Diverse Fossil Research Articles

Osteohistology of Uberabatitan ribeiroi (Dinosauria, Sauropoda) provides insight into the life history of titanosaurs

ABSTRACT The Serra da Galga Formation is a geological unit that has provided a taxonomically diverse fossil record for the Late Cretaceous of Brazil. The formation highlights the richest evidence of titanosaurs in this country, with a handful of described species, (e.g. Uberabatitan ribeiroi). Over time, palaeobiological works based on the osteohistology of fossils are becoming more frequent. However, U. ribeiroi has never been the subject of a purely histological study. We performed osteohistological descriptions of specimens referred to this species. The results support that the hyper-elongated cervical ribs of U. ribeiroi are tendons that have developed through metaplasia, as occur in other neosauropods. Further, samples show rapid and uninterrupted growth, evidenced by a continuous deposit of fibrolamellar tissue. Subsequently, growth would have ceased with the appearance of periodic interruptions (at least in appendicular bones), in the most advanced stages of development. The variable presence of an external fundamental system reveals that not all the specimens studied here reached somatic maturity. Finally, the high degree of bone remodelling described in the samples, especially in the ribs, is higher than expected for other neosauropods in the same ontogenetic stages. This supports the previous idea that this feature would be typical of Titanosauria.

A diverse Late Pliocene fossil fauna and its paleoenvironment at Māngere, Auckland, New Zealand

ABSTRACT Excavations at Māngere Wastewater Treatment Plant, Auckland, in 2020 provided New Zealand’s richest and most diverse fossil faunas of mid-Pliocene age (Waipipian Stage, 3.7–3.0 million years old). The vast excavated heap of sandy shell was extensively searched and sieved resulting in the recovery of 266 fossil taxa, (particularly rich in Mollusca including 77 Bivalvia, 105 Gastropoda, 32 Foraminifera, 13 Ostracoda, 11 Bryozoa). The fauna includes several undescribed taxa and additional warm-water Pliocene records for New Zealand. The fauna is most similar in composition and age to the fauna obtained from the Otahuhu Brewery well in the late 1940s. The fauna contains a mixture of taxa from many different shallow marine habitats, from intertidal and subtidal rocky shores and intertidal and shallow subtidal soft sediment flats to exposed and semi-exposed subtidal sandy habitats down to depths of 30–40 m. The shelly deposit is inferred to have accumulated in a current swept subtidal channel during one of the mid-Pliocene warm periods when sea level was high and had flooded an incised river valley that flowed from east to west across the Auckland region.

In search of lost time: tracing the fossil diversity of Podocarpaceae through the ages

Abstract The Podocarpaceae are a morphologically diverse conifer family that have a cryptic fossil record reported since the Permian. We reviewed the fossil record of Podocarpaceae, tested the affinities of its oldest records using phylogenetic analyses, compiled macrofossil occurrence records, and investigated the diversity, distribution, and morphology of Podocarpaceae through time. We found that Permian, Triassic, and some Jurassic fossils referred to Podocarpaceae should not be placed in the family. Our total-evidence phylogenetic analyses, which sampled all major conifer lineages, recovered the Triassic Rissikia and the Jurassic Nothodacrium as stem-group conifers and the Jurassic Mataia as part of the Araucariales stem group. We further discuss the phylogenetic position of the Mesozoic enigmatic conifers Pararaucaria (Cheirolepidiaceae) and Telemachus (Voltziales), which were recovered most frequently in the conifer stem group. We conclude that the earliest reliable Podocarpaceae occurrences are from the Jurassic of both hemispheres and have scale-like leaves. Most extant genera appear in the fossil record between the Late Cretaceous and the Early Cenozoic. Many extant leaf morphologies appear in the Early Cretaceous, coeval with angiosperm diversification, consistent with the hypothesis that expanded leaves in Podocarpaceae are adaptive responses for light harvesting in angiosperm-dominated environments today.

