| Abstract: | Here, we describe a new primitive Erinaceidae species, Oligoechinus lanzhouensis n. gen. n. sp., based on a specimen from late Oligocene strata of the Lanzhou Basin, Gansu Province. Its characteristics are as follows: the M1 width is longer than the length, the metastyle extends far disto-labially, the posterior margin has strong curve and a distinct metaconule that is connected to the protocone by a postprotocrista is located in the centre of the tooth. The posterior arm of the metaconule is poorly developed. In the P4, the pterion of the metastyle is less developed and the metacone is carinate. In addition, O. lanzhouensis has a premolar larger than the canine tooth (P2 > C) and P3 had no molarisation, characters also possessed by Erinaceus. Overall, O. lanzhouensis was similar to Mioechinus based on architectural tooth features, demonstrating a closed genetic relationship. Fossil Erinaceidae are relatively rare before the Miocene. The discovery of O. lanzhouensis provides an important insight into the origin of Mioechinus in China and the early evolution of the Erinaceidae. Our analysis shows that a relatively recent ancestor of Mioechinus had probably existed in the early Oligocene and that O. Lanzhouensis was likely an ancestral type of Mioechinus gobiensis, and its systematic position should be located at a transitional position between Amphechinus and Mioechinus. |
