Fossil Research Articles

Zircon U-Pb Ages of the Chiapas Amber-Lagerstätte in the Uppermost Simojovel Formation, Southeastern Mexico

The Chiapas Amber-Lagerstätte is a fossil preservation site in southern Mexico, consisting of three central localities: Simojovel, Totolapa, and Estrella de Belén. It is a repository that preserves a diverse range of estuarine-associated biota. These include but are not limited to arboreal, aerial, land-dwelling, soil-based, amphibiotic, aquatic, and microbial organisms. The age and stratigraphy of the amber-bearing beds near Simojovel have been interpreted differently. The amber outcrops were initially considered part of the late Oligocene to Early Miocene La Quinta Formation. Further studies identified several outcrops as part of the Early Miocene Mazantic Shale and the Middle Miocene Balumtum Sandstone. We present the zircon U-Pb dating results conducted on the amber-bearing beds in the uppermost section of the Simojovel Formation. The data indicate a maximum depositional age of 24 ± 1 Ma, corresponding to the uppermost late Oligocene. A limited section of the amber deposit in Totolapa is likely contemporary with the lowermost Early Miocene, ca. 20 Ma. Hence, the amber biota is constrained to the uppermost late Oligocene and the lowermost Early Miocene (ca. 24-20 Ma). Our data also suggest that the sedimentary environment of the upper strata oscillates from estuary to shallow shelf. It is characterized by low-energy zones with a constant influx of terrigenous sediments consisting of siltstone and fine-grained sandstone, with gastropods, bivalves, coral fragments, trace fossils, plant remains, lignite, and amber.

Phylogenetic signal in primate tooth enamel proteins and its relevance for paleoproteomics.

Ancient tooth enamel, and to some extent dentin and bone, contain characteristic peptides that persist for long periods of time. In particular, peptides from the enamel proteome (enamelome) have been used to reconstruct the phylogenetic relationships of fossil taxa. However, the enamelome is based on only about 10 genes, whose protein products undergo fragmentation in vivo and post mortem. This raises the question as to whether the enamelome alone provides enough information for reliable phylogenetic inference. We address these considerations on a selection of enamel-associated proteins that has been computationally predicted from genomic data from 232 primate species. We created multiple sequence alignments for each protein and estimated the evolutionary rate for each site. We examined which sites overlap with the parts of the protein sequences that are typically isolated from fossils. Based on this, we simulated ancient data with different degrees of sequence fragmentation, followed by phylogenetic analysis. We compared these trees to a reference species tree. Up to a degree of fragmentation that is similar to that of fossil samples from 1-2 million years ago, the phylogenetic placements of most nodes at family level are consistent with the reference species tree. We tested phylogenetic analysis on combinations of different enamel proteins and found that the composition of the proteome can influence deep splits in the phylogeny. With our methods, we provide guidance for researchers on how to evaluate the potential of paleoproteomics for phylogenetic studies before sampling valuable ancient specimens.

Bioerosion Structures on Dinosaur Bones Probably Made by Multituberculate Mammals and Dermestid Beetles (Guichón Formation, Late Cretaceous of Uruguay)

Bioerosion Structures on Dinosaur Bones Probably Made by Multituberculate Mammals and Dermestid Beetles (Guichón Formation, Late Cretaceous of Uruguay)

Magnetostratigraphic and Sedimentological Insights into the Late Campanian Uberaba Formation of the Bauru Group, Southeast Brazil

The Uberaba Formation, a significant paleontological site within the Bauru Group, was deposited over the Early Cretaceous volcanic rocks of the Paraná Basin in southern Brazil. It occupies a restricted northeastern area of the basin surrounding the homonymous city. Recent works on stratigraphy and paleontology indicate a Campanian age, a novel finding that challenges the previously held belief of a Cenomanian age based on dinosaur bones. Paleomagnetic work on seven sections of the Uberaba formation has resulted in the calculation of a paleomagnetic pole at 82.2 ºS 350.8 ºE (N = 89; k = 23; A95 = 3.2º) after correcting for the shallowing of the magnetic inclination caused by overload. The formation is dated to ∼73 Ma (Campanian) age based on magnetostratigraphic data and comparisons with other Late Cretaceous poles. This age implies an interval of about 40 Myr separates the deposition of the Uberaba and Caiuá formations– the latter being the first post-magmatic sedimentation in the Paraná Basin. The area stayed as a highland until the tectonic events related to the northward emplacement of the alkaline provinces. High deposition rates were determined, at least for the upper part of the formation, based on the magnetostratigraphic characteristics.