Morphological and molecular analysis of Ephydatia fluviatilis (Porifera: Spongillida: Spongillidae) from Nanjing, China

We present a comprehensive morphological description of Ephydatia fluviatilis collected in Nanjing for the first time in studies of freshwater sponges in China, based on scanning electron micrography of the sponge meshwork, the megascleres, the gemmules, and the delicate gemmuloscleres, in comparison with relevant data reported worldwide. The morphotype revealed in this study shows a peculiar spicular complement of the skeleton composed of two types of megascleres (the normal oxeas and occasional styles) with abundant tiny, centrally distributed microspinoses, gemmules (ca. 440 μm in diameter) bearing two types of spinose decoration on the shaft (i.e., erect long spines and microspinoses). We report the first complete ITS sequences of the morphotype of E. fluviatilis from China, which, combined with homologous sequences of related taxa from GenBank, are used in a phylogenetic analysis in order to understand the species relationship within Ephydatia and neighbouring taxa. Combining the ITS phylogeny and the gemmulosclere morphotypes, we identify three clades in the paraphyletic genus Ephydatia that are distinguished by different birotule gemmulosclere morphotypes for gemmule-bearing species. Multiple losses of gemmules within endemic taxa, as previously proposed, are confirmed in this study in a phylogenetic context obtained herein. Additionally, genetic similarities are found in some morphologically diverse species, likely indicating recent endemism leading to morphological specialization. Considering the diverse fossil record of Ephydatia from Cenozoic sedimentary strata of wide geographic ranges, we hypothesize that Ephydatia might have a deep root in the Paleogene or earlier and experienced a rapid, Quaternary radiation with emergences of specialized endemic species that lost gemmules under glacial-interglacial paleoenvironment.

Earth’s interior dynamics drive marine fossil diversity cycles of tens of millions of years

The fossil record reveals that biotic diversity has fluctuated quasi-cyclically through geological time. However, the causal mechanisms of biotic diversity cycles remain unexplained. Here, we highlight a common, correlatable 36 ± 1 Myr (million years) cycle in the diversity of marine genera as well as in tectonic, sea-level, and macrostratigraphic data over the past 250 Myr of Earth history. The prominence of the 36 ± 1 Myr cycle in tectonic data favors a common-cause mechanism, wherein geological forcing mechanisms drive patterns in both biological diversity and the preserved rock record. In particular, our results suggest that a 36 ± 1 Myr tectono-eustatically driven sea-level cycle may originate from the interaction between the convecting mantle and subducting slabs, thereby pacing mantle-lithospheric deep-water recycling. The 36 ± 1 Myr tectono-eustatic driver of biodiversity is likely related to cyclic continental inundations, with expanding and contracting ecological niches on shelves and in epeiric seas.

On a skeletally immature individual of Unaysaurus tolentinoi (Dinosauria: Sauropodomorpha) from the upper Triassic of southern Brazil.

The lineage of sauropodomorph dinosaurs raised some of the most impressive animals that ever walked on Earth. However, the massive titans of the Mesozoic Era originated from far smaller dinosaurs. The Triassic beds from Brazil yielded the earliest part of this evolutionary history. Despite the diverse fossil record of early sauropodomorphs, juvenile specimens, as well as certain species are poorly sampled. This is the case for Unaysaurus tolentinoi, an unaysaurid sauropodomorph from Caturrita Formation (ca. 225 Ma; early Norian, Late Triassic). The holotype and only specimen of U. tolentinoi was excavated from the Água Negra Locality (São Martinho da Serra, Rio Grande do Sul, Brazil) in 1998. More than two decades later, no other fossil vertebrates have been reported from the same fossiliferous site. Here we describe a skeletally immature specimen which was found in association with the holotype of U. tolentinoi. The specimen was discovered after a first-hand examination of the holotype and comprises some isolated vertebrae and elements from the posterior autopodium. According to linear regressions, its metatarsal I is approximately 41.7 mm in length, compared to approximately 75.9 mm in the holotype. The repeated elements and reduced size indicates that it does not belong to the elements originally used to erect U. tolentinoi. Rather, the specimen is assigned to U. tolentinoi by topotypy and shared morphology. In addition to the reduced size, distinct lines of evidence (e.g., neurocentral sutures; bone texture) support its assignment to a skeletally immature individual. In sum, the new material expands the record of U. tolentinoi, and represents an additional juvenile dinosaur from the Caturrita Formation.

