Some recent items and papers not yet mentioned (mainly non-dino stuff):
Geological Society of America Annual Meeting Sept. 22-25, 2019 abstracts are now posted online. Presumably, there is an embargo on discussing the content until the actual presentations and posters are officially made public.
Search terms for dinosaur, pterosaur, etc., will bring up abstracts.
Previously posted in Russian version, now in English translation:
A new study of the holotype of Riabininohadros weberae from the Upper Cretaceous (upper Maastrichtian) of Crimea (Besh-Kosh) reveals previously unknown fragments of femur, astragalus, and calcaneus. This taxon is characterized by a complex of primitive characters found in Iguanodontia and basal Ornithischia and its phylogenetic position can be defined as Styracosterna indet. The second dinosaur record from Crimea (Aleshino) is represented by a fragmentary skeleton, including cervical and dorsal vertebrae. It may belong to a derived iguanodontian or a primitive hadrosauroid. Thus, at least two species of dinosaurs coexisted in the Maastrichtian of Crimea.
Previously posted in Russian version, here in English translation:ÂÂ
M. A. Rogov, N. G. Zverkov, V. A. Zakharov & M. S. Arkhangelsky (2019)
Marine Reptiles and Climates of the Jurassic and Cretaceous of Siberia.
Stratigraphy and Geological Correlation 27(4): Â398-423
All current data on the Jurassic and Cretaceous climates of Siberia based on isotope, paleontological, and lithological proxies are summarized. The late Pliensbachian cooling episode, early Toarcian warming, promptly replaced by long-term Middle Jurassic cooling at the end of the Toarcian, and a long-term warm interval in the Late Jurassic are clearly recorded. From the end of the Ryazanian, a gradual cooling episode began, which apparently continued throughout the Early Cretaceous except for a brief warming episode in the early Aptian. At the beginning of the Late Cretaceous, the climate became warmer; the peak of warming is recorded at the CenomanianâTuronian boundary. Then, the middleâlate Turonian was marked by a relatively cold episode. Later, in the ConiacianâCampanian, the climate warmed again, but at the end of the Campanian another cooling episode occurred. New findings of marine reptiles are described from the Toarcian, Kimmeridgian, Volgian, and Santonian-Campanian deposits of north of Eastern Siberia. All existing records of marine reptiles known from the Jurassic and Cretaceous of Siberia are revised, and all the findings (from 51 localities) are positioned in relation to paleolatitudes. It is established that the majority of occurrences of these fossils were within the polar paleolatitudes (70Ââ87Â). We found no direct correlation between climate fluctuations and the distribution of these organisms. Taking into account the newest data showing that representatives of the majority of Jurassic and Cretaceous large groups of marines reptiles were able to maintain a more or less constant body temperature and were also able to undertake large-scale seasonal migrations, it is reasonable to be cautious in interpreting the presence of remains of these animals as indicators of a warm climate.
This article was posted earlier in the Russian version, now in English translation with free pdf link:
Gorynychus sundyrensis sp. nov.Â
Two new localities of Mesozoic mammals have been discovered: Bolâshoi Ilek and Berezovaya River (Russia, Krasnoyarsk Territory, Lower Cretaceous, Ilek Formation). Bolâshoi Ilek locality yields an edentulous fragment of the maxillary of Docodonta indet. A fragment of dentary without teeth attributed to Mammalia indet. (presumably eutriconodontan or symmetrodontan) is presented in the Berezovaya River locality. New localities fill the geographical gap between previously known mammalian localities of Ilek Formation in the basins of Kiya and Bolâshoi Kemchug rivers.
Feathers are the most complex skin appendages of vertebrates. Mature feathers consist of interconnected dead keratinocytes that are filled with heavily cross-linked proteins. Although the molecular architecture determines essential functions of feathers, only few feather proteins have been characterized with regard to their amino acid sequences and evolution. Here, we identify Epidermal Differentiation protein containing DPCC Motifs (EDDM) as a cysteine-rich protein that has co-evolved with other feather proteins. The EDDM gene is located within the avian epidermal differentiation complex (EDC), a cluster of genes that has originated and diversified in amniotes. EDDM shares the exon-intron organization with EDC genes of other amniotes, including humans, and a gene encoding an EDDM-like protein is present in crocodilians, suggesting that avian EDDM arose by sequence modification of an epidermal differentiation gene present in a common ancestor of archosaurs. The EDDM protein contains multiple sequence repeats and a higher number of cysteine residues than any other protein encoded in the EDC. Immunohistochemical analysis of chicken skin and skin appendages showed _expression_ of EDDM in barb and barbules of feathers as well as in the subperiderm on embryonic scutate scales. These results suggest that the diversification and differential _expression_ of EDDM, besides other EDC genes, was instrumental in facilitating the evolution of the most complex molecular architecture of feathers.
