First Report of Small Shelly Fossils from the Cambrian Miaolingian Limestones (Zhangxia and Hsuzhuang Formations) in Yiyang County, Henan Province of North China

Abstract

Small Shelly Fossils (SSFs) from the Cambrian are widely distributed and well known across different paleocontinents of the world. However, middle Cambrian SSFs from North China Platform have only rarely been documented until now. In this paper, we presented the first report on SSFs from bioclastic and oolitic limestones of the Zhangxia and Hsuzhuang formations of Henan province, North China. The carbonate-hosted fauna includes brachiopods (Micromitra sp., M. modesta, Eoobolus sp., and Schizopholis sp.), helcionellids (Oelandiella accordionata and O. aliciae), hyolithids, Hyolithellus sp., Chancelloria eros, sponge spicules, echinoderm ossicles, and chancelloriid sclerites. In terms of preservation, the brachiopod shell valves of M. modesta appeared to be homogeneous, consisting of tightly packed phosphate grains. Eoobolus sp. is composed of primary layer and secondary baculate, both of which consist of tightly compacted phosphate grains. Schizopholis sp. has multiple-lamellar phosphatized microstructures that distinctly differ from the other brachiopods recovered from the Longwanggou section. A similar multiple-lamellar microstructure was also revealed in conchs of Hyolithellus, with tightly compacted phosphate grains. The argillaceous shell of Oelandiella accordionata and O. aliciae, and the calcitic inner molds of hyolith did not preserve any shell structure. The helcionellids O. accordionata and O. aliciae and the brachiopod M. modesta were reported for the first time from North China. The fauna is most similar to the middle Cambrian faunas of South Australia, in the brachiopod and mollusk components; it is also similar in composition of brachiopods and mollusks to coeval faunas from South China. The new fauna of SSFs in the Yiyang Longwanggou Section indicated that the Hsuzhuang and Zhangxia formations are late Drumian to middle Guzhuangian in age, most likely correlating with the Murrawong Creek Formation of South Australia.

An Eocene conger eel (Teleostei, Anguilliformes) from the Lillebælt Clay Formation, Denmark

“…23) in silicified specimens of Dorispira merino (Runnegar & Jell, 1976) from the Coonigan Formation of New South Wales. Similar structures were reported in Miaolingian material from Utah by Robison (1964) and by Hu et al (2021) from China. Two deep grooves on the internal mould are usually present, but some specimens show four grooves that may even be flanked by a third, discontinuous pair (Fig.…”

“…Most of the other seven families were considered to be gastropods of Subclass Archaeobranchia Parkhaev, Tall specimens identified as Oelandiella cf. accordionata were described from the Tsinghsutung Formation (Cambrian Stage 4) of Guizhou, South China by Yang et al (2012) and from the Miaolingian of Henan Province, North China by Hu et al (2021) Description. Slowly expanding isostrophic cone coiled through half to two thirds of a whorl, with the uniformly curved supra-apical surface traversed by two broad, shallow constrictions (in available material) on the internal mould prior to the latest growth stage.…”

“…2, figs 7, 8) is only slightly coiled and resembles the species described as Helcionella callahani Resser, 1938 from Cambrian Series 2, Stage 4 in the southern Appalachians, USA (Resser 1938), a shell form not known from the present North Greenland collections. Hu et al (2021) assigned Miaolingian (Drumian-Guzhangian) fossils from Henan Province, North China, to Oelandiella accordionata also without reference to Dorispira. The erect shell clearly distinguishes the illustrated specimens from Oelandiella, as discussed by Parkhaev & Demidenko (2010), and illustrated by Rozanov et al (2010) Discussion.…”

First Report of Small Skeletal Fossils from the Upper Guojiaba Formation (Series 2, Cambrian), Southern Shaanxi, South China

“…China consists of tectonically stable platforms such as the South China, North China, Qiadam, and Tarim platforms, along with some orogenic belts and terranes (Figure 1A). The well-developed and continuous Cambrian strata found across these platforms provide extensive material for studying early metazoans [7,9,10,[34][35][36][37][38]. The Dayingcun Section is located near Micang Mountain in Fucheng Town, Nanzheng County, Shaanxi Province, on the northwest margin of the South China Platform (Figure 1B).…”