The compacted macrofossil Protomelission? sp. from the early Cambrian Xiaoshiba Lagerstaette was recently ascribed to early dasycladalean green algae and used to disprove the bryozoan affinity of coeval phosphatized microfossils, which made the puzzling question whether the bryozoans originated in early Cambrian pending again. Our new analyses of multiple specimens which are conspecific with Protomelission? from the Chengjiang Lagerstaette indicate that they are not dasycladaleans but one of the three groups of archaeocyath-like sponges that atypically inhabited siliciclastic substrates. All the archaeocyath-like fossils share the same preservation mode and exhibit archaeocyath-type external skeletal features. Particularly, the Protomellision? -like fossils preserve structures indicative of archaeocyath aquiferous system and ontogeny. They represent the first recognized one-walled archaeocyath sponges in South China and evidence the niche expansion of archaeocyaths on their way of global radiation from Siberia, 518 million years ago. The origin of the bryozoans remains a mystery. less

The fossil record of parasitism is poorly understood, due largely to the scarcity of strong fossil evidence of parasites. Understanding the preservation potential for fossil parasitic evidence is critical to contextualizing the fossil record of parasitism. Here, we present the first use of X-ray computed tomography (CT) scanning and finite elements analysis (FEA) to analyze the impact of a parasite-induced fossil trace on host preservation. Four fossil and three modern decapod crustacean specimens with branchial swellings attributed to an epicaridean isopod parasite were CT scanned and examined with FEA to assess differences in the magnitude and distribution of stress between normal and swollen branchial chambers. The results of the FEA show highly localized stress peaks in reaction to point forces, with higher peak stress on the swollen branchial chamber for nearly all specimens and different forces applied, suggesting a possible shape-related decrease in the preservation potential of these parasitic swellings. Broader application of these methods as well as advances in the application of 3D data analysis in paleontology are critical to understanding the fossil record of parasitism and other poorly represented fossil groups. less

The 3-D structure and organization of type-1 collagen protein and vasculature for a set of ancient permafrost bones is extensively documented at the nanoscale (up to 150,000x magnification) for the first time. The chemical mapping technique ToF-SIMS is additionally used to directly localize chemical signal to these structures; C:N and isotope measurements are also reported for the bulk organic bone matrix. These analyses test the hypothesis that biomolecular histology of collagen and vasculature from the permafrost bones supports their taphonomic classification as \'subfossils\' rather than \'fossils\'. Results indicate the original collagenous scaffolding and vasculature are still present, the former of which is well-preserved, thus supporting the hypothesis. This study is the first to taphonomically classify a set of pre-Holocene bones as \'subfossils\' based on the preserved state of their biomolecular histology. These methods can be readily expanded to specimens of warmer thermal settings and earlier geologic strata. Doing so has potential to establish/formalize at what point a bone has been truly \'fossilized\'; that is, when it has transitioned from \'subfossil\' status to being a true \'fossil\' bone. This will elucidate the fossilization process for ancient vertebrates and lead to a deeper understanding of what it means to be a \'fossil\'. less

The Arlington Archosaur Site (AAS) between Dallas and Fort Worth, Texas, is known as a rich fossiliferous section. The age of these rocks is generally considered to be mid Cenomanian, but conflicting evidence suggests the age may be as young as the late Cenomanian early Turonian. To address the issue, a palynological study was designed and conducted based on the close sampling of the lithofacies. Palynological samples were processed according to the standard acid preparation. The study was quantitative and focused on associations to determine the paleoenvironment, paleoclimate, biostratigraphy, and age of exposure. The rich palynological assemblages comprise spores from seedless plants, gymnosperms, angiosperms, fungi, algae, and dinoflagellate cysts. Bryophytes were abundant mainly in Facies A and B, with Zlivisporis cenomanianus taking over the bryophytes\' habitat in Facies D. Lycophytes abundant in the alluvial and coastal plains are considered to have been transported. Conifers were the predominant group of gymnosperms, also mainly transported into the section. Freshwater algal remains include Schizophacus laevigatus/Ovoidites parvus, Schizosporis reticulatus, Botryococcus sp., and Pediastrum sp. Acanthomorph acritarchs present in low abundance and diversity appear following shallow marine dinoflagellates\' spikes and before freshwater colonial algal spikes. The vegetation signal at Noto\'s Facies A and B indicates tropical to subtropical shallow marine to coastal plains, while Noto\'s Facies D indicates tidally influenced areas. Also, picks of the diversity and abundance of dinoflagellate cysts are interpreted as an increased marine influence and proposed as possible flooding surfaces. The results support the alternation of marine incursions within deltaic and floodplain sequences, related to regional climate oscillation that affected the vegetation on the upland drainage area. Key palynological markers point to an early Late Cenomanian age, and the presence of the Cyclonephelium compactum - C. membraniphorum (Ccm morphological plexus) signals that the incursion of boreal waters during the Plenus Cold Event of the Ocean Anoxic Event 2 may have reached as far south as the AAS area. This coincides with vegetation trends that suggest a cooler and less humid climate at the start of Facies A, where Ccm is more abundant. less

