对晚始新世古蒙语鼠相似种(啮齿目：壮鼠科)的综合研究

doi:10.19615/j.cnki.2096-9899.250620

摘要/Abstract

摘要：

内蒙古四子王旗白音敖包地区新发现一保存较为完整的啮齿类化石，材料包含门齿、颊齿及头后骨骼。运用多种研究手段对其开展综合研究。根据形态对比，这一新化石被归入壮鼠科蒙语鼠属并鉴定为古蒙语鼠相似种(Hulgana cf. H. ertnia)。对其门齿釉质微观结构进行分析，结果显示为典型的散系釉质结构。骨组织学分析指示该标本为一年轻个体，这一结果也与其颊齿发育阶段以及磨蚀程度相符。新标本跟骨的几何形态测量学分析结果和股骨与指骨的骨组织学证据均支持蒙语鼠为一种擅奔跑的地栖型啮齿类，同时具备一定掘穴能力，与部分现生仓鼠及地松鼠等相似。

关键词: 内蒙古白音敖包, 晚始新世, 蒙语鼠属, 几何形态测量学, 运动方式, 釉质微观结构, 骨组织学

Abstract:

A relatively well-preserved rodent fossil, including its incisors, cheek teeth, and postcranial skeleton, was collected from the Baiyin Obo in Siziwang Banner, Nei Mongol. A multifaceted research approach was undertaken in this study to conduct a comprehensive analysis on the newly discovered specimen. Based on a morphological comparison, the new specimen was identified as Hulgana cf. H. ertnia within the Ischyromyidae family. Incisive enamel microstructure analysis revealed the typical pauciserial enamel structure of Hulgana. Bone histological analysis indicates that the specimen represents a juvenile individual, which is consistent with the ontogenetic stage indicated by dental developmental stage and wear pattern. The application of geometric morphometrics to the calcaneus and bone histology of the femur and phalanx further substantiates the taxonomic classification of Hulgana as a terrestrial and cursorial rodent, exhibiting a degree of fossorial ability. This classification is analogous to that of certain extant cricetids and ground squirrels.

Key words: Baiyin Obo, Nei Mongol, Late Eocene, Hulgana, geometric morphometrics, locomotion, enamel microstructure, bone histology

中图分类号:

Q915.873

李岚馨, 李茜. 对晚始新世古蒙语鼠相似种(啮齿目：壮鼠科)的综合研究. 古脊椎动物学报, 2025, 63(3): 189-209.

LI Lan-Xin, LI Qian. Comprehensive research on Late Eocene Hulgana cf. H. ertnia (Rodentia: Ischyromyidae). Vertebrata Palasiatica, 2025, 63(3): 189-209.

图/表 9

Fig. 1 Materials of Hulgana cf. H. ertnia from the Baiyin Obo, Nei Mongol, China A. IVPP V33668.1, left M1-2 with fragmentary maxilla and palate; B. V33668.2, right M2; C. V33668.3, right M1 with root of P4, fragmentary right maxilla, jugal and palate; D. V33668.4, left m3; E. V33668.5, left m2; F. V33668.6, right m2

Fig. 2 Morphology of left calcaneus (IVPP V33668.7) (A) and right navicular in Hulgana cf. H. ertnia (V33668.8) (B) from the Baiyin Obo, Nei Mongol, China Bones shown in dorsal (A1, B3), ventral (A2), lateral (A3), medial (A4), proximal (B1) and distal (B2) views Abbreviations: ast. astragalar facet; cacu. calcaneocuboid articulation facet; cb. calcaneal body; cff. calcaneal groove for tendon or flexor fibularis muscle; cnl. calcaneonavicular ligament; ct. calcaneal tuber; dpt. distal plantar tubercle; ect. ectocuneiform facet; ef. ectal facet; gtpb. groove for tendon of peroneus brevis muscle; gtpl. groove for tendon of peroneus longus muscle; lpct. lateral process of calcaneal tuber; mes. mesocuneiform facet; mpct. medial process of calcaneal tuber; php. plantar heel process; pp. peroneal process; su. sustentaculum tali with sustentaculum facet

Table 1 Measurements of cheek teeth of Hulgana cf. H. ertnia and H. ertnia (mm)