Manubriosternal Morphology of Anthropoid Primates.

The purpose of this paper is to examine the proportions of the manubrium and sternebrae across anthropoid primates to explore variation hypothesized to be related to thoracic shape and locomotor specialization, and to determine whether the sternoclavicular joint orientation in hominoids reflects hypothesized differences in shoulder joint positioning relative to the thorax. Metric data and sternoclavicular joint orientation data were collected from calibrated photographs of manubria and sternebrae from a large sample (n = 244) of extant anthropoid primates, as well as a small sample of fossil taxa. Manubriosternal and rib cage metric data were also collected from CT scans of an additional 52 extant anthropoid torsos. The data were analyzed using descriptive statistics, regression analyses, and linear correlations. Manubriosternal morphology varies among anthropoids and appears to track thoracic shape and positional repertoire. Hominoids tend to have broader manubria and sterna than monkeys. Ekembo and Equatorius appear to most closely resemble colobines and Alouatta in sternebral shape, suggesting a thorax most similar to these taxa. Neandertals and early anatomically modern humans are most similar to humans, providing no evidence for a relatively broad rib cage. Sternoclavicular joint orientation also differs among hominoids, with all hominoids having more cranially inclined joint surfaces than humans. The human-like value observed for Australopithecus sediba supports the hypothesis that the clavicle in this species was not inclined laterally in resting posture. Given the correlation between manubriosternal breadths and thoracic form across anthropoids, this study suggests that manubriosterna may provide useful information for interpreting skeletal form and positional repertoires in fossil anthropoids.

A new freshwater gobioid from the Lower Miocene of Turkey in a significantly amended total evidence phylogenetic framework

The extant gobioid fishes form a highly diverse group comprised of eight families and over 2000 species. They pose many taxonomic and phylogenetic challenges, particularly when working with fossils. Here we introduce †Simpsonigobius gen. nov., a new freshwater gobioid of small size (≤ 34 mm) from the Lower Miocene of Turkey, and analyse its relationships using a total evidence phylogenetic framework from a previous study that we have significantly improved and expanded upon. †Simpsonigobius gen. nov. exhibits a unique combination of characters, including five branchiostegal rays, a palatine with a weakly ‘T’-shaped head, an additional ray in the anal fin relative to the second dorsal fin, and rounded-to-quadrangular otoliths with a pronounced posterodorsal projection. Undated and tip-dated analyses in a total evidence Bayesian framework, utilizing our updated and expanded data set (48 extant in-group species, 10 fossil species, 48 morphological characters, data from five genes), indicate its relationship with the Oxudercidae, which is reinforced by our comparative morphological analysis. Our results reveal †Simpsonigobius gen. nov. as the oldest skeleton-based member of the Oxudercidae and the oldest freshwater species of the clade Gobiidae + Oxudercidae. The tip-dating analysis estimates divergence ages for Gobiidae (34.13 Ma) and Oxudercidae (34.83 Ma), which are in accordance with previous node-dating analyses. Additionally, based on our time-calibrated tree, we conduct the first reconstruction of ancestral habitat types employing stochastic character mapping and incorporating fossil taxa. The outcome reveals that the ancestor of the Gobioidei likely did not exclusively inhabit freshwater environments, challenging previous assumptions and emphasizing the importance of considering combined habitat types among early-splitting extant taxa. Our study represents the first simultaneous analysis of fossil and extant gobioid species, along with dating of the tree, and our data emphasize the ability of this approach to place gobioid fossils within a reliable chronological and phylogenetic context. http://zoobank.org/urn:lsid:zoobank.org.pub:5000841F-1836-43D8-BE75-4C090A478566

MORPHOLOGY AND PRESERVATION OF GAOJIASHANIA, AN ENIGMATIC TUBULAR FOSSIL FROM THE UPPER EDIACARAN DUNFEE MEMBER, DEEP SPRING FORMATION, NEVADA, USA

