A new three-dimensional geometric morphometrics analysis of the Ouranopithecus macedoniensis cranium (Late Miocene, Central Macedonia, Greece).

OBJECTIVES: This study aims to virtually reconstruct the deformed face (XIR-1) and maxilla (RPl-128) of the Late Miocene hominoid Ouranopithecus macedoniensis from Greece, through the application of mirror-imaging and segmentation. Additionally, analysis was conducted through 3D geometric morphometrics, utilizing a comparative sample of fossil hominoids, extant great apes (Gorilla, Pan, and Pongo) and humans, so as to explore shape variation and phenetic similarities between them. MATERIALS AND METHODS: High-resolution computed tomography was used to create digital representations of the XIR-1 and RPl-128 specimens. The virtual reconstruction of the XIR-1 cranium was achieved by mirror-imaging, while the RPl-128 maxilla was virtually segmented and reattached in a correct anatomical position. Anatomical landmarks were registered in three dimensions on a comparative sample of adult crania of extant great apes, humans and fossil hominoids. The data were processed with Procrustes superimposition and analyzed using multivariate statistics methods. RESULTS: Results show that Ouranopithecus macedoniensis falls within or close to the Gorilla convex hull in the principal component analyses, and it is closer to the mean Procrustes shape distance of primarily Gorilla. Both specimens, XIR-1 and RPl-128, are classified as Gorilla based on discriminant function analyses. DISCUSSION: The results of our geometric morphometrics analyses indicate that Ouranopithecus macedoniensis is morphologically more similar to Gorilla than to Homo, Pan, or Pongo, results that can contribute to the evaluation of existing hypotheses about its phylogenetic position.

A 2Ma old baboon-like monkey from Northern Greece and new evidence to support the Paradolichopithecus - Procynocephalus synonymy (Primates: Cercopithecidae).

A new fossil cranium of a large papionin monkey from the Lower Pleistocene site of Dafnero-3 in Western Macedonia, Greece, is described by means of outer and inner morphological and metric traits using high-resolution micro-computed tomography. Comparisons with modern cercopithecids and contemporaneous Eurasian fossil taxa suggest that the new cranium could equally be ascribed to either the Eurasian Paradolichopithecus or to the East Asian Procynocephalus. The combination of the available direct and indirect fossil evidence, including the new cranium from Dafnero, revives an earlier hypothesis that considers these two sparsely documented genera as synonyms. The timing and possible causes of the rise and demise of Paradolichopithecus - Procynocephalus are discussed.

New Material of the Hominoid Ouranopithecus macedoniensis from the Late Miocene of the Axios Valley (Macedonia, Greece) with Some Remarks on Its Sexual Dimorphism.

New hominoid teeth from the late Miocene locality Ravin de la Pluie (RPl) of the Axios Valley (Macedonia, Greece) are studied in this article. Their morphology, dimensions and proportions are similar to the hominoid Ouranopithecus macedoniensis, allowing their attribution to this taxon. The studied material provides some new morphological characters for the female P3 (small asymmetry, small mesiobuccal crown projection, paracone higher than protocone) and the lower canine (mesial groove: large in the male and small in the female, distobuccal fovea: large in the female and small in the male). The new material enriches the collection of O. macedoniensis. The estimated degree of sexual dimorphism of the RPl O. macedoniensis, calculated by the multivariate size dimorphism method, is compared with those of extant hominoids (Gorilla, Pan, Pongo) and of the late Miocene Lufengpithecus lufengensis from China, which is considered as more dimorphic than any living hominoid. The results suggest that Ouranopithecus multivariate size dimorphism for the premolar, molar and post-canine row is similar to those of Pongo and Lufengpithecus, slightly higher than that of Gorilla and clearly higher than that of Pan. Therefore, O. macedoniensis is apparently one of the most sexually dimorphic hominoids and the RPl assemblage is monospecific.

First discovery of postcranial bones of Ouranopithecus macedoniensis (Primates, Hominoidea) from the late Miocene of Macedonia (Greece).

Two well preserved phalanges, one proximal and one intermediate, are identified and described. They constitute the first postcrania ever described of Ouranopithecus macedoniensis (Primates, Hominoidea) from the late Miocene locality of Ravin de la Pluie (RPl), Macedonia (Greece). They are isolated specimens, and the only ones known for their genus. The hypotheses that these specimens derive either from the hand or from the foot were tested. Comparisons with living apes of known positional behaviour were made to assess the functional signal in these specimens. The proximal phalanx, either manual or pedal, closely matches the proximal phalanges of terrestrial quadrupedal primates or the bipedal primate Homo. With respect to the intermediate phalanx we show that it closely matches phalanges of quadrupedal terrestrial primates. The terrestriality of Ouranopithecus, here reconstructed from phalangeal remains, is in agreement with our previous results of dental studies (thick check teeth enamel and microwear pattern of incisors and molars), which indicate that it was a hard object feeder living near the ground.