		Hulgana cf. H. ertnia (V33668.1-6)			H. cf. H. ertnia Li and Li, 2023			H. ertnia Dawson, 1968
		n	range	mean	n	range	mean	n	range	mean
P4	L				1	3.15	3.15	2	3.50-3.90	3.70
	W				1	3.85	3.85	2	4.60-4.80	4.70
M1	L	2	3.42-3.63	3.53	7	3.40-3.70	3.53	2	4.10-4.40	4.25
	W	2	3.71-3.76	3.74	7	3.75-4.75	4.14	2	4.80	4.80
M2	L	2	3.62-3.71	3.67	2	3.35-3.55	3.45	2	3.70-3.90	3.80
	W	2	4.04-4.13	4.09	1	4.45	4.45	2	5.00-5.20	5.10
M3	L				1	3.40	3.40
	W				1	4.00	4.00
dp4	L				1	3.20	3.20
	W				1	2.60	2.60
p4	L				3	3.50-3.95	3.65	1	3.90	3.90
	W				4	3.00-3.40	3.18	1	3.90	3.90
m1	L				1	-	-	2	3.70-4.20	3.95
	W				1	-	-	2	3.90-4.30	4.10
m2	L	2	3.94-4.02	3.98	2	4.15-4.20	4.18	2	3.90-4.30	4.10
	W	2	3.47-3.61	3.54	2	3.75	3.75	2	4.10-4.40	4.25
m3	L	1	4.28	4.28	1	4.20	4.20	1	4.80	4.80
	W	1	3.65	3.65	1	3.50	3.50	1	4.60	4.60

Fig. 3 Results of principal component analysis of 15 calcaneal measurements for 17 taxa Circles mark 3 different known ecological types (terrestrial, arboreal, semiaquatic) of the 16 taxa Results support Hulgana cf. H. ertnia as a generally robust terrestrial ecomorph Colors for boxplots: highlighted red for Hulgana cf. H. ertnia; firebrick for terrestrial taxa; gold for generalists; deepskyblue for arboreal taxa

Fig. 4 PCA loading plot of calcaneal morphometrics showing variable contributions to principal components Note that percentage of explained variances is approximate

Fig. 5 SEM micrographs of transverse and longitudinal sections of upper incisive Schmelzmuster of Hulgana cf. H. ertnia (uncoded incisive specimen) from Baiyin Obo In transverse sections, EDJ is to the bottom while OES is to the top; in longitudinal sections, EDJ is to the bottom while the tip of the incisor is to the left A. transverse section; B. close-up view of transverse section; C. longitudinal section; D. close-up view of longitudinal section. Abbreviations: EDJ. enamel-dentine junction; HSB. Hunter-Schreger bands; IPM. interprismatic matrix; OES. outer enamel surface; P. prism; PE. portio externa; PI. portio interna; PLEX. prismless external layer

Fig. 6 SEM micrographs of transverse and longitudinal sections of lower incisive Schmelzmuster of Hulgana cf. H. ertnia (uncoded incisive specimen) from Baiyin Obo In transverse sections, EDJ is to the bottom while OES is to the top; in longitudinal sections, EDJ is to the bottom while the tip of the incisor is to the right A. transverse section; B. close-up view of transverse section; C. longitudinal section; D. close-up view of longitudinal section. Note that PLEX (prismless external layer) is hardly seen in the lower incisor Abbreviations see Fig. 5

Fig. 7 Histological features evident in femur of Hulgana cf. H. ertnia (V33668.9) from Baiyin Obo A. whole cross-section of the femur under normal light with posterior side at the top, showing suspected linea aspera; B. partial cross-section under normal light, showing Haversian bone, medullary cavity (MC), primary osteon (PO), resorption cavity (RC) and secondary osteon (SO); C. whole cross-section of the femur under polarized light with posterior side at the top, displaying resorption lines (RL); D. partial cross-section under polarized light, showing compact coarse cancellous bone (CCCB), drifted secondary osteon, Haversian bone, lamellar bone (LB), Sharpey's fiber, trabecular bone (TrB), woven bone (WB) and vascular canal (VC) Same plotting scale is utilized separately for A and C as well as for B and D

Fig. 8 Histological features evident in phalanx of Hulgana cf. H. ertnia (V33668.10) from Baiyin Obo A. whole cross-section of the phalanx under normal light with dorsal side at the top; B. partial cross-section under normal light, showing medullary cavity (MC), primary osteon (PO), secondary osteon (SO), Sharpey's fiber, vascular canal (VC) and suspective vascular notch (VN?); C. whole cross-section of the phalanx under polarized light with dorsal side at the top, displaying resorption cavity (RC), resorption line (RL) and Haversian bone; D. partial cross-section under polarized light, showing compact coarse cancellous bone (CCCB), endosteal bone (ELB), lamellar bone (LB), periosteal bone (PLB) and woven bone (WB) The style of usage for plotting scales is the same as in Fig. 7

