Morphometric analysis of hominoid lower molars from Yuanmou of Yunnan Province, China

Shape analyses of cross-sectional mandibular molar morphology, using Euclidean Distance Matrix Analysis, were performed on 79 late Miocene hominoid lower molars from Yuanmou of Yunnan Province, China. These molars were compared to samples of chimpanzee, gorilla, orangutan,Lufengpithecus lufengensis, Sivapithecus, Australopithecus afarensis, and human mandibular molars. Our results indicate that the cross-sectional shape of Yuanmou hominoid lower molars is more similar to the great apes that to humans. There are few differences between the Yuanmou,L. lufengensis, andSivapithecus molars in cross-sectional morphology, demonstrating strong affinities between these three late Miocene hominoids. All three of the fossil samples show strong similarities to orangutans. From this, we conclude that these late Miocene hominoids are more closely related to orangutants than to either the African great apes or humans.     

Preliminary investigation of dental microstructure in the Yuanmou hominoid (Lufengpithecus hudienensis), Yunnan Province,China

Fieldwork in the Yuanmou Basin of southern China has uncovered a large assemblage of late Miocene hominoid fossils assigned to Lufengpithecus hudienensis. Two mandibular first molars from this species were made available for histological analysis as part of a larger ongoing study on the ontogeny of dental development in Miocene to Recent hominoids. Results are compared with published and unpublished data on tooth growth in a wide range of extant and extinct hominoids. The Yuanmou molars are smaller than those of Lufengpithecus lufengensis and have markedly shorter crown formation times, overlapping slightly with Pan, but most similar to Proconsul and Dryopithecus. In other aspects of molar development (including enamel extension rates and enamel thickness), L. hudienensis shows similarities with all extant hominoids, in particular, Pongo. Ultimately, charting the ontogeny of molar crown formation may help shed light on the relationship of Lufengpithecus hudienensis to orangutans, and other Miocene to Recent hominoids.     

Tooth Wear Difference Between the Yuanmou Hominoid and <Emphasis Type="Italic">Lufengpithecus</Emphasis>

The Late Miocene hominoids recovered from Lufeng (Lufengpithecus) and Yuanmou of Yunnan Province, China, are among the most numerous hominoid fossils in Eurasia. They have yielded critical evidence for the evolutionary history, biogeography and paleobiology of Miocene hominoids. We examined and compared the wear pattern and differences of 804 molars of the Yuanmou hominoid and Lufengpithecus. Our results indicate that both the upper and lower molars of the Yuanmou hominoids were more heavily worn than those of Lufengpithecus. The wear patterns of the individual molars between the Yuanmou hominoid and Lufengpithecus also are different. The heaviest wear of lower molars of the Yuanmou hominoid occur in M₂, followed by M₁ and M₃. In Lufengpithecus, M₁ and M₃ were more heavily worn than M₂. There are differences in wear between the upper and lower molars for the two hominoids. Among the various factors related to tooth wear, we suggest that the main reason for the tooth wear differences between the Yuanmou hominoid and Lufengpithecus may be that they had different diets. More soft dietary items like leaves and berries were probably consumed by Lufengpithecus, and the Yuanmou hominoid may mainly have feed on harder or frugivorous diets. This result complements findings from previous studies of tooth size proportion, and the development of lower molar shearing crests in the 2 samples. Enamel thickness, living environment, behavior patterns, and population structure also might account for dental wear differences between the Yuanmou hominoid and Lufengpithecus.     

云南开远小龙潭动物群的性质及时代的进一步探讨

本文在前人工作的基础上,结合新材料,对小龙潭动物群作了新的补充与论述.小龙潭动物群在组合面貌上与西瓦立克的 Chinji, Nagri 层动物群相近,动物群的时代不早于 Chinji 层而早于云南禄丰石灰坝动物群,为晚中新世.     

云南中新世杉科化石木研究

利用光学显微镜和扫描电镜首次对云南省楚雄州晚中新世石灰坝组石鼓村层的钙化木材进行了解剖学研究.鉴定出两种类型的木材:柳杉型落羽杉型木(Taxodioxylon cryptomeripsoides Schonfeld)和杉木型落羽杉型木(Taxodioxylon cunninghamioides Watari).二者分别与现代柳杉属和杉木属具有最接近的亲缘关系.根据这两种杉科化石木现存最近亲缘种的生态环境,并综合其他资料,推测该地区在晚中新世为温暖湿润的亚热带气候环境.     

