26Al/10Be Burial Dating of Xujiayao-Houjiayao Site in Nihewan Basin,Northern China

The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years). This paper reports the application of ²⁶Al/¹⁰Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ). The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site’s lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL) dating at 160–220 ka.     

Magnetochronology and stratigraphy at Gran Dolina section, Atapuerca (Burgos, Spain).

The Atapuerca Site (Burgos, N. Spain) is an extensive archaeological site which has yielded numerous human fossil remains. The Gran Dolina section, one of the open-air excavations and subject of this study, consists of a sedimentary infilling of 18 m thickness in a gallery originated by karstification of the host Cretaceous limestones. In this paper we present new stratigraphic and paleomagnetic evidence for the age and the sedimentary environment of the karst infilling where the archaeological site is located. Paleomagnetic dating places the hominids (Aurora stratum) in the Matuyama reversed Chron, hence before 780 ka. We also report evidence for a short normal polarity event at the bottom of the section that we speculate as being Jaramillo or Kamikatsura. The early and well-constrained date of the Atapuerca archaeological site, its location in the cul-de-sac we know as Europe, its stratigraphic context, the abundant fossil remains and the stone tool industry make it one of the most important localities for the question of the earliest human occupation in Europe.     

广西崇左木榄山智人洞的鼠科化石

最近在广西崇左木榄山智人洞遗址采集到1件具有现代智人解剖特征初始状态的下颌骨和丰富的哺乳动物化石。啮齿类中的鼠科化石有锡金小鼠(Mus pahari)、中华姬鼠(Apodemus draco)、黑线姬鼠(Apodemus agrarius)、似德氏狨鼠(Hapalomys cf.H.delacouri)、笔尾树鼠(Chiropodomys gliroides)、社鼠(Niviventer confucianus)、针毛鼠(Niviventer fulvescens)、爱氏巨鼠(Leopoldamys edwardsi)、印度板齿鼠(Bandicota indica)、褐家鼠(Rattus norvegicus)和黄毛鼠(Rattus losea)共8属11种。这种全部由当地或邻近地区现生种类构成的组合显然比当地早更新世的三合大洞和川黔地区中更新世歌乐山期的鼠类组合进步, 而与广西田东雾云洞的鼠类组合相似, 其动物群的时代为晚更新世早期, 与不平衡铀系法得到的测年结果(距今约11万年)相吻合。智人洞鼠科动物的组合明显具有东洋界热带-亚热带动物群的特点, 其中林灌和草地型所占比例较大表明当时的森林面积可能减少、林灌和草地面积可能增加, 反映出当时的气候相对干旱。     

许家窑-侯家窑遗址地层穷究

许家窑-侯家窑遗址是中国旧石器时代中期一处重要的考古遗址, 出土的化石"许家窑人"属于早期智人。按照现行地层古生物学常规判断, 其地层应该属于上更新统。目前, 许家窑组是泥河湾盆地乃至东亚地区发现的上更新统包含古人类及其旧石器文化遗物和古哺乳动物化石相当丰富的一个地层剖面, 但断代存在理念误区。     

New Luminescence Ages for the Galería Complex Archaeological Site: Resolving Chronological Uncertainties on the Acheulean Record of the Sierra de Atapuerca,Northern Spain