Stable isotope ecology of Miocene bovids from Northern Greece and the ape/monkey turnover in the Balkans.

Eurasia was home to a great radiation of hominoid primates during the Miocene. All were extinct by the end of the Miocene in Western Eurasia. Here, we investigate the hypothesis of climate and vegetation changes at a local scale when the cercopithecoid Mesopithecus replaced the hominoid Ouranopithecus along the Axios River, Greece. Because they are herbivorous and were much more abundant than primates, bovids are preferred to primates to study climate change in the Balkans as a cause of hominoid extinction. By measuring carbon stable isotope ratios of bovid enamel, we conclude that Ouranopithecus and Mesopithecus both evolved in pure C3 environments. However, the large range of δ(13)C values of apatite carbonate from bovids combined with their molar microwear and mesowear patterns preclude the presence of dense forested landscapes in northern Greece. Instead, these bovids evolved in rather open landscapes with abundant grasses in the herbaceous layer. Coldest monthly estimated temperatures were below 10°C and warmest monthly temperatures rose close to or above 20°C for the two time intervals. Oxygen isotope compositions of phosphate from bulk samples did not show significant differences between sites but did show between-species variation within each site. Different factors influence oxygen isotope composition in this context, including water provenience, feeding ecology, body mass, and rate of amelogenesis. We discuss this latter factor in regard to the high intra-tooth variations in δ(18)Op reflecting important amplitudes of seasonal variations in temperature. These estimations fit with paleobotanical data and differ slightly from estimations based on climate models. This study found no significant change in climate before and after the extinction of Ouranopithecus along the Axios River. However, strong seasonal variations with relatively cold winters were indicated, conditions quite usual for extant monkeys but unusual for great apes distributed today in inter-tropical regions.

A functional multivariate analysis of Mesopithecus (Primates: Colobinae) humeri from the Turolian of Greece.

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.

3D geometric morphometrics analysis of mandibular fragments of Ouranopithecus macedoniensis from the late Miocene deposits of Central Macedonia, Greece.

OBJECTIVES: To explore mandibular shape differences between Ouranopithecus macedoniensis and a comparative sample of extant great apes using three-dimensional (3D) geometrics morphometrics. Other objectives are to assess mandibular shape variation and homogeneity within Ouranopithecus, explore the effects of size on mandibular shape, and explore the degree of mandibular sexual size dimorphism in Ouranopithecus. MATERIALS AND METHODS: The comparative sample comprises digitized mandibles from adult extant great apes. The 3D analysis includes three datasets: one with landmarks registered on the mandibular corpus and symphysis of mandibles preserving both sides, one on hemimandibles only, and one focused on the ramus and gonial area. Multivariate statistical analyses were conducted, such as ordination analyses (PCA), intra-specific Procrustes distances pairs, pairwise male-female centroid size differences, and correlation analyses. RESULTS: The male and female specimens of Ouranopithecus have mandibular shapes that are quite similar, although differences exist. The Procrustes distances results suggest more shape variation in Ouranopithecus than in the extant great apes. Ouranopithecus shows some similarities in mandibular shape to the larger great apes, Gorilla and Pongo. Moreover, the degree of sexual dimorphism in the small Ouranopithecus sample is greater than any of the great apes. Based on our correlation analyses of principal components (PC) with size, some PCs are significantly correlated with size, with correlation varying from moderate to substantial. DISCUSSION: This study attempted to understand better the variation within the mandibles of O. macedoniensis and the expression of sexual dimorphism in this taxon in more detail than has been done previously. The overall mandibular morphology of Ouranopithecus shows some similarities to those of the larger great apes, which likely reflects similarities in size. Compared to Gorilla and Pongo, O. macedoniensis shows an elevated degree of morphological variation, although limitations relating to sample size apply. Sexual dimorphism in the mandibles of O. macedoniensis appears to be relatively high, seemingly greater than in Gorilla and high even in comparison to Pongo, but this again is possibly in part an artifact of a small sample size.

The earliest known crown-Testudo tortoise from the late Miocene (Vallesian, 9 Ma) of Greece.

We here report on fossil remains of the earliest known crown-Testudo, an extant clade of Mediterranean testudinid tortoises from the late Miocene (Vallesian, MN 10) from the hominoid locality Ravin de la Pluie (RPl) in Greece. The material studied is a small, nearly complete carapace with a clearly distinct hypo-xiphiplastral hinge. This supports the sensu stricto generic assignment. This new terrestrial testudinid specimen is characterized by a possible tectiform, narrow, elongated shell with a pentagonal pygal and a long, posteriorly elevated, lenticular and rounded dorsal epiplastral lip. These unique features differ from those of other known Mediterranean hinged forms and allow the erection of the new species Testudo hellenica sp. nov. This taxon is phylogenetically close to two Greek species, the extant T. marginata and the fossil T. marmorum (Turolian, around 7.3 Ma). This record provides evidence for the first appearance of the genus Testudo sensu stricto at a minimum age of 9 Ma.

