil branchiopod calibration points or a COI substitution rate of 1.4% per million years, dated to the Cretaceous. This was when the South American lineage split from the Asian-Australian lineage, with the latter diverging further in the Paleogene. Today's circumtropic distribution of Cyclestheria may be best explained by a combination of Gondwana vicariance and later dispersal across Asia and Australia when the tectonic plates of the two continents drew closer in the early Miocene. The lack of morphological differentiation that has taken place in this taxon over such a long evolutionary period contrasts with the high level of differentiation and diversification observed in its sister taxon the Cladocera. Further insights into the evolution of Cyclestheria may help us to understand the evolutionary success of the Cladocera.

We present a revised molecular phylogeny of the Drosophila repleta group including 62 repleta group taxa and nine outgroup species based on four mitochondrial and six nuclear DNA sequence fragments. With ca. 100 species endemic to the New World, the repleta species group represents one of the major species radiations in the genus Drosophila. Most repleta group species are associated with cacti in arid or semiarid regions. Contrary to previous results, maximum likelihood and Bayesian phylogenies of the 10-gene dataset strongly support the monophyly of the repleta group. Several previously described subdivisions in the group were also recovered, despite poorly resolved relationships between these clades. Divergence time estimates suggested that the repleta group split from its sister group about 21 million years ago (Mya), although diversification of the crown group began ca. 16 Mya. Character mapping of patterns of host plant use showed that flat leaf Opuntia use is common throughout the phylogeny and that shifts in host use from Opuntia to the more chemically complex columnar cacti occurred several times independently during the history of this group. Although some species retained the use of Opuntia after acquiring the use of columnar cacti, there were multiple, phylogenetically independent instances of columnar cactus specialization with loss of Opuntia as a host. Concordant with our proposed timing of host use shifts, these dates are consistent with the suggested times when the Opuntioideae originated in South America. We discuss the generally accepted South American origin of the repleta group.

Examination of two pieces of amber from the mid-Cretaceous of Myanmar revealed seven inclusions of leafy liverworts that we assign to the extinct Frullania cretacea Hentschel et al. 2009. These inclusions show a suite of characters that were not visible in the type specimen of F. cretacea . The new gametophytes consistently display rectangular to ovate underleaves that have two long-ciliate apical teeth in addition to 0–2 blunt lateral teeth. A narrow stylus is present on at least some leaves. The lobules usually form water sacs that are 1.2–2.3 times longer than wide, and are arranged at some distance from the stem. The observed combination of character states is not present in extant crown group lineages of Frullania . A syninclusion in one of the amber pieces is interpreted as a detached gynoecium of a second Cretaceous Frullania species and is described as F. baerlocheri , sp. nov. The subgynoecial underleaves of the syninclusion are suborbicular in shape, and allow for a separation of this species from F. cretacea . The described amber inclusions are the oldest representatives of an extant genus of leafy liverworts known so far.

The Drosophila virilis group is one of the major lineages of Drosophila previously recognised and it has been used as a model for different types of studies. It comprises 13 species whose phylogenetic relationships are not well resolved. In the present study, six nuclear genes (Adh, fused, Gpdh, NonA, CG9631 and CG7219) and the mitochondrial ribosomal RNA genes (12S-16S) have been used to estimate the evolutionary tree of the group using different methods of phylogenetic reconstruction. Different competing evolutionary hypotheses have also been compared using the Approximately Unbiased test to further evaluate the robustness of the inferred trees. Results are, in general, consistent with previous studies in recovering the four major lineages of the group (D. virilis phylad, Drosophila montana subphylad, Drosophila kanekoi subphylad and Drosophila littoralis subphylad), although D. kanekoi, D. littoralis and Drosophila ezoana are here inferred to be more closely related to the D. virilis phylad than to the D. montana subphylad. The age of the crown group, estimated with a Bayesian method that assumes a relaxed molecular clock, is placed in the late Miocene (∼ 10 Mya). The oldest lineages also appeared during this period (∼ 7.5 to ∼ 8.9 Mya), while the ages of the basal nodes of the montana subphylad and the virilis phylad are located in the early Pliocene (∼ 4.9 and ∼ 4.1 Mya). Major cladogenesis events correlate to geological and palaeoclimatic occurrences that most likely affected the freshwater and deciduous forests where these species are found. The inferred biogeographical history of the group, based on the statistical dispersal-vicariance analysis, indicates that the last common ancestor of the group had a Holarctic distribution from which the North American and the Eurasian lineages evolved as a result of a vicariant event.

