Reappraisal of some perissodacyl fossils from the Middle Eocene of the Lijiang Basin, Yunnan, China with a revision of tapiroid Diplolophodon

doi:10.19615/j.cnki.2096-9899.220721

Abstract

Abstract:

The Lijiang Fauna from the Lijiang Formation of Lijiang, western Yunnan, was dominated by 13 species of perissodactyl fossils, and its age ranged from Irdinmanhan to Sharamurunian Asian Land Mammal Ages (ALMA) according to previous research. Based on reanalysis of some perissodactyls from the Lijiang Fauna, it is suggested here that Rhodopagus yunnanensis is a junior synonym of Lijiangia zhangae, which is similar to Lophiohippus and placed in Anchilophini within the Palaeotheriidae. The enigmatic and scarce Lunania is here regarded as a palaeothere rather than a chalicothere based on its morphological similarities with Paranchilophus, and Lophiohippus probably represents the upper dentitions of Lunania. Furthermore, deperetellid Diplolophodon is revised and comprised of three species: D. similis, D. lunanensis, and D. xiangshanensis (comb. nov.). Teleolophus xiangshanensis from the Lijiang Formation is reassigned to Diplolophodon xiangshanensis. The revised perissodactyls from the Lijiang Fauna are comparable to those from the Rencun Member of the Hedi Formation of the Yuanqu Basin, and its age is confined to Sharamurunian ALMA.

Key words: Lijiang Fauna, Yunnan, Middle Eocene, Anchilophini, Lijiangia, Deperetellidae, Diplolophodon

摘要：

云南西部丽江盆地中始新世丽江组中的哺乳动物群以奇蹄类占据优势，之前已经报道了13个种，丽江动物群的时代被认为从伊尔丁曼哈期延续到沙拉木伦期。重新研究了丽江盆地的部分奇蹄类化石，认为Rhodopagus yunnanensis是Lijiangia zhangae的次同物异名，而后者具有和Lophiohippus相似的特征，所以将Lijiangia置于古兽科(Palaeotheriidae)的Anchilophini, 而不是最初有疑问地归入的蹄齿犀科(Hyracodontidae)。Lunania也代表了一类和Paranchilophus相似的古兽而不是爪兽；如果Lophiohippus的正型标本代表了Lunania的上臼齿，那么Lophiohippus是Lunania的次同物异名。通过对戴氏貘科(Deperetellidae) Diplolophodon的厘定，认为该属包括了3个种：D. similis, D. lunanensis 和D. xiangshanensis (新组合), 其中丽江盆地的Teleolophus xiangshanensis应归入到Diplolophodon xiangshanensis。丽江盆地的奇蹄类化石组合和垣曲盆地河堤组任村段的奇蹄类化石相似性最高，且丽江动物群的时代应限于中始新世沙拉木伦期。

关键词: 云南丽江盆地, 中始新世, Anchilophini, Lijiangia, Deperetellidae, Diplolophodon

CLC Number:

Q915.877

BAI Bin. Reappraisal of some perissodacyl fossils from the Middle Eocene of the Lijiang Basin, Yunnan, China with a revision of tapiroid Diplolophodon. Vertebrata Palasiatica, 2023, 61(1): 26-42.

白滨. 2023, 61(1): 26-42, 云南丽江盆地中始新世奇蹄类化石再研究及Diplolophodon的修订. 古脊椎动物学报.

Figures/Tables 7

Fig. 1 Paleogene mammal fossil localities in the Yunnan Province (modified from GS(2017)1267)

Fig. 2 Maxillae and upper molars of Lijiangia zhangae from the Lijiang Formation of Lijiang Basin, Yunnan A. right maxilla with P4-M2 (IVPP V9908, holotype) in occlusal (A1), lingual (A2), and labial (A3) views;B. left maxilla with DP2-DP4 and M1 (V9909, holotype of ‘Rhodopagus yunnanensis’) in occlusal (B1), labial (B2), and lingual (B3) views; C. left maxilla with broken M1 and M2 (V 9909.1) in occlusal view;D. left M1/2 (V9909.3) in occlusal (D1), labial (D2), and lingual (D3) views;E. right M3 (V9909.2) in occlusal (E1), labial (E2), and lingual (E3) views

