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Morphometric Study on the Mandible of Colobine Fossil (Mesopithecus pentelicus) Found in East Asia, a Comparison With Extant Taxa
Abstract
A tooth-bearing mandible fossil of a colobine monkey discovered at Shuitangba, Zhaotong, Yunnan, China, was morphometrically analyzed and compared with extant Asian colobines. Our previous qualitative and quantitative descriptions indicate that it can be safely attributed to Mesopithecus pentelicus, a Miocene fossil colobine widely found in Europe and South Asia. The present research aims to explore fossil association with extant colobines and functionally propose its dietary preferences based on multivariate morphometric analyses of mandibular morphology. The results indicate that this fossil species presents a mosaic association with extant langurs (Presbytis, Trachypithecus, and Semnopithecus) and odd-nosed monkeys (Pygathrix, Nasalis, and Rhinopithecus), with most similarities of size-related traits and size-adjusted shapes, and a notable difference from extant Rhinopithecus, due to the increased body size of the latter since the Pliocene. The allometric analysis showed that, like the fossils of the same species in other sites, its mandibular structure appears more adapted to crushing hard seed shells than chewing leaves. Moreover, our findings also imply that the Asian colobines significantly modified their dietary preferences over the last 6 million years following the ecological and environmental changes triggered by the accelerated uplift of the Qinghai-Tibet Plateaus and severe monsoons. Morphologically, the more developed condyle length and moment arms of the temporomandibular joint and medial pterygoid muscles appear to accommodate a more folivorous dietary selection, functionally related to the intake of rigid fibers in leaves that require frequent one or two-side mandibular chewing and grinding.
... Sex dimorphism, which distinguishes male and female morphological features, is one of the important topics in this research arena. Morphometrics has fundamental utility beyond forensic identification and contributes to a better understanding of the various populations [63,64]. The present study aimed to systematically examine and precisely collect data and interpret the findings within the broader form of existing knowledge. ...
The present study aimed to evaluate the sex dimorphism in morphometrics of permanent canines using mesiodistal and cervicoincisal widths in the Saudi Arabian population. The study was performed using dental casts of patients attending the prosthodontics department, College of Dentistry, Majmaah University, Saudi Arabia. The inclusion criteria involved the presence of all four permanent canines (maxillary left and right (13 and 23) and mandibular left and right (33 and 43)) without any form of developmental anomalies or dental caries with a complete eruption. Mesiodistal width and cervicoincisal width were measured using a digital caliper, ensuring precision and consistency. Statistical tests included t-tests and correlation analyses using IBM Statistics (version 21) with p ≤ 0.05 significance level. A total of 94 sets of dental casts of patients with a mean age of 24.6 ± 4.06 were available in the study for evaluation. Tooth 13 was found to have a higher mesiodistal width (8.12 ± 0.57 mm), while tooth 43 was observed to have a higher cervicoincisal width (9.3 ± 0.9 mm). The study observed gender-based differences in mean scores, with females generally having slightly lower mean scores in mesiodistal and where males (p < 0.05) observed with slightly low cervicoincisal widths compared to females. Positive correlations were found between age and mesiodistal and cervicoincisal scores across various dimensions (p < 0.005). There was evidence of difference in mesiodistal and cervicoincisal widths among antimeres. The percentage of sex dimorphism varied across dimensions, with some showing more pronounced gender-related differences. The study establishes the mesiodistal and cervicoincisal widths of all permanent canines can be used to identify sex dimorphism in the Saudi Arabian population.
Fallback foods (FBF), categorized into staple and filler types, are suboptimal food sources chosen by animals in response to a scarcity of preferred food items during specific periods. Using lichens as FBF by Yunnan snub‐nosed monkeys ( Rhinopithecus bieti ) represents a distinctive ecological adaptation and evolutionary development within nonhuman primates. This study delves into the annual dietary choices of the species to address issues, elucidate the nutritional value, and understand the ecological significance of lichens for this primate species, which resides at the highest altitudes and experiences the coldest weather among global primates. The findings reveal that the lichens consumed by the monkeys serve as the staple FBF, with Bryoria spp. and Usnea longissima being the primary dietary species. The former is the preferred choice, providing higher digestible fiber (neutral detergent fiber) levels but lower tannin, fat, ADF, and energy levels. During the dry season, lichens dominate as the monkeys' primary food and nutritional resources. In the wet season, they act as a fundamental food selection rather than an ideal dietary choice, substituting nutrients from fruits, seeds, and leaves. Compared to other Asian colobine counterparts, this species exhibits the highest lichen consumption but the lowest proportions of leaves, flowers, and seeds. This study provides valuable evidence and information for developing or amending conservation strategies and guidelines for the dietary management of captive breeding of monkeys, one of the world's critically endangered primate species.
The dual impact of climate change and human activities has precipitated a sharp decline in primate biodiversity globally. China is home to the most diverse primate species in the Northern hemisphere, which face severe ecological threats due to the expansion of modern agriculture, extensive exploitation and consumption of natural resources, and excessive land development during its transition from an agricultural to a modern society. In response, China has implemented various ecological conservation measures, including habitat restoration and protection. These efforts have made substantial strides in biodiversity conservation, with certain regions witnessing an increase in primate populations. In the current study, we conducted a systematic review of historical documents and field research data related to Chinese primates, evaluating the endangered status of primate species in China. Despite improvements in the habitats of most primate species and some population growth, many species still face severe threats, including declining and small populations. Species such as the Myanmar snub-nosed monkey, eastern black crested gibbon, and Hainan gibbon remain particularly vulnerable due to their limited distribution ranges and extremely small populations. Insufficient scientific data, fragmented information, and not enough studies in conservation biology further compound the challenges. Moreover, there is a notable lack of detailed population monitoring data for species such as the Bengal slow loris, pygmy slow loris, Indochinese gray langur, Shortridge’s langur, and capped langur, which hinders the development of practical and targeted conservation management strategies. Therefore, for national biodiversity conservation, there is an urgent need for specialized primate surveys, enhancing habitat protection and restoration, and increasing focus on cross-border conservation strategies and regional cooperation. There is also a need to establish a comprehensive and systematic research database platform, conduct continuous and in-depth research in primate biology, and actively engage in the scientific assessment of ecotourism. Additionally, strengthening public awareness and education on wildlife conservation remains essential. Such integrated and systematic efforts will provide scientific support for the current and future conservation and management of primate species in China.
The fossil colobine genus Mesopithecus is the oldest European monkey, ranging from the Late Miocene to the earliest Pleistocene. It is one of the most successful genera of Old World monkeys since the late Neogene. Its ecology, as an indicator of Late Miocene environments, is of particular interest. Several investigations have clarified the locomotor adaptations of the middle and late Turolian Balkan Meso-pithecus pentelicus, but such studies are virtually absent for the earliest known taxon, the early Turolian Mesopithecus delsoni, due to the lack of fossil material. However, a large collection of postcranial material of M. delsoni from the Bulgarian Early Turolian locality of Hadjidimovo provides the first opportunity for such an analysis. The present study examines the functional morphology of the fossil humeri of M. delsoni from Hadjidimovo, Bulgaria, and of M. pentelicus from Bulgarian and Greek fossil localities. We provide detailed comparative qualitative descriptions and use univariate and multivariate quantitative analyses of one angular and 12 linear measurements in comparison with 149 extant Cercopithecidae, representing 14 genera and 34 species. Our analyses demonstrate that the humeral elements from Hadjidimovo show important morphological differences from those of M. pentelicus from Pikermi, Kalimantsi, and Gorna Sushitsa, suggesting strong terrestrial tendencies for M. delsoni. This finding, when considered together with the paleobiologial inference of semiterrestriality for the early cercopithecoid Victoriapithecidae, might indicate that the first colobines (still unknown) were also semiterrestrial. Finally, the morphological features related to terrestriality in M. delsoni, which differ from those of the later M. pentelicus, provide additional data in support of the idea that the older taxon represents a separate species.