This study provides the first phylogenetic reconstruction of the ant genus Leptomyrmex Mayr, a prominent endemic component of rain forest and wet sclerophyll forest in Australia, New Guinea and New Caledonia. Five genes are used to reconstruct phylogeny and estimate of ages of diversification in order to test congruence of the history of nuclear and mitochondrial genes: three protein-coding nuclear genes: arginine kinase (argK, 897 bp), long wavelength rhodopsin (LW Rh, 546 bp) and wingless (Wg, 409 bp), as well as the large subunit ribosomal gene 28S (482 bp) and the mitochondrial gene cytochrome oxidase I (COI, 658 bp). Four different partitioning schemes were tested for optimal resolving power; results show that partitioning by gene, translational pattern and codon position were uniformly favoured over less complex partitions. Nuclear markers showed relatively minor sequence divergence and provided strongly supported topology; phylogeny based solely on mtDNA produced somewhat conflicting topology but offered little power to resolve species complexes. Monophyly of the genus Leptomyrmex was recovered, as was the sister-group relationship of ‘micro-’ and ‘macro-’ Leptomyrmex species. Divergence dating analyses estimate that Leptomyrmex arose in the Eocene (stem age ∼44 million years ago (ma)), and that the ‘macro-’ species diverged from the ‘micro-’ species in the early Oligocene (∼31 ma). Diversification of the crown group ‘macro-’ and ‘micro-’ Leptomyrmex occurred in the Miocene (∼15 ma and 7.9 ma, respectively). New Guinean and New Caledonian lineages appear to have diverged from Australian lineages only recently (∼4.7 ma and 10.3 ma, respectively), and the latter clade is inferred to have reached New Caledonia from Australia via long distance dispersal. These results challenge previous hypotheses of Leptomyrmex classification and assumptions about their historical dispersal, but are in agreement with the current knowledge of the geological history of Melanesia.

An archaeal origin of eukaryotes is often equated with the engulfment of the bacterial ancestor of mitochondria by an archaeon. Such an event is problematic in that it is not supported by archaeal cell biology. We show that placing phylogenetic results within a stem-and-crown framework eliminates such incompatibilities, and that an archaeal origin for eukaryotes (as suggested from recent phylogenies) can be uncontroversially reconciled with phagocytosis as the mechanism for engulfment of the mitochondrial ancestor. This is significant because it eliminates a perceived problem with eukaryote origins: that an archaeal origin of eukaryotes (as under the Eocyte hypothesis) cannot be reconciled with existing cell biological mechanisms through which bacteria may take up residence inside eukaryote cells.

Acrochordus is a species-poor but highly distinctive aquatic snake genus currently distributed from India to the western edge of the Pacific. We provide the first phylogeny for the three extant species using Bayesian and parsimony analyses of one mitochondrial and two nuclear gene sequences. Acrochordus javanicus is strongly recovered as sister to A. arafurae + A. granulatus , counter to expectations from superficial ecology, external phenotype and former taxonomy. We review and revise key fossil calibrations for dating snake divergences. Bayesian relaxed-clock analysis of the two nuclear loci yields deep interspecific divergences among extant species that occurred during the Miocene ∼16 and ∼20 Mya (million years ago), pre-dating at least two of the three other living marine snake lineages. New morphological data for A. arafurae , and our molecular timescale, provide support for the placement of fossil taxon A. dehmi within the Acrochordus crown group, as sister to A. javanicus among nominate species. Finally, Acrochordus phylogeny provides an improved basis for taxon selection and character polarization in higher snake phylogenetics. Our study highlights the three Acrochordus species as old and highly distinct lineages that comprise an important component of the threatened Indo-Australian biodiversity.