The archaeological karstic infill site of Galería Complex, located within the Atapuerca system (Spain), has produced a large faunal and archaeological record (Homo sp. aff. heidelbergensis fossils and Mode II lithic artefacts) belonging to the Middle Pleistocene. Extended-range luminescence dating techniques, namely post-infrared infrared stimulated luminescence (pIR-IR) dating of K-feldspars and thermally transferred optically stimulated luminescence (TT-OSL) dating of individual quartz grains, were applied to fossil-bearing sediments at Galería. The luminescence dating results are in good agreement with published chronologies derived using alternative radiometric dating methods (i.e., ESR and U-series dating of bracketing speleothems and combined ESR/U-series dating of herbivore teeth), as well as biochronology and palaeoenvironmental reconstructions inferred from proxy records (e.g., pollen data). For the majority of samples dated, however, the new luminescence ages are significantly (∼50%) younger than previously published polymineral thermoluminescence (TL) chronologies, suggesting that the latter may have overestimated the true burial age of the Galería deposits. The luminescence ages obtained indicate that the top of the basal sterile sands (GIb) at Galería have an age of up to ∼370 thousand years (ka), while the lowermost sub-unit containing Mode II Acheulean lithics (base of unit GIIa) was deposited during MIS 9 (mean age = 313±14 ka; n = 4). The overlying units GIIb-GIV, which contain the richest archaeopalaeontological remains, were deposited during late MIS 8 or early MIS 7 (∼240 ka). Galería Complex may be correlative with other Middle Pleistocene sites from Atapuerca, such as Gran Dolina level TD10 and unit TE19 from Sima del Elefante, but the lowermost archaeological horizons are ∼100 ka younger than the hominin-bearing clay breccias at the Sima de los Huesos site. Our results suggest that both pIR-IR and single-grain TT-OSL dating are suitable for resolving Middle Pleistocene chronologies for the Sierra de Atapuerca karstic infill sequences.     

Speleology and magnetobiostratigraphic chronology of the GD 2 locality of the Gondolin hominin-bearing paleocave deposits, North West Province, South Africa

Speleological, paleomagnetic, mineral magnetic, and biochronological analyses have been undertaken at the Gondolin hominin-bearing paleocave, North West Province, South Africa. Two fossiliferous but stratigraphically separate sequences, GD2 and GD1/3, which were once part of a large cavern system, have been identified. Although some comparative paleomagnetic samples were taken from the GD 1, 3, and 4 localities that are currently under investigation, the research presented here focuses on the fossil-rich, in situ deposits at locality GD 2, excavated by E.S. Vrba in 1979. The GD 2 deposits are dominated by normal-polarity calcified clastic deposits that are sandwiched between clastic-free flowstone speleothems. The lower flowstone has a sharp contact with the red siltstone deposits and is of reversed polarity. The capping flowstone shows a change from normal to reversed polarity, thereby preserving a polarity reversal. While the paleomagnetic work indicates that the GD 2 fossil material was deposited during a normal-polarity period, the shortness of the sequence made matching of the magnetostratigraphy to the geomagnetic polarity time scale (GPTS) impossible without the aid of biochronology. While lacking multiple time-sensitive taxa, the recovery of specimens attributable to Stage III Metridiochoerus andrewsi is consistent with a deposition date between 1.9 and 1.5 Ma. A comparison of the magnetostratigraphy with the GPTS therefore suggests that the fauna-bearing siltstone of GD 2 date to the Olduvai normal-polarity event, which occurred between 1.95 and 1.78 Ma, and that the reversal from normal to reversed polarity identified in the capping flowstone dates to 1.78 Ma. The main faunal layers therefore date to slightly older than 1.78 Ma. Deposits from the GD 1 locality are dominated by reversed directions of magnetization, which show that this deposit is not of the same age as the faunal layers from the GD 2 locality.     

更新世中期中国古人类演化区域连续性与多样性的化石证据

以往,在东亚大陆发现的更新世中期人类化石被分别归入直立人和古老型智人。这种分类的主要依据是化石形态特征以及年代。魏敦瑞对周口店第一地点人类化石研究描述的一些头骨、下颌骨和牙齿特征通常被作为判定直立人的标准。根据这些化石的年代分布,一般将30万年前的中更新世晚期作为划分直立人与古老型智人的大致年代界限。近20年来,在非洲、欧洲和东亚新发现了一些更新世中期人类化石,目前古人类学界对中国更新世中期人类化石特征及演化有了与以往不同的认识。最近对大荔、许家窑、盘县大洞、许昌、华龙洞等人类化石的研究显示,近30万年以来东亚大陆人类演化呈现复杂的多样性,将这一时期人类全部归入古老型智人难以准确反映更新世中期中国古人类演化模式及规律。本文结合近年中国更新世中期人类演化研究进展,选择部分具有演化及分类价值的形态特征,分析这些特征在更新世中期中国古人类化石的表现特点。在此基础上,对更新世中期中国古人类演化模式做了尝试性探讨。本研究发现,周口店、和县、沂源、南京等中更新世早期人类化石呈现有较多的区域性特征,形态特征表现相对稳定;而大荔、金牛山、许家窑、许昌、华龙洞、马坝、盘县大洞等中更新世晚期人类在化石形态特征表现复杂多样,变异范围大。此外,在这一时期人类化石上发现较多与生存活动、健康、环境适应有关的证据。根据这些发现,作者认为中国中更新世早期组人类演化以形态连续性为主;进入中更新世晚期,中国古人类演化区域性特征减弱,演化模式以多样性为主。一系列新的化石发现和研究证据提示中更新世晚期东亚大陆可能生存有不同的古人类成员。根据目前掌握的化石形态和年代证据,大约30万年前是中国更新世中期演化变化关键时间节点。     