Jaw morphology is closely linked to both diet and biomechanical performance, and jaws are one of the most common Mesozoic mammal fossil elements. Knowledge of the dietary and functional diversity of early mammals informs on the ecological structure of palaeocommunities throughout the longest era of mammalian evolution: the Mesozoic. Here, we analyse how jaw shape and mechanical advantage of the masseter (MAM) and temporalis (MAT) muscles relate to diet in 70 extant and 45 extinct mammals spanning the Late Triassic-Late Cretaceous. In extant mammals, jaw shape discriminates well between dietary groups: insectivores have long jaws, carnivores intermediate to short jaws, and herbivores have short jaws. Insectivores have low MAM and MAT, carnivores have low MAM and high MAT, and herbivores have high MAM and MAT. These traits are also informative of diet among Mesozoic mammals (based on previous independent determinations of diet) and set the basis for future ecomorphological studies.
A dentate mandible and proximal femur of Mesopithecus pentelicus Wagner, 1839 are described from the Shuitangba lignite mine in Zhaotong Prefecture, northeastern Yunnan Province, China. The remains were retrieved from sediments just below those that yielded a juvenile Lufengpithecus cranium and are dated at about ∼6.4 Ma. The mandible and proximal femur were found in close proximity and are probably of the same individual. The lower teeth are metrically and morphologically closely comparable with those of confirmed M. pentelicus from Europe, and on this basis, the specimen is assigned to this species. The anatomy of the proximal femur indicates that the Shuitangba Mesopithecus was a semiterrestrial quadruped that engaged in a range of mostly arboreal activities, including walking, climbing, and occasional leaping, with an abducted hip joint. The Shuitangba Mesopithecus is dentally typical for the genus but may have been more arboreal than previously described for M. pentelicus. M. pentelicus is well known from late Miocene (MN 11–12) sites in Europe and southwest Asia. Its estimated average rate of dispersal eastward was relatively slow, although it could have been episodically more rapid. The presence of a colobine, only slightly lower in the same section at Shuitangba that produced Lufengpithecus, is one of the only two well-documented instances of the near or actual co-occurrence of a monkey and ape in the Miocene of Eurasia. At Shuitangba, M. pentelicus occupied a freshwater-margin habitat with beavers, giant otters, swamp rabbits, and many aquatic birds. The presence of M. pentelicus in southwest China near the end of the Miocene further attests to the ecological versatility of a species long recognized as widespread and adaptable. The modern colobines of Asia, some or all of which are probable descendants of Mesopithecus, have gone on to inhabit some of the most highly seasonal and extreme habitats occupied by nonhuman primates.
Plain Language Summary
Animals and plants in many regions had to survive a gradual drying and cooling environment during the Late Miocene epoch (ca. 12–5 Ma). Exploring the drivers and mechanisms behind Late Miocene climate change is helpful when considering current global warming trends. Although the exact reason for these Late Miocene changes remains unclear, two suspects have been identified, that is, a decline in CO2 levels and/or regional tectonic activity. In this study we used microbial cell membrane lipid fossils to reconstruct the quantitative paleotemperatures and paleoaltitudes of the Xining Basin, on the northeastern Tibetan Plateau, during the Late Miocene. Our results revealed a surficial uplift event (~10.5–8 Ma) delineated by the identification of a rapid cooling process during a period that experienced constant sea surface temperatures, leading to an increasingly dry climate and ecosystem changes over large areas. Moreover, the amplitude of this cooling over land appears to have been less than that observed over the ocean during the CO2‐dominated Late Miocene cooling event (~7–5.4 Ma). Therefore, we would posit that regional tectonic activities played a more important role than CO2 levels in the changes to terrestrial climate patterns and ecosystems during the Late Miocene.
This study aims to explore the feeding ecology of two terrestrial papionins, Papio and Theropithecus from the Shungura Formation in Ethiopia, the most complete stratigraphic and paleontological record of the African Plio-Pleistocene. Two aspects were evaluated using Dental Microwear Texture Analysis: differences in diet between the extinct genera and their extant relatives, and any potential dietary fluctuations over time. Amongst more than 2,500 cercopithecid dental remains, 154 Theropithecus molars and 60 Papio molars were considered. Thirty-nine extant wild baboons and 20 wild geladas were also considered. The results show that diets of extinct monkeys from Member G already differed between genera as it is the case for their extant representatives. The shearing facets on the Theropithecus molars display significant variations in microwear textures, suggesting several dietary shifts over time. Two events point to higher intakes of herbaceous monocots (tougher than dicots foliages), at about 2.91 Ma (between members B and C) and at 2.32 Ma (between members E and F). These two events are separated by an inverse trend at about 2.53 Ma (between members C and D). Some of these variations, such as between members E and F are supported by the enamel carbon isotopic composition of herbivorous mammals and with paleovegetation evidence.
The genus Mesopithecus is quite common in the late Miocene of Greece being recognized in various localities. After its first discovery in Pikermi, near Athens, it was found in Axios Valley, Serres Basin, Thessaly and Chalkidiki Peninsula. In the present article the Greek sample of Mesopithecus is compared and analyzed by multivariate methods. The following taxa can be recognized. The type species M. pentelicus was recorded in Pikermi and Chomateres both dated to the uppermost middle Turolian (MN 12). A largesized species named M. delsoni was recognized in the locality Ravin des Zouaves-5 of Axios Valley, dated to early Turolian (MN 11) at -8.2 Ma. A form intermediate between the above mentioned species, named M. delsoni/pentelicus was found in the localities Vathylakkos2, 3 of Axios Valley and in the locality ofPerivolaki in Thessaly; both localities are dated to middle Turolian (MN 12) at -7.5 Ma and 7.3-7.1 Ma respectively. Two forms similar to M. pentelicus but with some minor differences are known from the late Turolian (MN 13) localities Dytiko-1, 2, 3 of Axios Valley; they are referred to as M. cf. or aff. M. pentelicus. A small-sized form is also known from the late Turolian locality Dytiko-2 of Axios Valley, which is similar to M. monspessulanus and it is referred to as M. cf. M. monspessulanus. The Mesopithecus from the localities Maramena (Serres Basin) and Kryopigi (Chalkidiki Peninsula) cannot be certainly determined and they are referred to as Mesopithecus sp.
New material of Mesopithecus, including two cranial parts, is described from the late Miocene (early Turolian) locality of "Vathylakkos 2" (VTK) of the lower Axios valley, Macedonia, Greece. Its morphological characters are similar to those of the type material of Mesopithecus pentelicus from Pikermi. However the size of the lower and upper molars either reaches the maximal values of M. pentelicus or exceeds them indicating similarities with M. delsoni. Thus the VTK material of Mesopithecus is referred to M. cf. pentelicus. The biostratigraphical significance of the genus, as well as its palaeoecology are discussed.
