辽宁北票早白垩世义县组松柏类金钱松属(Pseudolarix)的发现及其起源与演化意义

Discovery of Pseudolarix from Lower Cretaceous Yixian Formation in Beipiao of Liaoning and its significance for origin and evolution

报导辽宁北票下白垩统义县组尖山沟层松柏类金钱松属一新种Pseudolarix gaoi sp.nov.和一个新联合种Pseudolarix chilitica(Sun et Zheng)Zheng,com b.nov.,前者是一个保存较好的带叶小枝,具长枝和短枝,长枝又可分为主枝和侧枝,侧枝长短不一,其上着生有许多呈螺旋状排列的桶状短枝;叶在短枝上簇生,线形或披针状线形,扁平,上表面中脉不隆起,下表面沿隆起的中脉有两条气孔带;气孔为单唇式,极副卫细胞为伸长的长方形。后者是以分散保存的Schizolepis式的雌球果和果鳞、Pityospermum式的翅籽、着生于短枝末端上的雄球果以及Pityocladus式的带叶小枝为代表。上述两种松柏类化石可能代表仅幸存于中国南方现生金钱松属单型种Pseudolarix amabilis(Nelson)Rehd.的先驱分子。有一部分Schizolepis式的雌球果可能与金钱松属的起源与演化有关。

A new species of conifer, Pesudolarix gaoi sp. nov. , and a species of new combination Pseudolarix chilitica （Sun et Zheng） Zheng comb. nov. , are reported here. The specimens were collected from Lower Cretaceous Jianshangou fossil-bearing bed of Yixian Formation in Beipiao of Liaoning. The former is a leafy shoots consisting of dwarf and long shoots bearing lateral shoots and short shoots, which is similar in habit to living Pseudolarix. The latter consists of female cone and seed-scale simplex of Sc type, male cones borne on the end of dwarf, and leaf shoots of Pityocladus-type. These coniferous fossils suggest that they might be ancient representative of living Pseudolarix. Some female cones of Schizolepis-type are possibly related to Pseudolarix in origin and evolution.