Abstract: In September 1990, I collected three bird specimens from the Early Cretaceous of Liaoning, China. Among them, the best one (V 9769) has been published and named Cathayornis yandica (Zhou et al., 1992); the second (V 9941), with only a sternum impression, has not been referred to any known taxa yet; and the third (V9770), an incompletely articulated individual, is significantly different from either Cathayornis and Chaoyangia (Hou et Zhang, 1993) from the same site or any other known Early Cretaceous birds. The third specimen is described here as a new genus and species: Boluochia zhengi, and further referred to Enantiornithes as at least four enantiornithine synapomorphies can be recognized in this specimen: (1) intercondylar fossa of tibiotarsus narrow, medial condyle of tibiotarsus with fairly flat anterior margin in distal view; (2) metatarsus IV reduced; (3) slender lateral process of sternum with expanded distal end; and (4) presence of a peculiar dorsal process on proximal ischium. Boluochia is believed to be a new enantiornithine bird from the Early Cretaceous of China, since Cathayornis from the same site had previously been proposed to be included in Enantiornithes (Zhou, in press). Boluochia is distinguished from Cathayornis in many respects, such as (l) skull with hooked bill; (2) presence of a concave surface between main body and nasal process of premaxilla; (3) lateral process of sternum only slightly expanded distally; (4) trochanter of femur relatively developed; and (5) trochleas for digits 2—4 close in height. Finally, comparisons between Boluochia and extant birds in the skull and hindlimb structures also indicate that Boluochia is probably a bird with not only strong perching capability but also somewhat raptorial habit, although the primitiveness of many of its structures rules out the possibility of its being a raptorial bird in strict modern sense.

摘要： 本文记述了在辽宁朝阳地区，早白垩世地层中发现的一种新的小型鸟类。依据它所具有的以下几点特征:(1)胫附骨远端髁间沟窄，远视内髁前缘较为平缓;(2)第四蹠骨相对较为细弱;(3)坐骨近端向背方伸出一个显著突起;(4)胸骨侧突细长，并在远端扩大。本文将其归人反鸟亚纲(Enantiornithes)。此外，依据新材料所特有的，头骨及跗蹠骨远端的结构，不同于其它反鸟亚纲鸟类的特点，本文建立了一鸟类的新属新种:郑氏波罗赤鸟Baluochia zhengi。最后，本文通过对新材料和现生鸟类在爪的形态，头骨结构等方面的比