Riostegotherium yanei from the ItaboraÃ Basin, Brazil, is the oldest known Xenarthra. This paper aims to describe the internal morphology of the osteoderms of Riostegotherium yanei from the perspective of histology and micro-CT approaches, expanding the available data on cingulate osteoderm microstructure. Seven osteoderms of R. yanei were used for the internal microstructure description and eight of Dasypus novemcinctus for comparison. The osteoderms of Riostegotherium yanei lacks the diploÃ-like structure typical of glyptodonts but has a three-layered structure composed of two layers of non-Haversian compact bone enclosing a central layer of primary and secondary osteons. This internal organization is distinct from other Astegotheriini of comparable age, but similar to Dasypus. The 3D reconstruction of Riostegotherium yanei revealed two patterns of internal organization. Pattern 1 of movable osteoderm is composed of large remodeled areas at the base and a more compact bone at the tongue; in Pattern 2 (both movable and buckler), the internal cavities are much smaller, more numerous, and more interconnected to each other. In one buckler osteoderm, the cavities are organized somewhat radially with a compact central region (Pattern 1). Pattern 1 of both movable and buckler osteoderms resemble that of Dasypus.
Espen M. Knutsen & Emma Oerlemans (2019)
The last dicynodont? Re-assessing the taxonomic and temporal relationships of a contentious Australian fossil.
Gondwana Research (advance online publication)
Archives, geochemistry and anatomy reunite fossil specimens after 100âyears.
Cretaceous dicynodont material now referred to Late Cenozoic mammalian megafauna.
No evidence for a post-Triassic ghost lineage of Cretaceous dicynodonts
Dicynodonts, a lineage of non-mammalian therapsids, who's derived taxa evolved edentulous beaked jaws sporting a pair of caniniform tusks, dominated the herbivorous terrestrial vertebrate fauna for much of the Permian and Triassic periods. Long assumed to have met their demise during the end-Triassic extinction event, the discovery of a fragmentary possible dicynodont in Cretaceous rocks in Queensland Australia, potentially extended the longevity of the lineage by nearly 100 million years. This study reassesses the geological, anatomical and historical aspects of this specimen through museum archival research, detrital zircon geochronology, trace element analysis and x-ray synchrotron microtomography, and present new knowledge regarding its temporal, geographical and biological origins, supporting a late Cenozoic (Pliocene-Pleistocene) mammalian megafaunal affinity for the specimen, resulting in a lack of evidence for post-Triassic survival of dicynodonts.
Only an abstract for now, full paper to come later:
Non-ophidian ophidiomorphs, colloquially referred to as 'dolichosaurs,' are small-bodied aquatic lizards that lived in shallow seaways, rivers, and reef environments during the Late Cretaceous. Preservational, geographic, and taphonomic biases in this group make trends in biodiversity difficult to assess. This is exemplified by the fact that the majority of the described species are monotypic and known only from single specimens, imparting very little information on morphological or spatial variation. Here we present a revision of the spatial and temporal distributions of non-ophidian ophidiomorph lizards ('dolichosaurs') from Cretaceous sediments worldwide. The fossil record of dolichosaurs begins in the Valanginian (Early Cretaceous). The late Early Cretaceous records are sparse but suggest a wide geographic distribution spanning the Tethys and Western Pacific. This is followed by a dense Cenomanian record from Tethyan and British deposits, and rarer specimens from North America. Though there is a substantial drop in the number of specimens recorded from the Turonian-Maastrichtian, these rare occurrences represent the largest geographical distribution of dolichosaurs: spanning Europe, North America, and South America before going extinct during the end-Cretaceous mass extinction. These occurrences indicate that ophidiomorphs most likely originated in the Jurassic Tethys and continued to radiate spatially and phylogenetically until the end of the Mesozoic, showing much more temporally and environmentally diverse patterns than previously indicated.