First reliable fossil record of the family Isonychiidae (Insecta, Ephemeroptera) from Cretaceous Kachin amber

We report the oldest fossil record of Istiophoridae from the Northern Alpine Foreland Basin (Western Paratethys) in Pucking, Austria (Lower Miocene, lower Aquitanian, ∼22.4 Ma). The studied specimen consists of fragments of five articulated vertebrae and a partially preserved second dorsal fin. We found that the Pucking specimen is only surpassed in age by an isolated vertebra from the Chandler Bridge Formation (South Carolina, U.S.A.), with ∼24.7–23.5 Ma. Pucking and the Chandler Bridge Formation differ in age by ∼1.1–2.6 Ma. The fossil istiophorid from the Chandler Bridge Formation was considered controversial due to the large gap in the fossil record between the first appearance of Istiophoridae and the last appearance of any other extinct billfish clade. Here we report that Pucking (Lower Miocene) and South Carolina (Oligocene) share the occurrence of Istiophoridae, †Xiphiorhynchinae (Xiphiidae), and †Aglyptorhynchinae (†Palaeorhynchidae). Our finding demonstrates that the coexistence of different groups of billfishes is maintained over time and that the Chandler Bridge specimen is a reliable record. Our work closes a temporal gap of ∼4.4 Ma between the previously recognized oldest Istiophoridae (∼18 Ma) and the last appearance of †Xiphiorhynchinae and †Aglyptorhynchinae. This result supports a longer evolutionary history for Istiophoridae, establishes continuity in the billfish fossil record, and is significant for future time calibrated phylogenies.

Background: Celastraceae is a morphologically heterogeneous family. For this reason, the inclusion of some taxa within this group is controversial. Recently this problem has become significant since its fossil record is recognized as an important source of information for evolutionary studies, especially those using molecular clocks which require a robust, reliable fossil record.
 Questions: What are the most reliable fossil records of Celastraceae? What morphological characters are used to assign fossils in the family?
 Study site and dates: Compilation of records contained in paleontological databases, and paleobotanical literature, covering publications from 1869 to 2018.
 Methods: Published information on the Celastraceae fossil record was compiled and analyzed using the most recent classification system and specialized literature on the family.
 Results: A total of 168 fossil records were examined, of which nine are proposed for use as molecular clock calibration points. Each specimen has a description based on a character set used for its identification, a photograph and/or illustration, their geological age is well supported, their geographic origin is known, and the specimens are in accredited home institutions with publicly accessible collections.
 Conclusions: The identification and establishment of relationships between fossil and extant taxa have important limitations that depend on the critical interpretation of morphology in a phylogenetic context. Therefore, it is essential to incorporate only those morphological studies in Celastraceae that help clarify its fossil record.

History of commensal rodents on Ishigaki Island (southern Ryukyus) reconstructed from Holocene fossils, including the first reliable fossil record of the house mouse Mus musculus in Japan

A Taxus leafy branch with attached ovules from the Lower Cretaceous of Inner Mongolia, North China

Interpretation of the biogeography of the genus Mahonia (Berberidaceae) is limited by the lack of fossil records in East Asia. Compressed fossil foliage, described here as Mahonia mioasiatica sp. nov., were collected from the Upper Miocene Xiaolongtan Formation in Wenshan, Yunnan, southwest China. These specimens represent the oldest reliable fossil record of Mahonia in East Asia. This new fossil species shows a general similarity to Group Orientales and is most similar to the extant eastern Asian Mahonia conferta. Considering other fossil evidence of Mahonia, we propose a migration route of this genus to Asia over the North Atlantic Land Bridge rather than the Bering Land Bridge. Our results also suggest that North America, Europe and East Asia have been successive centers of diversity for the genus, as a consequence of diversification in Group Orientales potentially related to historical climate change.