Paleoenvironmental variations indicated by microfossils in the upper paleozoic Konservat-Lagerstätte of the Paraná Basin, Santa Catarina, Brazil

The Lontras Shale is a Brazilian Paleozoic Konservat-Lagerstätte that preserves a remarkable diversity of fossils in an exceptional way. In this study, we aimed to refine the paleoenvironment of the Lontras Shale, in the city of Mafra at Santa Catarina State, using microfossils and phytoclasts as proxies. Sampling was conducted in twelve layers of the shale (1A, 1B, 1C, 1D, 2A, 2B, 3A, 3B, 3C, 3D, 4A, 4B) in a 1.2m outcrop. The samples were collected every 10 cm and weighed 1 kg each. The collected material underwent chemical treatment with 15% hydrogen peroxide for 24 h. Samples were then washed and dried, and all the total fractions were observed under a stereomicroscope. A total of 316 bioclasts (entire fossils or fragments) were identified. Thirty-three of the specimens were analyzed in a scanning electron microscope. As a result, we identified Foraminifera classified as Saccammina sp., Psammosphaera irregularis and Ammobaculitessp. The preservation level of the phytoclasts suggests that these fragments were deposited under a proximal environment. The analysis of the microfossils suggests that the Lontras Shale Konservat-Lagerstätte in the city of Mafra experienced significant changes in its paleoenvironment settings during deposition. The high concentration on the layer 3D suggests an increase in the nutrient supply or temperature variation during the Lontras Shale deposition. Finally, the data provided through microfossil analyses combined with preterit information could support that the Lontras Shale Konservat-Lagerstätte was deposited under a proximal environment such as an estuary or a fjord.

Lost world of complex life and the late rise of the eukaryotic crown.

Eukaryotic life appears to have flourished surprisingly late in the history of our planet. This view is based on the low diversity of diagnostic eukaryotic fossils in marine sediments of mid-Proterozoic age (around 1,600 to 800 million years ago) and an absence of steranes, the molecular fossils of eukaryotic membrane sterols1,2. This scarcity of eukaryotic remains is difficult to reconcile with molecular clocks that suggest that the last eukaryotic common ancestor (LECA) had already emerged between around 1,200 and more than 1,800 million years ago. LECA, in turn, must have been preceded by stem-group eukaryotic forms by several hundred million years3. Here we report the discovery of abundant protosteroids in sedimentary rocks of mid-Proterozoic age. These primordial compounds had previously remained unnoticed because their structures represent early intermediates of the modern sterol biosynthetic pathway, as predicted by Konrad Bloch4. The protosteroids reveal an ecologically prominent 'protosterol biota' that was widespread and abundant in aquatic environments from at least 1,640 to around 800 million years ago and that probably comprised ancient protosterol-producing bacteria and deep-branching stem-group eukaryotes. Modern eukaryotes started to appear in the Tonian period (1,000 to 720 million years ago), fuelled by the proliferation of red algae (rhodophytes) by around 800 million years ago. This 'Tonian transformation' emerges as one of the most profound ecological turning points in the Earth's history.

X-ray micro-computed tomography of minute hooded beetles (Coleoptera: Corylophidae) reveals its hidden paleodiversity in the Eocene Baltic amber

Fossil Corylophidae are poorly known. Three fossil representatives of the family were described until now: one from mid-Cretaceous (Mesozoic) and two from Eocene (Cenozoic) deposits. We revise corylophid material from Baltic amber using X-ray micro-computed tomography (μCT) and describe two new species: Clypastraea venedorum n. sp. and C. groehni n. sp. The systematic placement of the previously described Baltic amber fossil Clypastraea primainterparesAlekseev, 2016 was confirmed. The re-description and diagnosis will help the systematic study on the extant and extinct species of the family. Micro-CT was used for the first time to study a members of Corylophidae. An identification key for Eocene representatives of the genus Clypastraea is provided. The species-rich palaeofauna of this group of corylophid beetles (the most diverse fossil record to date) is briefly discussed in the context of diverse plant communities of Eocene amber forest.

