New Fossil Pig Found From the Upper Miocene Deposits of the Linxia Basin, China

Oct 26, 2014     Email"> PrintText Size

Chleuastochoerus is a small late Miocene-early Pliocene fossil pig from North Asia, mainly discovered from the upper Miocene “Hipparion Red Clays” of northern China. With both primitive palaeochoerid-like characters and some progressive character like in modern Suinae, the systematic position of Chleuastochoerus was highly controversial. In a paper published October 13 in the journal of Zootaxa 3872(5), Dr. HOU Sukuan and Prof. DENG Tao from the Institute of Vertebrate Paleontology and Paleoanthropology of Chinese Academy of Sciences (IVPP) reported a new species, Chleuastochoerus linxiaensis, from the upper Miocene deposits of the Linxia Basin, Gansu Province, China, and found it is a basal taxon of the subfamily Hyotheriinae rather than a member of Suinae, helping better understand the systematics and evolutionary history of this genus.

The Linxia Basin is located in the transitional zone between the Tibetan and Loess plateaus. The new specimens are found from the middle-upper part of the Liushu Formation to the base of the Hewangjia Formation, which consists of light yellowish brown carbonate-cemented siltstones with thin intercalated mudstones and marls.

Most of the reported specimens of Chleuastochoerus were found from northern China since the genus Chleuastochoerus being erected in 1928, and were included into a single species, Chleuastochoerus stehlini, until a new genus, Chleuastochoerus tuvensis being reported from the Asiatic Russia in 2009. The systematic position of Chleuastochoerus was highly controversial, which was assigned to either the subfamily Hyotheriinae or the subfamily Suinae.

In recent years, abundant specimens of Chleuastochoerus have been collected from the Neogene deposits of the Linxia Basin, Gansu Province, China, including male, female, and juvenile individuals. Two morphotypes can easily be recognized on the basis of the cranium and tooth morphology, one bearing a relatively short facial region and simple cheek teeth, the other having a relatively long facial region and more complicated cheek teeth. The first kind resembles the type species C. stehlini, whereas researchers described the second type as a new species, Chleuastochoerus linxiaensis, representing another lineage of this genus.

In order to evaluate the phylogenetic relationships of Chleuastochoerus with respect to the other genus of the family Suidae, researchers performed a cladistic analysis with a matrix including 41 taxa and 133 morphological characters, and the final result supports to place Chleuastochoerus in the subfamily Hyotheriinae as a relatively basal taxa rather than a member of Suinae.

This work was supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences, the State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS), the Ministry of Science and Technology of China, and the Key Deployment Project of Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.

Fig.1 Cranium of Chleuastochoerus linxiaensis (holotype)(Image by HOU Sukuan)

 

Fig. 2 Mandible of Chleuastochoerus linxiaensis (Image by HOU Sukuan)

 

Fig.3 Cladogram of Suoidea(Image by HOU Sukuan)