Ben Creisler
Recent non-dino papers:
Pavel P. Skutschas, Pavel G. Saburov, Elizaveta A. Boitsova & Veniamin V.Kolchanov (2019)
Ontogenetic changes in long-bone histology of the cryptobranchid Eoscapherpeton asiaticum (Amphibia: Caudata) from the Late Cretaceous of Uzbekistan.
Comptes Rendus Palevol (advance online publication)
This paper presents histological data on the long bones of different size (age) individuals of the basal cryptobranchid salamander Eoscapherpeton asiaticum from the Upper Cretaceous (Turonian) of Uzbekistan. E. asiaticum is similar to modern members of Cryptobranchidae in being relatively large (estimated body length up to 50â60 cm), aquatic, and neotenic. The analysis of growth series of femora demonstrates a significant histological maturation during ontogeny, expressed by the progressive appearance of highly organized parallel-fibred bone in the peripheral part of the periosteal cortex, appearance and increasing number of bone remodeling features, progressive resorption of calcified cartilage in the diaphyseal areas and formation of endochondral bone lining the erosion cavities in the calcified cartilage, progressive thickening of endosteal inner circumferential layer and increasing of vascularity and appearance of vascular network of longitudinal and oblique canals in the cortex. These ontogenetic changes in the long-bone histology of E. asiaticum generally correspond to those of other salamanders, except the appearance of the vascular network in the periosteal cortex â the feature that is characteristic for cryptobranchids and connected with their large body size. According to new data, the large Cenozoic cryptobranchids appear to have attained their larger size by extending the skeletal growth period.
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Marianella Talevi, Bruce Rothschild, Marta FernÃndez, Marcelo Reguero & MatÃas Mitidieri (2019)
A pathological scapula in a mosasaur from the upper Maastrichtian of Antarctica: evidence of infectious arthritis and spondyloarthropathy.
Cretaceous Research (advance online publication)
Highlights
First report of a paleopathology of a marine reptile from the southern hemisphere.
Infectious arthritis and spondyloarthropathy in a juvenile mosasaur from Antarctica.
The individual did not continue to grow for a long time after the lesion.
Abstract
We describe infectious arthritis and spondyloarthropathy in a juvenile mosasaur recovered from the upper Maastrichtian of Antarctica, representing the first report of a skeletal pathology of a mosasaur from the southern hemisphere. Macroscopic examination of the scapula revealed a remodelled, deeply excavated and expanded gleno-humeral joint with adjacent linear disruption. X-ray examination revealed a deep excavation expanding the glenoid fossa, with disorganized subchondral bone and a focal spherical defect. The individual did not continue to grow for a long time after the appearance of the lesion. Although not directly related to the mosasaur death, this condition may have contributed to the demise of the animal by reducing its effectiveness at obtaining food or increasing susceptibility to fatal disease, additional injury, or even predation.
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Also may be of interest (more Antarctica stuff):
Viviana D. Barreda, Luis Palazzesi & Eduardo B. Olivero (2019)
When flowering plants ruled Antarctica: evidence from Cretaceous pollen grains.
New Phytologist (advance online publication)
Summary
The replacement of seedâfree plants and gymnosperms by flowering plants during the Cretaceous is one of the most important biotic events in the evolution of life. However, the magnitude of this global turnover remains largely unknown.
âHere we present samplingâstandardized diversity estimates from a high resolution palynological record of the Late Cretaceous (85â66 Ma) from Antarctica, in the context of the past climatic events.
Our fossil evidence reveals the occurrence of a rich Campanian flora peaking at ~80 Myr, with angiosperms as the most diverse group of plants for the first time in Antarctica. This peak of diversity was followed by a period of a stepwise deterioration; 60% of ferns and 40% of gymnosperms became locally extinct from the early/mid Campanian to the late Maastrichtian. Although angiosperms also faced several extinctionsâ25% became extinctâthey were far less affected than nonâangiosperms.
The onset of deterioration of the greenhouse conditions at the end of the Cretaceousâlow CO2 and global cooling trendsâwould have led to our observed pattern of change. Overall, our study reveals the beginning of a profound floristic turnover in the highest southern latitudes that predates the major extinction event of the end of the Cretaceous by 15 Myr.