In their paper \'A refined proposal for the origin of dogs: the case study of Gnirshoehle, a Magdalenian cave site\', Baumann and colleagues claim that their data \'support the hypothesis that the Hegau Jura was a potential center of early European wolf domestication\', and that \'such a scenario becomes plausible considering a close proximity of canids and humans thereby introducing a controlled, or at least a restrictive diet\'. The study focusses on fossil remains of \'large canids\' from the Gnirshoehle cave site in SW Germany. Morphometric data on only one specimen, GN-999, as well as collagen delta15N and delta13C isotopic data and mitochondrial DNA analyses on the Gnirshoehle specimens and a comparative sample were used to conclude that the Gnirshoehle specimens shed light on the \'origin of dogs\' as purported by the title of the paper. Here we argue that the paper is fundamentally flawed and excluded available relevant data. less

Elucidating the most probable compositions of the first cell membranes prior to the origin of life, within a laboratory setting, requires experiments with organic molecules and chemical conditions representative of those present on the early Earth. As such, the membrane forming molecules used in these experiments are described as \"prebiotically plausible\", i.e., they could have formed through abiotic reactions and be available for membrane formation prior to the emergence of biology. Similarly, the chemical properties of solutions in which these membranes are formed (e.g., pH, temperature, ionic strength) must represent the early Earth environmental conditions under investigation. Here, using a combined confocal and transmission electron microscopy approach, we show that prebiotically plausible organic molecules, in solutions representative of Hadean submarine alkaline hydrothermal vents, form aggregated structures with substantial morphological diversity. The structures hold the potential for use as traces of prebiotic processes in the ancient rock record. In addition, many of the structures are morphologically similar to those which are presented as early microfossils, thus highlighting the limitations of morphological interpretation in these types of studies. Detailed analyses of abiotic organic structures are essential for our understanding of the earliest living organisms on Earth, as well as for our interpretation of any potential biosignatures recovered in the future from extra-terrestrial bodies. less

We present Isotopia, an open-access database compiling over 36,000 stable isotope measurements ({delta}13C, {delta}15N, {delta}18O, {delta}34S, 87Sr/86Sr, 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 207Pb/206Pb, and 208Pb/206Pb) on human, animal, and plant bioarchaeological remains dating to Classical Antiquity (approximately 800 BCE - 500 CE). These were recovered from different European regions, particularly from the Mediterranean. Isotopia provides a comprehensive characterisation of the isotopic data, encompassing various historical, archaeological, biological, and environmental variables. Isotopia is a resource for meta-analytical research of past human activities and paleoenvironments. The database highlights data gaps in isotopic classical archaeology, such as the limited number of isotopic measurements available for plants and animals, limited number of studies on spatial mobility, and spatial heterogeneity of isotopic research. As such, we emphasise the necessity to address and fill these gaps in order to unlock the reuse potential of this database. less