The fossil record of Araceae pollen beginning in the late Early Cretaceous and peaking in the Paleocene/Eocene is very sparse up to now, consisting of three highly distinctive types: zona-aperturate pollen of the Monstera or Gonatopus type (very similar to Proxapertites operculatus), an ulcerate-spiny type typical for Limnobiophyllum, and a polyplicate, omniaperturate pollen type (an ephedroid pollen with non-gnetalean affinities) which was recently reported from the late Early Cretaceous (Mayoa portugallica). An extensive literature search has shown that some distinctive Ephedripites forms (the Paleogene Ephedripites vanegensis, and the Late Cretaceous Ephedripites elsikii) are very similar to pollen of Spathiphyllum and both species are here transferred from Ephedripites to Spathiphyllum (as comb. nov.). We also add new fossil findings to the Araceae record. The new findings include a zona-aperturate, microperforate to microreticulate pollen type from the Palaeocene of Colombia, highly similar to extant Gonatopus or Zamioculcas or Monstera pollen (Araceae) and to fossil Proxapertites operculatus, which is currently seen as a fossil equivalent; and, an ulcerate, spiny pollen from the Eocene of Stolzenbach, Germany, extending the range of Limnobiophyllum (Pandaniidites), which is thought to be an extinct member of extant Araceae. The three pollen types add considerably to the reliable fossil record of the family that now contains more than 20 records of these three pollen types: with the zona-aperturate type recorded from the tropical or subtropical regions of Northern and Southern America, Central Africa, Southern and Central Europe, from the Indian subcontinent and the Malayan Archipelago; the ulcerate type occurring in North America and Europe; and the polyplicate type mainly occurring in South America and South-West Europe. Now we have good evidence that some of the aroid subfamilies were already in existence in the Cretaceous, increasing in diversity and worldwide distribution in the Paleogene.

BackgroundThe origin of angiosperms has been under debate since the time of Darwin. While there has been much speculation in past decades about pre-Cretaceous angiosperms, including Archaefructus, these reports are controversial. The earliest reliable fossil record of angiosperms remains restricted to the Cretaceous, even though recent molecular phylogenetic studies suggest an origin for angiosperms much earlier than the current fossil record.ResultsIn this paper, after careful SEM and light microscopic work, we report fossils with angiospermous traits of the Jurassic age. The fossils were collected from the Haifanggou Formation (middle Jurassic) in western Liaoning, northeast China. They include two female structures and an associated leaf on the same slab. One of the female structures is physically connected to the apex of a short shoot. The female organs are borne in pairs on short peduncles that are arranged along the axis of the female structure. Each of the female organs has a central unit that is surrounded by an envelope with characteristic longitudinal ribs. Each central unit has two locules completely separated by a vertical septum. The apex of the central unit is completely closed. The general morphology places these fossils into the scope of Schmeissneria, an early Jurassic genus that was previously attributed to Ginkgoales.ConclusionBecause the closed carpel is a character only found in angiosperms, the closed apex of the central unit suggests the presence of angiospermy in Schmeissneria. This angiospermous trait implies either a Jurassic angiosperm or a new seed plant group parallel to angiosperms and other known seed plants. As an angiosperm, the Liassic age (earliest Jurassic) of Schmeissneria microstachys would suggest an origin of angiosperms during the Triassic. Although still uncertain, this could have a great impact on our perspective of the history, diversity and systematics of seed plants and angiosperms.

