重庆武隆早更新世地层中发现巨猿化石
Gigantopithecus blacki discovered in the Early Pleistocene strata of Wulong, Chongqing
通讯作者: 黄万波,研究员,主要从事古人类及第四纪哺乳动物研究。E-mail:huangwanbo@sina.com
收稿日期: 2023-08-29 修回日期: 2023-12-27
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Received: 2023-08-29 Revised: 2023-12-27
作者简介 About authors
胡海虔,博士研究生/高级工程师,主要从事第四纪哺乳动物及地层学研究。E-mail:
梅子湾大洞是重庆市武隆区白马镇的一处水平溶洞,新近发现了9枚步氏巨猿(Gigantopithecus blacki)牙齿和大量其他哺乳动物化石。经初步研究,梅子湾大洞巨猿的牙齿化石尺寸偏小、龋齿率高、中老年个体比例大,属于早期的步氏巨猿类型。伴生动物群的多个物种也曾在重庆巫山龙骨坡、广西柳城巨猿洞、贵州毕节扒耳岩和广西崇左百孔洞及布兵盆地吹风洞等产地出现,表明梅子湾大洞巨猿动物群的时代为早更新世早期。该地点为重庆地区继巫山龙骨坡遗址以来的第2个巨猿化石点,其发现扩大了长江中上游流域巨猿化石的分布范围,增添了早更新世巨猿地理分布点,在南北纵向分布上填补了重庆巫山龙骨坡与贵州毕节扒耳岩之间的地理分布空白。长江中上游巨猿化石的再次发现,对巨猿及其动物群的演化、绝灭、地理分布和环境背景等相关问题的研究具有重要的意义。
关键词:
The fossil materials studied in this paper, dominated by well-preserved isolated cheek teeth, were unearthed from a horizonal limestone cave named the Meiziwan Cave (29°25′22″N, 107°30′42″E, elevation 589 m asl) in Baima Town of Wulong District, Chongqing Municipality, China. Three premolars (right P4, right p3 and left p4) and six molars (two left M3s, two left m1, left m2 and right m3) were interpreted as Gigantopithecus blacki. Measurements and comparison indicate that giant ape specimens from the Meiziwan Cave are characterized by small sizes and high proportion of dental caries and with adult and old adult to be the majority, representing the primitive form of G. blacki. The deposits in the cave are mainly calcareous clay mixed with karst breccias, bearing abundant mammalian tooth fossils. The faunal association, consisting of at least six orders, fourteen families, seventeen genera, and eighteen species, coincides with those found in the Longgopo site in Wushan County, Chongqing Municipality, the Gigantopithecus cave in Liucheng County and the Baikong Cave in Chongzuo City and the Chuifeng Cave in Bubing basin, Guangxi Zhuang Autonomous Region (Guangxi ZAR) as well as the Pa’eryan Cave in Bijie City, Guizhou Province in light of the special components of the initial stage of the Early Pleistocene, for example, small-sized G. blacki, Hystrix magna, Sinomastodon yangziensis, Stegodon huananensis, Ailuropoda microta, Ursus thibetanus primitinus, Equus cf. yunnanensis, Hesperotherium sinense, Tapirus sanyuanensis, Sus xiaozhu, S. peii and Cervavitus ultimus. G. blacki become larger through time from the Early Pleistocene to the Middle Pleistocene due to the comparison of tooth measurements. In addition to G. blacki, increase of body size can be found in giant panda, tapir and black bear. Considering occurred in the Mid-Pleistocene climate transition, the tendency can be thought to be bound up with prominent climate transition and ecosystem changes, corresponding to the hypothesis of the Bergman’s Rule that endothermy animals grow larger as the climate cools.
The Meiziwan Cave is one more G. blacki locality in Chongqing, situated within the area between the Longgupo site in Wushan, Chongqing and the Pa’eryan Cave in Bijie, Guizhou. The presence of G. blacki in the Meiziwan Cave enriches the localities found near the upper and middle reaches of the Yangtze River and broadens the biogeographic distribution ranges, highlighting the significance of the evolution, extinction, paleogeographic distributions, and paleoecosystem of the Gigantopithecus fauna. Fortunately, given the abundance of karst pits, fissures and caves in the area from 30° to 18° latitudes in southern China, further investigations, excavations and research will potentially contribute to figuring it out.
