New exceptionally well-preserved specimens of “Zangerlia” neimongolensis from Bayan Mandahu, Inner Mongolia, and their taxonomic significance

Abstract

Two exceptionally well-preserved specimens of “Zangerlia” neimongolensis provide additional information on the structure of the skull, shell and limbs of this taxon. These specimens show that the carapace is more similar to that of Hanbogdemys than was previously recognized. A PAUP analysis results in a single most parsimonious cladogram in which the type species of Zangerlia, Zangerlia testudinimorpha is separated from other species that have been included in that genus while “Z.” neimongolensis, “Zangerlia” ukaachelys and “Zangerlia” dzamynchondi and Jiangxichelys are grouped together. Both specimens are exceptional in being preserved in a life-like position: one is preserved with the skull in a retracted position; the other with the head and left forelimb both protracted and in a raised position. These positions suggest that they were entombed while still alive. Thus these specimens provide additional examples of rapid burial of vertebrates in the Bayan Mandahu locality, most likely from either by sand storms that dumped massive amounts of sand over a short period of time or by collapse of individuals in burrows.