Cricetids (Rodentia, Mammalia) from the Late Miocene Yihachi locality of Gansu, China

doi:10.19615/j.cnki.2096-9899.251117

Abstract

Abstract:

Our purpose in this paper is to describe the hamster-like rodents (Cricetidae) from a Late Miocene age site in Linxia Basin, Gansu Province, and discuss their significance for the changing ecology of central Asia. The micromammal site known as Yihachi was introduced previously (Qiu et al., 2023; Qiu and Li, 2023), when its squirrels were discussed in some detail. We take this opportunity to describe the more abundant cricetids. There are four genera, common Nannocricetus and Sinocricetus plus the less abundant living Mesocricetus. A few specimens represent the high-crowned and lophodont Rhinocerodon. The cricetids and other faunal elements indicate an early Late Miocene age, and the pattern of occurrence of the hamster species is consistent with a picture of a changing paleoenvironment due to increasing effects of the East Asia monsoon system. After the disappearance of older and archaic genera, Yihachi represents growing endemism in the Late Miocene of northern China due to increasing seasonal rain and the declining average temperature.

Key words: Yihachi, Linxia, Gansu, Late Miocene, “Liushu” Formation, Cricetidae, taxonomy

摘要：

记述了甘肃临夏盆地晚中新世伊哈池地点的仓鼠类啮齿动物，并讨论了其在中亚生态环境变化中的重要意义。该地点主要产出小哺乳动物遗骸，此前已对化石组合及相关问题做了初步报道，对其中的松鼠类进行了详细的描述和讨论(Qiu et al., 2023; Qiu and Li, 2023)。伊哈池的仓鼠共4属：有常见的微仓鼠(Nannocricetus)和中华仓鼠(Sinocricetus), 动物群中不多见且为现生的中仓鼠(Mesocricetus), 以及只有几件标本为代表的高冠、脊型齿的犀齿鼠(Rhinocerodon)。仓鼠类和其他成员指示了伊哈池动物群晚中新世早期的地质时代，揭示了其种群出现的格局与东亚季风影响加强导致的古环境变化的一致性。伊哈池动物群代表了中国北方地区在晚中新世期间，由于季节性雨水增强和年平均气温下降，随着较古老的属种的消失而出现的一个渐具强烈地方色彩的动物组合。

关键词: 甘肃临夏伊哈池, 晚中新世, “柳树” 组, 仓鼠科, 分类学

CLC Number:

Q915.873

QIU Zhu-Ding, Lawrence J. FLYNN, WANG Ban-Yue, LI Lu. Cricetids (Rodentia, Mammalia) from the Late Miocene Yihachi locality of Gansu, China. Vertebrata Palasiatica, 2026, 64(1): 1-25.

邱铸鼎, 王伴月, 李录. 2026, 64(1): 1-25, 甘肃晚中新世伊哈池地点的仓鼠化石. 古脊椎动物学报.

Figures/Tables 13

Fig. 1 Section of the fossil locality Yihachi

Fig. 2 Molars of Nannocricetus primitivus from Yihachi, Gansu A. l M1 (IVPP V34185.376); B. r M1 (V34185.1); C. l M2 (V34185.377); D. r M2 (V34185.2); E. l M3 (V34185.378); F. r M3 (V34185.3); G. l m1 (V34185.379); H. r m1 (V34185.4); I. l m2 (V34185.380); J. r m2 (V34185.5); K. l m3 (V34185.381); L. r m3 (V34185.6) A-L. occlusal views; A1, G1. lingual views; A2, G2. buccal views

Fig. 3 Size ranges and averages of length and width in the first molars of various species of Nannocricetus from Yihachi, Gansu and other localities in China Measurements of Lantian N. primitivus, N. wuae, Ertemte N. mongolicus and N. qiui are cited from Zhang et al., 2008, 2011; Wu, 1991, and Li et al., 2018, respectively Numbers inside the parentheses are specimen numbers

Fig. 4 Scatter diagrams showing the length and width of the first two molars of Nannocricetus primitivus from Yihachi, Gansu and some other localities in northern China Measurements of specimens from Lantian, Shengou and Baogeda Ula are cited from Zhang et al., 2008, Qiu and Li, 2008, 2016

Table 1 Measurements of molars of Nannocricetus primitivus from Yihachi, Gansu (mm)

Tooth	Length			Width
Tooth	N	Range	Average	N	Range	Average
U-YHC (upper lens)
M1	67	1.60‒1.90	1.71	70	1.02‒1.25	1.15
M2	63	1.22‒1.45	1.33	64	1.02‒1.20	1.11
M3	52	0.90‒1.15	1.03	52	0.90‒1.15	1.01
m1	52	1.45‒1.70	1.59	51	0.95‒1.10	1.03
m2	66	1.20‒1.40	1.30	65	0.95‒1.15	1.07
m3	60	1.10‒1.35	1.21	60	0.85‒1.10	0.98
L-YHC (lower lens)
M1	30	1.65‒1.95	1.78	30	1.05‒1.25	1.18
M2	35	1.20‒1.45	1.34	35	1.05‒1.20	1.13
M3	14	0.92‒1.05	1.00	14	0.92‒1.05	1.00
m1	32	1.45‒1.70	1.56	36	0.95‒1.10	1.01
m2	43	1.15‒1.35	1.28	42	1.00‒1.16	1.07
m3	21	1.05‒1.27	1.19	21	0.90‒1.05	0.98