Keywords:
本文引用格式
胡海虔, 黄万波, 魏光飚, 代辉, 熊璨, 何树兴, 姜涛.
HU Haiqian, HUANG Wanbo, WEI Guangbiao, DAI Hui, XIONG Can, HE Shuxing, JIANG Tao.
步氏巨猿(Gigantopithecus blacki)是灵长目人猿超科的一个长期备受关注的物种,代表了体型最大的灵长动物。最早在1935年由荷兰古生物学家孔尼华(von Koenigswald GHR)发现于香港中药铺[1]。此后,在广西大新、柳城、武鸣、巴马、崇左、田东,湖北建始,重庆巫山,贵州毕节,以及海南昌江等多个地区洞穴或裂隙均发现了丰富的步氏巨猿化石,材料包括4件不完整下颌骨和1000余枚牙齿[2⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓-24]。研究显示,步氏巨猿最早出现在早更新世初期,以广西柳城巨猿洞、重庆巫山龙骨坡、贵州毕节扒耳岩和广西崇左百孔洞、吹风洞为代表[2,3,7,11,12,15⇓-17]。学界普遍认为步氏巨猿灭绝于中更新世(距今约为29.5~21.5万年)[19],末现位的产地包括广西武鸣布拉利山洞、崇左合江洞和一线天洞[5,20,21]。近年来的研究显示,从早更新世初期到中更新世以来,步氏巨猿的颊齿尺寸呈增大趋势[6,22]。
本文报道的武隆梅子湾大洞,是重庆地区迄今发现的第2个步氏巨猿化石地点。考虑到该地点巨猿及其动物群对研究中国南方第四纪以来哺乳动物迁徙、演化与古环境重建的重要意义,特此报道。
1 地理及地质背景
1.1 地理位置
图1
图1
重庆武隆梅子湾大洞
A.洞穴剖面图 the profile view of the cave;B.洞穴平面图 the plane view of the cave showing the excavated area;
C.沉积地层剖面图 the stratigraphic profile of the deposits;D.洞口照片 the photograph of the cave entrance
Fig.1
The Meiziwan Cave in Wulong District, Chongqing
1.2 地质背景
2022年,重庆市地质调查院、重庆市地矿局208地质队和重庆自然博物馆对梅子湾大洞进行了多次调查,并完成了13个探方的试掘工作。经调查,早在1967-1968年当地农民就在梅子湾大洞挖掘“龙骨”,导致原生地层破坏极其严重,仅在洞穴深部保存着面积较小的化石露头。然而彼时挖掘“龙骨”在洞室厅地表留下了大量次生堆积物,包括角砾岩块、卵石和化石碎屑,本文视为一个地层单元。据此,武隆梅子湾洞堆积地层可划分为3个地层单元(图1: C-a)。
1.2.1 第1堆积单元
本堆积单元分布范围限于洞底,为挖掘“龙骨”的遗留物。为查明其物质结构及厚度,以T3探方(2×2×3.2 m)出露层序为其标志,自上而下可区分为4层(图1: C-a):
1.次生堆积土。质地疏松,含大量挖掘“龙骨”残留的哺乳动物化石牙齿、骨块和灰岩角砾,与下覆地层为假整合接触。厚30 cm。
2.浅褐色砂质黏土夹石灰岩角砾,局部胶结,不含化石。厚170 cm。
3.浅褐色钙质胶结砂土,局部夹石灰岩角砾,不含化石。厚20 cm。
4.褐色砂质黏土,结构稳定,不含化石。厚>100 cm。
1.2.2 第2堆积单元
出露地点在洞穴深部,距洞口约65 m,岩性为砂质黏土含石灰岩角砾,钙质胶结。整体色调深灰,局部褐黄。靠近洞壁或缝隙呈现碳酸盐类物质富集层或方解石晶体。试掘出土的哺乳动物化石有:硕豪猪(Hystrix magna)、小种大熊猫(Ailuropoda microta)、扬子中华乳齿象(Sinomastodon yangziensis)、裴氏猪(Sus peii)和最后祖鹿(Cervavitus ultimus)等。这些属种与第1单元次生堆积出土的硕豪猪、小种大熊猫、扬子中华乳齿象、裴氏猪、最后祖鹿等面貌完全吻合,证实挖掘“龙骨”的地层系本堆积单元。可见厚度200 cm(图1: C-b)。
