POSSIBLE MARKUELIA EMBRYOS FROM THE EARLY CAMBRIAN (TERRENEUVIAN) YANJIAHE FORMATION IN HEBEI PROVINCE OF SOUTH CHINA
Phosphatized embryos of the genus Markuelia, likely a scalidophoran ecdysozoan, have been reported from lower Cambrian to lower Ordovician rocks in Siberia, South China, Australia, and Laurentia. Markuelia fossils consist of an annulated wormlike body folded into a sphere, and a smooth outer envelope or “chorion.”
We have extracted Markuelia-like embryos from a fossiliferous bituminous limestone member of the lower Cambrian Yanjiahe Formation in western Hubei Province of South China. These fossils are spherical and about 200 micrometers in diameter. They are poorly preserved, with a phosphatic envelope and a calcitic interior. Nonetheless, some specimens show a folded wormlike structure with annulations, features characteristic of Markuelia. There are some differences between the Markuelia-like fossils found in this study and those in previous studies. Markuelia specimens in previous studies are 300 micrometers in diameter or larger, except when taphonomically shrunk. Markuelia-like fossils in this study fall in a narrow range around 200 micrometers in diameter, with no evidence of desiccation. Previously reported Markuelia fossils are always pervasively phosphatized, whereas in our specimens have only the chorion is phosphatized and the interior is preserved in calcite (hence the poor preservation of internal structures). The discovery of new Markuelia-like fossils from the Yanjiahe Formation represents a new locality and a new taphonomic mode of this important group of animal embryo fossils.