Numerous remains of Mesopithecus have recently been recovered from the late Miocene mammalian localities of Macedonia, northern Greece. Three mandibles from the early Turolian are identified as M. delsoni, sp. nov., probably ancestral to M. pentelicus of Pikermi. Others, dated to the latest Turolian, differ from M. pentelicus, but most of the teeth are so worn that they must be identified as Mesopithecus, aff. M. pentelicus. A last set, coming also from the latest Turolian, could possibly be attributed to Mesopithecus, cf. M. monspessulanus. The evolution of the genus Mesopithecus can be used as a biostratigraphic tool in late Miocene continental deposits.
The evolutionary origin of the vertebrate jaw persists as a deeply puzzling mystery. More than 99% of living vertebrates have jaws, but the evolutionary sequence that ultimately gave rise to this highly successful innovation remains controversial. A synthesis of recent fossil and embryological findings offers a novel solution to this enduring puzzle. The Mandibular Confinement Hypothesis proposes that the jaw evolved via spatial confinement of the mandibular arch (the most anterior pharyngeal arch within which the jaw arose). Fossil and anatomical evidence reveals: (i) the mandibular region was initially extensive and distinct among the pharyngeal arches; and (ii) with spatial confinement, the mandibular arch acquired a common pharyngeal pattern only at the origin of the jaw. The confinement occurred via a shift of a domain boundary that restricted the space the mesenchymal cells of the mandibular arch could occupy. As the surrounding domains replaced mandibular structures at the periphery, this shift allowed neural crest cells and mesodermal mesenchyme of the mandibular arch to acquire patterning programs that operate in the more posterior arches. The mesenchymal population within the mandibular arch was therefore no longer required to differentiate into specialized feeding and ventilation structures, and was remodelled into a jaw. Embryological evidence corroborates that the mandibular arch must be spatially confined for a jaw to develop. This new interpretation suggests neural crest as a key facilitator in correlating elements of the classically recognized vertebrate head 'segmentation'.
© 2015 Cambridge Philosophical Society.
Patterns of stress were analyzed in the mandibular symphysis of Macaca fascicularis using rosette strain gages. During jaw opening, the mandibular symphysis is bent due to medial transverse bending of the mandibular corpora. Levels of stress and strain are relatively low at this time, and the source of this stress is the medially-directed component of force from the lateral pterygoid muscles. During the power stroke of mastication, the symphysis is maximally stressed. At this time the symphysis experiences dorsoventral shear and bending due to lateral transverse bending of the mandibular corpora, i.e., "wishboning." The dorsoventral shear is due to the vertical component of the balancingside adductor muscle force; the "wishboning" is due to the laterally-directed components of the bite and jaw adductor muscle forces. Unlike dorsoventral shear, "wishboning" results in considerable levels of stress and strain, particularly along the most lingual aspect of the symphysis. The most effective way to counter this stress is to increase the thickness of the symphysis in the labio-lingual direction. The stress analysis and an allometric analysis of mandibular dimensions in female cercopithecine (Old World) monkeys indicates that allometric changes in the symphysis are readily understood if the mandible is modelled as a curved beam. With increasing body size, symphyseal thickness in cercopithecines must increase in a positively allometric fashion so as to prevent the occurrence of dangerously high levels of stress along the most lingual aspect of the symphysis. This is because increasing body size is associated with three factors thathave important consequences within the context of the biomechanics of curved beams: (1) jaw length is positively allometric to body size, (2) mandibular-arch width is negatively allometric to body size, and (3) there is a tendency to use relatively greater amounts of balancing-side jaw muscle force with increased body size because of dietary changes and allometricconstraints on total jaw muscle force.
This paper analyses the diversity and spatial pattern of the altitudinal belts in the Hengduan Mountains in China. A total
of 7 types of base belts and 26 types of altitudinal belts are identified in the study region. The main altitudinal belt lines,
such as forest line, the upper limit of dark coniferous forest and snow line, have similar latitudinal and longitudinal spatial
patterns, namely, arched quadratic curve model with latitudes and concave quadratic curve model along longitudinal direction.
These patterns can be together called as “Hyperbolic-paraboloid model”, revealing the complexity and speciality of the environment
and ecology in the study region. This result further validates the hypnosis of a common quadratic model for spatial pattern
of mountain altitudinal belts proposed by the authors. The spatial pattern of altitudinal belts is closely related with moisture-related
exposure effect in the Hengduan Mountains. Different combinations (spectra) of altitudinal belts and different base belt types
appear in windward and leeward flanks and even in the same flanks of different ranges. This is closely related with the parallel
mountain ranges of the Hengduan Mountains, which, at nearly right angle with the moving direction of prevailing moisture-laden
air masses from west and east, hold up the warm and humid monsoon wind from moving into the core region and result in different
moisture conditions in windward and leeward flanks. However, how to quantitatively describe the moisture-related exposure
effect needs further study. In addition, the data quality and data accuracy at present also affect to some extent the result
of quantitative modeling and should be improved with RS/GIS in the future.
Superimposition methods for comparing configurations of landmarks in two or more specimens are reviewed. These methods show
differences in shape among specimens as residuals after rotation, translation, and scaling them so that they align as well
as possible. A new method is presented that generalizes Siegel and Benson's (1982) resistant-fit theta-rho analysis so that
more than two objects can be compared at the same time. Both least-squares and resistant-fit approaches are generalized to
allow for affine transformations (uniform shape change). The methods are compared, using artificial data and data on 18 landmarks
on the wings of 127 species of North American mosquitoes. Graphical techniques are also presented to help summarize the patterns
of differences in shape among the objects being compared.
Habitudes alimentaires du premier colobiné européen, Mesopithecus: apports de l'analyse comparative des micro-usures dentaires avec des cercopithecidés actuels. Cette étude vise à déterminer les habitudes alimentaires des premiers colobinés européens, du genre Mesopithecus (Miocène supérieur) par l'analyse du type de micro-usure dentaire sur les molaires. Cinquante-sept spécimens attribués à Mesopithecus sont comparés à 162 individus sauvages représentant neuf espè ces actuelles de cercopithecidés africains et asiatiques. À travers une analyse en composante principale couplée à des analyses de variances, Mesopithecus apparaît significativement différent des colobinés actuels. Aucune différence significative n'est détectée entre les Mesopithecus et Chlorocebus aethiops et Papio hamadryas. Une analyse interspécifique dédicacée à Mesopithecus pentelicus ne révèle aucune différence entre les échantillons bulgares grecs. En résumé, les espèces de Mesopithecus se distinguent des colobinés actuels, principalement folivores. En prenant en compte les données paléoenvironnementales, leur distribution paléogéographique, leur anatomie postcrânienne, et leurs habitudes alimentaires ici reconstituées, les Mesopithecus peuvent être dépeints comme des singes semiterrestres et généralistes vis-à-vis de leur bol alimentaire.
CARBON isotopes from soil carbonate1-4 and soil organic matter5,6 yield palaeoecological information because the carbon in the soil carbonate forms in isotopic equilibrium with local soil CO2 (refs 1, 7), the isotopic composition of which is in turn determined by local plant cover. Siwalik Group sediments in northern Pakistan contain a well exposed palaeosol record spanning the past 18 Myr. Here we report on stable-carbon-isotope results from associated pedogenic carbonate which indicate a dramatic ecological shift from C3- to C4-dominated floodplain biomass beginning ~7.4-7.0 Myr ago. The earlier C3 floodplain biomasses were probably mainly composed of trees and shrubs, whereas C4 grasslands dominated in the Plio-Pleistocene. Oxygen isotopes also exhibit a shift in the latest Miocene, probably corresponding to a major climate change which may have induced the forest-to-grassland transition. This dramatic ecological shift in the latest Miocene may mark the inception or a marked strengthening of the Asian monsoon system.
