AndrÃs SolÃrzano, MÃnica NÃÃezâFlores, Oscar InostrozaâMichael & CristiÃn E. HernÃndez (2019)
Biotic and abiotic factors driving the diversification dynamics of Crocodylia.
Palaeontology (advance online publication)
doi:
https://doi.org/10.1111/pala.12459https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12459Data archiving statement:
Data for this study are available in the Dryad Digital Repository:
https://doi.org/10.5061/dryad.sb5844cSpecies diversity patterns are governed by complex interactions among biotic and abiotic factors over time and space, but are essentially the result of the diversification dynamics (differential speciation and extinction rates) over the longâterm evolutionary history of a clade. Previous studies have suggested that temporal variation in global temperature drove longâterm diversity changes in Crocodylia, a monophyletic group of large ectothermic organisms. We use a large database of crocodylian fossil occurrences (192 spp.) and body mass estimations, under a taxic approach, to characterize the global diversification dynamics of crocodylians since the Cretaceous, and their correlation with multiple biotic and abiotic factors in a Bayesian framework. The diversification dynamic of crocodylians, which appears to have originated in the Turonian (c. 92.5 Ma), is characterized by several phases with high extinction and speciation rates within a predominantly low longâterm mean rate. Our results reveal longâterm diversification dynamics of Crocodylia to be a highly complex process driven by a combination of biotic and abiotic factors which influenced the speciation and extinction rates in dissimilar ways. Higher crocodylian extinction rates are related to low body mass disparity, indicating selective extinctions of taxa at both ends of the body mass spectrum. Speciation rate slowdowns are noted when the diversity of the clade is high and the warm temperate climatic belt is reduced. Our finding supports the idea that temporal variations of body mass disparity, selfâdiversity, and the warm climate belt size provided more direct mechanistic explanations for crocodylian diversification than do proxies of global temperature.
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YI Jian & LIU Jun (2019)
Pareiasaur and dicynodont fossils from upper Permian of Shouyang, Shanxi, China.
Vertebrata PalAsiatica (advance online publication)
DOI: 10.19615/j.cnki.1000-3118.191121
http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201911/t20191121_5439657.htmlFree pdf:
http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201911/P020191121386792311929.pdfChinese Permian tetrapods have been studied for decades. Many dicynodont fossils were reported from Xinjiang and Nei Mongol, only several pareiasaur species were reported in Shanxi (North China), where no dicynodonts have been reported. In this paper, a pareiasaur specimen and a dicynodont specimen are reported from the Shangshihezi Formation and the Sunjiagou Formation of Shouyang, Shanxi respectively. The pareiasaur specimen is more similar to Honania than Shihtienfenia based on iliac morphology. This suggests that the element of the Jiyuan Fauna (Honania Assemblage Zone) also occurs in the Shangshihezi Formation of Shanxi. The dicynodont fossil, an incomplete skull, is referred to Cryptodontia, and is probably the first representative of a new subclade within Cryptodontia in China.