Monophyly of Arthropoda is emphatically supported from both morphological and molecular perspectives. Recent work finds Onychophora rather than Tardigrada to be the closest relatives of arthropods. The status of tardigrades as panarthropods (rather than cycloneuralians) is contentious from the perspective of phylogenomic data. A grade of Cambrian taxa in the arthropod stem group includes gilled lobopodians, dinocaridids (e.g., anomalocaridids), fuxianhuiids and canadaspidids that inform on character acquisition between Onychophora and the arthropod crown group. A sister group relationship between Crustacea (itself likely paraphyletic) and Hexapoda is retrieved by diverse kinds of molecular data and is well supported by neuroanatomy. This clade, Tetraconata, can be dated to the early Cambrian by crown group-type mandibles. The rival Atelocerata hypothesis (Myriapoda+Hexapoda) has no molecular support. The basal node in the arthropod crown group is embroiled in a controversy over whether myriapods unite with chelicerates (Paradoxopoda or Myriochelata) or with crustaceans and hexapods (Mandibulata). Both groups find some molecular and morphological support, though Mandibulata is presently the stronger morphological hypothesis. Either hypothesis forces an unsampled ghost lineage for Myriapoda from the Cambrian to the mid Silurian.

The detailed structure of the lophophore is a key diagnostic character in the definition of higher brachiopod taxa. The problematic Heliomedusa orienta Sun and Hou, from the Lower Cambrian Chengjiang Lagerstatte of Yunnan, southwestern China, has a well-preserved lophophore, which is unlike that of any known extant or extinct brachiopods. Based on a comparative study of lophophore disposition in H. orienta and the extant discinid Pelagodiscus atlanticus, the in- and excurrent pattern and shell orientation of H. orienta are described and discussed. Reconstructions of lophophore shape and function are based on numerous specimens and comparison with P. atlanticus. The lophophore is composed of a pair of lophophoral arms that freely arch posteriorly rather than coiling anteriorly as commonly seen in fossil and recent lingulids. The lophophore is attached to the dorsal lobe of the mantle; it has neither calcareous nor chitinous supporting structures, and is disposed symmetrically on either side of the valve midline. The mouth can be inferred to be located at the base of the two brachial tubes, slightly posterior to the anterodorsal projection of the body wall. The lophophoral arms bear laterofrontal tentacles with a double row of cilia along their lateral edge, as in extant lingulid brachiopods. The main brachial axes are also ciliated, which presumably facilitated transport of mucous-bound nutrient particles to the mouth. The unique organization of the lophophore in Heliomedusa is not like any known fossil and living brachiopods. This clearly demonstrates that H. orienta is not a member of any crown group. It is here considered as a member of the brachiopod stem group, which challenges recent interpretations of a close discinid affinity. (C) 2009 Elsevier Masson SAS. All rights reserved.

Despite their medical interest, the phylogeny of the snake family Viperidae remains inadequately understood. Previous studies have generally focused either on the pitvipers (Crotalinae) or on the Old World vipers (Viperinae), but there has been no comprehensive molecular study of the Viperidae as a whole, leaving the affinities of key taxa unresolved. Here, we infer the phylogenetic relationships among the extant genera of the Viperidae from the sequences of four mitochondrial genes (cytochrome b, NADH subunit 4, 16S and 12S rRNA). The results confirm Azemiops as the sister group of the Crotalinae, whereas Causus is nested within the Viperinae, and thus not a basal viperid or viperine. Relationships among the major clades of Viperinae remain poorly resolved despite increased sequence information compared to previous studies. Bayesian molecular dating in conjunction with dispersal-vicariance analysis suggests an early Tertiary origin in Asia for the crown group Viperidae, and rejects suggestions of a relatively recent, early to mid-Tertiary origin of the Caenophidia.

