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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.

Saetaspongia so far cannot be confidently assigned to any class-level crown group. Clarifying its phylogenetic position requires new information provided by more detailed studies of previously described and/or new material. Some sponge fossils with the typical skeletal architecture of Saetaspongia have recently been recognized in the Cambrian (Stage 4) Balang Biota of Guizhou, China, including S. jianhensis new species and S. cf. S. densa. The new taxon is characterized by the following features: spicules are fine monaxons and are inclined to be loosely to densely arranged into plumose arrays; skeleton is composed primarily of one major plumose bundle, with an uncertain number (perhaps two) of small plumose arrays; and primary skeleton is occasionally interspersed with some irregularly oriented individual spicules. An additional specimen consisting of large monaxons, with plumose structures and overlying irregular coarse monaxons, closely fits the description and illustrations of previously described S. cf. S. densa. By combining information from previous studies and the present research, fossil evidence indicates that the plumose architecture is a critical feature diagnostic of Saetaspongia and that there are no hexactine-based spicules in this genus. The new material from the Balang Biota further supports the notion that Saetaspongia has a protomonaxonid rather than a hexactinellid affinity. Fossil evidence suggests that Saetaspongia had a wide biogeographic distribution during the early Cambrian and the stratigraphic distribution of this genus extends up to Stage 4.UUID: http://zoobank.org/e9ca5e4a-134c-4daa-9266-19085e32614f.

BackgroundThe stem-group of Ephemeroptera is phylogenetically important for understanding key steps in evolutionary history of early pterygote insects. However, these taxa have been mostly studied from the taxonomy point of view focused on the pattern of wing venation and often using only classical optical microscopy devices. In-depth studies on detailed morphology of the different body structures are scarcely performed, although the results are critical for elucidation of life history traits and their evolutionary pattern among the basal pterygotes.ResultsNew information is presented on the morphology of two species ofMisthodotes, which are stem-mayflies from the Early Permian. Based on new results obtained from a re-examination of the type specimens and supplementary material, we infer the life history traits of both the adult and larval stages of these Palaeozoic insects and reconsider previous interpretations. For the first time, we report the structure of the thoracic pleura and the articulation at the base of the wing in a stem-group of Ephemeroptera and compare them with those of extant mayflies. We also provide additional support for the systematic placement of investigated taxa and an amended diagnosis of the genusMisthodotes.ConclusionsAdultMisthodotes sharoviandMisthodotes zalesskyi had chewing mouthparts, which enabled them to scavenge or feed on plants. The wing apparatus was adapted for slow powered flapping flight and gliding, using long caudal filaments for steering. The wing base does not have rows of articulary sclerites as previously hypothesized for some Palaeozoic taxa but inflexible axilla similar to that found in modern mayflies. The structure of the thoracic pleura is also similar to that in the crown group of Ephemeroptera, while differences in the course of sutures may be explained by an evolutionary trend towards more powerful dorsoventral flying musculature and forewing-based flight (anteromotorism) in modern taxa. There is no evidence for swarming behaviour and mating in the air as occurs in modern mayflies as they had none of the associated morphological adaptations. Putative larvae ofMisthodotescan not be unambiguously associated with the adults. They also exhibit some morphological specializations of Protereismatidae like 9 pairs of abdominal tracheal gills supporting their benthic lifestyle with legs adapted to burrowing.

PREMISE Fossils provide fundamental evidence of the evolutionary processes that crafted today's biodiversity and consequently for understanding life on Earth. We report the finding of Myrtaceidites eucalyptoides pollen grains preserved within the anthers of a 52-million-year-old Eucalyptus flower collected at Laguna del Hunco locality of Argentinean Patagonia and discuss its implications in understanding the evolutionary history of the iconic Australian genus Eucalyptus. METHODS Pollen grains were extracted from the flower's anthers and were then observed under light microscopy and scanning electron microscopy. The phylogenetic position of the fossil was investigated by adding pollen data to a previously published total-evidence matrix and analyzing it using parsimony. RESULTS We erect the species Eucalyptus xoshemium for the fossil flower. Pollen extracted from E. xoshemium belongs to the species Myrtaceidites eucalyptoides, which, until now, was only known as dispersed pollen. The numerous pollen grains recovered from the single flower allowed estimation of M. eucalyptoides' variability. Results of the phylogenetic analysis reinforce the position of this fossil within crown group Eucalyptus. CONCLUSIONS The discovery of these pollen grains within a Patagonian Eucalyptus fossil flower confirms the hypothesis that Myrtaceidites eucalyptoides represents fossil pollen in the Eucalyptus lineage, extends the geographic and stratigraphic fossil pollen record, and supports an earlier age for crown-group eucalypts.