Collagen from paleontological bones is an important organic material for isotopic measurement, radiocarbon and paleoproteomic analyzes, to provide information on diet, dating and taxonomy. Current paleoproteomics methods are destructive and require from a few milligrams to several tenths of milligrams of bone for analysis. In many cultures, bones are raw materials for artefact which are conserved in museum which hampers to damage these precious objects during sampling. Here, we describe a low-invasive sampling method that identifies collagen, taxonomy and post-translational modifications from Holocene and Upper Pleistocene bones dated to 130,000 and 150 BC using dermatological skin tape-discs for sampling. The sampled bone micro-powders were digested following our highly optimized eFASP protocol, then analyzed by MALDI FTICR MS and LC-MS/MS for identifying the genus taxa of the bones. We show that this low-invasive sampling does not deteriorate the bones and achieves results similar to those obtained by more destructive sampling. Moreover, this sampling method can be performed at archaeological sites or in museums. less

Nutrient foramina are small openings in the periosteal surface of long bones that traverse the cortical layer and reach the medullary cavity. They are important for the delivery of nutrients and oxygen to bone tissue, and are crucial for the repair and remodeling of bones over time. The nutrient foramina in the femur's diaphysis are related to the energetic needs of the femur, and have been shown to be related to the maximum metabolic rate (MMR) of taxa. Here, we investigate the relationship between nutrient foramen size and body mass as a proxy to the aerobic capacity of taxa in living and extinct xenarthrans, including living sloths, anteaters, and armadillos, as well as extinct xenarthrans such as glyptodonts, pampatheres, and ground sloths. Sixtynine femora were sampled, including 19 from extant taxa and 50 from extinct taxa. We obtained the blood flow index (Qi) based on foramina area and performed PGLS and phylogenetic ANCOVA in order to explore differences among mammalian groups. Our results show that among mammals, taxa commonly associated with lower metabolism like marsupials and living xenarthrans showed relatively smaller foramina, while the foramina of giant extinct xenarthrans like ground sloths and glyptodonts overlapped with non-xenarthran placentals. Consequently, Qi estimations indicated aerobic capacities comparable to other placental giant taxa like elephants or some ungulates. Furthermore, the estimation of the MMR for fossil giant taxa showed similar results, with almost all taxa showing high values except for those for which strong semi-arboreal or fossorial habits have been described. Moreover, the results are compatible with the diets predicted for extinct taxa, which indicate a strong consumption of grass similar to ungulates and in contrast to the folivorous or insectivorous diets of extant xenarthrans. The ancestral reconstruction of the MMR values indicated a lack of a common pattern for all xenarthrans, strongly supporting the occurrence of low metabolic rates in extant forms due to their particular dietary preferences and arboreal or fossorial habits. Our results highlight the importance of considering different evidence beyond the phylogenetic position of extinct taxa, especially when extinct forms are exceptionally different from their extant relatives. Future studies evaluating the energetic needs of giant extinct xenarthrans should not assume lower metabolic rates for these extinct animals based solely on their phylogenetic position and the observations on their extant relatives. less

The ability to enroll for protection is an effective defensive strategy that has convergently evolved multiple times in disparate animal groups ranging from euarthropods to mammals. Enrollment is an evolutionary staple of trilobites, and their biomineralized dorsal exoskeleton offers a versatile substrate for the evolution of interlocking devices. However, it is unknown whether trilobites also featured ventral adaptations for enrolment. Here, we report ventral exoskeletal adaptations that facilitate enrollment in exceptionally preserved trilobites from the Upper Ordovician Walcott-Rust Quarry in New York State, USA. Walcott-Rust trilobites reveal the intricate three-dimensional organization of the non-biomineralized ventral anatomy preserved as calcite casts, including the spatial relationship between the articulated sternites (i.e., ventral exoskeletal plates) and the wedge-shaped protopodites. Enrollment in trilobites is achieved by ventrally dipping the anterior margin of the sternites during trunk flexure, facilitated by the presence of flexible membranes, and the close coupling of the wedge-shaped protopodites. Comparisons with the ventral morphology of extant glomerid millipedes and terrestrial isopods reveal similar mechanisms used for enrollment. The wedge-shaped protopodites of trilobites closely resemble the gnathobasic coxa/protopodite of extant horseshoe crabs. We propose that the trilobites\' wedge-shaped protopodite simultaneously facilitates tight enrollment and gnathobasic feeding with the trunk appendages. less