Ben Creisler
Recent avian papers:
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Two fragmentary remains of giant birds from uppermost Paleocene deposits at the Petit-PÃtis locality at Rivecourt (Oise, northern France) are described. One is an isolated zygapophysis of a very large bird, identified as belonging to the neognath Gastornis sp. The other one is an incomplete posterior cervical vertebra referred to the palaeognath Remiornis. Both taxa also occur together at classical Thanetian localities in the Reims area farther east. The specimens from Rivecourt show that right at the end of the Paleocene the largest terrestrial tetrapods in Europe were herbivorous giant birds. While Gastornis survived into the Eocene and dispersed from Europe to North America and Asia, Remiornis appears to have become extinct at the end of the Paleocene.
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Free pdf:
SHEN Wei, Thomas A. STIDHAM & LI Zhi-Heng (2021)
Reexamination of the oldest pigeon (Aves: Columbidae) from Asia: Columba congi from the Early Pleistocene of Zhoukoudian, Beijing, China.
Vertebrata PalAsiatica (advance online publication)
DOI: 10.19615/j.cnki.1000-3118.210304
http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/202103/t20210305_5970138.html
Columba congi is an extinct species that was described as part of the Early Pleistocene (~1.7 Ma) fauna from locality 12 of the UNESCO Zhoukoudian or âPeking Manâ site in Beijing, China. Only four partial humeri of the original type series of 11 bones can be located, and the features present in those specimens do not support the original diagnosis. However, our study and redescription shows that the straight and flat margin of the pneumotricipital fossa rim (in ventral view) and the relative distal position of the dorsal supracondylar tubercle may support the continued recognition of C. congi as a valid extinct species. Columba congi appears to be the oldest fossil of Columba in Asia, and it lived during a warmer and wetter period of time of the Pleistocene with a forested Zhoukoudian. Further study of pigeons from all localities at Zhoukoudian should help to resolve questions about pigeon biogeography and evolution, including possibly the time and center of origin of the globally distributed C. livia.
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Also:
Iodineâbased contrasting agents for computed tomography (CT) have been used for decades in medicine. Agents like Lugol's iodine enhance the contrasts between soft tissues and mineralized (skeletal) tissues. Because a recent study on extant avian heads showed that iodineâethanol (I2E) is a better contrast enhancer overall than the standard Lugol's iodine, here, we tested if I2E could also enhance the CT contrasts of two fossilized skeletal tissues: bone and calcified cartilage. For this, we used a partial ankle joint from an extinct pheasant from the Late Miocene of Northwest China (Linxia Basin). The preâstaining CT scans showed no microstructural details of the sample. After being immersed into a solution of 1% I2E for 8 days and scanned a second time, the contrasts were drastically enhanced between the mineralized tissues (bony trabeculae and calcified cartilage) and the sediments and minerals inside vascular spaces. After three other stainingâscanning cycles in 2%, 3%, and 6% I2E solutions, the best contrasts were obtained after immersion in 6% I2E for 7 days. Energy Dispersive Spectroscopy showed that iodine was preferentially absorbed by the mineralized tissues and the minerals in the vascular spaces, but not by the sediments. This method not only effectively increased the contrasts of two different fossilized skeletal tissues, it was also nonâdestructive and reversible because part of the fossil was successfully deâstained after a few days in pure ethanol. These preliminary results indicate that iodineâethanol has the potential to be used widely in vertebrate paleontology to improve CT imaging of fossilized tissues.