16th International Conference on the Modelling of Casting, Welding, and Advanced Solidification Processes

Preface The 16th International Conference on the Modelling of Casting, Welding, and Advanced Solidification Processes (MCWASP XVI) was held from June 18 to 23, 2023, in Banff, Canada, at the Banff Centre for Arts and Creativity. Founded in 1933, the Centre in Treaty 7 Territory within Banff National Park—Canada’s first National Park—is a learning organization built upon an extraordinary legacy of excellence in artistic and creative development. The “all-inclusive” nature of the conference and the remote setting meant that participants dined, attended oral and poster presentations, and participated in social activities as a group, fostering outstanding opportunities for networking.Given that the MCWASP community had not met in person since 2015 in Japan (the 2020 edition of MCWASP was virtual owing to COVID-19), the 2023 conference provided the opportunity to renew old friendships and make new ones as well as discuss the science of solidification and related processes—all within the backdrop of the beautiful Canadian Rocky Mountains.The technical program comprised more than 70 oral and poster presentations. In addition to content related to modelling of casting, welding, and advanced solidification processes, keynotes were invited to talk about related subjects (artificial intelligence/machine learning, and permeability modelling in shale rock) as well as the rich diversity of fossils, especially dinosaurs, found in Alberta.The oral technical program was organized with as a single session (i.e., no concurrent presentations). It featured all aspects of solidification modelling, including solidification process technologies (continuous and semi-continuous casting, shape casting, additive manufacturing, and welding), coupled multi-physics simulations, defect formation, fluid flow, micro- and macro-structure formation, numerical methods, and related experimentation, especially in-situ observation of solidification.The four-day technical program was spread over five days to give participants the opportunity to explore the stunning Canadian Rocky Mountains.In these proceedings, the papers are organized by major theme. The dominant topics are Additive Manufacturing and Welding and Microstructure Formation, followed by Continuous Casting – Shape Casting, Heat Transfer and Fluid Flow, Alloy Segregation, Defects, Imaging of Solidification, Thermomechanics, and Materials Properties. In these themes, the authors report advances in numerical modelling techniques, new scientific and process developments in solidification, and related in-situ experimentation.Although significant progress has been made over these past 16 MCWASP conferences covering 43 years, it is clear that the complexity of advanced solidification phenomena as related to conventional and emerging manufacturing technologies still attracts a great deal of scientific and industrial interest to support technological innovation. André Phillion Banff, Canada, June 2023MCWASP XVI 2023List of Peer Reviewers, Sponsors, MCWASP XVI Organizers, International Scientific Committee are available in this Pdf.

Geochemistry and provenance of Mesozoic sandstones in Khon Kaen Geopark: Implication for tectonics of the western Khorat Plateau of Thailand.

Khon Kaen Geopark, representing an area of dinosaur fossil diversity, was selected for investigations to reveal the origin and tectonic setting of the Khorat Group. The area occupied by Mesozoic sedimentary rocks of four formal formations of the Khorat Group, namely the Phra Wihan Formation (PWF), Sao Khua Formation (SKF), Phu Phan Formation (PPF), and Khok Kruat Formation (KKF). A field investigation and macroscopic observations suggested that the immature sedimentary rocks of the study area are mainly clast-supported, pebbly sandstone and siltstone with few calcretes. The 50 rock samples that were selected for petrographical and geochemical investigations revealed that the sandstones of the PWF and PPF are quartz arenite and sublitharenite, with some subarkose, whereas those of the SKF are mainly subarkose and sublitharenite. In addition, the KKF dominantly presents sublitharenite with pebbles and calcretes. Mesozoic sandstones contain quartz, feldspars, various types of rock fragments, and accessory minerals (biotite, muscovite, zircon, and tourmaline), with siliceous, ferrous, and calcareous cement. Petrographic (Q-F-L) and geochemical (major and trace element) data suggested that the sources of sediments are mostly quartzose sedimentary rocks and some felsic-intermediate igneous rocks. Chondrite-normalized rare earth element patterns indicated that the origins of the studied sandstones are quartzose sedimentary rocks deposited in a passive continental margin or an upper continental crust. Geochemical traits of the sedimentary successions demonstrated that the provenance of the Khorat Basin prior to reworking by fluvial processes was situated in the passive continental margin or recycled orogen of the paleo-volcanic arc during the Mesozoic period.