The internal cast of a turtle shell, found near the town of Cabrejas del Pinar (Soria Province, Castile and Leon Autonomous Community, Spain), is presented here. It is the first fossil vertebrate recognized in the vicinity of that town. This specimen was found in a middle Cretaceous bed (Cenomanian), deposited in a coastal marine environment. It is recognized as attributable to a member of the crown group Pleurodira. No representative of this clade had so far been found in pre-Campanian strata in the Castile and Leon Autonomous Community. In fact, the pre-Campanian record of the crown Pleurodira is very limited in Laurasia. The hitherto known record of pre-Campanian turtles from Castile and Leon consisted of basal forms (members of the terrestrial clade Helochelydridae and of the freshwater Pleurosternidae) and of freshwater representatives of Eucryptodira, all of them found in layers older than that where the new turtle remain was found. The availability of characters in the analyzed specimen allows it to be recognized as compatible with the littoral bothremydid turtle Algorachelus.

The acquisition of terrestrial, limb-based locomotion during tetrapod evolution has remained a subject of debate for more than a century1,2. Our current understanding of the locomotor transition from water to land is largely based on a few exemplar fossils such as Tiktaalik3, Acanthostega4, Ichthyostega5 and Pederpes6. However, isolated bony elements may reveal hidden functional diversity, providing a more comprehensive evolutionary perspective7. Here we analyse 40 three-dimensionally preserved humeri from extinct tetrapodomorphs that span the fin-to-limb transition and use functionally informed ecological adaptive landscapes8–10 to reconstruct the evolution of terrestrial locomotion. We show that evolutionary changes in the shape of the humerus are driven by ecology and phylogeny and are associated with functional trade-offs related to locomotor performance. Two divergent adaptive landscapes are recovered for aquatic fishes and terrestrial crown tetrapods, each of which is defined by a different combination of functional specializations. Humeri of stem tetrapods share a unique suite of functional adaptations, but do not conform to their own predicted adaptive peak. Instead, humeri of stem tetrapods fall at the base of the crown tetrapod landscape, indicating that the capacity for terrestrial locomotion occurred with the origin of limbs. Our results suggest that stem tetrapods may have used transitional gaits5,11 during the initial stages of land exploration, stabilized by the opposing selective pressures of their amphibious habits. Effective limb-based locomotion did not arise until loss of the ancestral ‘L-shaped’ humerus in the crown group, setting the stage for the diversification of terrestrial tetrapods and the establishment of modern ecological niches12,13. Analysis of humeri from fossils that span the fin-to-limb transition reveal that the change in the humerus shape is driven by both ecology and phylogeny, and is associated with functional trade-offs related to locomotor performance.

Mesozoic birds display considerable diversity in size, flight adaptations and feather organization1–4, but exhibit relatively conserved patterns of beak shape and development5–7. Although Neornithine (that is, crown group) birds also exhibit constraint on facial development8,9, they have comparatively diverse beak morphologies associated with a range of feeding and behavioural ecologies, in contrast to Mesozoic birds. Here we describe a crow-sized stem bird, Falcatakely forsterae gen. et sp. nov., from the Late Cretaceous epoch of Madagascar that possesses a long and deep rostrum, an expression of beak morphology that was previously unknown among Mesozoic birds and is superficially similar to that of a variety of crown-group birds (for example, toucans). The rostrum of Falcatakely is composed of an expansive edentulous maxilla and a small tooth-bearing premaxilla. Morphometric analyses of individual bony elements and three-dimensional rostrum shape reveal the development of a neornithine-like facial anatomy despite the retention of a maxilla–premaxilla organization that is similar to that of nonavialan theropods. The patterning and increased height of the rostrum in Falcatakely reveals a degree of developmental lability and increased morphological disparity that was previously unknown in early branching avialans. Expression of this phenotype (and presumed ecology) in a stem bird underscores that consolidation to the neornithine-like, premaxilla-dominated rostrum was not an evolutionary prerequisite for beak enlargement. A crow-sized stem bird, Falcatakely forsterae, possesses a long and deep rostrum—a beak morphology that was previously unknown among Mesozoic birds and is similar to that of some crown-group birds, such as toucans.

