Thursday, September 11, 2014

[PaleoMammalogy • 2014] Three New Jurassic euharamiyidan species Reinforce early Divergence of Mammals

Arboreal Mammals in a Jurassic forest.
The three animals on the left side represent the three new species of euharamiyidan mammals. The other two represent a gliding species and another euharamiyidan, respectively, that were reported earlier.
reconstruction: Zhao Chuang

The phylogeny of Allotheria, including Multituberculata and Haramiyida, remains unsolved and has generated contentious views on the origin and earliest evolution of mammals. Here we report three new species of a new clade, Euharamiyida, based on six well-preserved fossils from the Jurassic period of China. These fossils reveal many craniodental and postcranial features of euharamiyidans and clarify several ambiguous structures that are currently the topic of debate. Our phylogenetic analyses recognize Euharamiyida as the sister group of Multituberculata, and place Allotheria within the Mammalia. The phylogeny suggests that allotherian mammals evolved from a Late Triassic (approximately 208 million years ago) Haramiyavia-like ancestor and diversified into euharamiyidans and multituberculates with a cosmopolitan distribution, implying homologous acquisition of many craniodental and postcranial features in the two groups. Our findings also favour a Late Triassic origin of mammals in Laurasia and two independent detachment events of the middle ear bones during mammalian evolution.

Xianshou songae, mouse-sized animal was a tree dweller in the Jurassic forests and belonged to an extinct group of Mesozoic mammals called Euharamiyida.
reconstruction: Zhao Chuang

Figure 1: The holotypes of three euharamiyidan species.
 a, Holotype (LDNHMF2001) of Shenshou lui. b, Holotype (IVPP V16707A) of Xianshou linglong. c, Holotype specimen (BMNHC-PM003253) of Xianshou songae.

Mammalia Linnaeus, 1758

Allotheria Marsh, 1880

Euharamiyida (new clade)

Shenshou lui gen. et sp. nov. Bi, Wang, Guan, Sheng and Meng

Etymology. Shen, from pinyin of the Chinese word, meaning deity, divinity or cleaver; shou, from pinyin of the Chinese word for creature, animal or beast; specific name after Lu Jianhua, the collector of the holotype.

Eleutherodontidae Kermack et al., 1998

Xianshou gen. nov. Wang, Meng, Bi, Guan and Sheng

Etymology. Xian, from pinyin of the Chinese word meaning celestial being or immortal.

Xianshou linglong sp. nov. Wang, Meng, Bi, Guan and Sheng

Etymology. linglong, from pinyin of the Chinese word, meaning ‘exquisite’, and also after the town name Linglongta where the specimen came from.

Xianshou songae sp. nov. Meng, Guan, Wang, Bi and Sheng

Etymology. The specific name is after Rufeng Song, the collector of the holotype specimen.

 Bi, Shundong; Wang, Yuanqing; Sheng, Xia and Meng, Jin 2014. Three New Jurassic euharamiyidan Species Reinforce early Divergence of Mammals. Nature. doi:

Fossils of New Squirrel-like Species Support Earlier Origin of Mammals