Origines du peuplement mammalien en Afrique du Nord durant le miocène terminal

The late Miocene North African mammalianassemblage is considered here from three viewpoints: survivals, extinctions, and immigrations. The Eurasiatic affinities of the large mammals slightly prevail over the Ethiopian affinities. Amongst the North African large mammals, 4 to 8 taxa are Eurasiatic immigrants, while 4 to 6 are of Subsaharian origin. Contrarily, the micromammalian fauna is highly endemic, with only one species, a murid (Paraethomys miocaenicus), considered here as being related to an Asiatic form (Karnimata darwini). Our study of Eurasian and African Miocene faunas reveals that during the late Astaracian-early Turolian interval, the Saharo-Arabic belt permitted very little latitudinal faunal exchanges. However, during the middle and late Turolian such faunal exchanges became frequent. The micromammal record unequivocally indicates that a brief period of faunal exchange occurred between Africa and western Europe at the end of the Miocene, corresponding with the Messinian Salinity Crisis. The increased intercontinental faunal exchange between Africa and Eurasia during the late Miocene coincides with, and counterbalances the extinction of more than 10 taxa at the Mio/Pliocene boundary.     

First record of late middle Miocene Moschidae from Turkey: Micromeryx and Hispanomeryx from Catakbağyaka (Muğla,SW Turkey)

Here, we describe remains of Micromeryx sp. and Hispanomeryx sp. from the middle Miocene locality Catakbağyaka (MN 7/8). This is the first record for Miocene Moschidae for the late middle Miocene in Turkey and verifies the importance of Turkey as a corridor for the dispersal of Eurasian mammals. Furthermore, the record from Catakbağyaka confirms that the sympatric co-occurrence of two Miocene moschid taxa in one locality appears to be a common phenomenon.     

The Miocene mammal record of the Vallès-Penedès Basin (Catalonia)

The land mammal record of the Vallès-Penedès Basin (Catalonia, NE Spain) ranges from the early Miocene (Ramblian) to the late Miocene (Turolian), that is from about 20 to 7 Ma. Here we present an updated review of the mammal succession focusing on biochronology as well as on environmental and faunal changes. Based on faunal similarities with central Europe, we interpret this basin as a transitional zone between the forested environments of northern regions and the more arid landscapes of the inner Iberian Peninsula. The quality of the Vallès-Penedès record and its chronostratigraphic control is clearly better for the late Aragonian and the Vallesian (between 12.6–9.0 Ma), especially for small mammals. Therefore, we analyze small mammal diversity dynamics during this interval. Contrary to previous analyses, which found an abrupt extinction event coinciding with the early/late Vallesian boundary (the Vallesian Crisis), our results show that this pattern is due to uneven sampling. Instead, taxonomic richness slowly decreased since the late Vallesian as a result of a series of extinctions that mostly affected forest-dwelling taxa.     

Miocene snakes from northeastern Kazakhstan: new data on the evolution of snake assemblages in Siberia

Abstract

The Neogene snake fauna from the central and eastern regions of Eurasia is still largely unknown. This paper reports on a unique snake fauna from the late middle Miocene of the Baikadam and Malyi Kalkaman 1 and 2 localities, northeastern Kazakhstan, which represents the best-documented Miocene snake assemblage in Central Asia. Previous studies admitted that snake fauna could be homogeneous over a large part of Eurasia during the Miocene, with the late middle to early late Miocene assemblages similar to snake assemblages that inhabited Europe in the late early and early middle Miocene. This assumption is partially supported by the presence of Texasophis bohemiacus and Coluber cf. hungaricus, as well as vipers of the ‘V. aspis’ complex. However, the presence of taxa which are (1) probably not related to European representatives (‘Colubrinae’ A and B), (2) probably never occurred in Central and Western Europe and (3) are closely related to species recently inhabiting southern Siberia (Elaphe aff. dione, Gloydius sp.) indicates that faunal dissimilarity was relatively high within Eurasia during the late middle Miocene. This assumption is in accordance with studies of small mammal assemblages which show a decreasing homogenity in the Eurasia in the course of the middle Miocene.     

Environmental control on the biogeographical distribution of Desmanella (Soricomorpha,Mammalia) in the Miocene of the Iberian Peninsula

Abstract: This paper reports the first record of Desmanella (Mammalia, Soricomorpha) from the Granada Basin in southern Iberian Peninsula, which represents its south‐westernmost occurrence in all Eurasia. It is a controversial taxon whose systematic assignment has been discussed for a long time. This genus belongs to the family Talpidae, a group of insectivores that include extant moles, shrew moles and desmans. Desmanella was very abundant in the late Miocene and early Pliocene of Eurasia, including several basins of northern Iberian Peninsula, but it has not been found until now in southern Iberia. Previous studies have shown that the faunal record and the climatic conditions during the Neogene in the Granada Basin were different from other areas of the Iberian Peninsula. The particular distribution of Desmanella supports the hypothesis that specific climatic features (wetter than neighbouring areas) prevailed in the Granada Basin during the late Turolian (late Miocene).     