Taxon sampling is a central aspect of phylogenetic study design, but it has received limited attention in the context of total-evidence dating, a widely used dating approach that directly integrates molecular and morphological information from extant and fossil taxa. We here assess the impact of commonly employed outgroup sampling schemes and missing morphological data in extant taxa on age estimates in a total-evidence dating analysis under the uniform tree prior. Our study group is Pimpliformes, a highly diverse, rapidly radiating group of parasitoid wasps of the family Ichneumonidae. We analyze a data set comprising 201 extant and 79 fossil taxa, including the oldest fossils of the family from the Early Cretaceous and the first unequivocal representatives of extant subfamilies from the mid-Paleogene. Based on newly compiled molecular data from ten nuclear genes and a morphological matrix that includes 222 characters, we show that age estimates become both older and less precise with the inclusion of more distant and more poorly sampled outgroups. These outgroups not only lack morphological and temporal information but also sit on long terminal branches and considerably increase the evolutionary rate heterogeneity. In addition, we discover an artifact that might be detrimental for total-evidence dating: “bare-branch attraction,” namely high attachment probabilities of certain fossils to terminal branches for which morphological data are missing. Using computer simulations, we confirm the generality of this phenomenon and show that a large phylogenetic distance to any of the extant taxa, rather than just older age, increases the risk of a fossil being misplaced due to bare-branch attraction. After restricting outgroup sampling and adding morphological data for the previously attracting, bare branches, we recover a Jurassic origin for Pimpliformes and Ichneumonidae. This first age estimate for the group not only suggests an older origin than previously thought but also that diversification of the crown group happened well before the Cretaceous-Paleogene boundary. Our case study demonstrates that in order to obtain robust age estimates, total-evidence dating studies need to be based on a thorough and balanced sampling of both extant and fossil taxa, with the aim of minimizing evolutionary rate heterogeneity and missing morphological information. [Bare-branch attraction; ichneumonids; fossils; morphological matrix; phylogeny; RoguePlots.]

Phylogenomic and paleontological data constitute complementary resources for unraveling the phylogenetic relationships and divergence times of lineages, yet few studies have attempted to fully integrate them. Several unique properties of echinoids (sea urchins) make them especially useful for such synthesizing approaches, including a remarkable fossil record that can be incorporated into explicit phylogenetic hypotheses. We revisit the phylogeny of crown group Echinoidea using a total-evidence dating approach that combines the largest phylogenomic data set for the clade, a large-scale morphological matrix with a dense fossil sampling, and a novel compendium of tip and node age constraints. To this end, we develop a novel method for subsampling phylogenomic data sets that selects loci with high phylogenetic signal, low systematic biases, and enhanced clock-like behavior. Our results demonstrate that combining different data sources increases topological accuracy and helps resolve conflicts between molecular and morphological data. Notably, we present a new hypothesis for the origin of sand dollars, and restructure the relationships between stem and crown echinoids in a way that implies a long stretch of undiscovered evolutionary history of the crown group in the late Paleozoic. Our efforts help bridge the gap between phylogenomics and phylogenetic paleontology, providing a model example of the benefits of combining the two. [Echinoidea; fossils; paleontology; phylogenomics; time calibration; total evidence.]

A new wood wasp, Cratosirex sennlaubi gen. et sp. nov., is described and figured from one specimen collected from the Lower Cretaceous Crato Formation in northeastern Brazil. This new genus is placed in the new siricid subfamily Cratosiricinae subfam. nov., based on a combination of plesiomorphic and autapomorphic characters. The presence of small and sub-equal forewing cells 1R1 and 2R1 is a synapomorphy with the extant subfamily Siricinae, absent in the other extinct subfamilies †Auliscinae and †Gigasiricinae, supporting a sister group relationships with the Siricinae. Our new discovery expands the distribution range of Siricidae fossil records, highlights the antiquity of the family, and emphasizes the need for more studies of this particular insect lineage in the Mesozoic deposits. Currently, all the representatives of the crown group of the extant Siricidae are Cenozoic.