The fossil record of angel sharks is reviewed with special focus on skeletal remains. A new family †Pseudorhinidae is established for two species based on complete specimens from the Late Jurassic and a possible third species based on isolated teeth. This clade is a member of the stem lineage of Squatiniformes. Squatinidae represents the crown with a reliable fossil record extending back into the Aptian based on a partial skeleton displaying characteristic morphological traits of Squatina. We also present revised morphological descriptions of the skeletal remains of †Squatina baumbergensis (Campanian of Germany) and †Squatina sp. (Miocene of Japan). In this study, we used reliable skeletal remains and a modified approach to establish the origin and divergence of the Squatiniformes and the Squatinidae. Isolated teeth are considered to be unreliable because of the poor knowledge of squatiniform dental character traits and their evolution. We estimate a ‘hard' minimum age constraint of 156.2 Ma and a ‘soft' maximum age constraint of 181.74 Ma for the origin of the Squatiniformes. For the crown represented by the Squatinidae, we estimate a ‘hard' minimum age constraint of 114 Ma and a ‘soft' maximum age constraint of 157.59 Ma. These age constraints most likely designate the timing of the origin of identifiable squatiniform and squatinid characters as currently understood rather than the origin of the Squatiniformes or the divergence between the †Pseudorhinidae and the Squatinidae. The lack of pre-Late Jurassic pseudorhinids and pre-Cretaceous squatinids probably represents an artefact because characteristic squatiniform tooth morphologies, which generally provide only a restricted set of diagnosable features, might not have yet been fully developed. Consequently, skeletal remains of neoselachians from the Early and Middle Jurassic are crucial for establishing reliable characters of stem-lineage representatives and to avoid misinterpretations resulting from transferring morphological traits of the crown to fossil groups with unresolved interrelationships, as well as sister-group relations. http://zoobank.org/urn:lsid:zoobank.org:pub:5A5FA554-C834-48E3-AE44-6F92DE9CB5F1

A new subgenus and species of the braconid parasitoid of the tribe Centistini s. l. (Euphorinae), Centistoides (Palaeoides) magnioculus Belokobylskij, subgen. et sp. nov., from late Eocene Danish amber are described and illustrated from one female. This is the first time the tribe of euphorine parasitoids is reliably documented in the fossil record. A key to all genera and subgenera of this suprageneric taxonomic group is compiled. The discussion about position of the genus Parasyrrhizus Brues, composition of the tribe Centistini s. l., and the composition of the Danish amber hymenopteran fauna are provided.

A fossil of Oniscidea, Tylidae gen. et sp. indet. from Kachin amber (Cretaceous Cenomanian), Myanmar, is described here. The convex body, the cephalon with a triangular protrusion between the antennae, and pereonites 2–6 with epimera demarcated from tergites indicate that this specimen belongs to the family Tylidae, but since it is not an adult the identification of the genus and species is uncertain. This specimen has a convex body and shows an ability to conglobate, like all Tylidae. It is the first specimen of Oniscidea with a conglobation ability found in Burmese amber. Up to now, the fossil record of terrestrial isopods has included a total of 20 families and 54 records (36 species and 18 not formally identified species), 20% of which are from the Cretaceous period. These fossil records from the Cretaceous period show that terrestrial isopods were highly diversified as early as in the Cenomanian.

Simple SummaryThis paper describes the aquatic plants of Trapa L. and Hemitrapa Miki from the upper Eocene of Bailuyuan Formation in the Weihe Basin, central China. The discoveries represent the earliest known Trapa records in the world and the earliest Hemitrapa record in Asia. Furthermore, the new species identified in this study is the most reliable leaf fossil record of Trapa so far. These occurrences provide a new clue to investigate the origin of Trapa and its evolutionary relationships with Hemitrapa. The unexpected aquatic plant assemblage indicates that central China was warm and humid, with freshwater ponds or lakes, in the late Eocene.Both Trapa L. and the extinct Hemitrapa Miki are aquatic plants in the family Lythraceae, with abundant fossil records in Eurasia and North America in the Cenozoic. However, documented materials are mainly based on fruit and pollen grains without reliable leaf fossils. Here, we report fossil leaves, fruit, and roots of Trapa and fruit of Hemitrapa from the late Eocene of Weinan, the Weihe Basin of central China. The fossil leaves are identified as a new species, Trapa natanifolia Z. C. Han et H. Jia sp. nov., which represents the earliest known record of a Trapa leaf fossil. It is remarkably similar to extant species of Trapa, mostly due to the unique inflated petiole structures found in both of them. While displaying prominent intergeneric differences, the incomplete fossil fruits are assigned to Trapa sp. indet. and Hemitrapa sp. indet. The former is the earliest fossil fruit record of Trapa, and the latter represents the earliest fossil record of Hemitrapa found in Asia. These new fossil discoveries suggest that the divergence of Trapa and Hemitrapa occurred at least by the late Eocene. It is believed that modern Trapa most likely originated in China. Furthermore, this unexpected aquatic plant fossil assemblage indicates that central China was warm and humid, with freshwater ponds or lakes, in the late Eocene and not as arid as previously thought.