Major Radiations in the Evolution of Caviid Rodents: Reconciling Fossils,Ghost Lineages,and Relaxed Molecular Clocks

Background

Caviidae is a diverse group of caviomorph rodents that is broadly distributed in South America and is divided into three highly divergent extant lineages: Caviinae (cavies), Dolichotinae (maras), and Hydrochoerinae (capybaras). The fossil record of Caviidae is only abundant and diverse since the late Miocene. Caviids belongs to Cavioidea sensu stricto (Cavioidea s.s.) that also includes a diverse assemblage of extinct taxa recorded from the late Oligocene to the middle Miocene of South America (“eocardiids”).

Results

A phylogenetic analysis combining morphological and molecular data is presented here, evaluating the time of diversification of selected nodes based on the calibration of phylogenetic trees with fossil taxa and the use of relaxed molecular clocks. This analysis reveals three major phases of diversification in the evolutionary history of Cavioidea s.s. The first two phases involve two successive radiations of extinct lineages that occurred during the late Oligocene and the early Miocene. The third phase consists of the diversification of Caviidae. The initial split of caviids is dated as middle Miocene by the fossil record. This date falls within the 95% higher probability distribution estimated by the relaxed Bayesian molecular clock, although the mean age estimate ages are 3.5 to 7 Myr older. The initial split of caviids is followed by an obscure period of poor fossil record (refered here as the Mayoan gap) and then by the appearance of highly differentiated modern lineages of caviids, which evidentially occurred at the late Miocene as indicated by both the fossil record and molecular clock estimates.

Conclusions

The integrated approach used here allowed us identifying the agreements and discrepancies of the fossil record and molecular clock estimates on the timing of the major events in cavioid evolution, revealing evolutionary patterns that would not have been possible to gather using only molecular or paleontological data alone.     

Badenian and Sarmatian s.str. from the Carpathian area: Overview and ongoing research on Hungarian and Romanian small vertebrate evolution

The fossil record from the Carpathian area plays a key role for the understanding of the processes leading to the faunal interchanges between western Europe and Asia Minor during the late part of the Middle Miocene. Important mammal successions are now available from the Central Paratethys, especially Hungary and Romania. Here, we present the current state-of-the-art of the ongoing research concerning these faunas, especially small mammals and herpetofauna. We underscore the relevance of the Middle to earliest Late Miocene fossil record from these countries for chrono(bio)stratigraphic and palaeoenvironmental studies at the Eurasian scale.     

Diversification and extinction patterns among Neogene perimediterranean mammals

The best mammalian fossil record during the Neogene of Western Europe is that of the rodents, the most successful and diversified mammal order. The study of origination and extinction during the Neogene (24-3 Ma BP) in one of the best-documented areas, Spain and southern France, gives an insight into the dynamics of these communities and indicates the possible nature of the driving forces. Three main periods of time show a high rate of origination: the late Burdigalian (17.5 Ma BP), the early Vallesian (11.5-11 Ma BP) and the early Pliocene (4.2-3.8 Ma BP). Two of these high origination-rate periods are immediately followed by important extinction events during which all cohorts are deeply affected (11.5-11 Ma BP and 4.2-3.8 Ma BP). The most important extinction event seems to occur during the early Vallesian (11.5-11 Ma BP), which probably includes the middle/late Miocene boundary. At the Miocene/Pliocene boundary, and during the early Pliocene, the faunal turnover seems to become faster, inducing a strong decrease of the mean species duration. Whereas the main immigration event, which occurs at 17.5 Ma BP, can be related to other faunal migrations in terms of the closure of the Tethys, as it occurs also in eastern Africa and in southwest Asia, the middle/late Miocene boundary event may have been related to a period of ice growth in the Southern Hemisphere. The extinction event that affects the planktonic foraminifera at 12 Ma BP cannot be chronologically correlated to this southwestern European land-mammal extinction event, because the calibration of the marine fossil record during that time-span has to be precise. Some limited terrestrial faunal exchanges that occur during the Messinian between southwestern Europe and northwestern Africa do not deeply affect the general faunal dynamics. Both allochthonous cohorts of immigrants become rapidly extinct. Several endemic rodent faunas, indicating insular conditions, have been reported from the southern edge of the western European continent from the middle Miocene up to the Pliocene. All show low taxonomic diversity, strong endemism and short survival. Some of them, like those of the Gargano Islands during the late Miocene, underwent peculiar morphological changes and also speciation. The large number of rodent genera coevolving in the Gargano Islands is indicative of the large surface areas of these islands. The general geographic pattern of southwestern Europe during the Neogene may therefore correspond to a large continental province including Spain and southern France with some kind of fast-modifying archipelago on its southern rim.     