A stress analysis of the primate mandible suggests that vertically deep jaws in the molar region are usually an adaptation to counter increased sagittal bending stress about the balancing-side mandibular corpus during unilateral mastication. This increased bending stress about the balancing side is caused by an increase in the amount of balancing-side muscle force. Furthermore, this increased muscle force will also cause an increase in dorsoventral shear stress along the mandibular symphysis. Since increased symphyseal stress can be countered by symphyseal fusion and as increased bending stress can be countered by a deeper jaw, deep jaws and symphyseal fusion are often part of the same functional pattern. In some primates (e.g., Cercocebus albigena), deep jaws are an adaptation to counter bending in the sagittal plane during powerful incisor biting, rather than during unilateral mastication.
The stress analysis of the primate mandible also suggests that jaws which are transversely thick in the molar region are an adaptation to counter increased torsion about the long axis of the working-side mandibular corpus during unilateral mastication. Increased torsion of the mandibular corpus can be caused by an increase in masticatory muscle force, an increase in the transverse component of the postcanine bite force and/or an increase in premolar use during mastication.
Patterns of masticatory muscle force were estimated for galagos and macaques, demonstrating that the ratio of working-side muscle force to balancing-side muscle force is approximately 1.5:1 in macaques and 3.5:1 in galagos during unilateral isometric molar biting. These data support the hypothesis that mandibular symphyseal fusion is an adaptative response to maximize unilateral molar bite force by utilizing a greater percentage of balancing-side muscle force.
The genus Mesopithecus is well represented in the late Miocene of Greece by several recognized species. The present paper investigates functional aspects of the humeri of Mesopithecus delsoni/pentelicus, M. pentelicus and M. aff. pentelicus of several Turolian sites from central and northern Greece, using multivariate approaches. For these purposes, we selected significant humeral functional features, which were represented by 23 linear dimensions and three angles on 14 fossil humeri and 104 humeri from 10 genera and 22 species of extant African and Asian Colobines. All size-adjusted measurements were examined through a principal components analysis, followed by a discriminant function analysis, and a canonical variates analysis. All analyses revealed that the selected characters were able to discriminate between extant colobine genera. Functional groups, such as arboreal walking/climbing, arboreal walking/suspensory and semi-terrestrial walking, were set apart from a central cluster formed by the arboreal walking and arboreal walking/terrestrial groups. This cluster also grouped the three studied Mesopithecus species, which were mainly classified as arboreal walkers with significant terrestrial activities. These observations match with paleoenvironmental reconstructions and the suggested opportunistic feeding habits. Moreover, the overall arboreal/terrestrial locomotor tendencies of these fossil forms are discussed in relation to their earlier migration from Africa and later dispersal to eastern and southern Asia.
The analysis of ratios of body measurements is deeply ingrained in the taxonomic literature. Whether for plants or animals, certain ratios are commonly indicated in identification keys, diagnoses, and descriptions. They often provide the only means for separation of cryptic species that mostly lack distinguishing qualitative characters. Additionally, they provide an obvious way to study differences in body proportions, as ratios reflect geometric shape differences. However, when it comes to multivariate analysis of body measurements, for instance, with linear discriminant analysis (LDA) or principal component analysis (PCA), interpretation using body ratios is difficult. Both techniques are commonly applied for separating similar taxa or for exploring the structure of variation, respectively, and require standardized raw or log-transformed variables as input. Here, we develop statistical procedures for the analysis of body ratios in a consistent multivariate statistical framework. In particular, we present algorithms adapted to LDA and PCA that allow the interpretation of numerical results in terms of body proportions. We first introduce a method called the "LDA ratio extractor," which reveals the best ratios for separation of two or more groups with the help of discriminant analysis. We also provide measures for deciding how much of the total differences between individuals or groups of individuals is due to size and how much is due to shape. The second method, a graphical tool called the "PCA ratio spectrum," aims at the interpretation of principal components in terms of body ratios. Based on a similar idea, the "allometry ratio spectrum" is developed which can be used for studying the allometric behavior of ratios. Because size can be defined in different ways, we discuss several concepts of size. Central to this discussion is Jolicoeur's multivariate generalization of the allometry equation, a concept that was derived only with a heuristic argument. Here we present a statistical derivation of the allometric size vector using the method of least squares. The application of the above methods is extensively demonstrated using published data sets from parasitic wasps and rock crabs.
Apart from northern and central China, the fossil record of the latest Miocene and Early Pliocene of Asia is not well documented and the record of South China during this interval is especially poor. Shuitangba, a site in Yunnan Province, offers a rare window into the paleoenvironment of the latest Miocene in southwestern China. Over 2400 vertebrate and macrobotanical specimens have been recovered from the site. The faunal assemblage is dominated by aquatic avian taxa and many of the mammalian taxa are those that indicate densely vegetated, water-margin habitats. Pollen and carpological remains indicate a temperate to subtropical, broad-leaved/ coniferous forest around standing water, with more open areas containing grasses and herbs. Analyses of clay minerals, chemical weathering, and enamel stable isotopes suggest that Shuitangba was warmer and more humid than today, possibly with more pronounced seasonality. Results of community structure analysis indicate that the Shuitangba mammalian community was different from those of other Late Miocene Chinese sites in the high proportions of aquatic-dependent mammalian taxa. While Shuitangba shared mammalian faunal elements with other Late Miocene sites in Yunnan, it was still faunally distinct. Further, Shuitangba was depauperate in its mammalian fauna, which may have been a result of the depositional setting rather than a true reflection of regional faunal diversity.
Knowledge of primate evolutionary history from the Late Miocene to the present in East Asia is necessary to develop a conservation strategy for primates today and future. This background is especially evident from the distributions of fossil-bearing sites in the Pleistocene and historical records over the past 800 years. We illustrate catarrhines' early dispersal and radiation routes, paths, and later shrinking trajectories, providing robust evidence and information for making or amending conservation strategies. Catarrhines (apes and Old-World monkeys) in East Asia are analyzed in this study. The results indicate that their spread during the Pleistocene from the west to east remarkably involved the three river systems (Yangtze, Yellow, and Pearl) and the coastlines, resulting in broad distributions in the Far East (Taiwan, Korea, and Japan). Unfortunately, their continental taxa significantly suffered reductions from ancient to modern Holocene, leading to a tremendous biodiversity loss in East Asia. These events corresponded to major periodic social upheavals and anthropogenic activities, particularly in the first half of the last century and the post-war period after 1950 that has involved unparalleled environmental devastation and natural resource depletion. Except for the taxa in Taiwan and Japan, primates in East Asia will finally be confined to Southwest China, especially a Convergence-Divergence Center (CDC) that has played a unique role in shielding primates and other animals, as well as the plants since the Later Miocene. Thus, developing a specific conservation priority is critical for the CDC and its adjacent regions to mitigate primate extinction in East Asia.