Antlion-like lacewings (Myrmeleontiformia) have comparably large predatory larvae; most well-known are the larvae of antlions (Myrmeleontidae) and owlflies (Ascalaphidae). Yet, larvae of spoon-winged lacewings (Nemopterinae, also an ingroup of Myrmeleontiformia) are less well studied and differ in their overall habitus, with a broader head and stouter mouthparts. We here review the known record of spoon-winged lacewing larvae and report two new fossil larvae preserved in 99 million-year-old Kachin amber from Myanmar that have some characteristics of spoon-winged lacewing larvae. We quantitatively compare morphological aspects of all these larvae with those from other myrmeleontiformian larvae. Our analyses suggest that one fossil larva may indeed be closely related to extant spoon-winged lacewings, but retains some plesiomorphies shared with Crocinae, the sister group of Nemopterinae. The other larva shows many unique features, but also some similarities to spoon-winged lacewing larvae, hence might be a highly specialised early representative of the lineage. These two larvae are the first potential larvae of Nemopterinae in the fossil record. Therefore, they are important indicators for the structure of the early diversification of lacewings.

Beetle larvae often differ significantly in morphology from their adult counterparts. Therefore, it should be surprising that these immatures are often not considered to the same extent as the adult beetles. As an example, the fossil record of most beetle groups is largely represented by adult specimens. Representatives of Mordellidae, the group of tumbling flower beetles, have a cosmopolitan distribution with myriads of formally described species, based mostly on adult male specimens. Mordellidae is also well represented in the fossil record, but again only by adults; not a single fossil specimen of a larva has been reported until now. We report a new well-preserved beetle larva in 99 million-year-old Kachin amber. The larva possesses specialisations not known from the modern larvae of Mordellidae, but otherwise is clearly similar to them in many aspects. It appears possible that the fossil represents yet another holometabolan larva in Kachin amber that is associated with life within wood and/or fungi, and therefore, may have contributed to carbon cycling of the past.

Upper Cretaceous record of non-belemnitid coleoid jaws from Hokkaido, Japan, and its evolutionary implications

BackgroundMultilocus data are becoming increasingly important in determining the phylogeny of closely related species and delimiting species. In species complexes where unequivocal fossil calibrations are not available, rigorous dating of the coalescence-based species trees requires accurate mutation rates of the loci under study but, generally, these rates are unknown. Here, we obtained lineage-specific mutation rates of these loci from a higher-level phylogeny with a reliable fossil record and investigated how different choices of mutation rates and species tree models affected the split time estimates. We implemented this strategy with a genus of water shrews, Neomys, whose taxonomy has been contentious over the last century.ResultsWe sequenced 13 introns and cytochrome b from specimens of the three species currently recognized in this genus including two subspecies of N. anomalus that were originally described as species. A Bayesian multilocus species delimitation method and estimation of gene flow supported that these subspecies are distinct evolutionary lineages that should be treated as distinct species: N. anomalus (sensu stricto), limited to part of the Iberian Peninsula, and N. milleri, with a larger Eurasian range. We then estimated mutation rates from a Bayesian relaxed clock analysis of the mammalian orthologues with several fossil calibrations. Next, using the estimated Neomys-specific rates for each locus in an isolation-with-migration model, the split time for these sister taxa was dated at 0.40 Myr ago (with a 95 % confidence interval of 0.26 – 0.86 Myr), likely coinciding with one of the major glaciations of the Middle Pleistocene. We also showed that the extrapolation of non-specific rates or the use of simpler models would lead to very different split time estimates.ConclusionsWe showed that the estimation of rigorous lineage-specific mutation rates for each locus allows the inference of robust split times in a species tree framework. These times, in turn, afford a better understanding of the timeframe required to achieve isolation and, eventually, speciation in sister lineages. The application of species delimitation methods and an accurate dating strategy to the genus Neomys helped to clarify its controversial taxonomy.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0485-z) contains supplementary material, which is available to authorized users.