参考文献 50

[1]	Adams N F, Rayfield E J, Cox P G, et al. 2019. Functional tests of the competitive exclusion hypothesis for multituberculate extinction. R Soc Open Sci, 6(3): 181536
[2]	Bhat M S, Chinsamy A, Parkington J, 2019. Long bone histology of Chersina angulata: interelement variation and life history data. J Morphol, 280(12): 1881-1899
[3]	Candela A M, Munoz N A, García-Esponda C M, 2017. The tarsal-metatarsal complex of caviomorph rodents: anatomy and functional-adaptive analysis. J Morphol, 278(6): 828-847 DOI PMID
[4]	Chen Z, Pei X, Song J, et al. 2023. Systematics and evolutionary history of the genus Micromys (Mammalia: Rodentia: Muridae). Mamm Biol, 103(4): 389-403
[5]	Danell K, 1996. Introductions of aquatic rodents: lessons of the muskrat Ondatra zibethicus invasion. Wildl Biol, 2(3): 213-220
[6]	Dashzeveg D, Meng J, 1998. A new Eocene cylindrodont rodent (Mammalia, Rodentia) from the Eastern Gobi of Mongolia. Am Mus Novit, 3253: 1-18
[7]	Dawson M R, 1968. Oligocene rodents (Mammalia) from East Mesa, Inner Mongolia. Am Mus Novit, 2324: 1-12
[8]	Dawson M R, Wang B Y, 2001. Middle Eocene Ischyromyidae (Mammalia: Rodentia) from the Shanghuang fissures, Southeastern China. Ann Carnegie Mus, 70(3): 221-230
[9]	Emry R J, Thorington Jr R W, 1984. The tree squirrel Sciurus (Sciuridae, Rodentia) as a living fossil. In: Eldredge N, Stanley S M eds. Living Fossils:Casebooks in Earth Sciences. New York: Springer. 23-31
[10]	Feng A Y T, Himsworth C G, 2014. The secret life of the city rat: a review of the ecology of urban Norway and black rats (Rattus norvegicus and Rattus rattus). Urban Ecosyst, 17: 149-162
[11]	Flynn L J, Wahlert J H, 1978. SEM study of rodent incisors: preparation and viewing. Curator, 21(4): 303-310
[12]	Flynn L J, Jacobs L L, Cheema I U, 1986. Baluchimyinae, a new ctenodactyloid rodent subfamily from the Miocene of Baluchistan. Am Mus Novit, 2841: 1-58
[13]	Fostowicz-Frelik Ł, Li Q, Ni X J, 2018. Oldest ctenodactyloid tarsals from the Eocene of China and evolution of locomotor adaptations in early rodents. BMC Evol Biol, 18(1): 1-13
[14]	Fostowicz-Frelik Ł, López-Torres S, Li Q, 2021. Tarsal morphology of ischyromyid rodents from the middle Eocene of China gives an insight into the group's diversity in Central Asia. Sci Rep, 11(1): 11543 DOI PMID
[15]	Ginot S, Hautier L, Marivaux L, et al. 2016. Ecomorphological analysis of the astragalo-calcaneal complex in rodents and inferences of locomotor behaviours in extinct rodent species. PeerJ, 4: e2393
[16]	Harrison D L, 2004. A new genus and species of ‘paramyid' rodent (Rodentia: Ischyromyidae) from the Creechbarrow Limestone Formation (late Middle Eocene) of Dorset, England. Cainoz Res, 4(1/2): 51-60
[17]	Koenigswald W V, Sander P M, 1997. Glossary of terms used for enamel microstructures. In: Koenigswald W V, Sander P M eds. Tooth Enamel Microstructure. Rotterdam: Balkema. 267-280
[18]	Korth W W, 1988a. Paramys compressidens Peterson and the systematic relationships of the species of Paramys (Paramyinae, Ischyromyidae). J Paleontol, 62(3): 468-471
[19]	Korth W W, 1988b. The rodent Mytonomys from the Uintan and Duchesnean (Eocene) of Utah, and the content of the Ailuravinae (Ischyromyidae, Rodentia). J Vert Paleont, 8(3): 290-294
[20]	Kumar R, Borthakur D, Nomani K, et al. 2023. Third trochanter of femur: evolutionary and biomechanical significance. Acta Sci Anat, 3(1): 1-4
[21]	Larimer S C, Fritzsche P, Song Z, et al. 2011. Foraging behavior of golden hamsters (Mesocricetus auratus) in the wild. J Ethol, 29: 275-283
[22]	Li C K, Wilson R W, Dawson M R, et al. 1987. Chapter 3. The origin of rodents and lagomorphs. In: Genoways H H ed. Current Mammalogy Vol 1. New York: Springer Science + Business Media. 97-108
[23]	Li Q, Li Q, 2023. The Sharamurunian rodent fauna in the Erlian Basin, Nei Mongol, China. Vert PalAsiat, 61(1): 43-70
[24]	Li Q, Meng J, 2013. Eocene ischyromyids (Rodentia, Mammalia) from the Erlian Basin, Nei Mongol, China. Vert PalAsiat, 51(4): 289-304
