Some non-dino papers:
Saxochelys gilberti gen. et sp. nov.Â
Tyler R. Lyson, Jacob L. Sayler & Walter G. Joyce (2019)
A new baenid turtle, Saxochelys gilberti, gen. et sp. nov., from the uppermost Cretaceous (Maastrichtian) Hell Creek Formation: sexual dimorphism and spatial niche partitioning within the most speciose group of Late Cretaceous turtles.
Journal of Vertebrate Paleontology Article: e1662428
doi: https://doi.org/10.1080/02724634.2019.1662428
https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1662428
The uppermost Cretaceous (Maastrichtian) Hell Creek Formation in North America has yielded a diverse assemblage of fossil turtles dominated by baenids. A population of over 30 individual skeletons from the Hell Creek Formation of North Dakota comprises a new baenid turtle, Saxochelys gilberti, increasing the number of recognized Hell Creek turtles to at least 26, 11 of which are baenids. Saxochelys gilberti is differentiated from all other baenids based on the presence of a nuchal scale, finely sculptured shell, absence of an omega-shaped femoral-anal sulcus, presence of an omega-shaped extragular-humeral sulcus, a cavum tympani that is relatively smaller than the diameter of the orbit, presence of a robust single scale on the posteromedial portion of the parietals, and jugal exclusion from the orbital margin. Two distinct plastral morphologies, concave (Nâ=â8) and flat (Nâ=â9), are interpreted as representing male and female individuals, respectively. A ca. 10% size difference between the sexes indicates that S. gilberti is a sexually size-dimorphic turtle with larger females. This suggests female mate choice in this baenid turtle. A referred S. gilberti skeleton from above the CretaceousâPaleogene boundary provides evidence for the survival of yet another species of turtle across this extinction event. The type locality of S. gilberti is close both stratigraphically and geographically to another locality consisting of a completely different assortment of baenid species, suggesting a fine degree of spatial niche partitioning in baenid turtles that may help explain the extremely high diversity of the group within the Hell Creek Formation.
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Also might be interest...
Free pdf:
John B. Iverson, Peter V. Lindeman & Jeffrey E. Lovich (2019)
Understanding reproductive allometry in turtles: A slippery "slope".
Ecology and Evolution (advance online publication)
doi: Âhttps://doi.org/10.1002/ece3.5697
https://onlinelibrary.wiley.com/doi/10.1002/ece3.5697
John B. Iverson, Peter V. Lindeman & Jeffrey E. Lovich (2019)
Understanding reproductive allometry in turtles: A slippery "slope".
Ecology and Evolution (advance online publication)
doi: Âhttps://doi.org/10.1002/ece3.5697
https://onlinelibrary.wiley.com/doi/10.1002/ece3.5697
Free pdf:
https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.5697
Measures of reproductive output in turtles are generally positively correlated with female body size. However, a full understanding of reproductive allometry in turtles requires logarithmic transformation of reproductive and body size variables prior to regression analyses. This allows for slope comparisons with expected linear or cubic relationships for linear to linear and linear to volumetric variables, respectively. We compiled scaling data using this approach from published and unpublished turtle studies (46 populations of 25 species from eight families) to quantify patterns among taxa. Our results suggest that for logâlog comparisons of clutch size, egg width, egg mass, clutch mass, and pelvic aperture width to shell length, all scale hypoallometrically despite theoretical predictions of isometry. Clutch size generally scaled at ~1.7 to 2.0 (compared to an isometric expectation of 3.0), egg width at ~0.5 (compared to an expectation of 1.0), egg mass at ~1.1 to 1.3 (3.0), clutch mass at ~2.5 to 2.8 (3.0), and pelvic aperture width at 0.8â0.9 (1.0). We also found preliminary evidence that scaling may differ across years and clutches even in the same population, as well as across populations of the same species. Future investigators should aspire to collect data on all these reproductive parameters and to report logâlog allometric analyses to test our preliminary conclusions regarding reproductive allometry in turtles.
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Free pdf:
Laura Arppe, ÂJuha A. Karhu, Sergey Vartanyan, DorothÃe G. Drucker, Heli Etu-Sihvola & Hervà Bocherens (2019)
Thriving or surviving? The isotopic record of the Wrangel Island woolly mammoth population
Quaternary Science Reviews 222: 105884
doi: https://doi.org/10.1016/j.quascirev.2019.105884
https://www.sciencedirect.com/science/article/pii/S0277379119301398?via%3Dihub
Highlights
Thriving or surviving? The isotopic record of the Wrangel Island woolly mammoth population
Quaternary Science Reviews 222: 105884
doi: https://doi.org/10.1016/j.quascirev.2019.105884
https://www.sciencedirect.com/science/article/pii/S0277379119301398?via%3Dihub
Highlights
No sign of habitat or forage deterioration in Wrangel Island mammoth isotope levels.
Different energy economy compared to Siberian mammoths.
Increased weathering in mid-Holocene possibly led to freshwater quality issues.
Short-term or catastrophic events are suggested as the cause of extinction.
Abstract
The world's last population of woolly mammoths (Mammuthus primigenius) lived on Wrangel Island persisting well into the Holocene, going extinct at ca. 4000âcal BP. According to the frequency of radiocarbon dated mammoth remains from the island, the extinction appears fairly abrupt. This study investigates the ecology of the Wrangel Island mammoth population by means of carbon, nitrogen and sulfur isotope analyses. We report new isotope data on 77 radiocarbon dated mammoth specimens from Wrangel Island and Siberia, and evaluate them in relation to previously published isotope data for Pleistocene mammoths from Beringia and lower latitude Eurasia, and the other insular Holocene mammoth population from St. Paul Island. Contrary to prior suggestions of gradual habitat deterioration, the nitrogen isotope values of the Wrangel Island mammoths do not support a decline in forage quality/quantity, and are in fact very similar to their north Beringian forebears right to the end. However, compared to Siberian mammoths, those from Wrangel Island show a difference in their energy economy as judged by the carbon isotope values of structural carbonate, possibly representing a lower need of adaptive strategies for survival in extreme cold. Increased mid-Holocene weathering of rock formations in the central mountains is suggested by sulfur isotope values. Scenarios related to water quality problems stemming from increased weathering, and a possibility of a catastrophic starvation event as a cause of, or contributing factor in their demise are discussed.
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