In this study we present a new, extensive palaeobotanical and palaeoclimatic record from 85 microfloral assemblages of Middle Miocene (late Langhian–early Serravallian) age recovered from ten localities in the Madrid Basin. A large, shallow, slightly saline lacustrine system developed in the study area, promoting the occurrence of salt-tolerant plant communities on the lake margin. The regional landscape of the basin was characterised by grass-dominated, savannah-like vegetation under a warm (MAT: 13.8–18.8 °C) and semi-arid (MPwet: 151–71 mm, MPdry: 45–4 mm) climatic regime with marked seasonality of temperature and precipitation. These data re-open the debate on the origin of grasslands linked to dry conditions in Europe. Overall increased cooling and aridity through the Miocene led to the onset of grass-dominated habitats at the expense of forests, a process that in eastern Europe has been shown to occur from the Late Miocene. Our results, together with previous palaeobotanical and fossil mammal data from southern and central Spain, strongly indicate that open habitats were already prevalent in the Iberian Peninsula in the Middle Miocene, suggesting an earlier establishment here than in eastern Europe, possibly following a temporal pattern like the Anatolian Peninsula. The taxonomic diversity yielded by the samples from the Madrid Basin contributes to the understanding of the floristic composition of these early open habitats which were dominated by Poaceae, Amaranthaceae and Asteraceae with scattered shrubby and arboreal plants adapted to dry conditions such as Ricinus, Ephedra, Olea, Quercus, Acacia and Pinus. The age of the studied samples, coincident with the Middle Miocene Climatic Transition, indicates that this climatic episode marked an important step towards the establishment of open vegetation.
Extant colobine monkeys are specialized leaf eaters. But during the late Miocene, western Eurasia was home to colobines which were less efficient at chewing leaves than they were at breaking seed shells. To understand the link between folivory and granivory in this lineage, the dietary niche of Mesopithecus delsoni and M. pentelicus was investigated in southeastern Europe, where a major environmental change occurred during the late Miocene. We combined dental topographic estimates of chewing efficiency with dental microwear texture analysis of enamel wear facets. M. delsoni was more efficient at chewing leaves than M. pentelicus, the dental topography of which matches an opportunistic seed eater. Concurrently, microwear complexity increases in M. pentelicus, especially in the northernmost localities corresponding to present-day Bulgaria. This is interpreted as a dietary shift towards hard foods such as seeds or tubers, which is consistent with the savanna and open mixed forest biomes that covered Bulgaria during the Tortonian. The fact that M. delsoni was better adapted to folivory and consumed a lower amount of hard foods than M. pentelicus suggests that colobines either adapted to folivory before their dispersal to Europe, or evolved adaptations to leaf consumption in multiple occurrences.
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The Late Miocene witnessed significant changes in climate globally and was an important time in the evolution of hominoids. Here, we report the results of an isotopic study of Late Miocene mammalian teeth and freshwater shells from Shuitangba (Yunnan Province, China) – an important refugium for hominoids, and reconstruct paleoenvironmental conditions in the area. δ¹³C values of fossil enamel samples range from −15.5‰ to −1.0‰, with a mean of −11.3 ±2.3‰, and δ¹⁸O values vary from −14.2 to −4.6‰, averaging −9.7 ±2.2‰. Reconstructed diet-δ¹³C values for these fossil mammals indicate that although they fed mostly on C3 plants, many of them consumed some C4 vegetation. This suggests that the local ecosystem contained C4 grasses but was dominated by C3 plants. The intra-tooth δ¹⁸O variation of fossil herbivores is larger than what is found in modern herbivores. Reconstructed paleo-meteoric water δ¹⁸Ow values are on average lower than those inferred from modern samples and also lower than the average δ¹⁸Ow values of modern precipitation in the region. Similarly, δ¹⁸O values of fossil freshwater shells display a larger seasonal variation and are significantly lower than modern shells from Fuxian Lake in the same region. Thus, the δ¹⁸O data from both mammalian teeth and freshwater mollusk shells support a wetter climate, possibly with a stronger precipitation seasonality in the Late Miocene than today. Comparison of clumped isotope temperatures from fossil and modern shells suggests a mean annual temperature of ~15 to 16 °C in the Shuitangba area in the Late Miocene, which is ~3 to 4 °C higher than that of today. Taken together, our isotope results suggest that C4 grasses existed in local ecosystems in the area, likely in patches of grasslands or wooded grasslands in a mostly forested environment in the Late Miocene when the local and regional climate was warmer and wetter than today. Comparison of the δ¹³C records from Yunnan and the Siwalik region suggests that C4 biomass spread earlier in the Indian subcontinent on the southwest side of the Tibetan Plateau than in Yunnan on the southeast side of the Plateau. The transition from a relatively wet habitat to a more open and drier habitat is also more pronounced and begins earlier in the Siwalik region, relative to Yunnan. These regional differences in climate and ecosystem evolution may be linked to the unique growth history of the Himalayan-Tibetan Plateau.
Mandible morphology has yet to yield definitive information on primate diet, probably because of poor understanding of mandibular loading and strain regimes, and overreliance on simple beam models of mandibular mechanics.We used a finite element model of a macaque mandible to test hypotheses about mandibular loading and strain regimes and relate variation in muscle activity during chewing on different foods to variation in strain regimes. The balancing-side corpus is loaded primarily by sagittal shear forces and sagittal bending moments. On the working side, sagittal bending moments, anteroposterior twisting moments, and lateral transverse bending moments all reach similar maxima below the bite point; sagittal shear is the dominant loading regime behind the bite point; and the corpus is twisted such that the mandibular base is inverted. In the symphyseal region, the predominant loading regimes are lateral transverse bending and negative twisting about a mediolateral axis. Compared with grape and dried fruit chewing, nut chewing is associated with larger sagittal and transverse bending moments acting on balancing- and working-side mandibles, larger sagittal shear on the working side, and larger twisting moments about vertical and transverse axes in the symphyseal region. Nut chewing is also associated with higher minimum principal strain magnitudes in the balancing-side posterior ramus;
higher sagittal shear strain magnitudes in the working-side buccal alveolar process and the balancing side oblique line, recessus mandibulae, and endocondylar ridge; and higher transverse shear strains in the symphyseal region, the balancing-side medial prominence, and the balancing-side endocondylar ridge. The largest food-related differences in maximum principal and transverse shear strain magnitudes are in the transverse tori and in the balancing-side medial prominence, extramolar sulcus, oblique line, and endocondylar ridge. Food effects on the strain regime are most salient in areas not traditionally investigated, suggesting that studies seeking dietary effects on mandible morphology might be looking in the wrong places.
Apart from a juvenile hominoid, the locality of Shuitangba (southwestern China, 6.5–6.0 Ma) has yielded a mandible and proximal femur attributed to the colobine genus Mesopithecus. A complete colobine calcaneus also accompanies this material, but its association with the other Mesopithecus material remains to be confirmed. These fossil elements are very important as they represent the oldest known colobines from East Asia,
extend the dispersal of Mesopithecus to southwestern China, and underscore its close affinities and potential ancestry to the odd-nosed colobines. The present article focuses on the functional morphology of this complete calcaneus to reconstruct the positional habits, infer the paleocology, and understand the dispersal patterns of this fossil colobine. The studied characters corroborate the attribution of this element to colobines and support potential affinities with the Mesopithecus remains of the same locality. Functionally, characters such as the long and narrow tuber calcanei, the short proximal calcaneal region, and the relatively extended and long and narrow proximal calcaneoastragalar facet appear to enable habitual pedal flexion with conjunct inversion
that accommodate the foot on diversely oriented and differently sized arboreal substrates. On the other hand, the relatively short distal calcaneal region is functionally related to (mainly terrestrial) quadrupedal activities, wherein thrust and rapid flexion are required. This combination of characters suggests that the Shuitangba colobine could move at ease on arboreal substrates and was also able to occasionally use terrestrial substrates. The potential affinities of this calcaneus to Mesopithecus and its positional profile most likely imply an eastward migration via forested corridors. In Shuitangba, this fossil colobine could trophically and positionally exploit a wide range of habitats successfully coexisting with resident hominoids.