Publisher Correction: Bone histology provides insights into the life history mechanisms underlying dwarfing in hipparionins.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Bone histology provides insights into the life history mechanisms underlying dwarfing in hipparionins.

Size shifts may be a by-product of alterations in life history traits driven by natural selection. Although this approach has been proposed for islands, it has not yet been explored in continental faunas. The trends towards size decrease experienced by some hipparionins constitute a good case study for the application of a life history framework to understand the size shifts on the continent. Here, we analysed bone microstructure to reconstruct the growth of some different-sized hipparionins from Greece and Spain. The two dwarfed lineages studied show different growth strategies. The Greek hipparions ceased growth early at a small size thus advancing maturity, whilst the slower-growing Spanish hipparion matured later at a small size. Based on predictive life history models, we suggest that high adult mortality was the likely selective force behind early maturity and associated size decrease in the Greek lineage. Conversely, we infer that resource limitation accompanied by high juvenile mortality triggered decrease in growth rate and a relative late maturity in the Spanish lineage. Our results provide evidence that different selective pressures can precipitate different changes in life history that lead to similar size shifts.

Revision of Varanus marathonensis (Squamata, Varanidae) based on historical and new material: morphology, systematics, and paleobiogeography of the European monitor lizards.

Monitor lizards (genus Varanus) inhabited Europe at least from the early Miocene to the Pleistocene. Their fossil record is limited to about 40 localities that have provided mostly isolated vertebrae. Due to the poor diagnostic value of these fossils, it was recently claimed that all the European species described prior to the 21st century are not taxonomically valid and a new species, Varanus amnhophilis, was erected on the basis of fragmentary material including cranial elements, from the late Miocene of Samos (Greece). We re-examined the type material of Varanus marathonensis Weithofer, 1888, based on material from the late Miocene of Pikermi (Greece), and concluded that it is a valid, diagnosable species. Previously unpublished Iberian material from the Aragonian (middle Miocene) of Abocador de Can Mata (Vallès-Penedès Basin, Barcelona) and the Vallesian (late Miocene) of Batallones (Madrid Basin) is clearly referable to the same species on a morphological basis, further enabling to provide an emended diagnosis for this species. Varanus amnhophilis appears to be a junior subjective synonym of V. marathonensis. On the basis of the most complete fossil Varanus skeleton ever described, it has been possible to further resolve the internal phylogeny of this genus by cladistically analyzing 80 taxa coded for 495 morphological and 5729 molecular characters. Varanus marathonensis was a large-sized species distributed at relatively low latitudes in both southwestern and southeastern Europe from at least MN7+8 to MN12. Our cladistic analysis nests V. marathonensis into an eastern clade of Varanus instead of the African clade comprising Varanus griseus, to which it had been related in the past. At least two different Varanus lineages were present in Europe during the Neogene, represented by Varanus mokrensis (early Miocene) and V. marathonensis (middle to late Miocene), respectively.

The Villafranchian carnivoran guild of Greece: implications for the fauna, biochronology and paleoecology.

Knowledge on the Villafranchian faunas of Greece was limited for a long time, but over the past 3 decades several new fossiliferous sites have been discovered and new material has been unearthed. The carnivores constitute a remarkable part of this material and their study has provided useful information for the taxonomy, chronology and palaeoecology. The Villafranchian carnivoran guild includes numerous taxa belonging to various families. Some of them are interesting as they are differentiated from the other Eurasian families. They cover the entire Villafranchian but the mass is known from the Middle to the Epi-Villafranchian (EVC). Despite the discontinuous data, they provide useful biochronological results. The coexistence of Pliocrocuta perrieri and Pachycrocuta brevirostris in the locality of Gerakarou 1 is strong evidence for the Middle Villafranchian (MVC)/Late Villafranchian (LVC) boundary. The composition of the Villafranchian carnivores suggests that the canids predominate, while the felids, hyenids and mustelids are well represented; the ursids are represented by a single taxon, the well-known Ursus etruscus, which seems to be common during the entire Villafranchian. The carnivoran guild structure and the multivariate analysis of the Greek Villafranchian carnivoran assemblages (MVC, LVC and EVC) in comparison with modern assembalges from open and closed environments indicate a relatively open landscape, which is in agreement with previous results for the Villafranchian of Greece. During the EVC there is a faunal renewal that is related to a more open and dry environment, like savannah bushland/grassland.

Locomotor evolution of Mesopithecus (Primates: Colobinae) from Greece: evidence from selected astragalar characters.