Early Mid-Pleistocene mammal fauna from Yanlidong Cave, South China

ABSTRACT Yanlidong is a cave site in southern China where a diversity of vertebrate palaeontological fossils were recently discovered. Our previous study showed that the Yanlidong sediments can be divided into an early stage and a late stage. Here, we report our analysis of the mammal fossils from the deposits of the Early Stage in Yanlidong (DES-YLD). The age of DES-YLD is constrained to around 600 ka by Uranium-series dating on fossil teeth and layered flowstones. The fauna is characterised by the occurrence of extant taxa plentifully, but also a number of extinct species. Our paleoenvironmental and taphonomic analysis of the DES-YLD fauna indicates that the local environment was covered by subtropical forest and located in a shrub environment near water and rodents were largely responsible for the accumulation and modification of the macromammal remains. The findings from YLD serve to fill an important gap in the Early Middle Pleistocene of southern China. Besides the reconstructions of the paleoenvironment, it is interesting to observe that a large number of Early Pleistocene extinct taxa were replaced by species during the Early Middle Pleistocene that are still extant today. This faunal turnover may be related to the global Middle Pleistocene climate transition.

Fossil diversity in ‘dawn’ hexapods (Diplura: Projapygoidea), with direct evidence for being chemically predaceous in the Cretaceous

Abstract Diplurans are among the earliest hexapods in the geological record. These primitively wingless relatives of insects are infrequently encountered despite being pervasive in soil habitats. Two groups have disparate adaptations for hunting, one mechanical and the other chemical, in Japygoidea and Projapygoidea, respectively. Here, we report three genera (two new) and four species of fossil Projapygidae preserved in Mesozoic and Cenozoic ambers: Electroprojapyx alchemicus gen. et sp. nov. in mid-Cretaceous Myanmar amber, and Symphylurinopsis punctatus gen. et sp. nov. and two species (unnamed) of Symphylurinus in Miocene Dominican amber. The exceptionally preserved specimens possess cerci that are morphologically specialized for expelling a glandular substance on prey. The new Cretaceous E. alchemicus is a stem group to all living species of the family and provides conclusive Mesozoic evidence for a rare type of predation involving offensive (vs. defensive) secretions. The specimen was fossilized in a preying-and-spraying position with its presumptive meal, a Symphypleona springtail (Collembola), reflecting the behavioural predatory repertoire of modern relatives. Apart from one Cenozoic species, these rare specimens represent the only fossil record of the family Projapygidae. Our findings demonstrate that these basal hexapods were predators of small arthropods of ancient forest soils and enrich our understanding of palaeoecological associations and behavioural strategies paramount for the survival of species.

Earth Science Frontier at Urban Periphery: Geoheritage from the Vicinity of Kazan City, Russia

Characterizing geological heritage sites (geosites) available in Russia remains an urgent task. The present study focuses on two geosites from the vicinity of Kazan—a large city on the Volga River. They are attributed to the standardized geoheritage types and scored by means of several criteria. It is found out that the Pechischi geosite represents nine geoheritage types, from which the stratigraphical type (stratotype section of the Upper Kazanian regional unit of the Guadalupian) and the geohistorical type (history of the Permian System studies) are the most important. This geosite reaches 675 out of 750 maximum possible scores, and it is ranked globally. The Cheremushki geosite represents six geoheritage types, from which the stratigraphical type (reference section of the Urzhumian regional unit of the Guadalupian) and the paleontological type (locality of diverse fossils, including tetrapods) are the most important. This geosite reaches a score of 250 and is ranked nationally. The undertaken study allows for recommending several actions for the effective conservation and exploitation of these geosites. The innovative interpretation is that the presence of geosites at the urban periphery makes its general (not only geological) heritage value comparable to that of the city’s center.

An Anatomically Preserved Cone-like Flower from the Lower Cretaceous of China.