[25]	Luckett W P, Hartenberger J L, 2013. Evolutionary Relationships Among Rodents:A Multidisciplinary Analysis. New York: Springer Science + Business Media. 1-721
[26]	Marchetti L, MacDougall M J, Buchwitz M et al, 2024. Origin and early evolution of vertebrate burrowing behaviour. Earth-Science Rev, 250: 104702
[27]	Martin T, 1993. Early rodent incisor enamel evolution: phylogenetic implications. J Mamm Evol, 1: 227-254
[28]	Martin T, 1994. African origin of caviomorph rodents is indicated by incisor enamel microstructure. Paleobiology, 20(1): 5-13
[29]	Martin T, 1999. Evolution of incisor enamel microstructure in Theridomyidae (Rodentia). J Vert Paleont, 19(3): 550-565
[30]	Martin T, 2004. Evolution of incisor enamel microstructure in Lagomorpha. J Vert Paleont, 24(2): 411-426
[31]	Montoya-Sanhueza G, Chinsamy A, 2017. Long bone histology of the subterranean rodent Bathyergus suillus (Bathyergidae): ontogenetic pattern of cortical bone thickening. J Anat, 230(2): 203-233 DOI PMID
[32]	Netter F H, 2022. Netter Atlas of Human Anatomy:Classic Regional Approach. 8th ed. Philadelphia: Elsevier. 1-712
[33]	Prufrock K A, Ruff C B, Rose K D, 2021. Locomotor behavior and body mass of Paramys delicatus (Ischyromyidae, Rodentia) and commentary on other early North American paramyines. J Mamm Evol, 28: 435-456 DOI
[34]	Qi T, 1987. The middle Eocene Arshanto fauna (Mammalia) of Inner Mongolia. Carnegie Mus Nat Hist, 56: 1-73
[35]	Ray S, Mukherjee D, Bandyopadhyay S, 2009. Growth patterns of fossil vertebrates as deduced from bone microstructure: case studies from India. J Biosci, 34: 661-672
[36]	R Core Team, 2024. R: A language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing. URL: https://www.R-project.org/
[37]	Reznik G, Reznik-Schüller H, Mohr U, 1979. Clinical Anatomy of the European Hamster(Cricetus cricetus L). London: Castle House Publications. 1-135
[38]	Rinderknecht A, Blanco R E, 2008. The largest fossil rodent. Proc R Soc B: Biol Sci, 275: 923-928
[39]	Rose K D, Chinnery B J, 2004. The postcranial skeleton of Early Eocene rodents. Bull Carnegie Mus Nat Hist, 36: 211-244
[40]	Samuels J X, Van Valkenburgh B, 2008. Skeletal indicators of locomotor adaptations in living and extinct rodents. J Morphol, 269(11): 1387-1411 DOI PMID
[41]	Samuelson M M, 2022. Rodentia morphology. In: Vonk J, Shackelford T K eds. Encyclopedia of Animal Cognition and Behavior. Cham: Springer International Publishing. 6088-6090
[42]	Sobral G, 2022. Rodentia life history. In: Vonk J, Shackelford T K eds. Encyclopedia of Animal Cognition and Behavior. Cham: Springer International Publishing. 6073-6082
[43]	Stalheim-Smith A, 1984. Comparative study of the forelimbs of the semifossorial prairie dog, Cynomys gunnisoni, and the scansorial fox squirrel,Sciurus niger. J Morphol, 180(1): 55-68 PMID
[44]	Tong Y S, 1997. Middle Eocene small mammals from Liguanqiao basin of Henan Province and Yuanqu basin of Shanxi Province, central China. Palaeontol Sin, 26: 1-256
[45]	Tong Y S, Dawson M R, 1995. Early Eocene rodents (Mammalia) from Shandong Province, People's Republic of China. Ann Carnegie Mus, 64: 51-63
[46]	Wahlert J H, 1968. Variability of rodent incisor enamel as viewed in thin section, and the microstructure of the enamel in fossil and recent rodent groups. Breviora, 309: 1-18
[47]	Wang B Y, Zhai R J, Dawson M R, 1998. Discovery of Ischyromyinae (Rodentia, Manmalia) from the Middle Eocene of North China. Vert PalAsiat, 36(1): 1-12
[48]	Wang Y Q, Meng J, Beard C K, et al. 2010. Early Paleogene stratigraphic sequences, mammalian evolution and its response to environmental changes in Erlian Basin, Inner Mongolia, China. Sci China Earth Sci, 53: 1918-1926
[49]	Wang Y Q, Meng J, Jin X, 2012. Comments on Paleogene localities and stratigraphy in the Erlian basin, Nei Mongol, China. Vert PalAsiat, 50(3): 181-203
[50]	Wood A E, 1962. The early Tertiary rodents of the family Paramyidae. Trans Am Philos Soc, 52(1): 3-261