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1. Late Cretaceous sturgeons (Acipenseridae) from North America, with two new species from the Tanis site in the Hell Creek Formation of North Dakota

   https://doi.org/10.1017/jpa.2022.81  

   Hilton, Eric J.; Grande, Lance (January 2023, Journal of Paleontology)

   Abstract Although the Cretaceous is widely regarded as a time of great evolutionary transition for the freshwater fish fauna of North America, the fossil record of this period is notoriously poor, consisting mostly of fragments and isolated skeletal elements. Exceptions include the acipenseriforms, discussed in this paper, and some exceedingly rare teleosts. Here we describe two new species of well-preserved sturgeons (Acipenseridae) from the Tanis site in the Late Cretaceous Hell Creek Formation of North Dakota. The type and referred materials were preserved in a loosely consolidated matrix. † Acipenser praeparatorum n. sp. is represented by multiple body fossils (including the head and relatively complete postcranial remains) and a specimen of an intact, three dimensionally preserved skull and pectoral girdle. This taxon can be diagnosed based on features of the opercular elements (exceptionally tall and narrow branchiostegal). The second species, † Acipenser anisinferos n. sp., is represented by a partially preserved skull, and can be diagnosed by a relatively elongate preorbital region (i.e., snout) and the absence of thorn-like spines on the skull roofing bones. Most known sturgeon fossils from the Cretaceous are represented only by undiagnosable fragmentary remains (i.e., scutes and pectoral-fin spines) or poorly preserved partial skeletons (e.g., † Protoscaphirhynchus ), with † Priscosturion and † Anchiacipenser (both monotypic) being rare exceptions. Therefore, the newly discovered Tanis fossils give a rare glimpse into the evolution of Acipenseridae at a critical time in the phylogenetic history of acipenseriforms, and suggest significant morphological and taxonomic diversity early in the evolution of this group. UUID: http://zoobank.org/375b586a-2dd8-4a31-b6c4-42151e6e8fc8 

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2. Environmental factors affecting feather taphonomy

   https://doi.org/https://doi.org/10.3390/ biology11050703  

   Schweitzer MH; Zheng W; Equall N. (April 2022, Biology)

   Feathers are arguably the most complex integumentary structures in the entire animal kingdom. The evolutionary origins of feathers are still debated, but growing evidence from both molecular studies in extinct theropods [1–8] and living birds (e.g., [9–18]), as well as numerous fossil discoveries of structures morphologically consistent with feathers (e.g., [4,19–25]) indicate that feathers arose from filamentous structures first identifed in some theropod dinosaurs and birds more than 160 million years ago (e.g., [2,26,27]). However, some data suggest that integumentary structures similar to those from which feathers derived may have been present at the base of Dinosauria [28,29] or perhaps, the base of Archosauria ([30,31] and references therein). Because modern feathers are not biomineralized in life (contra [32,33]) their persistence in the fossil record is counterintuitive, but critical. The impressions of feathers in sediments surrounding skeletal elements led to the identification of Archaeopteryx as the first bird [34,35], but there was no organic trace with this specimen to suggest that any original material remained. However, the first specimen attributed to Archaeopteryx was a single, isolated feather [36]. This specimen presented differently from feather impressions surrounding the skeletal remains, instead visualized as a carbonized trace clearly distinct from the embedding sediments, suggesting that taphonomic processes resulting in preservation differed between the isolated feather and the skeletal specimen. The environmental factors resulting in these different modes of preservation remain relatively unexplored. 

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3. First sequencing of ancient coral skeletal proteins

   https://doi.org/10.1038/s41598-020-75846-4  

   Drake, Jeana L.; Whitelegge, Julian P.; Jacobs, David K. (December 2020, Scientific Reports)

   null (Ed.)

   Abstract Here we report the first recovery, sequencing, and identification of fossil biomineral proteins from a Pleistocene fossil invertebrate, the stony coral Orbicella annularis . This fossil retains total hydrolysable amino acids of a roughly similar composition to extracts from modern O. annularis skeletons, with the amino acid data rich in Asx (Asp + Asn) and Glx (Glu + Gln) typical of invertebrate skeletal proteins. It also retains several proteins, including a highly acidic protein, also known from modern coral skeletal proteomes that we sequenced by LC–MS/MS over multiple trials in the best-preserved fossil coral specimen. A combination of degradation or amino acid racemization inhibition of trypsin digestion appears to limit greater recovery. Nevertheless, our workflow determines optimal samples for effective sequencing of fossil coral proteins, allowing comparison of modern and fossil invertebrate protein sequences, and will likely lead to further improvements of the methods. Sequencing of endogenous organic molecules in fossil invertebrate biominerals provides an ancient record of composition, potentially clarifying evolutionary changes and biotic responses to paleoenvironments. 

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4. An Enigmatic Miniaturized and Attenuate Whole Lizard from the Mid-Cretaceous Amber of Myanmar

   https://doi.org/doi.org/10.3099/MCZ49.1  

   DAZA, JD; BAUER, AM; STANLEY, EL; BOLET, A; DICKSON, B; LOSOS, JB (November 2018, Breviora)

   We report the discovery of a new genus and species of amber-preserved lizard from the mid-Cretaceous of Myanmar. The fossil is one of the smallest and most complete Cretaceous lizards ever found, preserving both the articulated skeleton and remains of the muscular system and other soft tissues. Despite its completeness, its state of preservation obscures important diagnostic features.We determined its taxonomic allocation using two approaches: we used previously identified autapomorphies of squamates that were observable in the fossil; and we included the fossil in a large squamate morphological data set. The apomorphy-based identification of this specimen, including comparative data on trunk elongation in squamates, suggests its allocation to the stem-group Anguimorpha. Results from the phylogenetic analysis places the fossil in one of four positions: as sister taxon of either Shinisaurus crocodilurus or Parasaniwa wyomingensis, at the root of Varanoidea, or in a polytomy with Varanoidea and a fossorial group retrieved in a previous assessment of squamate relationships. It is clear that this fossil has many similarities with anguimorph squamates and, if this taxonomic allocation is correct, this fossil would represent the first amber-preserved member of stem Anguimorpha ever recorded, and the smallest known member of that group. It further emphasizes the role of amber inclusions in expanding our understanding of the diversity of Cretaceous lizard communities. 

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5. Sedimentary ancient DNA as a tool in paleoecology

   https://doi.org/10.1038/s43017-021-00158-8  

   Crump, Sarah E. (April 2021, Nature Reviews Earth & Environment)

   Over a century of paleoecological investigations have been dedicated to studying the preserved hard parts of organisms contained in geological archives. Although the fossil record has revealed valuable insights into past ecosystems, the vast majority of past life has remained undetected due to a lack of preservation. Sedimentary ancient DNA (sedaDNA), DNA sourced from proximal organisms and preserved in coeval sediments, is upending that limitation in the Late Quaternary record. Owing to recent advances in sequencing technology and genetics techniques, one small sediment sample can yield a broad snapshot of a past ecosystem, indicating the presence of species from microbes to mammals. 

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