Some new papers:
V. S. Tereshchenko (2020)
Sexual Dimorphism in the Postcranial Skeleton of Dinosaurs.
Paleontological Journal 54(12): 1410â1433
doi: https://doi.org/10.1134/S0031030120120047
https://link.springer.com/article/10.1134/S0031030120120047
Sex-related variability in the tetrapod skeleton has regular patterns that reflect the different ontogenetic pathways leading to the formation of adult sexual features. In dinosaurs (as well as amniotes in general), these features are most pronounced in the morphology of postcranial bones. In males, sex-related traits reflect improved adaptations of the locomotor apparatus, while in females they are associated with the adaptation to hatching and laying eggs. Therefore, beyond the specifics of sex differences in different taxa of dinosaurs, there are also common patterns: in all adult males, neural spines are higher and limb bones are more robust than in females, while the volume of the abdominal cavity and the width of the pelvis are greater in females. The case study of ceratopsians (Ornithischia: Neoceratopsia) shows that knowledge of basic sex-related characters (those most constant in tetrapods) facilitates the search for accessory characters (more taxon-specific) that are correlated with basic ones, which provide a way to establish the limits of sexual variability typical for a given taxon.
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I. Udroiu (2020)
Evolution of Red Blood Cells in Extant and Extinct Tetrapods.
Paleontological Journal 54(12): 1434â1442 Â
doi: Âhttps://doi.org/10.1134/S0031030120120059
https://link.springer.com/article/10.1134/S0031030120120059
Several authors showed that red blood cell volume (Mean Corpuscular Volume, MCV) is inversely correlated with metabolic rate; therefore, reconstruction of MCV can give useful hints on the physiology of extinct tetrapods. In the present study, the usefulness of histological parameters as proxies of MCV were evaluated. It was found that osteocyte size and vascular minimum diameter are significantly correlated with MCV in non-mammals, but are not correlated with MCV in mammals. This is due to the fact that mammalian red blood cells are enucleated. Using literature data, osteocyte size and vascular minimum diameter were used to reconstruct MCV in extinct non-synapsid tetrapods. Moreover, it was found when enucleation of red blood cells probably appeared in the synapsid lineage, and thus MCV was reconstructed also in Synapsida. My hypothesis is that enucleation of RBC in Eucynodontia allowed to efficiently oxygenate tissues with high metabolic demand, even in the presence of high affinity hemoglobins. This would not have been the case for dinosaurs, whose hemoglobin could have retained, like in birds, a low affinity (perhaps linked to their unidirectional respiratory system) and could easily release oxygen in tissues with high metabolic rates. Finally, a trend of MCV decrease over time (probably indicating an increase in metabolic rates) was found both in the synapsid and the ornithodiran lineages.
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Highlights
A framework to identify tracks in cross-section view is updated and systematized.
The size of the cross-section tracks indicates dinosaurs as probably trackmakers.
The Jurassic age suggested by conchostracans and stratigraphic evidences for PirambÃia Formation is reinforced.
PirambÃia Formation in the SÃo Paulo State is probably correlated with Guarà Formation in southern Brazil.
Oldest indirect evidence of dinosaurs in the SÃo Paulo State is recorded.
Abstract
Soft-sediment deformation structures are conspicuous features found in both ancient and modern, shallowly buried, loose, and water-saturated sediments related to diverse depositional environments. Numerous triggering mechanisms can induce their development, including seismicity, glaciotectonics, overload, and bioturbation. The presence of soft-sediment deformation in the Jurassic fluvial-eolian PirambÃia Formation has been known for a long time and was usually associated with seismic-induced triggers. Recently described synsedimentary structures in wet interdune deposits from the lower part of this unit, close to its type area in SÃo Paulo State, southeastern Brazil, are now interpreted as true cross-section tracks produced by large tetrapods based on examples from the literature and morphological analyzes. Based on their age, size, and comparisons with dinosaur tracks described in Jurassic lithostratigraphic units from Paranà Basin in Brazil (Guarà Formation) and Waterberg Basin (Etjo Formation), we suggest here, for the first time, that some of those deformational structures were produced by dinosaurs. Furthermore, the cross-section tracks from the PirambÃia Formation in SÃo Paulo State exceed in size the tracks with therapsid affinity described in the Permian-Triassic unit in southern Brazil, hindering their full correlation. This finding may potentially represent the oldest evidence of the presence of dinosaurs in the SÃo Paulo State territory, expanding our knowledge of the poorly known Jurassic tetrapod fauna of Brazil. Additionally, these cross-section tracks reinforce the possible correlation, at least in part, of the PirambÃia Formation in its northern occurrence (near to its type area) with the Jurassic Guarà Formation from southern Brazil.
Sexual Dimorphism in the Postcranial Skeleton of Dinosaurs.
Paleontological Journal 54(12): 1410â1433
doi: https://doi.org/10.1134/S0031030120120047
https://link.springer.com/article/10.1134/S0031030120120047
Sex-related variability in the tetrapod skeleton has regular patterns that reflect the different ontogenetic pathways leading to the formation of adult sexual features. In dinosaurs (as well as amniotes in general), these features are most pronounced in the morphology of postcranial bones. In males, sex-related traits reflect improved adaptations of the locomotor apparatus, while in females they are associated with the adaptation to hatching and laying eggs. Therefore, beyond the specifics of sex differences in different taxa of dinosaurs, there are also common patterns: in all adult males, neural spines are higher and limb bones are more robust than in females, while the volume of the abdominal cavity and the width of the pelvis are greater in females. The case study of ceratopsians (Ornithischia: Neoceratopsia) shows that knowledge of basic sex-related characters (those most constant in tetrapods) facilitates the search for accessory characters (more taxon-specific) that are correlated with basic ones, which provide a way to establish the limits of sexual variability typical for a given taxon.