元谋小河村古猿上颌骨化石的初步研究

１９８７年初和１９８９年１１月,分别在云南省元谋县小河村的蝴蝶梁子和盖排梁子,发现了两件古猿上颌骨化石（ＹＭ１２和ＹＭ１５０）,原研究者将前者订名为“腊玛古猿属蝴蝶种（Ｒａｍａｐｉｔｈｅｃｕｓｈｕｄｉｅｎｅｓｉｓ）。”作者研究了这两件标本,从形态上看,两者十分相似,从尺寸上可分为大、小两个类型,它们可能是同一种的雌雄个体,：即前者大,为雄性;后者小,为雌性。它们与禄丰古猿（Ｌｕｆｅｎｇｐｉｔｈｅｃｕｓｌｕｆｅｎｇｅｎｓｉｓ）的形态非常相似,它们应归为禄丰古猿属。但这两件小河的标本,又有它们的固有特点,所以暂归之于Ｌｕｆｅｎｇｐｉｔｈｅｃｕｓｓｐ．。     

The oldest Eurasian hominoid.

Engelswies is an early Miocene vertebrate locality in southern Germany with a rich assemblage of terrestrial mammals, invertebrates and fossil plants. It is dated to 16.5-17.0 Ma based on magnetostratigraphy, biostratigraphy and lithostratigraphy, and includes among the faunal remains a hominoid upper molar fragment, the oldest hominoid so far identified from Europe. The evidence from Engelswies suggests that hominoids arrived in Eurasia about 17 Ma, roughly contemporaneously with pliopithecoids and Deinotherium, and before the last marine transgression to isolate Eurasia from Africa. Thick enamel and low dentine penetrance may have been key adaptations that contributed to the success of hominoids of dentally modern aspect in western Eurasia and ultimately to their ability to spread to eastern Eurasia and Africa in the middle and late Miocene.     

Age at first molar emergence in Lufengpithecus lufengensis and its implications for life-history evolution

The late Miocene hominoid Lufengpithecus from Yunnan Province, China, is crucial for understanding hominoid evolution in Asia. Given that age at first permanent molar emergence is a key life-history trait in primates, the present study determined the age at death of the Lufengpithecus lufengensis juvenile PA868, which was in the process of erupting its first molar. Using a perikymata periodicity of 7-11 days, along with estimation of cusp formation time and the postnatal delay of crown mineralization, perikymata counts obtained from the permanent central incisor and canine germs indicate that the age at death of PA868 was 2.4-4.5 years based on the central incisor germ, and 2.5-4.7 years based on the canine germ. The age at the first molar emergence was actually slightly younger (by about 0.3 years), as demonstrated by tiny wear facets on this tooth, which indicate that gingival emergence had occurred sometime before death. The average age at first molar emergence of Lufengpithecus lufengensis PA868 is estimated to be 3.2-3.3 years, with a range of 2.1-4.4 years. In comparison to extant primates and other fossil hominoids, the life history of Lufengpithecus lufengensis is similar to that of extant great apes and the Miocene hominoids Afropithecus turkanensis and Sivapithecus parvada, as well as Plio-Pleistocene Australopithecus, and different from monkeys, gibbons, and modern humans.     

Khoratpithecus piriyai, a Late Miocene hominoid of Thailand

A Khoratpithecus piriyai lower jaw corresponds to a well-preserved Late Miocene hominoid fossil from northeastern Thailand. Its morphology and internal structure, using a microcomputed tomography scan, are described and compared to those of other known Miocene hominoids. It originated from fluviatile sand and gravel deposits of a large river, and was associated with many fossil tree trunks, wood fragments, and large vertebrate remains. A biochronological analysis by using associated mammal fauna gives an estimated geological age between 9-6 Ma. The flora indicates the occurrence of a riverine tropical forest and wide areas of grassland. K. piriyai displays many original characters, such as the great breadth of its anterior dentition, suggesting large incisors, large lower M3, a canine with a flat lingual wall, and symphysis structure. Several of its morphological derived characters are shared with the orangutan, indicating sister-group relationship with that extant ape. This relationship is additionally strongly supported by the absence of anterior digastric muscle scars. These shared derived characters are not present in Sivapithecus, Ankarapithecus, and Lufengpithecus, which are therefore considered more distant relatives to the orangutan than Khoratpithecus. The Middle Miocene K. chiangmuanensis is older, displays more primitive dental characters, and shares several dental characters with the Late Miocene form. It is therefore interpreted as its probable ancestor. But its less enlarged M3 and more wrinkled enamel may suggest an even closer phylogenetic position to orangutan ancestors, which cannot yet be supported because of the incomplete fossil record. Thus Khoratpithecus represents a new lineage of Southeast Asian hominoids, closely related to extant great ape ancestors.     