Abstract The upper Ediacaran stratigraphic record hosts fossil assemblages of Earth’s earliest communities of complex, macroscopic, multicellular life. Tubular fossils are a common and diverse, though frequently undercharacterized, component of many of these assemblages. Gaojiashania cyclus is an enigmatic tubular fossil and candidate index fossil found in upper Ediacaran strata globally and is best known from the Gaojiashan Lagerstätte of South China. Here we describe a recently discovered assemblage of Gaojiashania fossils from the Ediacaran Dunfee Member of the Deep Spring Formation of Nevada, USA. Both body and trace fossil affinities have been proposed for Gaojiashania; we present morphological and biostratinomic evidence for a body fossil affinity for the Dunfee specimens. Additionally, previous studies have highlighted that Ediacaran tubular fossils are characterized by a wide range of preservational modes, including association with pyrite, apatite, or clay minerals and preservation as carbonaceous compressions. Petrographic, SEM, and EDS data indicate that the Dunfee Gaojiashania specimens are preserved as ‘Ediacara-style’ external, internal and composite molds, in siltstone and sandstone with a clay mineral-rich matrix of both aluminosilicates and non-aluminous Mg- and Fe-rich silicate minerals that we interpret as authigenic clays. Authigenic clay-mediated fossilization of unmineralized tissues, including moldic preservation in heterolithic siliciclastic strata, as indicated by the Dunfee Gaojiashania, may be linked to the prevalence of both silica-rich and ferruginous seawater conditions prior to both the radiation of silica-biomineralizing organisms and the rise of ocean and atmospheric oxygen to modern levels. In this light, clay authigenesis may have played a critical role in facilitating multiple modes of Ediacaran and Cambrian exceptional fossilization, thus shaping the stratigraphic distribution of a range of Ediacara macrofossil taxa.

Spores constraining age of the Middle Devonian paleosol from Voronezh, Russia and their paleopedological and evolutionary significances

As a tangible record that formed on ancient landscape, paleosols provide unique evidence for the evolutionary, paleoecological, and paleoenvironmental understandings to land organisms. However, not all paleosols have a good potential for fossil preservation. Plant preservation of paleosols is highly dependent on Eh-Ph conditions of the past and usually favor reducing paleosols. In this study, we carry on palynological analysis for an acid sulfate paleosol from Voronezh, Russia. Abundant and well-preserved spores are recognized from the middle part of this paleosol and its overlying shale. The Ancyrospora tichonovitschi–Retispora archaeolepidophyta–Rhabdosporites langii (TAL) assemblage from the paleosol, including spores of 45 genera and 101 species, indicates a late Eifelian?–early Givetian age. This new age constraint on the paleosol is entrenched by another spore assemblage from the lowermost part of the overlying shale, namely Cristatisporites conannulatus–Geminospora decora–Membrabaculisporis comans (CDC) assemblage. This assemblage includes spores of 38 genera and 89 species, and can be well correlated with the early Givetian Cymbosporites magnificus–Hymenozonotriletes tichonovitschi (MT) Subzone in eastern Europe. Both the assemblages are characteristic for the humid subtropical flora. Assessments of sporopollenin degradation within the paleosol lead to the suggestion that low pH value probably plays a significant role in spore preservation and can explain the surprising diversity and abundance of spores. New palynological results indicate a flourishing land flora in the Kačák interval of Voronezh High, where terrestrial vegetation might have suffered from a collapse coincident with the Taghanic event.

Bayesian Total-Evidence Dating Reshapes the Age and Historical Biogeography of Parnassiinae

