中文摘要：

本文研究了辽西北票四合屯脊椎动物化石产地附近土城子组三段的孢粉组合，共计32属9种及25未定种。孢粉组合以松柏类两气囊花粉占绝对优势，三缝孢子含量低。当前组合中见有Cicatricosisporites , Lygodiois-porites , Jiaohepollis ,Rugubivesiculites等早白垩世特征分子，同时未见被子植物花粉，推测其时代为早白垩世早期，这与同位素测年结果相一致。这一孢粉组合以松柏类两气囊花粉的高含量及Classopollis的低含量为特征，明显不同于以往报道的土城子组的孢粉组合，却与辽西地区义县组下部层段的孢粉组合非常相似，表明辽西地区土城子组沉积的末期区域植物群面貌与义县组已无本质差别，尽管两套地层在岩相和沉积上差异明显。这一发现提示我们，土城子组的横向对比对于正确重建中国北方侏罗纪-白垩纪早期的沉积演化史十分关键，有必要在后续研究中进一步开展其他地区土城子组的孢粉等生物地层及区域间的对比工作。

英文摘要：

Pollen and spore assemblages from the uppermost part of the Third Member of the Tuchengzi Formation underlying the vertebrate-bearing beds of the Yixian Formation at Sihetun, Beipiao in the western Liaoning Province, Northeast China are studied in this paper. They comprise 32 genera, 9 species and 25 indeterminate species, in which the coniferous bisaccate pollen dominate the assemblages, and trilete spores are subordinate in abundance. The coe- xistence of Cicatricosisporites, L ygodioisporites, Jiaohepollis and Rugubivesiculites convinces an Early Cretaceous age for these pollen and spore assemblages. Meanwhile, the absence of angiosperm pollen grains implies a more confi- dant age constraint of the early Early Cretaceous. This is in accordance with previous isotopic dating results of the Tuchengzi Formation from comparable horizons. The present palynologieal assemblages are distinct from previous palynological records of the Tuchengzi Formation by the extreme abundance of bisaccate pollen and scarcity of Clas- sopollis, hut more comparable to that from the lower part of the Yixian Formation in the vicinity of western Liaoning. This implies that the palaeovegetation at western Liaoning area did not suffer from significant transfer from the upper Tuchengzi Formation through the lower Yixian Formation though it is distinct in lithology and sedimentology. The finding also reminds us that it is necessary to do further palynostratigraphic correlation of the Tuchengzi Formation in different areas of North China for approaching a proper reconstruction of the Jurassic Cretaceous basin evolution history.