Fig. 5 Molars of Sinocricetus primus sp. nov. from Yihachi, Gansu A. l M1 (IVPP V34186, holotype); B. r M1 (V34188.1); C. l M2 (V34187.1); D. r M2 (V34188.2); E. l M3 (V34187.2); F. r M3 (V34188.3); G. l m1 (V34188.4); H. r m1 (V34187.3); I. l m2 (V34188.5); J. r m2 (V34187.4); K. l m3 (V34188.6); L. r m3 (V34187.5) A-L. occlusal views; A1, G1. lingual views; A2, G2. buccal views

Fig. 6 Size ranges and averages of length and width in the first molars of Sinocricetus primus sp. nov. from Yihachi, Gansu and other species of the genus in China Measurements of S. zdanskyi from Ertemte, S. progressus from Bilike, and S. major from Gaotege are cited from Wu, 1991; Qiu and Storch, 2000; Li, 2010, respectively Numbers inside the parentheses are specimen numbers

Table 2 Measurements of molars of Sinocricetus primus sp. nov. from Yihachi, Gansu (mm)

Tooth	Length			Width
Tooth	N	Range	Average	N	Range	Average
U-YHC (upper lens)
M1	20	1.80‒2.30	2.09	21	1.10‒1.48	1.33
M2	19	1.35‒1.85	1.59	19	1.15‒1.40	1.31
M3	18	1.15‒1.55	1.39	18	1.05‒1.35	1.24
m1	10	1.65‒2.00	1.89	11	1.10‒1.25	1.19
m2	17	1.40‒1.65	1.57	16	1.05‒1.40	1.27
m3	12	1.20‒1.90	1.55	12	1.00‒1.30	1.17
L-YHC (lower lens)
M1	16	1.80‒2.05	1.93	17	1.12‒1.35	1.27
M2	12	1.34‒1.65	1.47	12	1.15‒1.36	1.25
M3	14	0.92‒1.05	1.00	14	0.92‒1.05	1.00
m1	10	1.56‒1.75	1.69	11	1.00‒1.20	1.08
m2	15	1.32‒1.55	1.44	15	1.05‒1.30	1.18
m3	10	1.32‒1.55	1.43	10	0.97‒1.40	1.12

Fig. 7 Molars of Mesocricetus fengi sp. nov. from Yihachi, Gansu A. l M1 (IVPP V34189, holotype); B. r M1 (V34190.2); C. l M2 (V34190.3); D. l M2 (V34191.1, reversed); E. l M3 (V34190.4); F. r M3 (V34190.5); G. l m1 (V34190.6); H. r m1 (V34190.7); I. l m2 (V34190.8); J. r m2 (V34190.9); K. l m3 (V34190.10); L. r m3 (V34190.11), M. right mandibular fragment with m1-2 (V34190.1) A-M. occlusal views; A1, G1, M1. lingual views; A2, G2, M2. buccal views. Scale bars: + for A-L, * for M

Table 3 Measurements of molars of Mesocricetus fengi sp. nov. from Yihachi, Gansu (mm)

Tooth	Length			Width
Tooth	N	Range	Average	N	Range	Average
U-YHC (upper lens)
M1	4	2.40‒2.70	2.58	5	1.50‒1.75	1.63
M2	5	2.10‒2.25	2. 15	5	1.55‒1.65	1.62
M3	3	1.70‒1.76	1.74	4	1.33‒1.55	1.45
m1	7	2.05‒2.30	2.18	9	1.35‒1.45	1.41
m2	7	1.85‒2.00	1.95	7	1.40‒1.65	1.50
m3	9	1.70‒2.06	1.94	7	1.20‒1.50	1.38
L-YHC (lower lens)
M2	2	1.95‒2.00	1.98	2	1.50‒1.60	1.55

Fig. 8 Molars of Rhinocerodon linxiamys sp. nov. from Yihachi, Gansu A. r M1 (IVPP V34192, holotype, reversed); B. r M1 (V34193.1, reversed); C. l M3 (V34194.1); D. l m1 (V34193.2); E. l m2 (V34194.2). A-E. occlusal views; A1, D1. lingual views; A2, D2. buccal views

Fig. 9 Scatter diagrams showing length and width in the first molars of Rhinocerodon from Yihachi, Gansu and other species of the genus from Kazakhstan and Nei Mongol Measurements of the specimens of the Kazakhstan species are cited from Zazhigin, 2003

Fig. 10 Biostratigraphic ranges of various species of the cricetid genera present in the Yihachi Fauna G. Z. in the China LMS/A column indicates Gaozhuangian; Shading indicates the proposed ages of Yihachi cricetid composition

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