Recent non-dino papers with free pdfs:
Free pdf:
Data for this study (including additional figures and tables, R scripts, and full GLS results) are available in the Dryad Digital Repository:
https://doi.org/10.5061/dryad.rxwdbrv4xTurtles are key components of modern vertebrate faunas and their diversity and distributions are likely to be affected by anthropogenic climate change. However, there is limited baseline data on turtle taxonomic richness through time or assessment of their past responses to global environmental change. We used the extensive Triassic-Palaeogene (252-223 Ma) fossil record of terrestrial and freshwater turtles to investigate diversity patterns, finding substantial variation in richness through time and between continents. Globally, turtle richness was low from their Triassic origin until the Late Jurassic. There is strong evidence for high richness in the earliest Cretaceous of Europe, becoming especially high following the Cretaceous Thermal Maximum and declining in all continents by the endâCretaceous. At the K-Pg boundary, South American richness levels changed little while North American richness increased, becoming very high during the earliest Palaeogene (Danian). Informative data are lacking elsewhere for this time period. However, the Selandian-Thanetian interval, approximately 5 myr after the K-Pg mass extinction, shows low turtle richness in Asia, Europe and South America, suggesting that the occurrence of exceptional turtle richness in the postâextinction Paleocene fauna of North America is not globally representative. Richness decreased over the Eocene-Oligocene boundary in North America but increased to its greatest known level for Europe, implying very different responses to dramatic climatic shifts. Time series regressions suggest number of formations sampled and palaeotemperature are the primary influencers of faceâvalue richness counts, but additional factors not tested here may also be involved.
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Free pdf:
Background
The microbiota plays a critical role in host homeostasis and has been shown to be a major driving force in host evolution. However, our understanding of these important relationships is hampered by a lack of data for many species, and by significant gaps in sampling of the evolutionary tree. In this investigation we improve our understanding of the host-microbiome relationship by obtaining samples from all seven extant species of sea turtle, and correlate microbial compositions with host evolutionary history.
Results
Our analysis shows that the predominate phyla in the microbiota of nesting sea turtles was Proteobacteria. We also demonstrate a strong relationship between the bacterial phyla SR1 and sea turtle phylogeny, and that sea turtle microbiotas have changed very slowly over time in accordance with their similarly slow phenotypic changes.
Conclusions
This is one of the most comprehensive microbiota studies to have been performed in a single clade of animals and further improves our knowledge of how microbial populations have influenced vertebrate evolution.
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Free pdf:
Amber, as an organic gem, is fossilized natural resin widely distributed around the world, especially Baltic region in Europe, Dominica-Mexico in Central America, and Myanmar in Asia. Insects are the most common inclusions in amber, while vertebrate inclusions are the rarest. However, compared to vertebrate fossils from sedimentary rocks, vertebrate inclusions trapped in amber pieces can provide additional information about the soft tissues, primitive death states, and living environment, as well as more visualized and refined 3D morphological information, all of which are important for studies in evolution, palae-oenvironmental restoration, palaeoecology and palaeoethology, which is more intuitive, stereoscopic and detailed than bone fossils. This paper reviews vertebrate inclusions from various amber biotae, including non-avian dinosaurs, aves, mammals, reptiles and amphibians, as well as their evolutionary implication, and also provides a framework of future researches.
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Free pdf:
Zhong-Jian Liu, Li-Jun Chen & Xin Wang (2020)
A whole-plant monocot from Lower Cretaceous.
Palaeoworld (advance online publication)
doi:
https://doi.org/10.1016/j.palwor.2020.03.008 https://www.sciencedirect.com/science/article/pii/S1871174X20300214The Yixian Formation (the Lower Cretaceous) of China is world famous for its fossils of early angiosperms. Despite their great diversity, few of these fossils are preserved as whole plants, making our understanding of early angiosperms incomplete. Here, we report a fossil angiosperm, Sinoherba ningchengensis n. gen. n. sp. (Sinoherbaceae n. fam.), from the Yixian Formation of China. The fossil is of a whole plant, including physically connected root with fibrous rootlets, a stem with branches and nodes, leaves with parallel-reticulate veins, and a panicle of female flowers with an ovary surrounded by perianth. Morphological and phylogenetic analyses reveal that Sinoherba is an herbaceous monocot. This fossil underscores the great diversity of angiosperms in the Lower Cretaceous Yixian Formation and an earlier, pre-Cretaceous origin of angiosperms.