We investigated individual-rich nemathelminth species from the Lower Cambrian Maotianshan-Shale (Chengjiang) biota comprising Chengjiang, Haikou and Shankou faunas near Kunming, southern China, with regard to morphology, life habits and their possible role in the early marine shallow-water ecosystems. Their body shapes can be grouped into four sets: long, worm-shaped forms, sac-like forms and tubiform forms with a conically tapering, stiff trunk, and forms with a body consisting of a grape-shaped anterior part and a similarly shaped trunk with cuticular plates along the long axis of the body. This latter shape matches the loricate trunk of extant larval priapulids and larval and adult loriciferans, both members of the scalidophoran Nemathelminthes. All Cambrian taxa share several features with the Scalidophora, comprising Loricifera, Priapulida and Kinorhyncha, such as the pharynx lined with internally curved spines and the frontal body region, introvert, which is similarly armed with hook-like spines. Living scalidophorans use their introvert for locomotion and the pharynx to swallow prey, which is assumed to be the case for the fossil forms too. Their inwardly curved pharyngeal spines prevent prey from escaping, while the introvert spines, the so-called scalids, may serve to anchor the body to the surface when pulling it forward. The living forms can withdraw their pharynx and introvert deeply into the body, which can be demonstrated only for the pharynx in the Lower Cambrian forms. Details of the arrangement and number of pharynx and introvert spines are considered useful features for a systematic positioning for the Lower Cambrian taxa. The structures themselves might have evolved, however, earlier than in the scalidophoran ground pattern and probably characterised already the stem species of cycloneuralian nemathelminths because of the presence of similar features in both taxa of the Nematoida, the nematomorphs (in the larvae) and the nematodes (circum-oral sensilla). Introverts with rings of six scalids in Nematoida opposite to rings of multiples of four or five in Scalidophora indicate a possible position of the fossil taxa close to the Scalidophora. We argue that the loricate Cambrian taxa (the fourth set) are derivatives of the stem lineage of the Loricifera. This implies that minute size, slight bilateralisation, a specific piercing apparatus developed along the evolutionary path of these animals toward life in the interstitial, characterise the crown group. Reconstructing the life habits of the fossil taxa, it seems to us that the forms investigated by us were most likely epi- or inbenthic, living in muddy sedimentary environments. A vertical burrowing into the sediment does not seem very likely, while a predatory life is plausible also for the Cambrian nemathelminths. We furthermore discuss the significance of these fossils with regard to the systematic status of the Nemathelminthes.

International audience; In order to better understand the parameters that drove evolution of actinopterygian fishes from the Late Jurassic to the Late Cretaceous (this being the time of diversification of crown group teleosts, by far the dominant fish group today), we define three environmental indicators, which are detectable as concordant patterns in the geological and fossil records. These are 1) freshwater radiations, 2) vicariant events and 3) sea temperature. We mapped the indicators onto a phylogeny of the Late Jurassic–Palaeocene actinopterygian taxa, and plotted the variations against time for each of the indicators. Our results show that for several of the marine clades, diversity is positively correlated with sea temperature and for one clade negatively correlated with sea temperature. The marine radiation is very important in the mid-Cretaceous, especially in the Tethys, which may have been a centre of origin for some clades. Vicariant events occurred in both marine and freshwater groups, and are abundant during the opening of the south Atlantic in the Early Cretaceous. Freshwater radiations, forming in some cases species flocks, are especially evident in the basal Cretaceous in Asia. Although these results are affected by biases related to the fossil record and to its study, we propose that these global patterns are genuine and reflect the strong impact of the Earth system on the evolution of fishes in the Late Mesozoic.

A postcranial skeleton of a small bird from the early Oligocene locality Pichovet in Southern France is described and identified as Eocuculus cf. cherpinae Chandler, 1999. It is the second fossil record of Eocuculus which was hitherto known from a postcranial skeleton from the late Eocene of North America only. Although Eocuculus shares some derived similarities with Cuculidae (cuckoos), it distinctly differs in a number of osteological features from crown group members of this taxon. If future, more complete skeletons prove its cuculiform affinities, Eocuculus is a stem lineage representative of this taxon and not within the crown group. Recognition of Eocuculus in the early Oligocene of France provides evidence for the presence of an extinct late Eocene/early Oligocene avian taxon with an intercontinental Northern Hemisphere distribution.