Background and AimsCunoniaceae are woody plants with a distribution that suggests a complex history of Gondwanan vicariance, long-distance dispersal, diversification and extinction. Only four out of ~27 genera in Cunoniaceae are native to South America today, but the discovery of extinct species from Argentine Patagonia is providing new information about the history of this family in South America.MethodsWe describe fossil flowers collected from early Danian (early Palaeocene, ~64 Mya) deposits of the Salamanca Formation. We compare them with similar flowers from extant and extinct species using published literature and herbarium specimens. We used simultaneous analysis of morphology and available chloroplast DNA sequences (trnL–F, rbcL, matK, trnH–psbA) to determine the probable relationship of these fossils to living Cunoniaceae and the co-occurring fossil species Lacinipetalum spectabilum.Key ResultsCunoniantha bicarpellata gen. et sp. nov. is the second species of Cunoniaceae to be recognized among the flowers preserved in the Salamanca Formation. Cunoniantha flowers are pentamerous and complete, the anthers contain in situ pollen, and the gynoecium is bicarpellate and syncarpous with two free styles. Phylogenetic analysis indicates that Cunoniantha belongs to crown-group Cunoniaceae among the core Cunoniaceae clade, although it does not have obvious affinity with any tribe. Lacinipetalum spectabilum, also from the Salamanca Formation, belongs to the Cunoniaceae crown group as well, but close to tribe Schizomerieae.ConclusionsOur findings highlight the importance of West Gondwana in the evolution of Cunoniaceae during the early Palaeogene. The co-occurrence of C. bicarpellata and L. spectabilum, belonging to different clades within Cunoniaceae, indicates that the diversification of crown-group Cunoniaceae was under way by 64 Mya.

—Species in the genus Coccoloba are trees, shrubs, and lianas present in low elevation tropical and sub-tropical forests. Since 1756, well over 400 taxa have been described for Coccoloba. Coccoloba species are natively distributed throughout the New World in a variety of habitats. Despite being distributed throughout the Neotropics, the concentration of Coccoloba species in a given area varies considerably, with four centers of diversity for the genus: southern and coastal Brazil, the West Indies, Mesoamerica, and Amazonia. We here present the first molecular phylogeny of Coccoloba and use this phylogeny to investigate geographic patterns of diversity within the genus. The topology of the phylogeny and the closest related genera to Coccoloba suggest a Mesoamerican origin for the genus. The South American species are recovered as the crown group of the phylogeny with one instance of a separate migration event from Mesoamerica to South America. Coccoloba species in Mesoamerica and the Caribbean show little to no geographic pattern to their diversification. Mesoamerica and the Caribbean are best considered as one phytogeographic region for Coccoloba.

Identifying marine or freshwater fossils that belong to the stem groups of the major terrestrial arthropod radiations is a longstanding challenge. Molecular dating and fossils of their pancrustacean sister group predict that myriapods originated in the Cambrian, much earlier than their oldest known fossils, but uncertainty about stem group Myriapoda confounds efforts to resolve the timing of the group’s terrestrialization. Among a small set of candidates for membership in the stem group of Myriapoda, the Cambrian to Triassic euthycarcinoids have repeatedly been singled out. The only known Devonian euthycarcinoid, Heterocrania rhyniensis from the Rhynie and Windyfield cherts hot spring complex in Scotland, reveals details of head structures that constrain the evolutionary position of euthycarcinoids. The head capsule houses an anterior cuticular tentorium, a feature uniquely shared by myriapods and hexapods. Confocal microscopy recovers myriapod-like characters of the preoral chamber, such as a prominent hypopharynx supported by tentorial bars and superlinguae between the mandibles and hypopharynx, reinforcing an alliance between euthycarcinoids and myriapods recovered in recent phylogenetic analysis. The Cambrian occurrence of the earliest euthycarcinoids supplies the oldest compelling evidence for an aquatic stem group for either Myriapoda or Hexapoda, previously a lacuna in the body fossil record of these otherwise terrestrial lineages until the Silurian and Devonian, respectively. The trace fossil record of euthycarcinoids in the Cambrian and Ordovician reveals amphibious locomotion in tidal environments and fills a gap between molecular estimates for myriapod origins in the Cambrian and a post-Ordovician crown group fossil record.

One of the most remarkable differences between Paleogene penguins and their living relatives is the shape and length of their beaks. Many of the Eocene and Oligocene penguins have a thin and elongated spear-like bill, which contrasts with the proportionally shorter and more robust bill of most living species. These differences suggest an important shift in their feeding strategies. This study explores the morphological disparity on the skull of penguins, emphasizing bill morphology and it relationship with feeding habits. For this, the skulls of 118 species of aquatic birds, including 21 fossil and living penguins, were analyzed using two-dimensional geometric morphometric. The results show that, unlike what has been reported for modern birds overall, in penguins and Aequornithes, bill elongation is related to a reduction of the braincase. The discriminant analysis shows that there are significant differences between penguins that feed near or far from the coast and between those that consume nectonic and planktonic prey, identifyingMadrynornisas the only extinct form with a possibly planktonic diet. Additionally, it is clear that Paleogene penguins occupy a region of morphospace unexplored by most diving birds, with the western grebe being their closest modern analogue. This is consistent with the hypothesis that giant penguins hunted by harpooning and not by biting as living forms do, signaling a significant change in the habits of those birds leading to the emergence of their crown group.