中国北方上中新统的早期玛姆象属(Mammut)及其在玛姆象科(Mammutidae)分化和演化中的意义

玛姆象属是长鼻类玛姆象科这一重要类群的最终成员.虽然这一属在上新世的欧亚大陆和更新世的北美大陆广泛分布,它早期的进化历史却鲜为人知.报道了中国北方上中新统发现的斜脊玛姆象(相似种)(Mammut cf.M.obliquelophus)的新材料,包括一个几乎完整的幼年头骨,这些材料显示了玛姆象科的许多原始特征,因此很好地解释了玛姆象属形态特征的形成过程.斜脊玛姆象(相似种)具有强烈向两侧扩展的枕部,在门齿窝的基部具有收缩,这些特征与莫罗托始轭齿象(Eozygodon morotoensis)和广河豕脊齿象(Choerolophodon guangheensis)均具有相似性,后两者分别为玛姆象科与豕脊齿象科的早期代表.因此,玛姆象科与豕脊齿象科(Choerolophodontidae)具有近的亲缘关系,二者同位于象形类(Elephantimorpha)系统发育中的基部.支序分析支持了这一结论.     

Dental Eruption Sequences in Fossil Colobines and the Evolution of Primate Life Histories

Unlike other catarrhines, colobines show early molar eruption relative to that of the anterior dentition. The pattern is variable, with Asian genera (Presbytina) showing a greater variability than the African genera (Colobina). The polarity of early relative molar eruption, as well as the degree to which it is related to phylogeny, are unclear. Schultz (1935) suggested that the trend reflects phylogeny and is primitive for catarrhines. More recently, however, researchers have proposed that life history and dietary hypotheses account for early relative molar eruption. If the colobine eruption pattern is primitive for catarrhines, it implies that cercopithecines and hominoids converged on delayed relative molar eruption. Alternatively, if the colobine condition is derived, factors such as diet and mortality patterns probably shaped colobine eruption patterns. Here we update our knowledge on eruption sequences of living colobines, and explore the evolutionary history of the colobine dental eruption pattern by examining fossil colobine taxa from Eurasia (Mesopithecus) and Africa (Kuseracolobus aramisi and Colobus sp.) and the basal cercopithecoid Victoriapithecus macinnesi. We scored specimens per Harvati (2000). The Late Miocene-Early Pliocene Mesopithecus erupts the second molar early relative to the incisors, while the Early Pliocene Kuseracolobus aramisi does not. These results demonstrate that the common colobine tendency for early molar eruption relative to the anterior dentition had appeared by the Late Miocene, and that some of the diversity observed among living colobines was already established in the Late Miocene/Early Pliocene. We discuss the implications of these results for phylogenetic, life history, and dietary hypotheses of dental development.     

云南禄丰古猿化石地点的豪猪化石

描述了产自云南禄丰古猿化石地点的豪猪化石禄丰豪猪 (新种 ) (Hystrixlufengensissp .nov.)。这是一种较原始的豪猪。它的个体中等 ;两上颊齿列往前靠近 ;下颌骨骨体较低 ,齿隙稍凹 ,其前端高于下颊齿冠面 ;颊齿齿冠较低 ;上颊齿舌侧沟横向较短 ;P4大 ,前尖通常孤立 ,中附尖很发达 ,不与中脊连 ;M3较少退化 ;上颊齿具 3齿根 ,大的内侧齿根具明显纵沟 ;下颊齿通常具 4齿根等。形态结构分析表明 ,H .lufengensis仅比H .parvae进步 ,比H .primigenia和H .sivalensis及其他种都原始。它可能代表亚洲目前已知最早、最原始的豪猪。其产出时代为晚中新世保德期 (狭义 )的较早期 (距今约 8Ma)。     

云南禄丰、元谋晚中新世古猿地点始鼠科化石

<正>始鼠科(Eomyidae)是一类绝灭了的啮齿类动物,渐新世和中新世时广布全北区,但亚洲远没有欧洲和北美常见。中国含始鼠类化石地点不多,发现的属只有渐新世的Eomys、Eomyodon和Pseudotheridomys,以及中新世的Keramidomys和Leptodontomys(Zheng and Li,1982;Falhbusch et al．,1983;Wang and Emry,1991;Qiu,1996;Wang,2002)。本文描述的云南始鼠类化石,系1983年在禄丰石灰坝和1999、2000年在元谋雷老两个古猿地点采集到的。材料不多,但至少代表始鼠科的两个新属,为我国惟一采自南方,并与古猿类共生的稀少啮齿类动物。新种的模式产地均为禄丰石灰坝。     