Although incomplete, the fossil record offers direct evidence for the existence of a lineage, providing insights into its age and geographic location. Reconstructing time-calibrated phylogenies, including both extant and fossil taxa as lineages (total-evidence dating) under the fossilized birth-death process, can provide new information about the phylogenetic position of fossil specimens, the time at which they diverged from closely related species, and can impact inferences of clades’ historical biogeography. Here, we focus on the origin and radiation of Apollo butterflies (Papilionidae: Parnassiinae), whose origin has been estimated in the late Eocene in Central Asia. The two fossil taxa recovered in the subfamily Parnassiinae, dated to the late Oligocene (†Thaites ruminiana Scudder) and late Miocene (†Doritites bosniaskii Rebel) in the Western Palearctic, thus challenge the Central Asian origin. We performed a Bayesian total-evidence dating approach to explore the impact of dating analyses and past fossil distributions on the estimation of the evolutionary history of the group. We obtained a more credible dating and historical biogeography for the group, placing its origin in the late Paleocene (ca. 57 Ma) in the Western Palearctic + Western Asia and Caucasus regions, followed by dispersals to Central Asia and the Himalayas. This study also highlights the importance of investigating fossil position in addition to clock partitioning and models for molecular dating. Furthermore, we confirm that a few fossils are sufficient to cast doubt on the origin and biogeographic history of a group, especially when those fossils were dispersed outside of the current center of diversity.

An Ediacaran bilaterian with an ecdysozoan affinity from South Australia.

Molecular clocks and Cambrian-derived metazoans strongly suggest a Neoproterozoic origin of many animal clades.1,2,3,4 However, fossil bilaterians are rare in the Ediacaran, and no definitive ecdysozoan body fossils are known from the Precambrian. Notably, the base of the Cambrian is characterized by an abundance of trace fossils attributed to priapulid worms,5,6 suggesting that major divisions among ecdysozoan groups occurred prior to this time. This is supported by ichnofossils from the latest Ediacaran or early Cambrian left by a plausible nematoid,7,8,9 although definitively attributing this inferred behavior to crown-Nematoida remains contentious in the absence of body fossils.10 Given the high probability of the evolution of Ecdysozoa in the Proterozoic, the otherwise prolific fossil record of the Ecdysozoa, and the identification of more than 100 distinct Ediacaran genera, it is striking that no Ediacaran body fossils have been confidently assigned to this group. Here, we describe Uncus dzaugisi gen. et. sp. nov. from the Ediacara Member (South Australia), a smooth, vermiform organism with distinct curvature and anterior-posterior differentiation. The depth of relief of Uncus is unique among Ediacara fossils and consistent with a rigid outer cuticle. Ecological relationships and associated trace fossils demonstrate that Uncus was motile. Body morphology and the inferred style of movement are consistent with Nematoida, providing strong evidence for at least an ecdysozoan affinity. This validates the Precambrian origin of Ecdysozoa, reconciling a major gap between predicted patterns of animal evolution and the fossil record.4.

High-precision age constraint for the Xiyingzi Bed of the Jiufotang Formation in western Liaoning, Northeast China

The Jehol Biota includes exceptionally well-preserved fossils that are major components of Early Cretaceous land ecosystems. The youngest example of the Jehol Biota occurs in the Jiufotang Formation, which potentially records palaeoenvironmental factors triggering evolutionary turnover. However, the lack of stratigraphic correlations and uncertain age horizons for many fossil taxa lead to conflicting interpretations of events. This study describes a new significant fossiliferous bed (Xiyingzi Bed) from the upper Jiufotang Formation of the Baomayingzi-Yuanjiawa outcrop in western Liaoning, Northeast China. High-precision CA-ID-TIMS U-Pb analysis of a tuff sample from the Xiyingzi Bed provides an age of 121.272 ± 0.040/0.068/0.15 Ma, representing the first reliable age for the upper Jiufotang Formation in western Liaoning.Vertebrate fossils preliminarily reported from this bed include the confuciusornithid and enantiornithine birds, the istiodactylid pterosaur, the non-hadrosaurid iguanodontian dinosaur, the long-necked choristoderan reptiles, the sinemydid turtles, and the polyodontid and sinamiid fish. These fossils were previously reported from the lower horizons, indicating stable development of the late Jehol Biota. New results from the Xiyingzi Bed provides a glimpse of the late Jehol biota before transforming into a typical mid-Cretaceous biota in western Liaoning. Systematic biostratigraphic and chronostratigraphic analysis of the Xiyingzi Bed helps the evolutionary interpretations of the late Jehol Biota and the correlation of the Jiufotang Formation within different basins of western Liaoning.