This paper reports our investigations into functional aspects of the astragalus of four samples of the genus Mesopithecus from Greece. More particularly, it aims to infer substrate preferences of M. delsoni/pentelicus from the Middle Turolian site of Perivolaki (central Greece), M. pentelicus from the late Middle Turolian site of Pikermi (southern Greece), and M. cf. pentelicus and M. cf. monspessulanus from the Late Turolian site of Dytiko (northern Greece). For these purposes, selected astragalar functional features, such as trochlea wedging, proximal facet curvature, and head rotation were expressed as linear measurements on both fossil and selected extant colobines. The size-adjusted measurements were used for univariate comparisons as well as a multivariate principal components analysis. Both approaches revealed that the selected characters were able to discriminate between extant arboreal and semiterrestrial colobines, but all fossil forms presented mosaic morphology. Thus, the oldest representative, M. delsoni/pentelicus was reconstructed as mainly semiterrestrial. On the other hand, the astragalus of M. pentelicus appeared to reflect semiterrestrial habits with a moderate adaptation to arboreality. Similar habitus reconstruction was allocated to the more recent M. cf. pentelicus, whereas the sympatric and synchronous M. cf. monspessulanus showed semiterrestrial adaptations with a slight preference of terrestrial substrates. The results mainly conform to paleoenvironmental reconstructions of the fossiliferous localities and denote that Mesopithecus was mainly a semiterrestrial radiation throughout its evolutionary history, with differential rates of use between arboreal and terrestrial substrates. These adaptations could have promoted the dispersal of the genus throughout Eurasia during the latest Miocene and Early Pliocene.

The deciduous lower dentition of Ouranopithecus macedoniensis (Primates, Hominoidea) from the late Miocene deposits of Macedonia, Greece.

Two mandibular fragments with associated milk teeth assigned to the late Miocene hominoid primate Ouranopithecus macedoniensis are analyzed. The fossils, which belong to a single individual, were found in the Vallesian locality of "Ravin de la Pluie" of the Axios Valley (Macedonia, Greece). The material is described here and compared with extant and extinct hominoids, allowing assessment of the evolutionary trends in the deciduous lower dentition within the Hominoidea. Hylobatids represent the more primitive pattern. Gorilla is slightly more derived than hylobatids, but less derived than Pongo and Pan, the latter being the most derived. With relatively smaller deciduous canines and more molarized deciduous premolars, Ouranopithecus is more derived than both Pan and Gorilla. Among the fossil hominoids, Proconsul, representing the primitive condition, has a very simple dp(3)and a dp(4)that has a trigonid that is taller than the talonid and which lacks a hypoconulid. Griphopithecus is more derived than Proconsul in having a dp(4) with a lower trigonid, a hypoconulid, and a less oblique cristid obliqua. Australopithecus and Paranthropus possess a similar morphology to that of Homo, while Ardipithecus appears to be more primitive than the latter genera. Ouranopithecus has a more derived lower milk dentition than Proconsul and Griphopithecus, but less derived than Australopithecus and Paranthropus. The comparison of the lower milk dentition of Ouranopithecus confirms our previous conclusions suggesting that this fossil hominoid shares derived characters with Australopithecus and Homo.

An examination of dental development in Graecopithecus freybergi (=Ouranopithecus macedoniensis).

This study examined enamel thickness and dental development in Graecopithecus freybergi (=Ouranopithecus macedoniensis), a late Miocene hominoid from Greece. Comparative emphasis was placed on Proconsul, Afropithecus, Dryopithecus, Lufengpithecus, and Gigantopithecus, fossil apes that vary in enamel thickness and patterns of development. In addition, comparisons were made with Paranthropus to investigate reported similarities in enamel thickness. Several sections of a right lower third molar were generated, from which enamel thickness and aspects of the enamel and dentine microstructure were determined. Data from parallel sections shed light on the effects of section obliquity, which may influence determination of both enamel thickness and crown formation time. Graecopithecus has relatively thick enamel, greater than any fossil ape but less than Paranthropus, with which it does show similarity in prism path and Hunter-Schreger band morphology. Aspects of enamel microstructure, including the periodicity and daily secretion rate, are similar to most extant and fossil apes, especially Afropithecus. Total crown formation time was estimated to be 3.5 years, which is greater than published values for modern Homo, similar to Pan, and less than Gigantopithecus. Data on dentine secretion and extension rates suggest that coronal dentine formation was relatively slow, but comparative data are very limited. Graecopithecus shares a crown formation pattern with several thick-enamelled hominoids, in which cuspal enamel makes up a very large portion of crown area, is formed by a large cell cohort, and is formed in less than half of the total time of formation. In Paranthropus, this pattern appears to be even more extreme, which may result in thicker enamel formed in an even shorter time. Developmental similarities between Paranthropus and Graecopithecus are interpreted to be parallelisms due to similarities in the mechanical demands of their diets.