Geopalaeontological setting,chronology and palaeoenvironmental evolution of the Baccinello-Cinigiano Basin continental successions (Late Miocene,Italy)

The Latest Miocene succession of the Baccinello-Cinigiano Basin in southern Tuscany (Italy) recorded a faunal turnover documenting the extinction of an older, insular, endemic faunal complex characterised by the extinct ape Oreopithecus bambolii and the setting of a new, continental, European faunal complex including the colobine monkey Mesopithecus. A similar turnover pattern (Late Miocene ape/Latest Miocene Cercopithecidae) is generally observed in Late Miocene continental successions of Eurasia, from Spain to central Europe, Southwest Europe, the near East, and Southwest Asia. Abundant literature reports that the Late Miocene Eurasian hominoid primate distribution closely tracks the climatic/environmental changes occurring during the 12–9 Ma interval, until their extinction in western Europe. In the primate record, the dispersion of Cercopithecidae and the contraction of hominids is interpreted as an event depicting a pattern of “continentalisation” in the Old World. The sedimentary succession of the Baccinello-Cinigiano basin, one of the longest continuous vertebrate-bearing continental successions in the Neogene Italian record, contributes to the debate on this hypothesis. This paper provides an overview of the main characteristics of the sedimentary succession, the chronological constraints (biochronology, radiometric datings, magnetostratigraphy), and the palaeoenvironmental evolution as derived from palaeobiological approaches and from the study of stable carbon and oxygen isotope contents along the entire sedimentary succession. The 2 myr geological history of the Baccinello Cinigiano Basin, which documents the evolutionary history of Oreopithecus and associated faunas, does not have a direct relation with the event of the Messinian Salinity Crisis. The evolutionary history of Baccinello-Cinigiano Basin and its palaeontological record have been mainly driven by the regional tectonism and palaeogeographic changes that affected the northern Tyrrhenian regions in Late Miocene (Latest Tortonian–Messinian) times.     

<Emphasis Type="Italic">Gryposuchus</Emphasis> (Crocodylia,Gavialoidea) from the early Miocene of Venezuela

Here, a fragment of a mandible recently discovered in the Cerro Zamuro site (Castillo Formation, Lara State, northwestern Venezuela) is assigned to the giant gavialoid Gryposuchus. This specimen, recovered from putative brackish environments of the early Miocene (~18 Ma) age, is unequivocally the earliest record of the genus in South America. Gryposuchus, together with the other gryposuchine previously recognized from the Castillo Formation, Siquisiquesuchus venezuelensis, increases the early Miocene taxonomic diversity of the group in the northern Neotropics. This new information from the Castillo Formation supports the conclusion that early gryposuchine evolutionary stages were in coastal, shallow marine or brackish environments, while the presence of some genera, such as Gryposuchus, in middle to late Miocene freshwater environments, is secondary habitat colonization late in the evolution of the clade. Freshwater colonization is probably the result of the gradual adaptation of early marine-adapted gryposuchines to the extensive estuarine-like environments of northern South America lowlands associated with marine transgressions that systematically occurred during the middle Eocene to early Oligocene. This new record is evidence of the wide chronological distribution of Gryposuchus in northern South America, highlighting the importance of this area as the center of origin and radiation of this successful Miocene gavialoid.     

New chiropterans from the middle Eocene of Shanghuang (Jiangsu Province,Coastal China): new insight into the dawn horseshoe bats (Rhinolophidae) in Asia

Until recently, the fossil record of Paleogene bats in Asia primarily included extinct families (i.e. ‘Eochiroptera’) from the early Eocene of Vastan in India and from the middle‐late Eocene of the Liguanqiao and Yuanqu basins in central China. Here, we describe a new fauna of Chiroptera from the middle Eocene Shanghuang fissure fillings of China. The fauna includes abundant material referred to a new rhinolophid (Protorhinolophus shanghuangensis gen. and sp. n.), one specimen of a possible rhinopomatid and several indeterminate rhinolophoids. This new bat assemblage constitutes the earliest record of extant families of microbats in Asia. Because it lacks representatives of ‘Eochiroptera’, this Shanghuang bat fauna indicates significant turnover in Asian bat communities. The dental pattern of P. shanghuangensis shows a mosaic of primitive and derived features (‘Eochiroptera’ vs Rhinolophidae dental characteristics), suggesting that this taxon occupies a basal position among the Rhinolophidae. Rhinolophids were already well diversified at the end of the late Eocene in Europe. Interestingly, many dental characteristics of Protorhinolophus are also found in a primitive rhinolophoid taxon, Vaylatsia, from the middle Eocene to late Oligocene of Europe, supporting a close relationship between these taxa. These affinities testify to the widespread Eurasian distribution of rhinolophoids during the Eocene and are consistent with a westward dispersal of the group from eastern Asia to Europe owing to the greater antiquity of Protorhinolophus.     