Bayesian tip-dated timeline for diversification and major biogeographic events in Muroidea (Rodentia), the largest mammalian radiation

BackgroundExtinct organisms provide vital information about the time of origination and biogeography of extant groups. The development of phylogenetic methods to study evolutionary processes through time has revolutionized the field of evolutionary biology and led to an unprecedented expansion of our knowledge of the tree of life. Recent developments applying Bayesian approaches, using fossil taxa as tips to be included alongside their living relatives, have revitalized the use of morphological data in evolutionary tree inferences. Eumuroida rodents represent the largest group of mammals including more than a quarter of all extant mammals and have a rich fossil record spanning the last ~ 45 million years. Despite this wealth of data, our current understanding of the classification, major biogeographic patterns, and divergence times for this group comes from molecular phylogenies that use fossils only as a source of node calibrations. However, node calibrations impose several constraints on tree topology and must necessarily make a priori assumptions about the placement of fossil taxa without testing their placement in the tree.ResultsWe present the first morphological dataset with extensive fossil sampling for Muroidea. By applying Bayesian morphological clocks with tip dating and process-based biogeographic models, we provide a novel hypothesis for muroid relationships and revised divergence times for the clade that incorporates uncertainty in the placement of all fossil species. Even under strong violation of the clock model, we found strong congruence between results for divergence times, providing a robust timeline for muroid diversification. This new timeline was used for biogeographic analyses, which revealed a dynamic scenario mostly explained by dispersal events between and within the Palearctic and North African regions.ConclusionsOur results provide important insights into the evolution of Muroidea rodents and clarify the evolutionary pathways of their main lineages. We exploited the advantage of tip dating Bayesian approaches in morphology-based datasets and provided a classification of the largest superfamily of mammals resulting from robust phylogenetic inference, inferring the biogeographical history, diversification, and divergence times of its major lineages.

Pleistocene fossil elephant tracks in the Addo Elephant National Park, South Africa

Fossilized elephant tracks, along with other vertebrate tracks, have been identified at several sites in the coastal Woody Cape section of the Addo Elephant National Park, in South Africa’s Eastern Cape Province. The tracks occur in aeolianites (cemented dunes). The track-bearing unit has been dated to 126 ± 8 ka, at approximately the boundary between the Middle Pleistocene and Late Pleistocene. In all probability, the trackmaker was the African savannah elephant (Loxodonta africana). Viewed in conjunction with the 35 elephant track sites that have been identified on South Africa’s Cape south coast, a widespread Pleistocene elephant presence can be inferred, which is not obvious from the body fossil record. Collaboration with Park management is aimed at developing an interpretive exhibit, which can be complemented by the physical recovery and exhibition of suitable fossilized elephant tracks or the creation of replicas using photogrammetry data.

A new biomechanical approach to cranial suture function: the role of contact elements in linear and nonlinear models

Abstract Understanding cranial sutures and how they relieve and dissipate stress is essential to assess their role in cranial biomechanics and to develop highly accurate predictive models. This involves examining how ontogeny affects cranial sutures, as well as their morphology and function, and how these changes through time may impact essential biomechanical loadings such as chewing or direct biting. In this work, we study the cranial sutures of Crocodylus niloticus in detail using contact elements under finite element analysis. Contact elements permit the creation of a physical relationship between two bones that are in contact and even the configuration of these relationships, for example, in terms of movement or flexibility. The definition of bone contacts may require linear and/or nonlinear computational solutions to attain higher accuracy. Herein, skull geometry is tested to determine how bones may be altered by different types of contacts under various conditions. As predicted, the absence of sutures or cranial kinesis leads to a reduction in stress distribution across the skull, whereas sutures and cranial kinesis help the skull relieve stress and prevent certain bones from sustaining high stress levels. The type of contact used in individual sutures has a significant effect on model outcomes. Additionally, feeding behaviors significantly impact cranial biomechanics, reflecting the influence of other variables that may be applied to the models. As highlighted by the results, in order to obtain accurate results when analyzing fossil taxa, the nature of the cranial sutures should be taken into account. Therefore, developing predictive models based on living taxa is invaluable, because it facilitates the study of extinct taxa for which there is a lack of information on the fibrous joints due to poor or no preservation in the fossil record.