We study the systematics and evolutionary history of the Afrotropical butterfly genus Mylothris (Lepidoptera: Pieridae) based on six gene regions (COI, EF1a, GAPDH, MDH, RpS5 and wingless). We find that the genus can be placed into five species groups, termed the jacksoni, elodina, rhodope, agathina and hilara groups. Within these species groups, we find that many species show very little genetic differentiation based on the markers we sequenced, suggesting they have undergone rapid and recent speciation. Based on secondary calibrations, we estimate the age of the crown group of Mylothris to be about 16 million years old, but that many of the species level divergences have happened in the Pleistocene. We infer that the clade has its origin in the forests of the Eastern part of Central Africa, and has spread out from there to other regions of Africa.

Funding Information: We thank Guido W. Grimm, Orleans, France for commenting an earlier version of this manuscript, and two anonymous reviewers for their suggestions to improve this manuscript. Publisher Copyright: © 2021 The Authors The fossil record of Lythrum is scarce and every new find brings an extra piece of the puzzle to the obscure phytogeographic history of this genus. Lythrum pollen is unique and has the potential to be recognized in palynological assemblages. Therefore, the few pre-Holocene fossil records are all pollen described from North America, Russia, and Europe. The European records are both most numerous and geologically younger than those from other parts of the Northern Hemisphere. Earliest European Lythrum pollen records are of late Miocene age and parallel to starting crown group radiation in the Eurasian clade of Lythrum. European Miocene to Pliocene Lythrum pollen morphology is comparable to that of extant species. Interestingly, the late Miocene expansion of Lythrum into Europe coincides with the decline of Decodon, and Lythrum appears to replace Decodon in late Neogene fossil palynological assemblages. publishersversion published

Three new taxa of odonates are described from the Upper Jurassic Solnhofen limestone from Eichstätt and Painten in Bavaria (Germany), including the first two genuine Zygoptera (Andrephlebia buergeri gen. et sp. nov. in fam. inc. sed. and Jurahemiphlebia haeckeli gen. et sp. nov. in Hemiphlebiidae) and a new taxon of Stenophlebioptera (Reschiostenophlebia koschnyi gen. et sp. nov. in Stenophlebiidae). With an age of about 152 million years, the holotype of Jurahemiphlebia from the Painten locality represents the oldest fossil record and thus a new calibration point for crown group Zygoptera, Lestoidea, and Hemiphlebiidae, and the oldest record for any living odonate family. Furthermore, the first relatively complete specimen of the dragonfly Prohemeroscopus kuehnapfeli (Prohemeroscopidae) is described, which was previously known only from a pair of isolated hind wings. A revised diagnosis is provided for the species and genus.

Crown birds are subdivided into two main groups, Palaeognathae and Neognathae, that can be distinguished, among other means, by the organization of the bones in their pterygoidpalatine complex (PPC). Shape variation of the vomer, which is the most anterior part of the PPC, was recently analysed with help of geometric morphometrics to discover morphological differences between palaeognath and neognath birds. Based on this study, the vomer was identified as sufficient to distinguish the two main groups (and even some inclusive neognath groups) and their cranial kinetic system. As there are notable size differences between the skulls of Palaeognathae and Neognathae, we here investigate the impact of allometry on vomeral shape and its implication for taxonomic classification by re-analysing the data of the previous study. Different types of multivariate statistical analyses reveal that taxonomic identification based on vomeral shape is strongly impaired by allometry, as the error of correct identification is high when shape data is corrected for size. This finding is evidenced by a great overlap between palaeognath and neognath subclades in morphospace. Correct taxonomic identification is further impeded by the convergent presence of a flattened vomeral morphotype in multiple neognath subclades. As the evolution of cranial kinesis has been linked to vomeral shape in the original study, the correlation between shape and size of the vomer across different bird groups found in the present study questions this conclusion. In fact, cranial kinesis in crown birds results from the loss of the jugal-postorbital bar in the temporal region and ectopterygoid in the PPC and the combination of a mobilized quadratezygomatic arch complex and a flexible PPC. Therefore, we can conclude that vomer shape itself is not a suitable proxy for exploring the evolution of cranial kinesis in crown birds and their ancestors. In contrast, the evolution of cranial kinesis needs to be viewed in context of the braincase, quadrate-zygomatic arch and the whole pterygoid-palatine complex.

