摘要
湖北蒲圻车埠和大冶金山店下侏罗统武昌组的双壳类化石可划分为2个组合:武昌组中部Qiyangia-Apseudocardinia组合和武昌组上部Hubeiconcha-Kija(Wuchangella)组合.前者时代为早侏罗世中晚期;后者暂归于早侏罗世最晚期.文中描述2新属1新亚属以及15新种.
The fossil bivalves were collected from the Lower Jurassic Wuchang Formation in southeastern Hubei, including 1 new family, 2 new genera, 1 new subgenus and 15 new species.
The bivalve fauna of the Wuchang Formation may be subdivided into the Qiyangia-Apseudocardinia assemblage in the middle part and the newly recognized Hubeiconcha-Kija (Wuchangella) assemblage in the upper part of the formation. The former was first found from the Dongyuemiao member of the Ziliujing Formation in Sichuan; it is referret to the Lower Jurassic and stratigraphically equivalent to the Qiyangia-Hunanella assemblage in Hunan and Jiangxi. The latter nearly consists of all new species; based on its statigraphic position above the Qiyangia-Apseudocardinia assemblage-zone and below the Middle Jurassic Eolamprotula-Psilunio assemblage-zone in the present area, it is considered as of the latest Early Jurassic age, although its time range has not yet been confirmed within a large area.
DESCRIPTION OF NEW FAMILY, GENERA AND SUBGENUS
Superfamily Pseudocardiniacea Martinson, 1961
Family Kijidae Ch. Kolesnikov, 1977
Genus Kija Lebedev, 1958, emend. nov.
Type species Kija tjazhinensis Lebedev, 1958 Diagnosis Shell small to medium, not exceeding 49mm in length in known species, ovate, subrotund or trigonal in form; test thin, with ligament external and opisthodetic; each valve with 2 anterior and 2 posterior lateral teeth, without carina; sturdy transverse ridges visible on the anterior lateral teeth, keeping to the inner side in LV; surface unornamanted except for growth lines and rugae.
Remarks Lebedev's (1958) diagnosis about the number of laterals in RV is wrong, probably due to a slip of the pen. The writer has emended the number of laterals by examining his text-figure (Fig. 7).
Distribution Jurassic; former USSR and South China.
Kija (Wuchangella) subgen, nov.
Type species Kija (Wuchangella) hubeiensis subgen. et sp. nov.
Diagnosis Shell medium-sized, about 28-49mm in length, ovate, elliptical or trigonal; 2 anterior and 2 posterior lateral teeth in each valve, with anterior lateral tooth keeping to the inner side in LV; transverse ridges sturdy; carina absent; anterior laterals short, extending posteriorly not beyond the umbo and anteriorly to anterior dorsal end; posterior laterals long, extending from umbo to posterior end.
Remarks In Kija (Kija), anterior laterals extend posteriorly beyond the umbo and anteriorly beyond the anterior dorsal end; while posterior laterals extend posteriorly beyond the posterior dorsal end. These features are different in Kija (Wuchangella).
Distribution Lower Jurassic; South China.
Dayeconcha gen. nov.
Type species Dayeconcha elongata gen. et sp. nov.
Diagnosis Shell about 7-14mm long, elliptical, ovate or trigonal; test thin, with ligament extenal and opisthodetic; umbo prominently rising above the hinge margin; carina absent; each valve with 2 anterior and 2 posterior lateral teeth; shell moderately inflated; shell surface marked with growth lines and rugae.
Distribution Lower Jurassic; South China.
Hubeiconcha gen. nov.
Type species Hubeiconcha, triangularis gen. et sp. nov.
Diagnosis Shell about 10-25mm long, subrotund or trigonal in shape. Test thin, with ligament external and opisthodetic; umbo small, generally low, prominently rising above hinge margin. According to the following dental formula:
?? cardinal 1 trigonal, with sturdy transverse ridges, present at posterior end of anterior lateral A I; teeth 3a and 3b joining under the umbo and tooth 2b weak, sloping down to posterior dorsal end. Regular transverse grooves occurring in all laterals. Posterior laterals starting from posterodorsal end and above posterior muscle scar, almost with no space between cardinals and posterior lamellars. Anterior muscle scar ovate in shape, with irregular striae; posterior muscle scar fusiform. Pallial line simple. Shell surface unornamanted except for growth lines and rugae.
Remarks The new genus differs from other genera in the Heterodont in having triangular tooth 1 with sturdy transverse grooves and almost no space left between the cardinals and posterior laterals.
Distribution Lower Jurassic; South China.
出处
《古生物学报》
CAS
CSCD
北大核心
1993年第6期725-739,809-812,共15页
Acta Palaeontologica Sinica
关键词
武昌组
早侏罗世
双壳类
化石
nonmarine Bivalvia
Lower Jurassic
Wuchang Formation
Southeastern Hubei
China