1.2.3 第3堆积单元
出露地点在洞穴深部,第2堆积单元下方。岩性为浅褐色砂质土,上部砂粒度细且含零星石灰岩角砾和卵石,局部胶结。下部颗粒略粗,色调略浅,不含化石。可见厚度超过240 cm(图1: C-c)。
2 材料与方法
牙齿解剖术语遵循张颖奇等研究中国南方巨猿化石时使用的术语[6],化石测量均采用游标卡尺进行测量,精度为0.1 mm,照片使用Canon数码相机进行拍摄,相关图件使用Photoshop CS6和Coreldraw X4软件进行处理。
迄今,梅子湾大洞出土了9枚巨猿牙齿和大量伴生哺乳动物牙齿化石。所有巨猿牙齿都来自第2堆积单元,包括3枚上颊齿(右P4,CYMW001;左M3,CYMW002;左M3,CYMW003)和6枚下颊齿(右p3,CYMW004;左p4,CYMW005;右m1,CYMW006;右m1,CYMW007;左m2,CYMW008;右m3,CYMW009),其中CYMW002、CYMW004、CYMW006和CYMW008采集自T2探方,CYMW001、CYMW003、CYMW009采集自T3探方,CYMW005采集自T4探方,CYMW007采集自T13探方。除1枚右p3(CYMW004)前尖基部局部缺失、1枚右m1(CYMW007)仅保留颊侧部分齿冠以外,其余齿冠均完好保存。
3 巨猿牙齿
3.1 标本描述
测量结果如表1所示。
表1 梅子湾大洞巨猿牙齿测量值
Tab.1
| 序号No. | 化石材料Fossil materials | 研究编号Catalog Number | 长Mesiodistal length (MD) | 宽Buccolingual breadth (BL) | 高Height of the crown (H) | 长宽指数MD/BL ratio | 粗壮度(长•宽)Occlusal area (L·b) |
|---|---|---|---|---|---|---|---|
| 1 | 右P4 | CYMW001 | 14.8 | 20.9 | 14.0 | 70.8 | 309.3 |
| 2 | 左M3 | CYMW002 | 15.9 | 18.2 | 11.4 | 87.4 | 289.4 |
| 3 | 左M3 | CYMW003 | 16.2 | 18.2 | >10.5 | 89.0 | 294.8 |
| 4 | 右p3 | CYMW004 | >14.0 | 12.6 | 13.4 | >111.1 | >176.4 |
| 5 | 左p4 | CYMW005 | 16.2 | 19.4 | 13.8 | 83.5 | 314.3 |
| 6 | 右m1 | CYMW006 | 18.9 | 17.9 | 12.6 | 105.6 | 338.3 |
| 7 | 右m1 | CYMW007 | 16.7 | / | 9.9 | / | / |
| 8 | 左m2 | CYMW008 | 22.5 | 20.1 | 11.2 | 111.9 | 452.3 |
| 9 | 右m3 | CYMW009 | 16.1 | 19.3 | 14.3 | 83.4 | 310.7 |
3.1.1 上齿系
上第4前臼齿(P4): 高冠,宽大于长,齿冠面呈卵圆形(图2: A)。仅发育2个主尖,前尖较原尖高大,二尖在近中侧被一个粗大的横脊相连,从而将中沟分割为一个较短的细缝形近中凹和较长细缝形中谷。前尖舌侧与原尖唇侧基部均被多个细沟横向分割多个小瘤突,前尖舌侧基部瘤突较原尖唇侧基部瘤突更为粗大。
图2
图2
梅子湾大洞巨猿牙齿
A. 右P4,CYMW001;B. 左M3,CYMW002; C. 左M3,CYMW003;D. 右p3,CYMW004; E. 左p4,CYMW005;
F. 右m1,CYMW006; G. 右m1,CYMW007;H. 左m2,CYMW008;I. 右m3,CYMW009
Fig.2
G. blacki teeth from the Meiziwan Cave