Here, we report on a new collection of mostly isolated molars of a colobine monkey from near Hasnot on the Potwar Plateau of Pakistan. The specimens are from three late Miocene localities, with ages constrained to between 7.9 and 7.1 Ma. Morphological and metrical comparisons of the new Hasnot molars with those of previously recognized Mesopithecus species and living Asian colobines lead to the conclusion that the Hasnot colobine is most probably Mesopithecus, but not Mesopithecus pentelicus. The most morphologically distinctive aspect of the Hasnot specimens is the lower third molars, which exhibit large and bulbous protoconids set off by deeply incised mesial buccal and median buccal clefts and large, broad distobuccally placed hypoconulids. Colobine specimens previously recovered from the Potwar Plateau have been assigned to Mesopithecus sivalensis, but because these specimens have not yet been fully described, a detailed comparison with the new Hasnot specimens is not yet possible. For these reasons, we assign the new Hasnot colobine fossils to cf. Mesopithecus sp. Mesopithecus was one of the most widespread and successful of late Miocene primates. As a colobine equipped with features of the molar teeth, limbs, and, presumably, gut enabling it to succeed in more highly seasonal woodland environments, Mesopithecus was able to rapidly disperse into and adapt to the conditions in South Asia brought about by profound climatic and concomitant environmental change during the latest Miocene.
The sample geometric mean (SGM) introduced by Cauchy in 1821, is a measure of central tendency with many applications in the natural and social sciences including environmental monitoring, scientometrics, nuclear medicine, infometrics, economics, finance, ecology, surface and groundwater hydrology, geoscience, geomechanics, machine learning, chemical engineering, poverty and human development, to name a few. Remarkably, it was not until 2013 that a theoretical definition of the population geometric mean (GM) was introduced. Analytic expressions for the GM are derived for many common probability distributions, including: lognormal, Gamma, exponential, uniform, Chi-square, F, Beta, Weibull, Power law, Pareto, generalized Pareto and Rayleigh. Many previous applications of SGM assumed lognormal data, though investigators were unaware that for that case, the GM is the median and SGM is a maximum likelihood estimator of the median. Unlike other measures of central tendency such as the mean, median, and mode, the GM lacks a clear physical interpretation and its estimator SGM exhibits considerable bias and mean square error, which depends significantly on sample size, pd, and skewness. A review of the literature reveals that there is little justification for use of the GM in many applications. Recommendations for future research and application of the GM are provided.
tThe fossil mammal localities of the Axios Valley (Macedonia, Greece) yielded a rich collec-tion of Mesopithecus remains, which were first described at the beginning of the 1990s. Thelate Turolian Dytiko localities include several specimens of Mesopithecus, which were origi-nally separated in two size-related forms: the relatively larger-sized M. cf. or aff. pentelicus,and the relatively smaller-sized M. cf. monspessulanus. However, some Dytiko specimenswere only partially described, or remained even undescribed because the cranium eitherwas still in connection with the mandible or was markedly deformed. Later, careful cleaningof the materials and their revision based on larger comparative samples indicate that theyrepresent two distinct species: the relatively larger-sized specimens belong to M. pentelicus,while the relatively smaller-sized ones to M. monspessulanus. The Dytiko M. pentelicus hasslightly smaller dental dimensions compared to M. pentelicus from Pikermi, indicating apossible trend for size decrease. The Dytiko M. monspessulanus, although close to the typi-cal form of this species, has somewhat larger dimensions. The semi-terrestrial M. pentelicusdisappeared at the end of the Miocene, while some of its populations adapted to the wet-ter and more woody Pliocene habitats, finally giving origin to M. monspessulanus, whoseelbow-joint indicates an arboreal lifestyle. M. monspessulanus was widely distributed inEurope, but its remains are very scarce and are all from the Pliocene. Some questionableindications for the presence of M. monspessulanus in the latest Miocene come from someItalian Messinian sites (Gravitelli, Baccinello V3), but this scenario still needs verification.However, even if its presence in some Italian localities was confirmed, the Dytiko M. mon-spessulanus nonetheless represents the earliest known occurrence of this species in Europe,as the Dytiko fauna is considered as latest Turolian (pre-Messinian, 7.0–6.0 Ma).
The characteristics of the evolution of the South Asian monsoon during the late Miocene through the Pliocene are highly debated. To obtain a better understanding, we studied the clay mineral assemblages and the clay fraction content of a high-quality sedimentary sequence (borehole core ZK1) spanning the interval of 8.8–2.62 Ma in the Zhaotong Basin, southwestern Yunnan Province, on the southeastern margin of the Tibetan Plateau. Smectite, kaolinite, illite and vermiculite were the four main clay minerals identified, and changes in their relative abundance reveal a distinct pattern of climate change during the study interval. Until the very late Miocene kaolinite and smectite, with a small amount of illite, were dominant, suggesting a relatively warm and humid climate; from ~6.2E to ~2.8 Ma smectite was dominant, with a minor amount of kaolinite and illite, indicating a relatively cool and humid climate; and from ~2.8 to 2.62 Ma vermiculite (HIV) and illite were dominant, with a minor amount of kaolinite, indicating a relatively cold and humid climate. The variation in clay mineral assemblages indicate substantial changes in the South Asian monsoon in the Zhaotong Basin that promoted a change from a warm and humid climate in the late Micoene to cool and humid climate in the very late Miocene through Pliocene, followed by a gradual trend towards a cold and humid climate in the very late Pliocene. Comparison with records from elsewhere indicates that the observed variations in the South Asian monsoon were mainly controlled by global cooling rather than by Tibetan Plateau uplift.
New material of the Mio-Pliocene colobine Mesopithecus from the Turolian locality of Kryopigi (Greece) is described here. It includes a complete skull with the atlas attached and other dental and postcranial elements representing at least five individuals (four males and one female). The material is compared with Mesopithecus delsoni, Mesopithecus pentelicus, Mesopithecus monspessulanus and intermediate forms from more than a dozen Turolian localities of the Greco-Iranian province. These comparisons support the attribution of the Kryopigi material to M. pentelicus. The chronostratigraphic distribution of Mesopithecus species and intermediate forms suggests that the Kryopigi fauna could be dated as younger than the Perivolaki locality with M. delsoni/pentelicus (7.1-7.3 Ma, MN12) and older than the Dytiko localities with M. aff. pentelicus, M. cf. pentelicus and M. cf. monspessulanus (?middle MN13). The dimensions of the atlas are within the distribution of extant colobines. The skull shows bite-marks, probably caused by the hyaena Adcrocuta eximia.