Investigating the Timing of Carbonate Precipitations and Their Potential Impact on Fossil Preservation in the Hell Creek Formation

Because fossilized skeletal remains and enclosing sedimentary rocks experience similar diagenetic conditions (i.e., temperature, pressure, and pore fluid interaction,) enclosing sedimentary rocks may provide insight into bone diagenesis. A fossil assemblage, including in situ dinosaur fossils, was discovered in Makoshika State Park near Glendive, MT. Fossil-bearing sandstone is a crevasse splay deposit, and fossils show no sorting or preferred orientation. Bone-bearing sandstone exhibits evidence for intense diagenesis, suggesting a maximum temperature of ~90 °C. Concretion associated with fossils includes two distinctive matrices: dark- and light-colored matrices. Another concretion was found in channel sandstone near the base of the outcrop. These carbonate phases have distinctive isotopic compositions; δ13C values for dark-colored matrices, light-colored matrices, and spheroidal concretion are −7.5, 2.1, and −22.4‰ (VPDB), respectively, and their δ18O values are 16.4, 25.9, and 17.8‰ (VSMOW), respectively. In contrast, fossilized bone δ13C and δ18O values were −4.4‰ (VPDB) and 20.6‰ (VSMOW), respectively, suggesting fractionation with pore fluid was limited. Early carbonate precipitation evidenced by grain coating may have reduced interaction between pore fluids and fossils. Although concretion formation and permineralization do not appear to directly aid in fossil preservation, concretions preserve valuable evidence for diagenetic history.

Extremely rapid, yet noncatastrophic, preservation of the flattened-feathered and 3D dinosaurs of the Early Cretaceous of China

Northeast China's Early Cretaceous Yixian Formation preserves spectacular fossils that have proved extraordinarily important in testing evolutionary hypotheses involving the origin of birds and the distribution of feathers among nonavian dinosaurs. These fossils occur either flattened with soft tissue preservation (including feathers and color) in laminated lacustrine strata or as three-dimensional (3D) skeletons in "life-like" postures in more massive deposits. The relationships of these deposits to each other, their absolute ages, and the origin of the extraordinary fossil preservation have been vigorously debated for nearly a half century, with the prevailing view being that preservation was linked to violent volcanic eruptions or lahars, similar to processes that preserved human remains at Pompeii. We present high-precision zircon U-Pb geochronology from cores and outcrops, demonstrating that Yixian Formation accumulation rates are more than an order of magnitude higher than usually estimated. Additionally, we provide zircon provenance and sedimentological data from 3D dinosaur fossils, which imply that their death and burial occurred in collapsed burrows, rather than via a catastrophic volcanogenic mechanism. In the studied area, the three principal fossil-rich intervals of the Yixian occur as a cyclic sequence that correspond to periods of high precipitation. Using Bayesian-Markov Chain Monte Carlo approaches, we constrain the total duration of the sequence to less than ~93,000 y and suggest that climatic precession paced the expression of these cyclic sediments. Rather than representing multiple, Pompeii-like catastrophes, the Yixian Formation is instead a brief snapshot of normal life and death in an Early Cretaceous continental community.

Uncovering the relationships among herring-like fossils (Clupei: Teleostei): a phylogenetic analysis

Abstract Research interest in the diversity and evolutionary history of herring-like fossils (subcohort Clupei) has increased in recent decades. However, little is known about the relationships between fossils assigned to Clupei, particularly those that are demonstrably related to extant herring-like members of the order Clupeiformes. To help bridge this gap, we present a new morphological phylogeny that includes representatives of all major clupeiform lineages. The data matrix consists of 192 characters, drawn from 79 extant and 37 fossil taxa and selected to be readily identifiable in fossils. Most clupeiform families are recovered as monophyletic, and their interrelationships are generally compatible with previous morphological hypotheses. The phylogenetic positions of six fossil clupeiform taxa are resolved, as the results of all analyses (unconstrained/constrained parsimony and Bayesian inference) are consistent. Twenty-one fossil taxa are incertae sedis, including two species of Ellimmichtyiformes, which are recovered as Clupeoidei in the parsimony analyses. The relationships of the rest of the fossils are interpreted with varying degrees of certainty. The evolution of key morphological characters is discussed in light of the new results, and four fossil taxa are proposed as calibration points for future dating studies.

