Abstract:

The Linxia Basin, located in Northwest China at the edge of the Tibetan Plateau, preserves a rich fossil record of mammals and birds. Here, we report an exquisitely preserved skeleton representing a new species of small-bodied phasianid from the Linxia Basin, dated to approximately the latest Miocene to Early Pliocene. Gracilisgallus linxia represents the first discovery in China of a taxon closely related to extant grouse and turkey. The new species exhibits a small body size and slender limb bones. Phylogenetic analysis supports its close relationship with extant grouse (Tetraoninae) and turkey (Meleagridinae). The scapula, carpometacarpus, femur, and tarsometatarsus of Gracilisgallus linxia share morphological similarities with its extant relatives, but diagnostic features—such as relatively long spurs on the tarsometatarsus—support its classification as a distinct genus and species, separate from both turkey and grouse. This fossil provides a Late Miocene to Early Pliocene calibration point for the divergence of the turkey—grouse lineages and reveals complex patterns in their radiation across North America and eastern Asia.

Key words: Linxia Basin, Neogene, Galliformes, Phasianidae, Gracilisgallus linxia, phylogenetic analysis, grouse, turkey

摘要：

甘肃临夏盆地位于中国西北部，为青藏高原边缘地区，保存了丰富的新近纪哺乳动物和鸟类化石。报道了一具保存极为精美的小型雉科动物的骨架，该化石产自临夏盆地，年代约为中新世最晚期至早上新世早期。临夏纤骨鸡(新属新种) (Gracilisgallus linxia gen et sp. nov.)体型较小，四肢骨骼纤细，是中国首次发现的与现生松鸡(Tetraoninae)和火鸡(Meleagridinae)关系密切的鸡形目新物种。系统发育分析确认了其与现生松鸡和火鸡密切的亲缘关系。尽管临夏纤骨鸡的肩胛骨、腕掌骨、股骨和跗跖骨在形态上与其现生近缘类群相似，但其跗跖骨上的距相对较长等骨骼特征均支持其作为一个独立于松鸡和火鸡的新属种。该化石为火鸡和松鸡在晚中新世至早上新世的分化提供了关键的内部校准点，并揭示了这一时期该类群在北美和东亚存在复杂的分化模式。

关键词: 临夏盆地, 新生代, 鸡形目, 雉科, 临夏纤骨鸡, 系统发育分析, 松鸡, 火鸡