上第3臼齿(M3): 齿冠面呈梯形,高冠,前宽大于后宽,原尖最大,前尖次之,后尖与次尖稍小,但几乎等大,前尖最高,其余三尖几乎等高(图2: B, C)。前附尖微弱发育,近中凹细长,而跟座谷较短,两侧边缘发育轻微褶皱。前、后尖和原、次尖也被小沟分割,前尖被近、远端细沟在基部分割成三个齿尖。
3.1.2 下齿系
下第3前臼齿(p3): 齿冠面呈卵圆形至梯形,高冠,下原尖比下后尖高大得多,二者被一细长的纵沟(中沟)分割(图2: D)。下原尖前棱和下后尖前棱在近中侧围成一个小坑形近中凹。中沟在前侧与近中凹相连,在后侧与五角星形下跟座远中凹相连。虽然近端部分缺失,前尖萎缩呈一个小瘤突紧邻中沟前边缘。
下第4前臼齿(p4): 较p3大,臼齿化,高冠,冠面近似正方形,向远端变窄,宽较长稍大,发育两个主尖(下原尖和下后尖)和一对远端瘤突,下原尖比下后尖几乎稍大(图2: E)。近中凹小且窄,边缘具有轻微的褶皱,下跟座谷(远中凹)较低,且比近中凹更扩展,边缘也发育轻微的褶皱。近中凹与远中凹被一个较深的中沟相连,将下原尖和下后尖分开。原尖后棱与后尖后棱较发育,分别紧靠下原尖和下后尖远端基部,与远端瘤突被远中谷隔开。
下第1前臼齿(m1): 高冠,冠面磨蚀极为严重,呈矩形,长大于宽;前宽和后宽几乎相当(图2: F, G)。下跟座比p4大得多,达到了齿冠面积的近一半。下后尖最大,下原尖次之,下内尖再次,下次尖最小。由于严重磨蚀,近中与远中都凹。下次尖近唇侧发育微弱齿带。与上臼齿相比,切割舌侧与颊侧主尖的两个细沟斜交,而上臼齿的两个细沟近平行。
下第2臼齿(m2): 高冠,冠面呈不规则的矩形,长大于宽,前宽与后宽几乎等大(图2: H)。近中颊侧角较为尖锐,其余角较为圆钝。整个冠面被严重磨蚀,齿尖高度无法判断,但仍可看出下后尖最大,其他几个主尖尺寸接近,下次小尖非常发育,比下原尖和下次尖稍小,发育明显的下跟座小尖,近中沟与远中沟也较为发育。
下第3前臼齿(m3): 高冠,冠面呈不规则的四边形,长大于宽,前宽也大于后宽(图2: I)。下跟座几乎达到了齿冠面积的一半。下后尖最高、下原尖次之,下次尖再次,内尖最矮。下次小尖比主尖小得多,中沟在近中侧与远中侧均分割成3-4个细沟。下原尖前棱和下后尖前棱及中部齿尖围成一个窄而深的近中凹。
3.2 与其他产地巨猿化石对比
张银运等和张颖奇等研究了巨猿牙齿的大小变化,认为从早更新世早期到中更新世,步氏巨猿颊齿有着逐渐增大的演化趋势[5,6,22]。在早更新世早期,步氏巨猿颊齿尺寸较小,以重庆巫山龙骨坡[3]、贵州毕节扒耳岩[7]、广西柳城巨猿洞[2,11]和布兵盆地吹风洞[15,16]等几个产地的步氏巨猿颊齿为代表;在早更新世中至晚期,步氏巨猿颊齿尺寸较早更新世早期的稍大,以湖北建始龙骨洞[10]、广西崇左三合大洞[12,13]和泊岳山巨猿洞[14]的化石为代表;而在中更新世,步氏巨猿颊齿尺寸最大,以广西武鸣布拉利山洞[5]、大新黑洞[23]、崇左合江洞[20]的化石为代表。武隆梅子湾大洞出土的巨猿牙齿,齿冠高,釉质层厚,前臼齿臼齿化。依其磨耗程度统计,亚成年个体较少(4个,占44.4%),中老年个体较多(5个,占55.6%)。长宽指数和粗壮度均处在目前发现的所有巨猿牙齿变异范围之内,与巫山龙骨坡[3]、毕节扒耳岩[7]、柳城巨猿洞[2,11]和布兵盆地吹风洞[15-16]的巨猿牙齿测量值重合,但明显小于广西武鸣的巨猿牙齿(表2)。综上,武隆梅子湾洞的巨猿牙齿尺寸偏小、时代偏早,处在最早期的阶段。
表2 巨猿上第四前臼齿测量值比较
Tab.2
| 产地Sample sites | 长L(mm) | 宽b(mm) | 长宽指数(b/L) | 粗壮度L·b |
|---|---|---|---|---|
| 重庆武隆梅子湾大洞Meiziwan Great Cave | 14.8 | 20.9 | 70.8 | 309.3 |
| 重庆巫山龙骨坡Longgupo in Wushan | 13.6 | 20.1 | 67.7 | 273.4 |