Fig. 3 Left mandible of Lunania youngae (IVPP V 9910) from the Lijiang Formation of the Lijiang Basin, Yunnan, in occlusal (A), labial (B), and lingual (C) views

Fig. 4 Mandibles of Diplolophodon similis A. Left mandible with p2-4 (IVPP V9901) from the Lijiang Formation of Lijiang Basin, Yunnan, in occlusal (A1), lingual (A2), labial (A3), and longitudinal section (A4) views; B-E. right mandible with talonid of the dp3, dp4, and developing p3-4 in the socket (V12471) from the Hedi Formation of Yuanqu Basin: B. mandible with dp3-4 in occlusal (B1), lingual (B2), and labial (B3) views with p3-4 in the socket; C. labial view of p3; D. occlusal view of the p3 and labial view of the p4 in situ; E. occlusal view of the p4 Abbreviations: co. cristid obliqua; hylod. hypolophid; palod. paralophid; phcd. posthypocristid; prlod. protolophid

Fig. 5 Left mandible of Diplolophodon similis (=D. qufuensis, holotype, SDM 84008) from the Huangzhuang Formation of Qufu, Shandong, in occlusal (A), labial (B), and lingual (C) views

Table 1 Measurements of Diplolophodon similis, D. lunanensis, and D. xiangshanensis (mm)

		D. similis						D. lunanensis			D. xiang
		PMUM 3440	RV 37105	V9904, 9904.1, 3	V 9904.4^*	V 5103^*	SDM 84008^*	GMC V 29 (Left)	GMC V 31^*	GMC V 713^*	V 9903, 9903.1^*
P1/p1	L								4.5^#
	W								4^#
	L/W								1.13
P2/p2	L		9.0			9			9^#
	W		10.8			5			5.2^#
	L/W		0.83			1.80^#			1.73^#
P3/p3/dp3	L	9.0^#	9.0	9.7		12		10	12.8		11.5
	W	11.5^#	12.3	11.9		7.5^#		12.8	8.1		6.8
	L/W	0.78^#	0.73	0.82		1.60^#		0.78	1.58		1.69
P4/p4/dp4	L	9.4	9.5			10.5	11.3	10.7	11.7	10.9	10.0
	W	13.4	13.0			8.5	8.0	14.3	10.0	10.4	8.0
	L/W	0.70	0.73			1.24	1.41	0.75	1.17	1.05	1.25
P1-4/p1-4	L					36.1			38.0
P2-4/p2-4	L		27.5			31.5			33.5
P3-4/p3-4/dp3-4	L	18.4^#	18.5			22.5		20.7	24.5		21.5
M1/m1	L	10.5			13.0	12.5	13.0			11.4	10.5
	W	14.0^#				9.5^#	9.6			11.5	9.2
	L/W	0.75^#				1.32^#	1.35			0.99	1.14
M2/m2	L	12.5		14.4	14.0	13	15.0			13.8	11.8
	W	15.5^#		16.3	11.5	11.5^#	10.9			13.6	9.0
	L/W	0.81^#		0.88	1.22	1.13^#	1.38			1.01	1.31
M3/m3	L	13.0		14.2	15.8	14.1				16.4
	W	16.4		16.7	12.0	11.8				13.3^#
	L/W	0.79		0.85	1.32	1.19				1.23^#
M1-3/m1-3	L	35.5			41.7	39.6				40.6

Fig. 6 Diplolophodon xiangshanensis from the Lijiang Formation of Lijiang Basin, Yunnan A-E. mandible with dp3-m1 and talonid of dp2 (IVPP V9903, holotype) in occlusal (A), labial (B), occlusolabial (C), lingual (D), and longitudinal section (E) views; F. right m2 (V9903.1) in occlusal (F1), labial (F2), and lingual (F3) views

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