Freshwater corbulid bivalves found in Miocene deposits of western Amazonia have been considered products of an endemic radiation of a marine clade within the large lacustrine system occupying the region at that time. Our reexamination of Paleocene freshwater corbulids of the Tongue River Formation of western North Dakota and eastern Montana, however, extends the stratigraphic and geographic range of three Amazonian taxa—Pachydon, Ostomya, and Anticorbula—to the Paleocene of the northern Great Plains of the United States. Both Paleocene and Miocene freshwater corbulid taxa occur in large freshwater systems with an intermittent marine connection. To test the phylogenetic relationships of one particularly widespread Paleocene species (Pachydon mactriformis), we conducted cladistic analyses using maximum parsimony and heuristic searches of matrices of conchologic characters. Seven species of Pachydon and Pebasia dispar from the western Amazonian Neogene, Pachydon mactriformis from the Paleocene of North Dakota, representative species of eight neotropical marine corbulid genera, and three additional corbulid taxa were included. Corbula was the outgroup. All analyses produced similar regions of stability within trees. One such area is a Pachydon crown group that includes P. mactriformis, indicating that Paleocene and Miocene Pachydon are not convergent. Our results also indicate that Pachydon does not represent a separate basal radiation within the family. However, we have not resolved a robust sister clade relationship for the Pachydon crown group. Two Amazonian Neogene taxa do not fall within the Pachydon crown group, and their phylogenetic position is not resolved. At this time, we do not have sufficient evidence to refine the definitions of Pachydon and Pachydontinae as monophyletic clades. Although we have evidence that three genera of corbulid bivalves (Pachydon, Ostomya, and Anticorbula) in the Pebas Formation are not endemic and have long geologic histories, a species-level radiation occurs within the Amazonian Miocene, especially within Pachydon. In this radiation, morphologic and ecologic divergence is dramatic, and one species, P. obliquus, successfully invaded and dominated extreme, dysoxic habitats.

Aspects of pantopod ontogeny have been known for a long time, but specific information is available for only a few species. Our account of the postembryonic development of Pycnogonum litorale is based on laboratory-reared individuals and SEM studies. We documented particularly all early developmental stages, with emphasis on morphogenetic changes of head structures and appendages. In P. litorale the protonymphal limbs, the chelicerae and two more uniramous legs, degenerate already during the larval phase; only the third one, the ovigers, reappears in male juveniles. Other Pantopoda vary in this aspect from retention of all three protonymphal appendages to their complete reduction, as in P. litorale. Accordingly, the two post-cheliceral larval appendages are separate legs in front of the walking legs in the adults, the ‘parapalps’ and the ‘ovigers’, but they do not occur in all pantopods. The scarcity of studies of the ontogeny of Pantopoda prevents us from a more conclusive picture, but our data are promising to state that additional such studies will increase the usability of ontogenetic data for a phylogenetic analysis of Pantopoda, the crown group of the Pycnogonida. We also discuss the phylogenetic implications of our data in the light of new information from Hox genes and developmental-biological data on body segmentation and tagmosis of the Chelicerata. These suggest the homology of chelicerae and antenn(ul)ae of other euarthropods. Accepting this, we conclude that the adult pycnogonid/pantopod head, the cephalosoma, corresponds to the euarthropod head and that the protonymph with three appendage-bearing segments may represent an even shorter, possibly phylogenetically older larval type than the euarthropod ‘head larva’ bearing four pairs of appendages. In further consequence, the fourth walking legs of Pycnogonida/Pantopoda should correspond to the first opisthosomal appendages, the chilaria, of euchelicerates. This implies that within Pycnogonida the post-prosomal region became compacted during evolution to a single leg-bearing segment plus a tubular end piece. Accordingly, neither the anterior nor the posterior functional boundaries of the walking-leg region correspond to the original tagma borders. q 2003 Elsevier Ltd. All rights reserved.

Sequencing of eukaryotic genomes allows one to address major evolutionary problems, such as the evolution of gene structure. We compared the intron positions in 684 orthologous gene sets from 8 complete genomes of animals, plants, fungi, and protists and constructed parsimonious scenarios of evolution of the exon-intron structure for the respective genes. Approximately one-third of the introns in the malaria parasite Plasmodium falciparum are shared with at least one crown group eukaryote; this number indicates that these introns have been conserved through >1.5 billion years of evolution that separate Plasmodium from the crown group. Paradoxically, humans share many more introns with the plant Arabidopsis thaliana than with the fly or nematode. The inferred evolutionary scenario holds that the common ancestor of Plasmodium and the crown group and, especially, the common ancestor of animals, plants, and fungi had numerous introns. Most of these ancestral introns, which are retained in the genomes of vertebrates and plants, have been lost in fungi, nematodes, arthropods, and probably Plasmodium. In addition, numerous introns have been inserted into vertebrate and plant genes, whereas, in other lineages, intron gain was much less prominent.