The Micropaleoecology Framework: Evaluating Biotic Responses to Global Change Through Paleoproxy, Microfossil, and Ecological Data Integration.

The microfossil record contains abundant, diverse, and well-preserved fossils spanning multiple trophic levels from primary producers to apex predators. In addition, microfossils often constitute and are preserved in high abundances alongside continuous high-resolution geochemical proxy records. These characteristics mean that microfossils can provide valuable context for understanding the modern climate and biodiversity crises by allowing for the interrogation of spatiotemporal scales well beyond what is available in neo-ecological research. Here, we formalize a research framework of "micropaleoecology," which builds on a holistic understanding of global change from the environment to ecosystem level. Location: Global. Time period: Neoproterozoic-Phanerozoic. Taxa studied: Fossilizing organisms/molecules. Our framework seeks to integrate geochemical proxy records with microfossil records and metrics, and draws on mechanistic models and systems-level statistical analyses to integrate disparate records. Using multiple proxies and mechanistic mathematical frameworks extends analysis beyond traditional correlation-based studies of paleoecological associations and builds a greater understanding of past ecosystem dynamics. The goal of micropaleoecology is to investigate how environmental changes impact the component and emergent properties of ecosystems through the integration of multi-trophic level body fossil records (primarily using microfossils, and incorporating additional macrofossil data where possible) with contemporaneous environmental (biogeochemical, geochemical, and sedimentological) records. Micropaleoecology, with its focus on integrating ecological metrics within the context of paleontological records, facilitates a deeper understanding of the response of ecosystems across time and space to better prepare for a future Earth under threat from anthropogenic climate change.

First fossil evidence of an extinct malvalean genus from India

ABSTRACT Hither, an extinct floral element of Florissantia Knowlton, unearthed from the early Eocene (~55–52 Ma) of the Gurha lignite mine, Rajasthan, western India, aids in highlighting the evolutionary significance of this angiosperm lineage in the Indian Cenozoic history. Comparison with fossil taxa from other regions supports the attribution to an extinct malvalean genus Florissantia. It is characterized by a transversely impressed, actinomorphic, gamosepalous flower with five rounded lobed sepals, each sepal fused at least 60% of its length, sinuses between sepal lobes shallowly incised and radiating reticulate venation. The occurrence of this extinct genus, previously known only from the Paleogene of North America and East Asia, is pertinent to the malvalean floristic diversification in India.

Parallel evolution of unusual ‘harpiform’ morphologies in distantly related trilobites

Abstract Harpetid and trinucleid trilobites share a similar and unusual morphology, the most striking feature of which is a wide, flattened cephalic brim with many pits or holes. This similarity was once interpreted as a sign that these two groups of trilobites were closely related, but in recent years it has instead been assumed that the ‘harpiform’ brim arose in both groups independently. However, relatedness and similarity can be difficult to disentangle in fossil taxa without close living relatives, and this assumption about the harpiform brim has never been explicitly tested. Our study re-evaluates the relationship between Harpetida and Trinucleioidea in order to test a longstanding assumption about trilobite relationships and as a case study in evaluating different kinds of morphological similarity in extinct groups. We inferred a new phylogenetic tree using parsimony methods and discrete morphological character data from a broad sampling of harpetids, trinucleids, and their relatives. Despite their gross morphological similarities, we found that harpetids and trinucleids were readily distinguished in our analyses, a result consistent with a hypothesis of multiple origins for the harpiform brim. By mapping brim-related characters across our new phylogeny, we identified a sequence of morphological innovations that arose in parallel in both groups and led ultimately in each case to the evolution of the harpiform brim. These results indicate that harpiform brims are a prime example of parallel evolution—the similar development of a morphological trait in distantly related taxa that nevertheless share a similar original morphology. In addition, our phylogeny supports the idea that trinucleids are specialized, harpiform asaphids, rather than an independent order of trilobites. We also provide new information on the relationships of the putative ‘basal-most’ members of Trinucleioidea, the Liostracinidae, and confirm recent assessments that this family is more distantly related to trinucleids.