四川自贡大山铺蜀龙动物群——简报Ⅴ 两栖类

本文对扁头中国短头鲵(新属新种) (Sinobrachyops placenticephalus gen. et sp. nov.) 的形态特征和分类位置进行简述.标本得自著名的恐龙化石产地——自贡大山铺,产出时代为中侏罗世.中国短头鲵是目前迷齿类中在地史上最年轻的一个属.它的发现使迷齿类在地球上生存时代的上限推移到中侏罗世.

A MIDDLE JURASSIC LABYRINTHODONT (SINOBRACHYOPS PLACENTICEPHALUS GEN. ET SP. NOV,) FROM DASHANPU, ZIGONG, SICHUAN PROVINCE

A new Labyrinthodant, Sinobraehyops placenticephalus gen. et sp. nov. known from the Lower Shaximiao Formation (Middle Jurassic) is described. It is based on an excellently-preserved skulll and mandibles, plus severul vertebrae refered to the same form. The specimens were found in Dashanpu dinosaurian Quarry, Zigong, Sichuan Province. Text-figures 1 and 2, respectfully reveal the dorsal and palatal aspects of the skull, which is shert and parabolic in outline. The external nares are almost confluent, and are set at the tip. The orbits are placed anteriorly. The lateral line grooves behind the orbits are lost; however, those bordering the medial side of the arbits are observable. The sutures are indistinct. mostly concealed by the hard matrix. The otic notch and the tabular horns are absent. The Paraspbenaid is well-developed, extending forward as a cultriform process to meet the vetoers. The interpterygoid vacuity is very large A pair of tusks is present in each of these palatal bones: i.e. Palatine, vomer and ectoptevygoid. Sinobrachyops is referred to known members of the family Brachyopidae on account of the similarity in having parabolic skull with anteriorly-situated orbits, in the upturning of lateral wings of the pterygoid, and the posterior positon of the occipital condyles behind the levels of the supraoccipitals. The Labyrinthodents are thought to be extinct at the Late Triassic-Early Jurassic time. In this connection, the discovery of Sinobrachyops from the Middle Jurassic of China is important for it represents the last record of Labyrinthodont anywhere in the world.