A large-sized caudal fin of the actinopteryigan Birgeria, from the Middle Triassic (Pelsonian, Anisian) Panxian Fauna in the Upper Member of the Guanlin Formation, Panxian County, Guizhou Province, China is described. It is the first report of Birgeria in the Panxian Fauna and represents the earliest fossil record of Birgeria in China. There are some specialized characters for this specimen in accordance with Bigeria: the speculated large size, narrow scales without ganoine ornament merely covering the posterodorsal portion of the caudal peduncle and the axial lobe of the caudal fin, single neural spine and haemal spine in caudal region, fulcra scales developed on the dorsal margin of the caudal fin, etc, which support the assignment of the current specimen to the genus Birgeria. Moreover, it distinguish from all known Birgeria species in its relatively large size (speculated total length over 2 m), a higher number of hypural (9), fulcras of the ventral margin of the caudal fin more developed and a bigger angle between the posterior margin of upper lobe and that of the lower lobe (>70º), but, a Birgeria sp. instead of a new species of Birgeria is assigned herein due to limited material. Birgeria is a kind of large carnivorous fish exsisting only in the Triassic ocean, which can be found from the Anisian Panxian Fauna to the Carnian Guanlin Fauna. The first appearance of Birgeria in China is later than that in West Tethys in Smithian, Early Triassic.

Ichthyosaurs, firstly appeared at the end of the Early Triassic. The previously reported Ichthyosaurs show very high level of adaptability to life in water, and their osteology shows structural characters that are fully adapted to life in water without any terrestrial characters that can relate them to their terrestrial ancestor. Two specimens are studied, one belonging to Cartorhynchus and the other to Chaohusaurus with embryos found from the Lower Triassic (Olenekian) of Chaohu, Anhui Province, South China. Based on studies of the number of presacral vertebra (i.e. 31), the ratio of snout length to skull length (i.e. 0.35), the ratio of forelimb length to presacral vertebra length (i.e. 0.45), and comparisons of these measurements and morphological characters with the derived Ichthyosaurs, Cartorhynchus is considered to be primitive in structural features and to have an amphibianlike habit. Combined with the analyses of the embryo-bearing specimens of the Early Triassic Chaohusaurus and the Jurassic Stenopterygius, Chaohusaurus appears more derives than Cartorhynchus in body structural characters and is fully adapted to life in water; however, Chaohusaurus retained a head-first birth posture when giving birth to offsprings. Therefore, during the evolution of Ichthyosaurs from terrestrial ancestors to marine types, the adaptive structural characters (such as flipper, and elongate snout) and the adaptive behavioral characters (such as the mode of reproduction) might have evolved in different tempo, and the former changed earlier.