New geochronological, paleoclimatological, and archaeological data from the Narmada Valley hominin locality, central India

The oldest known fossil hominin in southern Asia was recovered from Hathnora in the Narmada Basin, central India in the early 1980's. Its age and taxonomic affinities, however, have remained uncertain. Current estimates place its maximum age at >236 ka, but not likely older than the early middle Pleistocene. The calvaria, however, could be considerably younger. We report recent fieldwork at Hathnora and associated Quaternary type-sections that has provided new geological and archaeological insights. The portion of the exposed ‘Boulder Conglomerate’ within the Surajkund Formation, which forms a relict terrace and has yielded the hominin fossils, contains reworked and stylistically mixed lithic artifacts and temporally mixed fauna. Three mammalian teeth stratigraphically associated with the hominin calvaria were dated by standard electron spin resonance (ESR). Assuming an early uranium uptake (EU) model for the teeth, two samples collected from the reworked surface deposit averaged 49 ± 1 ka (83 ± 2 ka, assuming linear uptake [LU]; 196 ± 7 ka assuming recent uptake [RU]). Another sample recovered from freshly exposed, crossbedded gravels averaged 93 ± 5 ka (EU), 162 ± 8 ka (LU) or 407 ± 21 ka (RU). While linear uptake models usually provide the most accurate ages for this environment and time range, the EU ages represent the minimum possible age for fossils in the deposit. Regardless, the fossils are clearly reworked and temporally mixed. Therefore, the current data constrains the minimum possible age for the calvaria to 49 ± 1 ka, although it could have been reworked and deposited into the Hathnora deposit any time after 160 ka (given the LU uptake ages) or earlier (given the RU ages). At Hathnora, carbonaceous clay, bivalve shells, and a bovid tooth recovered from layers belonging to the overlying Baneta Formation have yielded ¹⁴C ages of 35.66 ± 2.54 cal ky BP, 24.28 ± 0.39 cal ky BP, and 13.15 ± 0.34 ky BP, respectively. Additional surveys yielded numerous lithics and fossils on the surface and within the stratigraphic sequence. At the foot of the Vindhyan Hills 2 km from the river, we recovered a typologically Early Acheulean assemblage comprised of asymmetrical bifaces, large cleavers with minimal working, trihedral picks, and flake tools in fresh condition. These tools may be the oldest Acheulean in the Narmada Valley. Several lithics recovered from the Dhansi Formation may represent the first unequivocal evidence for an early Pleistocene hominin presence in India. In situ invertebrate and vertebrate fossils, pollen, and spores indicate a warm, humid climate during the late middle Pleistocene. High uranium concentrations in the mammalian teeth indicate exposure to saline water, suggesting highly evaporative conditions in the past. Late Pleistocene sediment dated between 24.28 ± 0.39 cal ky BP and 13.15 ± 340 ky BP has yielded pollen and spores indicating cool, dry climatic conditions corresponding to Oxygen Isotope Stage 2 (OIS 2). An early Holocene palynological assemblage from the type locality at Baneta shows evidence for relatively dry conditions and a deciduous forest within the region. The Dhansi Formation provisionally replaces the Pilikarar Formation as the oldest Quaternary formation within the central Narmada Basin. The Baneta Formation, previously dated at 70 ka to 128 ka, correlates with the late Pleistocene and early Holocene. Our results highlight the need for further Quaternary geological and paleoanthropological research within the Narmada Basin, especially because dam construction threatens these deposits.     