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Free pdf:
D.A. Nelson & J.M. Cottle (2019)
Tracking voluminous Permian volcanism of the Choiyoi Province into central Antarctica.Â
Lithosphere (advance online publication)
Permian volcanic deposits are widespread throughout southwestern Gondwana and record voluminous silicic continental arc volcanism (e.g., Choiyoi Province) that may have contributed to Permian global warming and environmental degradation. Many Permian volcanic deposits of southwestern Gondwana (southern South America, southern Africa, West Antarctica and eastern Australia), however, remain to be accurately correlated to magmatic source regions along the active paleo-Pacific margin of Gondwana, and this lack of correlation limits our understanding of the timing and distribution of voluminous volcanism. Here we present detrital zircon U-Pb and Hf isotope data for Permian volcaniclastic sedimentary rocks from the Ellsworth Mountains, Pensacola Mountains, and the Ohio Range of central Antarctica in southwestern Gondwana used to determine their volcanic source along the paleo-Pacific margin of Gondwana. Rocks in central Antarctica record Permian (ca. 268 Ma) volcanism with a mean zircon ÎHfi of -0.04 Â 4.8 (2 standard deviation). Comparison of these zircon age and Hf data with compilations for adjacent regions along the Gondwana margin suggest derivation of the Antarctic zircons from a major episode of Permian explosive arc volcanism that is broadly synchronous with, and geochemically similar to, the voluminous Choiyoi Province in South America. This correlation also relates the source of synchronous volcaniclastic deposits in the Karoo Basin, South Africa, to the same major Permian volcanic episode associated with the Choiyoi Province. In aggregate, geochemical data from Permian zircon in central Antarctica support an along-arc variation in geochemistry, with isotopically enriched high-flux magmatism associated with thicker crust and lithospheric mantle in South America, and isotopically depleted magmatism and thinner crust and lithospheric mantle in Australia. The timing of inferred Choiyoi-related explosive arc volcanism recorded in the Antarctic sector, South African sector, and South American sector is contemporaneous with a documented increase in global arc flux, an increase in atmospheric CO2, a decrease in Î13C of benthic marine fossils, and mass extinction events. We suggest that the Choiyoi Province and correlated arc volcanism along the Gondwana margin contributed to increased global arc flux in the Permian leading to elevated background levels of atmospheric CO2 conducive to producing an environmental crisis during mafic large igneous province emplacement, and may serve as an example of continental arc outgassing exerting a first order control on climate.
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Cenozoic stuff...
Felix G. Marx, MÃnica R. Buono, Alistair R. Evans, R. Ewan Fordyce, Marcelo Reguero and David P. Hocking (2019)Â
Gigantic mysticete predators roamed the Eocene Southern Ocean.
Antarctic Science 31(2 ): 98-104
Modern baleen whales (Mysticeti), the largest animals on Earth, arose from small ancestors around 36.4 million years ago (Ma). True gigantism is thought to have arisen late in mysticete history, with species exceeding 10 m unknown prior to 8 Ma. This view is challenged by new fossils from Seymour Island (Isla Marambio), Antarctica, which suggest that enormous whales once roamed the Southern Ocean during the Late Eocene (c. 34 Ma). The new material hints at an unknown species of the archaic mysticete Llanocetus with a total body length of up to 12 m. The latter is comparable to that of extant Omura's whales (Balaenoptera omurai Wada et al. 2003), and suggests that gigantism has been a re-occurring feature of mysticetes since their very origin. Functional analysis including sharpness and dental wear implies an at least partly raptorial feeding strategy, starkly contrasting with the filtering habit of living whales. The new material markedly expands the size range of archaic mysticetes, and demonstrates that whales achieved considerable disparity shortly after their origin.
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Fossil "ibis bill" is a chimaeroid fish spine...
Federico Lisandro Agnolin, Sergio Bogan and SebastiÃn Rozadilla (2019)Â
Were ibises (Aves, Threskiornithidae) present in Antarctica?
Antarctic Science 31(1): 35-36