| 贵州毕节扒耳岩Ba'eryan in Bijie | 12.8 | 19.6 | 63.3 | 250.9 |
| 柳州巨猿洞C区Giant Ape Cave | 12.9 | 18.9 | 68.7 | 245.2 |
| 广西武鸣布拉利山洞Bulali Cave in Wuming | 17.5 | 25.0 | 70.0 | 423.5 |
4 梅子湾大洞动物群的时代
梅子湾大洞出土的哺乳动物化石共6目14科17属18种(图3),包括步氏巨猿(Gigantopithecus blacki)、咬洞竹鼠(Rhizomys troglodytes)、硕豪猪(Hystrix magna)、小种大熊猫(Ailuropoda microta)、亚洲黑熊原始亚种(Ursus thibetanus primitinus)、豹(Panthera pardus)、扬子中华乳齿象(Sinomastodon yangziensis)、华南剑齿象(Stegodon huananensis)、云南马相似种(Equus cf. yunnanensis)、中华黄昏爪兽(Hesperotherium sinense)、山原貘(Tapirus sanyuanensis)、犀科属种未定(Rhinocerotidae gen. et sp. indet.)、小猪(Sus xiaozhu)、裴氏猪(S. peii)、最后祖鹿(Cervavitus ultimus)、麂(未定种)(Muntiacus sp.)、丽牛(未定种)(Leptobos sp.)和山羊亚科属种未定(Caprinae gen. et sp. indet.)。中国其他含巨猿动物群的遗址有重庆巫山龙骨坡、贵州毕节扒耳岩洞、广西崇左百孔洞、湖北建始龙骨洞、广西柳城巨猿洞、广西武鸣布拉利山洞和广西崇左三合大洞和合江洞等[3,5,7,12,13,20,25,26]。其中,龙骨坡、巨猿洞、扒耳岩、百孔洞、吹风洞为早更新世早期动物群产地[12,27,28],化石材料很丰富,具有以下特征:1)化石种类中,保留新近纪的孑遗种,如扬子中华乳齿象、中华黄昏爪兽和最后祖鹿等;2)出现早更新世的特有动物,如小体型的步氏巨猿、硕豪猪、小种大熊猫、亚洲黑熊原始亚种、华南剑齿象、云南马相似种、山原貘等。以上这些具有鲜明时代标志的物种均出现在梅子湾动物群中,由此推断梅子湾大洞是除龙骨坡、巨猿洞、扒耳岩、百孔洞、吹风洞以外的又一个早更新世早期的动物化石地点。
图3
图3
重庆武隆梅子湾大洞的部分哺乳动物牙齿
A. CYMW010,硕豪猪H. magna,左M1;B. CYMW011, 硕豪猪H. magna,右p4;C. CYMW012,扬子中华乳齿象S. yangziensis,右M3;D. CYMW013,华南剑齿象 S. huananensis,左m2; E. CYMW014,亚洲黑熊原始亚种U. t. primitinus,右M1;F. CYMW015,亚洲黑熊原始亚种U. t. primitinus,右M2;G. CYMW016,亚洲黑熊原始亚种U. t. primitinus,左m1;H. CYMW017,小种大熊猫A. microta,左M1;I. CYMW018,豹 P. pardus, 左m1;J. CYMW019,豹 P. pardus, 右p4;K. CYMW020,云南马相似种Equus cf. yunnanensis,右m3;L. CYMW021,山原貘T. sanyuanensis, 右p4;M. CYMW022,中华黄昏爪兽H. sinense,左DP4 / M1 / M2;N. CYMW023,犀科属种未定 Rhinocerotidae gen. et sp. indet., 左p4;O. CYMW024,犀科属种未定 Rhinocerotidae gen. et sp. indet., 左m1;P. CYMW025,犀科属种未定 Rhinocerotidae gen. et sp. indet., 左m3;Q. CYMW026,小猪S. xiaozhu,左m2;R,S. CYMW027,裴氏猪S. peii,左M3;T. CYMW028,麂(未定种)Muntiacus sp., 右M3;U. CYMW029,最后祖鹿C. ultimus,右M3;V. CYMW030,丽牛(未定种)Leptobos sp.,右M1;W. CYMW031,山羊亚科属种未定 Caprinae gen. et sp. indet.,右M2。