Brief Communication: Beyond the South African cave paradigm—Australopithecus africanus from Plio–Pleistocene paleosol deposits at Taung

Following the discovery of the “Taung Child” (Australopithecus africanus) in 1924 in the Buxton‐Norlim Limeworks near Taung, the fossil‐bearing deposits associated with the Dart and Hrdli?ka pinnacles have been interpreted as the mined remnants of cave sediments that formed within the Plio–Pleistocene Thabaseek Tufa: either as a younger cave‐fill or as contemporaneous carapace caves. When combined with the Plio–Pleistocene dolomitic cave deposits from the “Cradle of Humankind,” a rather restricted view emerges that South African early hominins derived from cave deposits, whereas those of east and central Africa are derived from fluvio‐lacustrine and paleosol deposits. We undertook a sedimentological and paleomagnetic analysis of the pink‐colored deposit (PCS) from which the “Taung Child” is purported to have derived and demonstrate that it is a calcrete, a carbonate‐rich pedogenic sediment, which formed on the paleo‐land surface. The deposit extends 100 s of meters laterally beyond the Dart and Hrdli?ka Pinnacles where it is interbedded with the Thabaseek Tufa, indicating multiple episodes of calcrete development and tufa growth. The presence of in situ rhizoconcretions and insect trace fossils (Celliforma sp. and Coprinisphaera sp.) and the distinctive carbonate microfabric confirm that the pink deposit is a pedogenic calcrete, not a calcified cave sediment. Paleomagnetic and stratigraphic evidence indicates that a second, reversed polarity, fossil‐bearing deposit (YRSS) is a younger fissure‐fill formed within a solutional cavity of the normal polarity tufa and pink calcrete (PCS). These observations have implications for the dating, environment, and taphonomy of the site, and increase the likelihood of future fossil discoveries within the Buxton‐Norlim Limeworks. Am J Phys Anthropol 151:316–324, 2013. © 2013 Wiley Periodicals, Inc.     

Endocranial traits of the Sima de los Huesos (Atapuerca,Spain) and Petralona (Chalkidiki,Greece) Middle Pleistocene ursids. Phylogenetic and biochronological implications

A complete cranium of Ursus deningeri from Petralona (Chalkidiki, Greece) covered by a thick carbonate crust has been virtually liberated through CT scan and 3D image reconstruction, and compared with a specimen from the Sima de los Huesos, Sierra de Atapuerca (Spain) Middle Pleistocene site. X-ray computed tomography allowed for the identification of previously unrecognized and phylogenetically relevant traits. Analysis of these traits and an additional series of classically defined traits demonstrate the near identity of these specimens, thereby, confirming an early stage of the speloid “(cave bear)” condition. The replicate luminescence ages obtained for the SH deposit provide a combined minimum age estimate of 427 ± 12 ka for the underlying fossils. Based on a series of primitive and derived morphological features of these two crania, a similar age is here proposed for the Petralona and SH U. deningeri.     

Stratigraphy and tephra of the Kibish Formation, southwestern Ethiopia

The Kibish Formation in southwestern Ethiopia, with an aggregate thickness of ~105m, consists of lacustrine, marginal lacustrine, and deltaic deposits. It is divided into four members numbered I to IV on the basis of erosion surfaces (disconformities) between the strata of each member. It overlies the Mursi and Nkalabong formations, the latter of which is here shown to correlate with the Shungura Formation. Tephra layers in each member allow for secure correlation between geographically separated sections on the basis of the composition of their volcanic glass. Members I, III, and IV of the Kibish Formation appear to have been deposited at the same times as sapropels S7 (197ka), S4 (104ka), and S1 (8ka) in the eastern Mediterranean Sea, respectively. We correlate the KHS Tuff of the Kibish Formation with a >154-kyr-old unnamed tuff in the Konso Formation. Tephra in Member IV may derive from Mount Wenchi, a volcano situated on the divide between the Omo and Blue Nile drainage basins. Thin-bedded sedimentary layers probably represent annual deposition reflecting rapid sedimentation (~30m/kyr) of parts of the formation. This conclusion is supported by variation in paleomagnetic inclination through a sequence of these layers at KHS. Two fossils of early Homo sapiens (Omo I and Omo II) derive from Member I. Their stratigraphic placement is confirmed by analysis of the KHS Tuff in the lower part of Member II at both fossil sites. The KHS Tuff lies above a disconformity, which itself lies above the fossils at both sites. (40)Ar/(39)Ar dates provide an estimated age of ~195kyr for these fossils. Omo III, a third fossil H. sapiens, probably also derives from Member I of the Kibish Formation and is of similar age. Hominin fossils from AHS, a new site, also derive from Member I. Hominin fossils from CHS can only be placed between 104ka and 10ka, the H. sapiens specimen from JHS is most likely 9-13kyr in age, and a partial skeleton of H. sapiens from Pelvic Corner is most likely ~6.6kyr in age.     