Although diverse fossil angiosperms (including their reproductive organs) have been reported from the Early Cretaceous, few of them are well-documented due to poor preservation and limited technologies available to apply. For example, paraffin sectioning, a routine technology applied to reveal the anatomical details of extant plants, was hitherto at most rarely applied to fossil plants. This undermines the comparability between the outcomes of studies on fossil and extant plants, and makes our understanding on plants incomplete and biased. Here, we applied paraffin sectioning technology, in addition to light microscopy, SEM, and TEM, to document a fossil reproductive organ, Xilinia gen. nov., from the Early Cretaceous in Inner Mongolia, China. The anatomical details of this new reproductive organ were documented. Xilinia bears a remarkable resemblance to conifer cones, although its ovules are enclosed in carpels. The paradoxical cone-like morphology of Xilinia appears to represent a transitional snapshot of plant evolution that is absent in extant plants.

Allometry in Late Devonian Podocopa ostracods (Crustacea) and its implications for ostracod ontogeny

AbstractPodocopa ostracods have abounded in various marine and non‐marine habitats since the early Palaeozoic and left a diverse fossil record in strata worldwide. This is particularly useful for stratigraphic correlation and palaeoenvironmental and palaeogeographical reconstructions. However, despite being the most numerous ostracods during the Palaeozoic, their origins, evolution, ontogeny and phylogeny remain poorly defined. This paper represents the first study of morphological variation in Devonian Platycopida ostracods (an order of Podocopa) using a geometric morphometric approach. Our results identify substantial shape variation in Cribroconcha honggulelengensis Song & Crasquin from the Upper Devonian Hongguleleng Formation of western Junggar, northwest China, demonstrating a remarkable change in juveniles between stages A‐3 and A‐2. Using linear regressions between principal component scores from right lateral view and carapace length, we demonstrate allometric growth patterns for this species. The body plan of C. honggulelengensis developed along an ontological variable: from an ovate outline with rare pores to an oblong outline with dense and large pores. Environmental factors should play an important role in shape determination during ontogeny of C. honggulelengensis.

THE ROLE OF SURFICIAL BIOTURBATION IN THE LATEST EDIACARAN: A QUANTITATIVE ANALYSIS OF TRACE FOSSIL INTENSITY IN THE TERMINAL EDIACARAN–LOWER CAMBRIAN OF CALIFORNIA

ABSTRACT Bioturbating activities have played a vital role in shaping the marine ecosystem throughout metazoan history, influencing the abundance and preservation potential of body fossil-producing taxa and driving major environmental and geochemical changes. The earliest trace making behaviors arose during the late Ediacaran Period (∼ 560–541 Ma), disrupting the substrate previously occupied by dominantly sessile organisms. Simple dwelling and grazing behaviors exploited the organic-rich matgrounds, expanding into the underutilized microbial mat ecosystem. In the western United States, trace assemblages from Ediacaran–Cambrian boundary-spanning deposits document a thriving trace-maker ecosystem. One boundary-spanning deposit in this region, the lower member of the Wood Canyon Formation, crops out along the California-Nevada boundary and contains both trace and body fossil assemblages. The Chicago Pass section of the lower Wood Canyon Formation contains a suite of dominantly simple Ediacaran traces, which become commonplace in the upper part of the stratigraphic section, documenting the onset of prevalent trace-making behaviors in this region. While traces have been previously described from this locality, the addition of the complex trace Lamonte trevallis and quantification of trace fossil density of simple Ediacaran traces provides a more comprehensive ichnological view of the Chicago Pass section. Although Chicago Pass does not yield abundant tubicolous body fossils, as are found elsewhere in the region, the low diversity ichnoassemblages document both burgeoning surficial trace making groups and mat-targeted mining in the latest Ediacaran. The behaviors present at Chicago Pass are similar to those of the Dengying Formation in South China, and highlight the need for petrographic-based trace fossil studies. Additionally, studies of Nama Group trace fossils of the same age from Namibia report higher diversity and complexity in trace-making activities than what has been observed at Chicago Pass, but with similar, low Ediacara biota body fossil diversity. If Ediacara biota diversity is anticorrelated with trace-making behaviors, Chicago Pass represents a low-complexity end-member of the same phenomenon observed in Namibia. The effect of surface sediment disruption on the sessile Ediacaran communities may have been decoupled from complexity of the traces, more so influenced by the presence of general trace-making behaviors in aggregate, including simple traces.