Fig.3
Teeth of Some mammalians from the Meiziwan Cave in Wulong District, Chongqing
A~B比例尺为10 mm,C~W比例尺为20 mm。冠面视:A~H, J1, K2, L~V, W3;颊侧面视:I, J2, W1;舌侧面视:J3, K1, W2
5 讨论
自1935年孔尼华(von Koenigswald GHR)在香港中药铺发现步氏巨猿以来,东亚地区又陆续发现了至少19个地点(图4),分布范围从30°N向南至18°N,主要为湖北、重庆、贵州、广西和海南的部分地区。梅子湾大洞是重庆地区继巫山龙骨坡遗址以来第2个巨猿化石点,其发现扩大了长江中上游流域的巨猿活动范围,增添了早更新世巨猿地理分布点,在南北纵向分布上填补了重庆巫山龙骨坡[3]与贵州毕节扒耳岩[7]之间的地理分布空白。从分布来看,相对较高纬度产地的步氏巨猿以中-小体型为主,而相对较低纬度产地的步氏巨猿则存在不同体型的类型;然而,目前国内纬度最低的产地,即海南昌江信冲洞遗址发现的是体型最大的步氏巨猿[29]。从早更新世早期到中更新世,大熊猫[30,31]、貘[32]、黑熊[33,34]等伴生动物的体型,也如步氏巨猿一样,出现由小增大的趋势;这些伴生动物体型的增大大都发生在早更新世末至中更新世初,该时期为中更新世气候转型期[35,36],这与伯格曼法则中提出的寒冷地区动物体型更大的规律相符合[37],以上两点表明:早更新世早期以来,步氏巨猿体型的增大,可能与早更新世末至中更新世初的气候转冷和生态环境变化密切相关。
图4
图4
中国南方及东南亚地区巨猿化石地点分布图(审图号:4071688466)
1.重庆巫山龙骨坡 (Longgupo site in Wushan, Chongqing Municipality)[3];2.湖北建始龙骨洞 (Longgudong in Jianshi, Hubei Province)[24];3.重庆武隆梅子湾大洞 (Meiziwan Cave in Wulong, Chongqing Municipality);4.贵州毕节扒耳岩洞 (Pa’eryan Cave in Bijie, Guizhou Province)[7];5.广西柳城巨猿洞 (Gigantopithecus Cave in Liucheng, Guangxi ZAR)[26];6.广西巴马莫弄山 (Monongshan site of Bama, Guangxi ZAR)[4];7.广西田东吹风洞(Chuifeng Cave of Tiandong, Guangxi ZAR)[15⇓-17];8.广西田东么会洞 (Mohui Cave of Tiandong, Guangxi ZAR)[24];9.广西武呜拉利山洞 (Lalishan Cave in Wuming, Guangxi ZAR)[5];10.广西大新黑洞(Black cave in Daxin, Guangxi ZAR)[23];11-18.广西崇左百孔洞、缺缺洞、三合大洞、泊岳山巨猿洞、岩亮洞、双坛洞、合江洞、一线天洞 (Baikong Cave, Queque Cave, Sanhe Cave, Juyuan Cave in Boyue Mountain, Yanliang Cave, Shuangtan Cave, Hejiang Cave and Yixiantian Cave in Chongzuo, Guangxi ZAR)[12⇓-14,18⇓⇓ -21];19.海南昌江信冲洞(Xingchong Cave in Changjiang, Hainan Province)[29]