The Cretaceous–Paleogene (K–Pg) mass extinction 66 million years ago was characterized by a worldwide ecological catastrophe and rapid species turnover. Large‐scale devastation of forested environments resulting from the Chicxulub asteroid impact likely influenced the evolutionary trajectories of multiple clades in terrestrial environments, and it has been hypothesized to have biased survivorship in favour of nonarboreal lineages across the K–Pg boundary. Here, we evaluate patterns of substrate preferences across the K–Pg boundary among crown group mammals, a group that underwent rapid diversification following the mass extinction. Using Bayesian, likelihood, and parsimony reconstructions, we identify patterns of mammalian ecological selectivity that are broadly similar to those previously hypothesized for birds. Models based on extant taxa indicate predominant K–Pg survivorship among semi‐ or nonarboreal taxa, followed by numerous independent transitions to arboreality in the early Cenozoic. However, contrary to the predominant signal, some or all members of total‐clade Euarchonta (Primates + Dermoptera + Scandentia) appear to have maintained arboreal habits across the K–Pg boundary, suggesting ecological flexibility during an interval of global habitat instability. We further observe a pronounced shift in character state transitions away from plesiomorphic arboreality associated with the K–Pg transition. Our findings are consistent with the hypothesis that predominantly nonarboreal taxa preferentially survived the end‐Cretaceous mass extinction, and emphasize the pivotal influence of the K‐Pg transition in shaping the early evolutionary trajectories of extant terrestrial vertebrates., We explore the evolution of mammal ecology across the end‐Cretaceous mass extinction event, 66 million years ago. Our results suggest that nonarboreal mammals were selectively favored across this mass extinction event, congruent with the hypothesis that forest communities were devastated in the aftermath of the asteroid impact at the end of the Cretaceous.

We describe new fossils from the late Eocene of Mongolia, which show that the crane-like Eogruidae and Ergilornithidae are stem group representatives of the Struthioniformes (ostriches). Currently, both taxa are unanimously assigned to the neognathous Gruiformes (cranes and allies). However, ergilornithids show a progressive reduction of the second toe, and a few earlier authors likened these birds to ostriches, which are the only extant birds with just 2 toes. So far, eogruids and ergilornithids were mainly known from hindlimb bones from the Cenozoic of Asia, and here we provide important new data on the skeletal anatomy of these birds. A partial skull exhibits characteristic features of palaeognathous birds, and ostriches in particular. In its distinctive shape, it furthermore closely resembles the skull of the Eocene palaeognathous Palaeotididae, which are here also considered to be stem group representatives of the Struthioniformes. A femur from the late Eocene of Mongolia likewise corresponds to that of ostriches in derived traits, whereas cervical vertebrae exhibit features of neognathous birds. The fossils suggest that true ostriches (crown group Struthionidae) originated in Asia, and the Neognathae-like morphology of some bones opens a new perspective on the evolution of skeletal characteristics of palaeognathous birds. LAY SUMMARY Even though various fossil ostriches (Struthioniformes) have been described from late Cenozoic deposits, the early evolutionary history of these birds has remained elusive. Ostriches are the only extant birds with only 2 toes, but a didactyl condition also occurs in the Ergilornithidae from the Cenozoic of Asia. These fossil birds have so far mainly been known from hindlimb bones and are currently assigned to the Gruiformes (cranes and allies). Here we describe new fossils from the late Eocene of Mongolia, which corroborate earlier assumptions that the Ergilornithidae as well as the closely related Eogruidae are struthioniform birds. The fossils suggest that true ostriches originated in Asia and their unusual character mosaic opens a new perspective on the evolution of skeletal characteristics of palaeognathous birds.