Human Genetic Research in Wallacea and Sahul: Recent Findings and Future Prospects.

Genomic sequence data from worldwide human populations have provided a range of novel insights into our shared ancestry and the historical migrations that have shaped our global genetic diversity. However, a comprehensive understanding of these fundamental questions has been impeded by the lack of inclusion of many Indigenous populations in genomic surveys, including those from the Wallacean archipelago (which comprises islands of present-day Indonesia located east and west of Wallace's and Lydekker's Lines, respectively) and the former continent of Sahul (which once combined New Guinea and Australia during lower sea levels in the Pleistocene). Notably, these regions have been important areas of human evolution throughout the Late Pleistocene, as documented by diverse fossil and archaeological records which attest to the regional presence of multiple hominin species prior to the arrival of anatomically modern human (AMH) migrants. In this review, we collate and discuss key findings from the past decade of population genetic and phylogeographic literature focussed on the hominin history in Wallacea and Sahul. Specifically, we examine the evidence for the timing and direction of the ancient AMH migratory movements and subsequent hominin mixing events, emphasising several novel but consistent results that have important implications for addressing these questions. Finally, we suggest potentially lucrative directions for future genetic research in this key region of human evolution.

Grimmipollis burmanica gen. et sp. nov.: New genus of the soapberry family (Sapindaceae) from the late Eocene of central Myanmar

As a crossroads for plant dispersal between Laurasia and Gondwana since at least the late Eocene, the Central Myanmar Basins have yielded rich and diverse fossil pollen. Here we report Grimmipollis burmanica, a new genus and species in the soapberry family (Sapindaceae) from the upper Eocene Yaw Formation in the Central Myanmar Basins. We also investigate its similarity of pollen sculpture with other selected genera using hierarchical cluster analysis, and its source paleoecology with pollen diagrams. Grimmipollis pollen grains are characterized by parasyncolporate apertures with an apocolpial field at each side, distinct margines along the colpi, arcuate, tuberculate and rope-shaped mesocolpial ridges, and prominent, verrucate or fossulate apocolpia. These features distinguish this genus from other syncolporate and parasyncolporate types in the extant Sapindaceae genera, and fossil pollen genera. As most syncolporate and parasyncolporate types occur in the tribe Cupanieae, G. burmanica is likely derived from an extinct Cupanieae and thus a rainforest tree species. The hierarchical cluster analysis confirms our establishment of Grimmipollis, and reveals it is morphologically close to Meyeripollis. The sedimentary environment from which these pollen grains were retrieved suggests that G. burmanica could be a member of seasonal swamp forests.

The rangeomorph fossil Charnia from the Ediacaran Shibantan biota in the Yangtze Gorges area, South China

Abstract The terminal Ediacaran Shibantan biota (~550–543 Ma) from the Dengying Formation in the Yangtze Gorges area of South China represents one of the rare examples of carbonate-hosted Ediacara-type macrofossil assemblages. In addition to the numerically dominant taxa—the non-biomineralizing tubular fossil Wutubus and discoidal fossils Aspidella and Hiemalora, the Shibantan biota also bears a moderate diversity of frondose fossils, including Pteridinium, Rangea, Arborea, and Charnia. In this paper, we report two species of the rangeomorph genus Charnia, including the type species Charnia masoni Ford, 1958 emend. and Charnia gracilis new species, from the Shibantan biota. Most of the Shibantan Charnia specimens preserve only the petalodium, with a few bearing the holdfast and stem. Despite overall architectural similarities to other Charnia species, the Shibantan specimens of Charnia gracilis n. sp. are distinct in their relatively straight, slender, and more acutely angled first-order branches. They also show evidence that may support a two-stage growth model and a epibenthic sessile lifestyle. Charnia fossils described herein represent one of the youngest occurrences of this genus and extend its paleogeographic and stratigraphic distributions. Our discovery also highlights the notable diversity of the Shibantan biota, which contains examples of a wide range of Ediacaran morphogroups. UUID: http://zoobank.org/837216cd-4a4a-4e13-89e2-ee354ba48a4c