A new cranium of Metacervocerus longdanensis (Cervidae, Mammalia) and the genus Metacervocerus in China

doi:10.19615/j.cnki.2096-9899.251118

Abstract

Abstract:

This study documents a skull of the large cervid Nipponicervus longdanensis from the Early Pleistocene (~2.6-2.1 Ma) of Longdan, Gansu, China. Morphological comparisons indicate that N. longdanensis exhibits the type of “adaptive” distal fork (anterior tine smaller and oriented along the beam) that differs from the type species Nipponicervus praenipponicus, while it is aligned with Metacervocerus Dietrich, 1938, necessitating reclassification as Metacervocerus longdanensis. The cranium exhibits posteriorly inclined pedicles demonstrating phylogenetic affinity with M. elegans (Nihewan Basin) and M. rhenanus (Europe), while derived features including a shortened neurocranium, rostrally tapered basioccipital, and duplicated P4 protocone distinguish it as an advanced lineage within the genus. Character assessments reveal that Metacervocerus is potentially paraphyletic because Metacervocerus? shansius and Metacervocerus? punjabiensis retain plesiomorphic conditions (elongated braincase, simple P4 morphology), while they exhibit pronouncedly erected pedicles and lyrated antler beams, suggesting a divergent lineage from Metacervocerus longdanensis. Previously published isotopic data (δ¹³C = −10.9‰ ± 0.9‰, δ¹⁸O = −7.5‰ ± 0.9‰, n = 4) indicate a semi-open habitat and a browsing-to-mixed feeding ecology of M. longdanensis. This revision resolves persistent taxonomic uncertainties in Eurasian Cervinae while elucidating East Asia’s biogeographic significance in driving cervid morphological radiation during the Plio-Pleistocene transition.

Key words: Longdan, Gansu, Pleistocene, Cervidae, Metacervocerus, Nipponicervus, feeding ecology

摘要：

报道了产自甘肃龙担早更新世(约2.60-2.1 Ma)的一件鹿科头骨标本。其保存的角形态特征与龙担日本鹿(Nipponicervus longdanensis)相符。分类修订确认龙担日本鹿具有 “适应型” 的鹿角(远端分枝中前枝小于后枝且延伸方向与主枝相同), 与 “非适应型” 的日本鹿属型种前日本鹿(Nipponicervus praenipponicus)不同，而与后枝角鹿(Metacervocerus Dietrich, 1938)属相同，故将其重新命名为龙担后枝角鹿(Metacervocerus longdanensis)。该头骨具有后倾的角柄，显示其与泥河湾盆地的秀丽后枝角鹿(M. elegans)及欧洲的莱茵后枝角鹿(M. rhenanus)存在系统发育亲缘关系；而缩短的脑颅、前端逐渐收缩的基枕骨及较复杂的P4原尖等衍征则表明其属于该属内的进步类群。属内各种的特征对比显示Metacervocerus可能为并系群：山西后枝角鹿(Metacervocerus? shansius)和旁遮普后枝角鹿(Metacervocerus? punjabiensis)保留一些祖征状态(如较长的脑颅、简单的P4形态), 但具有显著直立的角柄和琴形的角冠主枝，暗示其与M. longdanensis存在演化分歧。已发表的同位素数据(δ¹³C = -10.9‰, δ¹⁸O = -7.5‰)表明M. longdanensis栖息于半开放环境，具有以食叶到混合食性的生态类型。解决了欧亚鹿亚科长期存在的分类学问题，同时阐明了东亚晚上新世-早更新世时期鹿科演化的生物地理学意义。

关键词: 甘肃龙担, 更新世, 鹿科, 后枝角鹿(Metacervocerus), 日本鹿(Nipponicervus), 食性生态

CLC Number:

Q915.876

WANG Shi-Qi, MA Jiao, FU Jiao, BAI Wei-Peng. A new cranium of Metacervocerus longdanensis (Cervidae, Mammalia) and the genus Metacervocerus in China. Vertebrata Palasiatica, 2026, 64(1): 59-73.