International audience; Teleost fishes comprise one-half of all vertebrate species and possess a duplicated genome. This whole-genome duplication (WGD) occurred on the teleost stem lineage in an ancient common ancestor of all living teleosts and is hypothesized as a trigger of their exceptional evolutionary radiation. Genomic and phylogenetic data indicate that WGD occurred in the Mesozoic after the divergence of teleosts from their closest living relatives but before the origin of the extant teleost groups. However, these approaches cannot pinpoint WGD among the many extinct groups that populate this 50- to 100-million-y lineage, preventing tests of the evolutionary effects of WGD. We infer patterns of genome size evolution in fossil stem-group teleosts using high-resolution synchrotron X-ray tomography to measure the bone cell volumes, which correlate with genome size in living species. Our findings indicate that WGD occurred very early on the teleost stem lineage and that all extinct stem-group teleosts known so far possessed duplicated genomes. WGD therefore predates both the origin of proposed key innovations of the teleost skeleton and the onset of substantial morphological diversification in the clade. Moreover, the early occurrence of WGD allowed considerable time for postduplication reorganization prior to the origin of the teleost crown group. This suggests at most an indirect link between WGD and evolutionary success, with broad implications for the relationship between genomic architecture and large-scale evolutionary patterns in the vertebrate Tree of Life.

Echinoids are key components of modern marine ecosystems. Despite a remarkable fossil record, the emergence of their crown group is documented by few specimens of unclear affinities, rendering much of their early history uncertain. The origin of sand dollars, one of its most distinctive clades, is also unclear due to an unstable phylogenetic context and discrepancies between molecular divergence times and fossil evidence. We employ seventeen novel genomes and transcriptomes to build a phylogenomic dataset with a near-complete sampling of major lineages. With it, we revise the phylogeny and divergence times of echinoids, and place their history within the broader context of echinoderm evolution. We also introduce the concept of a chronospace—a multidimensional representation of node ages—and use it to explore the effects of using alternative gene samples, models of molecular evolution, and clock priors. We find the choice of clock model to have the strongest impact on divergence times, while the use of site-heterogeneous models shows little effects. The choice of loci shows an intermediate impact, affecting mostly deep Paleozoic nodes, for which clock-like genes recover dates more congruent with fossil evidence. Our results reveal that crown group echinoids originated in the Permian and diversified rapidly in the Triassic, despite the relative lack of fossil evidence for this early diversification. We also clarify the relationships among sand dollars and their close relatives, showing that the genus Apatopygus represents a relict lineage with a deep Jurassic origin. Surprisingly, the origin of sand dollars is confidently dated to the Cretaceous, implying ghost ranges spanning approximately 50 million years, a remarkable discrepancy with their rich fossil record.

Ghost lineages have always challenged the understanding of organism evolution. They participate in misinterpretations in phylogenetic, clade dating, biogeographic, and paleoecologic studies. They directly result from fossilization biases and organism biology. The Cylindrotomidae are a perfect example of an unexplained ghost lineage during the Mesozoic, as its sister family Tipulidae is already well diversified during the Cretaceous, while the oldest Cylindrotomidae are Paleogene representatives of the extant genus Cylindrotoma and of the enigmatic fossil genus Cyttaromyia. Here we clarify the phylogenetic position of Cyttaromyia in the stem group of the whole family, suggesting that the crown group of the Cylindrotomidae began to diversify during the Cenozoic, unlike their sister group Tipulidae. We make a comparative analysis of all species in Cyttaromyia, together with the descriptions of the two new species, C. gelhausi sp. nov. and C. freiwaldi sp. nov., and the revision of C. obdurescens. The cylindrotomid biogeography seems to be incongruent with the phylogenetic analysis, the apparently most derived subfamily Stibadocerinae having apparently a ‘Gondwanan’ distribution, with some genera only known from Australia or Chile, while the most inclusive Cylindrotominae are Holarctic.

8-bit TIFF image stack of microCT scans through the premaxilla of Omorhamphus (YPM 13106; Lower Gray Bull Fm, Eocene, Big Horn Basin, Wyoming). Scan taken at University of Texas High-Resolution X-ray CT Facility by Matthew Colbert. Scan parameters: NSI scanner. Feinfocus source, high power, 200 kV, 0.14 mA, 1 aluminum filter, Perkin Elmer detector, 0.25 pF gain, 1 fps (999.911 ms integration time), no binning, no flip, source to object 218.58 mm, source to detector 1316.527 mm, continuous CT scan, no frames averaged, 0 skip frames, 3600 projections, 6 gain calibrations, 5 mm calibration phantom, data range [-10, 100] (grayscale range adjusted from NSI defaults), beam-hardening correction = 0.3. Voxel size = 0.0302 mm. Total slices = 1813., {"references":["Louchart A, Bhullar B-A, Riamon S and Field DJ (2021) The True Identity of Putative Tooth Alveoli in a Cenozoic Crown Bird, the Gastornithid Omorhamphus. Front. Earth Sci. 9:661699. doi: 10.3389/feart.2021.661699"]}