The evolutionary divergence of cnidarian and bilaterian lineages from their remote metazoan ancestor occurred at an unknown depth in time before the Cambrian, since crown group representatives of each are found in Lower Cambrian fossil assemblages. We report here a variety of putative embryonic, larval, and adult microfossils deriving from Precambrian phosphorite deposits of Southwest China, which may predate the Cambrian radiation by 25–45 million years. These are most probably of cnidarian affinity. Large numbers of fossilized early planula-like larvae were observed under the microscope in sections. Though several forms are represented, the majority display remarkable conformity, which is inconsistent with the alternative that they are artifactual mineral inclusions. Some of these fossils are preserved in such high resolution that individual cells can be discerned. We confirm in detail an earlier report of the presence in the same deposits of tabulates, an extinct crown group anthozoan form. Other sections reveal structures that most closely resemble sections of basal modern corals. A large number of fossils similar to modern hydrozoan gastrulae were also observed. These again displayed great morphological consistency. Though only a single example is available, a microscopic animal remarkably similar to a modern adult hydrozoan is also presented. Taken together, the new observations reported in this paper indicate the existence of a diverse and already differentiated cnidarian fauna, long before the Cambrian evolutionary event. It follows that at least stem group bilaterians must also have been present at this time.

Schizaeaceae fossils have been documented throughout Mesozoic and Cenozoic deposits, but our understanding of this fossil record is hampered by uncertainties with respect to the relationships of living species. To start building a phylogenetic framework for the family, an initial phylogenetic analysis of living species using plastid rbcL nucleotide sequence data is conducted. The analysis supports Schizaea s. lat. and Lygodium monophyly, but Anemia is resolved as paraphyletic to Mohria. In the Anemia/Mohria clade, monophyly of subgenus Anemiorrhiza is supported, but Coptophyllum is resolved as paraphyletic to subgenus Anemia. In Schizaea s. lat., both Schizaea s. str. and Actinostachys are well supported and Microschizaea is grouped with Schizaea s. str., although only one Microschizaea species (Schizaea pusilla) was included. These results are largely congruent with previous morphology-based analyses. In Lygodium however, results presented contrast with recent morphological analyses highlighting the problems of identifying Lygodium subgeneric groups. Using the resulting phylogeny as a framework, putative relationships of fossil species are discussed, tentative minimum age estimates for generic crown group diversifications are made, and possible conclusions with respect to the origins of habit and habitat preferences are discussed. The fossil evidence indicates that subgeneric groups within the Anemia/Mohria clade are comparatively ancient, originating during the Early Cretaceous, and the putative placement of fossil Anemia within the crown group of living subgenus Anemiorrhiza would indicate that their calcareous habitat preference may be a relic feature that has persisted ever since the Early Cretaceous. Lygodium on the other hand appears to have passed through a diversity bottleneck. Modern species diversity probably originated in the Neogene, and the earliest fossil evidence for the origin of their vining and trailing habit comes from the placement of Miocene fossil Lygodium within the crown group of living species.

The discovery of fossilised roots of a lindsaeoid fern within the trunk of the extinct tree fern Tempskya provides new fossil evidence for Lindsaeaceae in the Mesozic, as well as the first direct evidence of an ecological association between Tempskya and root-climbing epiphytes. Data were collected from permineralised Tempskya trunks from the Aspen Shale (Early Cretaceous, Albian), Wyoming (USA). The roots of the lindsaeoid fossil are clearly distinguishable from those of Tempskya and other living ferns based on a suite of distinctive anatomical features, which are described in detail. The foliage is unknown. The new fossil is interpreted as a root climber, and comparisons are made with similar living species in Lindsaea subgenus Odontoloma (Lindsaeaceae). The documentation of Lindsaeaceae in the Early Cretaceous adds to a small but growing body of data on the diversification of polypodiaceous ferns during this important period. These recent discoveries point to a much earlier (Early Cretaceous) crown group radiation of polypodiaceous ferns than previously suspected.