Fig.4
Location of G. blacki-bearing sites in South China and mainland Southeast Asia
目前,华南早-中更新世众多产地均发现巨猿化石[2⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓-26,29],但由于材料都不完整性,其分类地位仍存在争议。Weidenreich把巨猿修定为人,并经过魁人(Meganthropus)、爪哇猿人和北京猿人(Homo erectus)逐步演变为现代人[38]。吴汝康认为,巨猿的若干形态特征介于人类和猿类之间,并将巨猿归入人科[2]。王令红等则认为,巨猿牙齿的形态特征仍处在猿的范畴,并非人科成员[39]。后来的研究则将步氏巨猿归入人科的猩猩亚科,并认为其与猩猩Pongo及晚中新世的猩猩家族(包括禄丰古猿Lufengpithecus、安卡拉古猿Ankarapithecus和西瓦古猿Sivapithecus)互为姐妹群,而与人属Homo、黑猩猩属Pan及大猩猩属Goriila亲缘关系相对较远[40,41];近期,他们基于广西田东吹风洞古蛋白的系统发育分析认为,巨猿与猩猩互为姊妹群[17],这进一步支持了Begun等的推断[40]。
纵使巨猿的研究取得了诸多成果,但受限于完整头骨和骨架化石的缺乏,步氏巨猿的外貌、体型大小及其与更新世其他人科动物的关系仍值得深入探讨。长江中上游地区巨猿化石的再次发现,对巨猿及其动物群的演化、绝灭、地理分布和环境背景等相关问题的研究具有重要的指示意义,鉴于中国南方从30°N 至18°N 范围内发育有大量岩溶裂隙和洞穴,进一步的调查、发掘和研究工作将为阐明巨猿与人科其他动物的复杂关系提供可能。
6 结论
1)重庆武隆梅子湾大洞共发现9枚步氏巨猿颊齿化石,包括1枚上前臼齿、2枚上臼齿、2枚下前臼齿和4枚下臼齿。颊齿尺寸偏小,处在早更新世早期步氏巨猿颊齿变异范围。
2)重庆武隆梅子湾大洞是重庆继巫山龙骨坡遗址以来第2个巨猿化石点,其发现丰富了长江中上游地区巨猿化石的地理分布点,扩大了早更新世巨猿的分布范围,填补了重庆巫山龙骨坡与贵州扒耳岩在南北向上的地理分布空白。
3)重庆武隆梅子湾大洞发现的哺乳动物牙齿化石包括6目14科17属18种:步氏巨猿Gigantopithecus blacki、咬洞竹鼠 Rhizomys troglodytes、硕豪猪Hystrix magna、小种大熊猫Ailuropoda microta、亚洲黑熊原始亚种Ursus thibetanus primitinus、豹Panthera pardus、扬子中华乳齿象Sinomastodon yangziensis、华南剑齿象Stegodon huananensis、云南马相似种Equus cf. yunnanensis、中华黄昏爪兽Hesperotherium sinense、山原貘Tapirus sanyuanensis、犀科属种未定Rhinocerotidae gen. et sp. indet.、小猪Sus xiaozhu、裴氏猪S. peii、最后祖鹿Cervavitus ultimus、麂(未定种)Muntiacus sp.、丽牛(未定种)Leptobos sp.和山羊亚科属种未定 Caprinae gen. et sp. indet.,该动物群的年代为早更新世早期。
4)重庆武隆梅子湾大洞巨猿化石的发现,对巨猿及其动物群的演化、绝灭、地理分布和环境背景等相关问题的研究具有重要的指示意义,鉴于中国南方发育有大量岩溶裂隙和洞穴,进一步的调查、发掘和研究工作将为阐明巨猿与人科其他动物的复杂关系提供可能。
致谢
中国科学院古脊椎动物与古人类研究所同号文研究员就部分化石鉴定提供了帮助和建议,中国科学院大学熊武阳博士后就食肉类进行了有益讨论,探险家侯明、重庆自然博物馆赖东馆长在本化石点的调查和化石采集中提供了帮助,在此一并谨致谢意!
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