“蓝田人”的磁性地层年龄

蓝田附近两个地点更新世黄土中发现的蓝田人化石具有不同的年代。公王岭发现的蓝田人头盖骨的年代为距今115万年,陈家窝的下颌骨年代为距今65万年。年代资料来自于新的磁性地层学研究和黄土-古土壤序列的对比结果。公王岭地点蓝田人化石埋藏于反映了干冷气候的粉砂质黄土中的事实,以及与其相伴的“南方色彩”的哺乳动物群的存在表明,距今115万年前中国北方可能发生了一次重要的秦岭强烈隆起和气候干冷的地质事件。     

Age and stratigraphic reassessment of the fossil-bearing Laguna Umayo red mudstone unit, SE Peru, from regional stratigraphy, fossil record, and paleomagnetism

The thick red mudstone unit that crops out at Laguna Umayo (Puno department, southern Peru), here referred as LURMU, has yielded in different levels a fossil assemblage with plants and vertebrates (including mammals). On the basis of charophytes, the unit was initially assigned to the Vilquechico Formation (Maastrichtian-Danian), of regional extension, and the dinosaurian structure of egg fragments was interpreted as consistent with that age. Revision of the regional stratigraphy leads to reassignment of this unit to the Lower Muñani Formation (Early Tertiary). Mammals from the LU-3 and Chulpas levels present affinities with forms from the Upper Paleocene of South America (Patagonia, Brazil). A bunodont marsupial, Chulpasia, is evidence for chronologic proximity to a transantarctic interchange with Australia at the end of the Paleocene. Furthermore, magnetostratigraphy of the LURMU reveals a single reverse polarity zone of 300 m thickness. Because of the new stratigraphic and paleomammalogic data, this long reverse polarity zone is likely correlative to Chron 26r (early Late Paleocene) or Chron 24r (latest Paleocene-earliest Eocene), or, less likely, to Chron 29r (latest Cretaceous-earliest Paleocene). The arguments previously invoked in favor of a Cretaceous age (charophytes, dinosaurian eggs) are critically evaluated, and correlation to Chron 24r is favored.     

古人类遗址湖北郧西黄龙洞的铀系年代

湖北郧西黄龙洞为近年来发现的晚期智人遗址。本文报道该地点具明确层位意义的洞穴次生碳酸盐岩和骨化石样铀系测年的结果。含文化堆积下伏一局部钙板的年代为约100ka BP, 其中部偏上一局部钙板为约77ka BP, 表层钙板形成于27—57ka BP间。人类化石和石制品出土于文化堆积的底部, 其年代应在57—100ka BP, 并很可能在77—100ka BP间。与人牙化石同层的四枚犀牛牙化石在35—72ka BP间, 与基于次生碳酸盐岩的年代框架没有冲突。本文结果为中国现代人类的早期出现和距今40—100ka BP间有人类活动提供了有力证据。     

Early Pleistocene human humeri from the Gran Dolina-TD6 site (Sierra de Atapuerca, Spain)

