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The composition and structure of the Yarlung Zangbo Suture Zone (YZSZ) provide important constraints on long‐standing disputes about the evolution of the Neo‐Tethys Ocean and continental collision. The Permian tectonic blocks (mainly composed of limestones and volcanic rocks) are widely distributed in the YZSZ. There are still different understandings about the origin of these blocks and their relationship with the evolution of the Neo‐Tethys Ocean. Here, we report the first reliable palaeomagnetic results of the Permian tectonic blocks in the Gyanyima and Mayum areas, the western segment of the YZSZ. Fossil records and our new zircon U–Pb results provide 254–252 Ma and 249 ± 2 Ma age constraints for the strata in the Gyanyima and Mayum sections, respectively. A total of 109 specimens were subjected to stepwise thermal demagnetizations. Among them, 83 specimens yielded interpretable results. After removing a recent geomagnetic field direction at low to intermediate temperature ranges, characteristic remanent magnetization (ChRM) directions can be isolated from the upper Permian–lower Triassic Gyanyima Formation (Fm). Unblocking temperature spectra of the ChRM indicate magnetite and haematite as the main carriers in the basalt and limestone/andesitic‐basalt samples, respectively. The ChRM passed the fold tests and a reversal test at 95% confidence level, indicating that it is most likely a primary remanence. The tilt‐corrected mean direction for 14 sites is D = 18.0°, I = −14.4°, k = 20.5, and α95 = 9.0°, which corresponds to a palaeolatitude of 7.3°S and a palaeopole at 48.3°N, 233.3°E with A95 = 8.1°. Combining the rock assemblage, palaeomagnetic, palaeontological, and geochronologic data, we conclude that these blocks were most likely seamounts formed in the low‐latitude area of the Neo‐Tethys Ocean. The palaeolatitude and origin of these blocks indicate that the evolution of the Neo‐Tethys Ocean was a complex process interspersed with the development of a series of seamounts and microblocks. [ABSTRACT FROM AUTHOR]

Abstract: We conducted phylogenetic analyses to identify the closest related living relatives of the Xizang and Sichuan hot-spring snakes (T. baileyi and T. zhaoermii) endemic to the Tibetan Plateau, using mitochondrial DNA sequences (cyt b, ND4) from eight specimens, together with sequences from 95 additional caenophidian and five henophidian genera that were downloaded from GenBank. Phylogenetic trees were obtained using Bayesian Inference and Maximum likelihood methods. Results suggest that hot-spring snakes, which are adapted to high and cold environments, were clustered in the monophyletic Xenodontinae. Xenodontinae is one of the largest subfamilies of colubrid snakes, with about 90 genera and more than 500 species known, and are primarily tropical snakes previously thought to be restricted to the New World. Our data failed to provide any evidence that the New World xenodontines diverged from Thermophis and dispersed into the New World, also failed to suggest a colonization of Asia by New World xenodontines by dispersal from the New World. An alternative plausible scenario may be that Thermophis and the New World xenodontines evolved independently in Asia and America, respectively, after the divergence of their common ancestor. The divergence of the two species in Thermophis was caused by the barrier of the Hengduan Mountains, and the speciation had almost occurred when Tibetan Plateau attained present elevation. [Copyright &y& Elsevier]