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Other papers, but not free:
Presented is Os isotope stratigraphy of the Meishan PermianâTriassic interval.
Multiple unradiogenic Os isotope shifts are suggested to reflect pulses of volcanism.
A radiogenic Os isotope excursion is found above the mass extinction interval.
The radiogenic Os isotope shift may indicate enhanced weathering of the continent.
Abstract
The Permian-Triassic mass extinction event is the most severe biotic crisis during the Phanerozoic. The trigger of this event has been widely linked with massive volcanic activity associated with the Siberian Traps Large Igneous Province. However, the direct link is still lacking to fully understand the event. In this study, we apply osmium isotope (187Os/188Os, or Osi) stratigraphy across the Permian-Triassic boundary interval in the Meishan section of South China. The Os isotope stratigraphy reveals multiple shifts to more unradiogenic 187Os/188Os composition that are interpreted to reflect pulses of volcanism across the mass extinction interval. Additionally, a shift to a more radiogenic 187Os/188Os composition is also found immediately above the mass extinction interval, which is taken to reflect the enhanced weathering of the continental crust in response to greenhouse gas release into the atmosphere and the associated hyperthermal.
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First radiometric ages reported for syn-rift Mesozoic deposits exposed in the southern Cape of South Africa.
Rifting initiated in the Early Jurassic, > 10 Ma earlier than previously envisioned.
Syn-rift deposits exposed in the southern Cape represent a protracted > 40 Ma period of Jurassic to Cretaceous extension.
Abstract
Syn-rift deposits often provide the only means to determine the chronology of rift initiation and evolution. However, the earliest syn-rift packages deposited in Jurassic â Cretaceous rift basins that formed during the breakup of SW Gondwana are poorly understood because they are deeply buried beneath overlying passive margin sequences. The exhumed remnants of several such rift basins are exposed in the southern Cape of South Africa and contain the Suurberg and Uitenhage groups, which are predominantly continental, taphrogenic, fossiliferous strata interbedded with volcaniclastics. Here we present the first robust UâPb chronostratigraphic framework for these groups by dating zircon in nine pyroclastic and five resedimented volcaniclastic deposits using Laser Ablation â Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). To further improve the precision and accuracy of the results, we utilize Chemical Abrasion â Thermal Ionisation Mass Spectrometry (CA-TIMS) on four selected samples minimizing the effects of Pb-loss and further constraining depositional uncertainties. We thereby show that the Suurberg Group was deposited rapidly during the emplacement of the Karoo Large Igneous Province in the Early Jurassic and likely predates the main phase of rifting, whereas the Uitenhage Group was deposited over a prolonged (>40 Ma) period beginning in the Early Jurassic and continuing into the Early Cretaceous. The Uitenhage Group records two phases of rifting: an initial Jurassic episode that roughly coincides with the separation of East and West Gondwana and is contemporaneous with widespread volcanism in SW Gondwana, and a subsequent period of renewed rifting during the Early Cretaceous opening of the South Atlantic and initiation of the Agulhas Falkland Transform. This framework illustrates the complexity of long-lived rift-basin sedimentation and highlights the importance of high-resolution chronostratigraphy when investigating and integrating the tectonic, palaeogeographic and palaeontological records from the final stages of a unified SW Gondwana.
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Lida Xing & Lei Gu (2020)
The possible earliest epizoochorous fruit preserved in mid-Cretaceous Burmese amber.
Cretaceous Research 104498 (advance online publication)
doi:
https://doi.org/10.1016/j.cretres.2020.104498 https://www.sciencedirect.com/science/article/pii/S0195667120301841Including zoochory, mechanisms of seed dispersal varied along with the adaptive radiation of angiosperms, but few early fossil records had been reported with specialized pericarp structure. The present study describes a new specimen from Myanmar amber, denominated Rasenganus auricularus gen. et sp. nov. In this specimen, the spirally coiled structure possibly indicates a plant origin, and an aculeate surface adapted to epizoochory.