===
A. O. Averianov & A. A. Yarkov (2021)
The First Record of a Pteranodontid (Pterosauria, Pteranodontidae) from the Late Cretaceous of the Lower Volga Region.
Paleontological Journal 55(1): 101â104
doi: https://doi.org/10.1134/S0031030121010032
https://link.springer.com/article/10.1134/S0031030121010032
An ulna fragment of a pterosaur Pteranodontidae indet. is described from the locality Polunino 2 in Volgograd Oblast (Late Cretaceous, Campanian). This is the first record of Pteranodontidae in Lower Volga Region, which supports a wide distribution of this group in the Late Cretaceous of Eurasia.
The First Record of a Pteranodontid (Pterosauria, Pteranodontidae) from the Late Cretaceous of the Lower Volga Region.
Paleontological Journal 55(1): 101â104
doi: https://doi.org/10.1134/S0031030121010032
https://link.springer.com/article/10.1134/S0031030121010032
An ulna fragment of a pterosaur Pteranodontidae indet. is described from the locality Polunino 2 in Volgograd Oblast (Late Cretaceous, Campanian). This is the first record of Pteranodontidae in Lower Volga Region, which supports a wide distribution of this group in the Late Cretaceous of Eurasia.
=====
I. Udroiu (2020)
Evolution of Red Blood Cells in Extant and Extinct Tetrapods.
Paleontological Journal 54(12): 1434â1442 Â
doi: Âhttps://doi.org/10.1134/S0031030120120059
https://link.springer.com/article/10.1134/S0031030120120059
Several authors showed that red blood cell volume (Mean Corpuscular Volume, MCV) is inversely correlated with metabolic rate; therefore, reconstruction of MCV can give useful hints on the physiology of extinct tetrapods. In the present study, the usefulness of histological parameters as proxies of MCV were evaluated. It was found that osteocyte size and vascular minimum diameter are significantly correlated with MCV in non-mammals, but are not correlated with MCV in mammals. This is due to the fact that mammalian red blood cells are enucleated. Using literature data, osteocyte size and vascular minimum diameter were used to reconstruct MCV in extinct non-synapsid tetrapods. Moreover, it was found when enucleation of red blood cells probably appeared in the synapsid lineage, and thus MCV was reconstructed also in Synapsida. My hypothesis is that enucleation of RBC in Eucynodontia allowed to efficiently oxygenate tissues with high metabolic demand, even in the presence of high affinity hemoglobins. This would not have been the case for dinosaurs, whose hemoglobin could have retained, like in birds, a low affinity (perhaps linked to their unidirectional respiratory system) and could easily release oxygen in tissues with high metabolic rates. Finally, a trend of MCV decrease over time (probably indicating an increase in metabolic rates) was found both in the synapsid and the ornithodiran lineages.
=====
Beatriz Christofoletti, Bernardo C.P.M. Peixoto, Lucas V. Warren, Lucas Inglez, Marcelo Adorna Fernandes, Luciano Alessandretti, Josà Alexandre de Jesus Perinotto, Marcello G.SimÃes & Mario L.Assine (2021)
Dinos among the dunes: Dinoturbation in the PirambÃia formation (Paranà basin), SÃo Paulo State and comments on cross-section tracks.
Journal of South American Earth Sciences 103252
doi: https://doi.org/10.1016/j.jsames.2021.103252
https://www.sciencedirect.com/science/article/abs/pii/S0895981121000985
Dinos among the dunes: Dinoturbation in the PirambÃia formation (Paranà basin), SÃo Paulo State and comments on cross-section tracks.
Journal of South American Earth Sciences 103252
doi: https://doi.org/10.1016/j.jsames.2021.103252
https://www.sciencedirect.com/science/article/abs/pii/S0895981121000985
Highlights
A framework to identify tracks in cross-section view is updated and systematized.
The size of the cross-section tracks indicates dinosaurs as probably trackmakers.
The Jurassic age suggested by conchostracans and stratigraphic evidences for PirambÃia Formation is reinforced.
PirambÃia Formation in the SÃo Paulo State is probably correlated with Guarà Formation in southern Brazil.
Oldest indirect evidence of dinosaurs in the SÃo Paulo State is recorded.
Abstract
Soft-sediment deformation structures are conspicuous features found in both ancient and modern, shallowly buried, loose, and water-saturated sediments related to diverse depositional environments. Numerous triggering mechanisms can induce their development, including seismicity, glaciotectonics, overload, and bioturbation. The presence of soft-sediment deformation in the Jurassic fluvial-eolian PirambÃia Formation has been known for a long time and was usually associated with seismic-induced triggers. Recently described synsedimentary structures in wet interdune deposits from the lower part of this unit, close to its type area in SÃo Paulo State, southeastern Brazil, are now interpreted as true cross-section tracks produced by large tetrapods based on examples from the literature and morphological analyzes. Based on their age, size, and comparisons with dinosaur tracks described in Jurassic lithostratigraphic units from Paranà Basin in Brazil (Guarà Formation) and Waterberg Basin (Etjo Formation), we suggest here, for the first time, that some of those deformational structures were produced by dinosaurs. Furthermore, the cross-section tracks from the PirambÃia Formation in SÃo Paulo State exceed in size the tracks with therapsid affinity described in the Permian-Triassic unit in southern Brazil, hindering their full correlation. This finding may potentially represent the oldest evidence of the presence of dinosaurs in the SÃo Paulo State territory, expanding our knowledge of the poorly known Jurassic tetrapod fauna of Brazil. Additionally, these cross-section tracks reinforce the possible correlation, at least in part, of the PirambÃia Formation in its northern occurrence (near to its type area) with the Jurassic Guarà Formation from southern Brazil.