Extant colobine monkeys have been historically described as specialized folivores. However, reports on both their behavior and dental metrics tend to ascribe a more varied diet to them. In particular, several species, such as Pygathrix nemaeus and Rhinopithecus roxellana, are dedicated seasonal seed eaters. They use the lophs on their postcanine teeth to crack open the hard endocarp that protects some seeds. This raises the question of whether the bilophodont occlusal pattern of colobine monkeys first evolved as an adaptation to folivory or sclerocarpic foraging. Here, we assess the sclerocarpic foraging ability of the oldest European fossil colobine monkey, Mesopithecus. We use computed microtomograpy to investigate the three-dimensional (3D) dental topography and enamel thickness of upper second molars ascribed to the late Miocene species Mesopithecus pentelicus from Pikermi, Greece. We compare M. pentelicus to a sample of extant Old World monkeys encompassing a wide range of diets. Furthermore, we combine classic dietary categories such as folivory with alternative categories that score the ability to crack, grind and shear mechanically challenging food. The 3D dental topography of M. pentelicus predicts an ability to crack and grind hard foods such as seeds. This is consistent with previous results obtained from dental microwear analysis. However, its relatively thin enamel groups M. pentelicus with other folivorous cer-copithecids. We interpret this as a morphological trade-off between the necessity to avoid tooth failure resulting from hard food consumption and the need to process a high amount of leafy material. Our study demonstrates that categories evaluating the cracking, grinding or shearing ability, traditional dietary categories, and dental topography combine well to make a powerful tool for the investigation of diet in extant and extinct primates.
The late Miocene is a sub-epoch when hominoids became rare worldwide but managed to survive in a few refugia. Investigating the living conditions of the late Miocene hominoids is therefore crucial for a better understanding of how they survived in those refugia. In this study, we present relevant palaeobotanical evidence regarding the habitat, climate and possible plant food resources for the Shuitangba hominoid (Lufengpithecus cf. lufengensis) from the late Miocene Zhaotong Basin, Southwest China. A total of 14 plant taxa were recognized from carpological remains newly recovered from the Zhaotong Basin, among which ten taxa were not reflected in the previous pollen record. These new plant taxa expand our knowledge of the flora and indicate how diverse the ecosystem in the late Miocene Zhaotong Basin was. Based on our carpological taxa, we hypothesize that the Shuitangba hominoid lived in a stratified mixed forest composed of trees, shrubs, lianas, herbs and grasses, near a lake occupied by various aquatic plants. The quantitative palaeoclimate reconstruction using the Coexistence Approach (CoA) indicates that the late Miocene Zhaotong Basin had a mean annual temperature (MAT) of 11.3–17.6 °C and a mean annual precipitation (MAP) of 1042–1547 mm, suggesting a mildly warm and humid climate for the Shuitangba hominoid. It also indicates that the hominoid had warm and wet summers but cool and dry winters, under the influence of the Asian monsoon. Edible and nutritious fruits and seeds of a considerable size, e.g., nuts of Carya and Corylus, fruits of Euryale and Trapa, were possibly exploited by the Shuitangba hominoid. The harder fruits, e.g., nuts of Carya and Corylus, might have benefited the hominoid as a fallback resource in the winter when foods were scarce.
Investigations into the most plausible causes which triggered the Late Miocene global expansion of C4 grasslands have reached no consensus and are still being debated. The global decline in CO2 levels in the Late Miocene has been thought to be the most common driver. Although C4 grassland expansion was largely confined to the Late Miocene, their first appearance varied significantly in different parts of the Old and New world and therefore emphasizes role of local and/or regional factors may or may not be in combination with one or more global factors. The dynamic Himalayan orogen constitutes a significant global tectonic event that is believed to have affected global climate. Hence, a study of the Himalayan foreland basin sediments could help in gleaning out possible causes behind this major paleoecologic event, which could perhaps be directly or indirectly related. Stable carbon isotope analyses of a total of 141 pedogenic carbonates in the Mio-Pleistocene Siwalik paleosols of the Ramnagar sub-basin are coherent, providing a better insight into paleovegetational changes across the sub-basin on temporal and spatial scales. Furthermore, paleovegetational history during Oligocene is reconstructed from Dagshai paleosols exposed in the Subathu sub-basin. The isotopic results show dominance of C3 vegetation pre-7 Ma and dominance of C4 vegetation post-5 Ma. Percentage abundance of C4 vegetation was less than 20 % pre-7 Ma but increased to more than 40 % post-5 Ma, reaching up to 100 % in the youngest analyzed sediments. There is exclusive dominance of C3 vegetation during Oligocene. These results conform to the pattern of change in vegetation documented in other parts of the Himalayan belt. The global expansion of C4 grasslands largely during Late Miocene have long been linked with then climate changes, particularly brought by declining atmospheric CO2 level, large-scale fires, intensification of monsoon, seasonality, and aridity as demonstrated by various researchers. These major hypotheses explaining expansion of C4 grasslands during Late Miocene are not very convincing due to significant shortcomings associated with them, for example, expansion of C4 grasslands in non-monsoonal regions put serious constraints on the monsoonal intensification hypothesis. Likewise, aridity as being the primary driver of C4 grassland expansion seems hard to support since there is no substantial evidence that could suggest global onset of arid conditions at about same geologic time, and some most arid periods, like the Triassic, show no evidence of C4 plants. We suggest that the initial lowering of CO2 below 450 ppmV created an environment for the beginning of C4 vegetation, but the persistence of this threshold value for a considerable time during Late Miocene appears to be the probable cause of the Late Miocene global expansion of C4 grasslands irrespective of their time of first appearance. It has been deduced through the correlation of Himalayan tectonic events with atmospheric CO2 levels and paleovegetational changes since Upper Miocene times that it was indeed the Late Miocene continuous, intense tectonic instability of the Himalayas that significantly decreased atmospheric CO2 levels and which perhaps played a key role in changing the nature of photosynthetic pathways.
Although Bergmann’s rule – stating that among closely related species, the bigger ones will inhabit the colder climates/higher latitudes – was formulated for inter‐specific comparisons, most analyses that tested this pattern in mammals were on an intra‐specific level. To date, no large‐scale taxonomy‐driven cross‐species evaluation of the pattern predicted by Bergmann exists. Here we show, in a dataset comprising 3561 mammal species from 26 orders, that while there is no significant correlation between latitude and body mass using conventional methods, this correlation is highly significant when the phylogenetic structure of the dataset is accounted for, thus supporting Bergmann’s claim that the rule only applies to closely related species. Analyses of different subsets indicate that the Bergmann’s rule is evident across a variety of latitude ranges. In many taxonomic subsets, when analysed alone, there is no significant correlation between body mass and latitude. In combination with both the significant relationship in the overall dataset and with results of intra‐specific analyses from the literature, this suggests that Bergmann’s rule describes a fundamental principle within mammals, but that its expression has been modified by a variety of factors during mammalian diversification yet to be resolved.
Size-related shape changes in animals are studied within a general framework of size variables and shape vectors. Isometry, or independence of shape and size, is defined as the independence of some (all) shape vector(s) from a particular size variable. With mild restrictions it is shown that isometry is possible with respect to at most one size variable, or in other words that shape will always be related to a variety of size variables. The choice of a size variable is a hitherto neglected, but important, part of an allometric study.The use of functional relationships in allometry is contrasted with the approach developed here. Also, size and shape variables are used in characterizations of the lognormal, gamma and generalized gamma distributions. The results, given in a biological context, are of interest in size and shape studies generally.