In this report, we present a morphometric comparative study of two Early Pleistocene humeri recovered from the TD6 level of the Gran Dolina cave site in Sierra de Atapuerca, northern Spain. ATD6-121 belongs to a child between 4 and 6 years old, whereas ATD6-148 corresponds to an adult. ATD6-148 exhibits the typical pattern of the genus Homo, but it also shows a large olecranon fossa and very thin medial and lateral pillars (also present in ATD6-121), sharing these features with European Middle Pleistocene hominins, Neandertals, and the Bodo Middle Pleistocene humerus. The morphology of the distal epiphysis, together with a few dental traits, suggests a phylogenetic relationship between the TD6 hominins and the Neandertal lineage. Given the older geochronological age of these hominins (ca. 900 ka), which is far from the age estimated by palaeogenetic studies for the population divergence of modern humans and Neandertals (ca. 400 ka), we suggest that this suite of derived "Neandertal" features appeared early in the evolution of the genus Homo. Thus, these features are not "Neandertal" apomorphies but traits which appeared in an ancestral and polymorphic population during the Early Pleistocene.     

Fauna,environment and human presence during MIS5 in the North of Spain: The new site of Valdavara 3

Valdavara 3 is a new early late Pleistocene paleontological and archeological cave site in northwestern Iberia. Over 1400 fossils have been collected, representing about 40 species. The fauna is of interglacial aspect and is in accordance with the OSL dates from the fossiliferous layer, which indicate an age of 103–113 ka. The great taxonomical diversity indicates a varied landscape. A small collection of lithic artifacts was found associated with the fossils, demostrating presence of humans and suggesting short non-residential visits to the cave. The fossiliferous site was predominantly formed by natural processes. Many fossil localities have short or biased faunal lists, but the fossil fauna recovered from Valdavara 3 is remarkably diverse and may reflect the fauna which once lived there.     

U-series and radiocarbon analyses of human and faunal remains from Wajak,Indonesia

Laser ablation U-series dating results on human and faunal bone fragments from Wajak, Indonesia, indicate a minimum age of between 37.4 and 28.5 ka (thousands of years ago) for the whole assemblage. These are significantly older than previously published radiocarbon estimates on bone carbonate, which suggested a Holocene age for a human bone fragment and a late Pleistocene age for a faunal bone. The analysis of the organic components in the faunal material show severe degradation and a positive δ¹³C ratio indicate a high degree of secondary carbonatisation. This may explain why the thermal release method used for the original age assessments yielded such young ages. While the older U-series ages are not in contradiction with the morphology of the Wajak human fossils or Javanese biostratigraphy, they will require a reassessment of the evolutionary relationships of modern human remains in Southeast Asia and Oceania. It can be expected that systematic direct dating of human fossils from this area will lead to further revisions of our understanding of modern human evolution.     

Sapropels and the age of hominins Omo I and II, Kibish, Ethiopia

The provenance and age of two Homo sapiens fossils (Omo I and Omo II) from the Kibish Formation in southern Ethiopia have been much debated. Here we confirm that Omo I and the somewhat more primitive-looking Omo II calvariae are from similar stratigraphic levels in Member I of the Kibish Formation. Based on (40)Ar/(39)Ar age measurements on alkali feldspar crystals from pumice clasts in the Nakaa'kire Tuff, a tuffaceous bed in Member I just below the hominin levels, we place an older limit of 198+/-14ka (weighted mean age=196+/-2ka) for the hominins. A younger limit of 104+/-7ka (weighted mean age=104+/-1ka) is provided by feldspars separated from pumice clasts in the Aliyo Tuff in Member III. Geological evidence indicates rapid deposition of each member of the Kibish Formation, concurrent with deposition of sapropels in the Mediterranean Sea. The (40)Ar/(39)Ar age measurements, together with correlations with sapropels, indicate that the hominin fossils are close in age to the older limit. Our preferred estimate of the age of the hominins is 195+/-5ka, making them the earliest well-dated anatomically modern humans yet described.     

陕西府谷晚中新世Acerorhinus属(奇蹄目,犀科)一新种

记述的 Acerorhinus fuguensis sp. nov是 Acerorhinus属中一个相当进步的种。府谷 保存完整的标本使我们对Acerorhinus的特征有了更全面且准确的认识。新种以强烈外展的鼓后突和头骨顶面在眶前的骤然收缩区别于塞瓦斯托波尔的A. zernowi和柴达木的A.tsaidamensis。新种下门齿内刃上翻的特点显示Acerorhinus属有向Chilotherium属演化的趋势。     

贵州毕节麻窝口洞与智人伴生的长鼻类化石

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