摘要
前言节肢动物不仅是现代动物界中最为成功的生物类群,在长期演化历史中也一直是非常成功的类群。早期的节肢动物,除三叶虫外,大都骨骼化程度较差,不易保存为化石,只有在非常特异的地质条件下非三叶虫类节肢动物才可能保存成为化石。云南澄江下寒武统筇竹寺组玉案山段下部地层中最近发现了众多非三叶虫类节肢动物化石,这一发现填补了寒武纪早期非骨骼化节肢动物化石记录的缺环,其中部分化石已作了报道(张文堂、侯先光,1985;侯先光,
The preservation of soft parts in fossil is extremely rare. A notable exception is known from the basal Lower Cambrian Yuanshan Member (upper part of the Chiungchussu Formation) at the Maotian hill, Chengjiang, E. Yunnan, where completely soft-bodied groups, soft parts of creatures with resistant exoskeletons, and animals with fragile exoskeletons are beautifully preserved. Arthropods account for the largest part of the Chengjiang fauna in evidence of biomass and numbers of taxa. Information on their taxonomy accumulated in the last few years has resulted in the publications by Zhang and Hou (1985), Hou (1987 a, b, c) and Hou and Sun (1988). In addition, three new species belonging to three new genera are erected for non-trilobite arthropods, which are distinguished from one another by the broadly separate morphology of the exoskeleton; however, their body is unknown. These re Retifacies abnormalis gen. et sp. nov., Acanthomeridion serratum gen. et sp. nov. and Urokodia aequalis gen. et sp. nov., but all of them are rare. The first taxon bears a large, up to 75mm long, elliptically outlined exoskeleton covered with fine reticulate ornaments (Text-fig. 2). In contrast the second one is elongate, consisting of a cephalic shield,10 trunk tergites and a pair of fan-shaped telsons (Text-fig. 4), while the third one bears a relatively small exoskeleton, which consists of a cephalic shield, 14 trunk tergites nd a tail shield of cephalic shield analogy (Text-figs. 9, 10). All the specimens available for the present study were collected from the west (Coll. No. M_2, M_3 and M_4) and northwest (Coll. No. cf_3 and cf_6) slopes of the Maotian hill (Hou, 1987a, text-figs.4,5), and from 3 km southwest of the same hill, near the Dapotou village (Coll. No. Dj1 and Dj2) (Chen et al., 1989a, text-fig. 1). They are embedded in the moderately weathered, greyish-yellow mudstone beds in the lower part of the Yuanshan Member corresponding to the lower part of the Eoredlichia Zone in the trilobite succession. The Yuanshan Member is the
出处
《古生物学报》
CAS
CSCD
北大核心
1989年第1期42-57,共16页
Acta Palaeontologica Sinica