Megamacaca lantianensis, a cercopithecid of Early Pleistocene age from the Gongwangling locality of Lantian, Shaanxi Province, China, was first described in 1978 as a large cercopithecine with affinities to the living and fossil macaques of China. Recent examination of the type series has indicatedM. lantianensis is a large colobine rather than a cercopithecine.Megamacaca lantianensis was found to share several derived dental characters with extant Asian colobines, but not withMacaca. Characters unitingM. lantianensis to the Colobinae but not to the Cercopithecinae included a relatively wide P3 and lower molars with relatively short trigonids, high relief, and deeply incised lingual notches. Further, it was found thatM. lantianensis shared several derived characters withRhinopithecus (and its sister taxonPygathrix) that it did not share with other colobines. These features included: (1) a high and vertically oriented mandibular ramus; (2) a three-cusped P3; (3) irregularly wrinkled enamel on the unworn occlusal surfaces of the molars; (4) the presence of accessory cusplets, conules, and styles on the molars; and (5) molars with somewhat puffy buccal and lingual surfaces. Similarities in the morphology of the ramus, body, and symphysis of the mandible ramus between the fossil form andRhinopithecus (but notPygathrix) have led to the conclusion thatMagamacaca should be synonymized withRhinopithecus and that the Gongwangling cercopithecid be henceforth referred to asRhinopithecus lantianensis.
Stable-isotopic, clay-mineralogic, and bulk-chemical analyses were conducted on paleosols of the Neogene Siwalik sections in northern Pakistan in order to reconstruct floodplain environments over the past ∼ 17 Ma. The stable carbon isotopic composition of soil carbonate (mean δ¹³C (PDB) = -10.2%) and associated organic matter (mean δ¹³C (PDB) = −24.1%) in paleosols representing 17− ∼ 7.3 Ma reveal that floodplain vegetation was dominated by C3 plants. At 7.3 Ma, a shift toward more positive carbon isotopic values began, signaling the gradual expansion of C4 grasses onto the floodplain. From 6 Ma to present, carbon isotopic values for paleosol carbonate (mean δ¹³C (PDB) = +0.6%) and organic matter (mean δ¹³C (PDB) = −14.4%) are uniformly enriched in ¹³C, indicating the presence of nearly pure C4 grassland.
Scaling of mandibular dimensions in male Old World monkeys was investigated. Mandibular condyle length, width, and area were regressed separately against body mass and mandibular length for a total of 14 species of Cercopithecoids. Scaling of mandibular depth and width against both body mass and mandibular length were also investigated.
When results of regression analysis using the two different independent variables (body mass and mandibular length) were compared, there were significant pattern differences in scaling of cercopithecines versus colobines. Compared to body mass, male cercopithecines had relatively large mandibles (length, width, and depth) and also relatively large condyles (length, width, and area). However, compared to mandibular length, cercopithecines had relatively transversely thin and shallow mandibles and relatively narrow condyles.
It is shown that a “biomechanical” interpretation of mandibular scaling patterns against body mass in Old World monkeys demonstrates only that cercopithecines have prognathic faces, an already well-known and well-documented condition. When the biomechanical effects of prognathic faces are controlled for (by scaling against mandibular length), it is shown that cercopithecines possess special adaptations in condyle length while colobines possess special adaptations in condyle width and mandibular depth and width. These results clearly demonstrate the importance of selecting a relevant reference variable in scaling studies where biomechanical interpretations are attempted.
This work deals with the assessment of cranial sexual dimorphism in human skeletal samples applying geometric morphometric techniques. The purpose of this research is to apply such techniques to quantitatively describe in craniofacial traits the degree and pattern of shape and size sexual dimorphism. Likewise, we evaluate the precision and accuracy of semilandmark-based techniques for sex estimation. We employ a sample of 125 adult skulls of known sex from the Coimbra collection. A set of coordinate points was selected to describe glabella, mastoid, frontal and zygomatic processes. The results of intra-class correlation coefficient (ICC) show excellent intra- and inter-observer agreement (ICC > 0.96) in the location of the coordinates of points employed. The principal component analysis (PCA) performed on shape variables shows a large superposition of both sexes, suggesting a relatively low degree of dimorphism in shape. As a consequence, the average percentages of correct sex estimations based on these variables were of 60.12 and 68.90%, obtained by discriminant analysis with leave-one-out cross validation and k-means clustering respectively. Conversely, when centroid size is included in PCA, females and males exhibit large separation along the first component. The highest values of correct assignment (77.86 and 72.15%) were found using shape–size variables with discriminant and k-means clustering analysis, indicating that the traits analysed display marked sex differences related to the larger size and more robust features of males. Finally, the advantages of geometric morphometric techniques are discussed. Copyright © 2009 John Wiley & Sons, Ltd.
The last few decades of paleoanthropological research has raised important issues about the rate and chrono-geographical extent
of early hominin dispersals from Africa into Eurasia. Owing to its geographic position, the Indian subcontinent has a pivotal
role to play in addressing such issues. This ecologically diverse landmass critically lies between the three sources of the
oldest Homo fossils in the Old World and a southern route of expansion from Africa to Southeast Asia, through this region, has often
been inferred. Claims of Plio-Pleistocene Oldowan assemblages have been made since the 1960s and come from the Narmada Valley
in central India and from the Siwalik Hills in northern Pakistan and northern India. This paper critically reviews each of
these claims and broadly discusses associated Plio-Pleistocene environments and geographic routes of entry. A large majority
of these reported occurrences represents unsubstantiated claims and require further scientific verification through additional
evidence. Tentative scenarios for the current absence of paleoanthropological evidence older than the Middle Pleistocene are
also briefly discussed. This current lack of Oldowan assemblages, however, does not reflect an unquestionable absence of hominin
occupation in the region. Ecologically conducive environments in the form of open grasslands, a seasonal monsoon regime, diverse
fauna and eco-habitats (i.e., diverse hunting/scavenging opportunities), and an abundance of water and stone resources suggest
the possible earlier presence of hominins in South Asia. Obviously, much more field research is required to test and confirm
their early presence/absence in this geographically important region of the Old World.
KeywordsDispersal routes-Early Homo
-Lower Karewas-Narmada Valley-Paleoenvironments-Plio-Pleistocene-Siwalik Hills-South Asia
Analysis of size and shape has always figured largely in interpretations of multivariate analyses of measurements on organisms, although on premises that are not always unchallengeable. A recent surge of interest has led to important advances in formal analysis of variations in shape (geometric morphometrics) and phylogenetic significance of such changes. In connection herewith, an improved philosophy for the choice of variables suitable for depicting shape variation is evolving. Important results for statistical validity of multivariate analyses now are being made available by several workers (robust estimates of canonical vectors, etc., stability of eigenvectorial elements, effects of deviations from multivariate normality) with special reference to applications in morphometric studies. Such questions have been little considered in the past with the result that many multivariate analyses of biological and geological data are inexact.
The first fossil primate discovered in Afghanistan comes from the Late Miocene of Molayan, Khurdkabul Basin. The materials
consist of an almost-complete juvenile mandible and an isolated P3. These two specimens do not significantly differ from thePikermi Mesopithecus pentelicus and are assigned to this species. The primate mandible from the Late Miocene of Maragheh, Iran, which has always
been referred by all authors toM. pentelicus, differs from the Pikermi and Molayan materials. It must be assigned to another taxon, probably a new one. The geographic
range ofM. pentelicus turns out to be considerably wider in view of the discovery of the species in Molayan, eastern Afghanistan.