王世骐, 马姣, 付娇, 白炜鹏. 2026, 64(1): 59-73, 甘肃龙担后枝角鹿(Metacervocerus longdanensis) (鹿科，哺乳纲)头骨新材料及中国后枝角鹿属厘定. 古脊椎动物学报.

Figures/Tables 6

Fig. 1 Location map of the Longdan fossil site and the topology of the Linxia Basin

Fig. 2 New cranium of Metacervocerus longdanensis (IVPP V34161) from Longdan, the Early Pleistocene A-C. cranium with antlers, in rostodorsal (A), lateral (B), and caudoventral (C) views; D, E. cranium in dorsal (D) and ventral (E) views; F. cheek teeth (P4-M3) in occlusal view; G. petrosal bone in lateroventral view

Fig. 3 Crania and antlers of various Cervinae A, B. Metacervocerus longdanensis, HMV 1241, the type left antler from Longdan, Gansu, China, Early Pleistocene, in rostral (A) and medial (B) views, from Qiu et al. (2004:pl.32, fig.1); C, D. Metacervocerus? punjabiensis, AM 19911, the type cranium from Chandigarh, India (Late Pliocene?), in rostral (C) and lateral (D) views; E, F. Metacervocerus? shansius, HMV 2074, a cranium from Longdan, Gansu, China, Early Pleistocene, in rostral (E) and lateral (F) views; G. Nipponicervus trassaerti, the type cranium, from Teilhard de Chardin and Trassaert (1937:pl.5, fig.4), from Yushe Basin (Late Pliocene?), in rostral view; H, I. Axis porcinus, NACRC 37409, a cranium (living specimen), in rostral (H) and lateral (I) views; J. comparison of directions of antler in lateral view: AP. Axis porcinus, ML. Metacervocerus longdanensis, MP. Metacervocerus? punjabiensis, MS. Metacervocerus? shansius, also see the black lines ahead of the pedicles

Table 1 Cranial and antler measurements of Metacervocerus longdanensis (IVPP V34161) (mm)

Measurements	Left/Median	Right
Distance between pedicles	52.5
Distance between supra-orbital foramina	82.1
Pedicle base distance (distance of the anterior-most parts of the pedicles)	97.4
Pedicle medio-lateral diameter	49	43.9
Pedicle antero-posterior diameter	30.5	35.0
Pedicle inner length	49.8	41.6
Pedicle outer length	70.1	65.1
Length of frontal+parietal	171.6
Length of between bregma and inion	84.0
Length of frontal	115.3
Length of molar row (measured at alveoli)	64.1	62.0
Orbit diameter (parallel to tooth row)		50.6
Width across orbits (maximum width of frontals)	142.4
Width of braincase	104.6
Width of basioccipital anterior	41.5
Width of basioccipital posterior	36.8
Width of palate, measured at M3	63.2
Width of occipital	112.8
Length of antler below brow tine to the bottom of burr	37.6	41.8

Table 2 Upper cheek teeth measurements of Metacervocerus longdanensis (IVPP V34161), right side (mm)

	Length	Width	Height
P4	13.6
M1	20.4	21.7	12.4
M2	23.3	24.1	16.7
M3	21.7	22.3	16.4

Fig. 4 Biometric comparisons of cervine cranium (A) and pedicle (B) among species of Metacervocerus, Nipponicervus and some living cervines Data sources: Metacervocerus longdanensis and Metacervocerus? shansius (Longdan), this article; Nipponicervus trassaeti and Metacervocerus? shansius (Yushe), Teilhard de Chardin and Trassaert (1937); Metacervocerus pardinensis and M. rhenanus, Heintz (1970); Metacervocerus? punjabiensis, Croitor and Robinson (2020); living species of Axis and Rusa, IOZ collection

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