Advances in phylogenomics contribute toward resolving long-standing evolutionary questions. Notwithstanding, genetic diversity contained within more than a billion biological specimens deposited in natural history museums remains recalcitrant to analysis owing to challenges posed by its intrinsically degraded nature. Yet that tantalizing resource could be critical in overcoming taxon sampling constraints hindering our ability to address major evolutionary questions. We addressed this impediment by developing phyloHyRAD, a new bioinformatic pipeline enabling locus recovery at a broad evolutionary scale from HyRAD-X exome capture of museum specimens of low DNA integrity using a benchtop RAD-derived exome-complexity-reduction probe set developed from high DNA integrity specimens. Our new pipeline can also successfully align raw RNAseq transcriptomic and ultraconserved element reads with the RAD-derived probe catalog. Using this method, we generated a robust timetree for Carabinae beetles, the lack of which had precluded study of macroevolutionary trends pertaining to their biogeography and wing-morphology evolution. We successfully recovered up to 2,945 loci with a mean of 1,788 loci across the exome of specimens of varying age. Coverage was not significantly linked to specimen age, demonstrating the wide exploitability of museum specimens. We also recovered fragmentary mitogenomes compatible with Sanger-sequenced mtDNA. Our phylogenomic timetree revealed a Lower Cretaceous origin for crown group Carabinae, with the extinct Aplothorax Waterhouse, 1841 nested within the genus Calosoma Weber, 1801 demonstrating the junior synonymy of Aplothorax syn. nov., resulting in the new combination Calosoma burchellii (Waterhouse, 1841) comb. nov. This study compellingly illustrates that HyRAD-X and phyloHyRAD efficiently provide genomic-level data sets informative at deep evolutionary scales.

The Drosophila montium species group is a clade of 94 named species, closely related to the model species D. melanogaster. The montium species group is distributed over a broad geographic range throughout Asia, Africa, and Australasia. Species of this group possess a wide range of morphologies, mating behaviors, and endosymbiont associations, making this clade useful for comparative analyses. We use genomic data from 42 available species to estimate the phylogeny and relative divergence times within the montium species group, and its relative divergence time from D. melanogaster. To assess the robustness of our phylogenetic inferences, we use 3 non-overlapping sets of 20 single-copy coding sequences and analyze all 60 genes with both Bayesian and maximum likelihood methods. Our analyses support monophyly of the group. Apart from the uncertain placement of a single species, D. baimaii, our analyses also support the monophyly of all seven subgroups proposed within the montium group. Our phylograms and relative chronograms provide a highly resolved species tree, with discordance restricted to estimates of relatively short branches deep in the tree. In contrast, age estimates for the montium crown group, relative to its divergence from D. melanogaster, depend critically on prior assumptions concerning variation in rates of molecular evolution across branches, and hence have not been reliably determined. We discuss methodological issues that limit phylogenetic resolution - even when complete genome sequences are available - as well as the utility of the current phylogeny for understanding the evolutionary and biogeographic history of this clade.

The origin of amniotes was a key event in vertebrate evolution, enabling tetrapods to break their ties with water and invade terrestrial environments. Two pivotal clades of early tetrapods, the diadectomorphs and the seymouriamorphs, have played an unsurpassed role in debates about the ancestry of amniotes for over a century, but their skeletal morphology has provided conflicting evidence for their affinities. Using high-resolution X-ray microcomputed tomography, we reveal the three-dimensional architecture of the well preserved endosseous labyrinth of the inner ear in representative species belonging to both groups. Data from the inner ear are coded in a new cladistic matrix of stem and primitive crown amniotes. Both maximum parsimony and Bayesian inference analyses retrieve seymouriamorphs as derived non-crown amniotes and diadectomorphs as sister group to synapsids. If confirmed, this sister group relationship invites re-examination of character polarity near the roots of the crown amniote radiation. Major changes in the endosseous labyrinth and adjacent braincase regions are mapped across the transition from non-amniote to amniote tetrapods, and include: a ventral shift of the cochlear recess relative to the vestibule and the semicircular canals; cochlear recess (primitively housed exclusively within the opisthotic) accommodated within both the prootic and the opisthotic; development of a distinct fossa subarcuata. The inner ear of seymouriamorphs foreshadows conditions of more derived groups, whereas that of diadectomorphs shows a mosaic of plesiomorphic and apomorphic traits, some of which are unambiguously amniote-like, including a distinct and pyramid-like cochlear recess.