The micromammalian fauna from the Leilao, Yuanmou hominoid locality: implications for biochronology and paleoecology

The discovery of Lufengpithecus at Yuanmou, in Yunnan Province, China, provides important clues to understanding the evolution of early hominoids in eastern Asia. However, the age and paleoecology of the fauna remain to be established. An assemblage of micromammalian fossils, collected recently by screenwashing at Leilao, one of the hominoid-bearing localities at Yuanmou, contains 41 species belonging to 16 families and 4 orders, and represents the most diverse Neogene micromammalian fauna known from southwestern China. This paper presents an analysis of the taxonomy, age, and paleoecology of the micromammalian fauna. The Yuanmou hominoid fauna is now considered older than the Lufeng fauna, and is currently thought to correspond to an age of about 9 Ma. The micromammalian fauna indicates a predominantly forested habitat, with marginal environments consisting of bush-grassland.     

Enamel thickness,microstructure and development in Afropithecus turkanensis

Afropithecus turkanensis, a 17-17.5 million year old large-bodied hominoid from Kenya, has previously been reported to be the oldest known thick-enamelled Miocene ape. Most investigations of enamel thickness in Miocene apes have been limited to opportunistic or destructive studies of small samples. Recently, more comprehensive studies of enamel thickness and microstructure in Proconsul, Lufengpithecus, and Dryopithecus, as well as extant apes and fossil humans, have provided information on rates and patterns of dental development, including crown formation time, and have begun to provide a comparative context for interpretation of the evolution of these characters throughout the past 20 million years of hominoid evolution. In this study, enamel thickness and aspects of the enamel microstructure in two A. turkanensis second molars were quantified and provide insight into rates of enamel apposition, numbers of cells actively secreting enamel, and the time required to form regions of the crown. The average value for relative enamel thickness in the two molars is 21.4, which is a lower value than a previous analysis of this species, but which is still relatively thick compared to extant apes. This value is similar to those of several Miocene hominoids, a fossil hominid, and modern humans. Certain aspects of the enamel microstructure are similar to Proconsul nyanzae, Dryopithecus laietanus, Lufengpithecus lufengensis, Graecopithecus freybergi and Pongo pygmaeus, while other features differ from extant and fossil hominoids. Crown formation times for the two teeth are 2.4-2.6 years and 2.9-3.1 years respectively. These times are similar to a number of extant and fossil hominoids, some of which appear to show additional developmental similarities, including thick enamel. Although thick enamel may be formed through several developmental pathways, most Miocene hominoids and fossil hominids with relatively thick enamel are characterized by a relatively long period of cuspal enamel formation and a rapid rate of enamel secretion throughout the whole cusp, but a shorter total crown formation time than thinner-enamelled extant apes.     

Divergence time estimation in Cichorieae (Asteraceae) using a fossil-calibrated relaxed molecular clock

Knowing the age of lineages is key to understanding their biogeographic history. We aimed to provide the best estimate of the age of Cichorieae and its subtribes based on available fossil evidence and DNA sequences and to interpret their biogeography in the light of Earth history. With more than 1,550 species, the chicory tribe (Cichorieae, Asteraceae) is distributed predominantly in the northern Hemisphere, with centres of distribution in the Mediterranean region, central Asia, and SW North America. Recently, a new phylogenetic hypothesis of Cichorieae based on ITS sequences has been established, shedding new light on phylogenetic relationships within the tribe, which had not been detected so far. Cichorieae possess echinolophate pollen grains, on the surface of which cavities (lacunae) are separated by ridges. These lacunae and ridges show patterns characteristic of certain groups within Cichorieae. Among the fossil record of echinolophate pollen, the Cichorium intybus-type is the most frequent and also the oldest type (22 to 28.4 million years old). By using an uncorrelated relaxed molecular clock approach, the Cichorieae phylogenetic tree was calibrated with this fossil find. According to the analysis, the tribe originated no later than Oligocene. The species-rich core group originated no later than Late Oligocene or Early Miocene and its subtribes diversified no later than Middle/Late Miocene or Early Pliocene—an eventful period of changing geological setting and climate in the Mediterranean region and Eurasia. The first dispersal from Eurasia to North America, which resulted in the radiation of genera and species in North America (subtribe Microseridinae), also occurred no later than Middle or Late Miocene, suggesting the Bering land bridge as the route of dispersal.