A South American snake lineage from the Eocene Greenhouse of North America and a reappraisal of the fossil record of “anilioid” snakes

“Anilioidea” is a likely paraphyletic assemblage of pipe snakes that includes extant Aniliidae from equatorial South America, Uropeltoidea from South and Southeast Asia, and a fossil record that consists primarily of isolated precloacal vertebrae ranging from the earliest Late Cretaceous and includes geographic distributions in North America, South America, Europe, and Africa. Articulated precloacal vertebrae from the middle Eocene Bridger Formation of Wyoming, attributed to Borealilysia nov. gen., represent an unambiguous North American aniliid record and prompts a reconsideration of described pipe snakes and their resultant biogeographic histories. On the basis of vertebral apomorphies, the vast majority of reported fossils cannot be assigned to “Anilioidea”. Instead, most records represent stem taxa and macrostomatans erroneously assigned to anilioids on the basis of generalized features associated with fossoriality. A revised fossil record demonstrates that the only extralimital distributions of fossil “anilioids” consist of the North American aniliid record, and there is no unambiguous fossil record of Old World taxa. The occurrence of aniliids in the mid-high latitudes of the late early Eocene of North America is consistent with histories of northward shifts in equatorial ecosystems during the early Paleogene Greenhouse.     

中国与欧洲晚中新世猪类比较研究:生物地层学及古生态学

猪类对比研究表明,从晚中新世初期到晚中新世末(或上新世初期),中国与欧洲的古气候、古环境和猪类演化都受到了全球性自然变化的影响,有着相同或相似的发展经历。晚中新世早期(early Vallesian(MN9))中国与欧洲的猪类显示它们均受到先前来自南亚猪类的影响,南亚猪类可能通过东南亚扩散到中国南方,通过西亚扩散到欧洲。晚中新世中期(lateVallesian(MN10)and early Turolian(MN11)),中国和欧洲的猪类与南亚已基本没有交流,在各自地区相对独立地演化发展。晚中新世晚期(late Turolian(MN12、MN13))中国北方除了保留有从南方迁移来的种类外,欧洲的猪类也已出现,此时中国(北方)动物群与欧洲动物群关系较为密切。南亚动物群在晚中新世早期(或者更早些)似乎已经和中国及欧洲的动物群分离。受青藏高原隆升等自然因素的影响,晚中新世中后期中国南方的古环境有一个从较为封闭、湿热的森林类型向相对开阔、干冷稀树草原类型的演变过程,而在此期间北方的自然环境则可能是从早期的半干旱疏林草原逐步发展到晚中新世末期的湿润林地。晚中新世欧洲自然环境有一个与中国南方相似的变化过程,比较而言,晚中新世中后期欧洲的环境可能比中国北方更为开阔和干冷。古气候和古环境变化是影响晚中新世猪类分布演化的决定性因素。     

A succession of Miocene rodent assemblages from fissure fillings in southern France: palaeoenvironmental interpretation and comparison with Spain

An Early to Late Miocene sequence of rodent assemblages from southern France has been quantitatively studied. The resulting pattern seems very similar to a contemporary sequence from central Spain (Calatayud–Teruel Basin). The fossil mammal-bearing localities are of different types: mainly karst infills in France and localities situated in sedimentary basins in Spain. In order to interpret the fossil record, a comparison has been made between southern France faunas of similar age but collected in karst infills and in basin deposits. There seems to be no difference between the two kinds of faunas and thus there is no indication that karst infills systematically give a picture of drier and more open environments. Both types of localities may give a similar relative abundance of taxa and when differences exist they can be attributed to local conditions. The comparison between southern France and the Calatayud–Teruel Basin (central Spain) shows that: (1) similar trends occurred in the two areas; (2) differences between spectra were more important during the late Early Miocene than during the Middle Miocene; (3) the shift between the late Early Miocene and the Middle Miocene environments in southern France does not seem to be correlated with a general drop in temperatures as inferred from the analysis of central Spain faunas.     

Crocodylian assemblage from the middle Eocene Ikovo locality (Lugansk Province,Ukraine), with a discussion of the fossil record and geographic origins of crocodyliform fauna in the Paleogene of Europe

The known fossil record of crocodyliforms in Europe during the Paleogene is significantly biased, in that the fauna of Western Europe is far better sampled and understood compared to that of Eastern Europe. We describe in detail all known crocodyliform remains from the middle Eocene (Lutetian) Ikovo locality in Ukraine. We conclude that at least two taxa were present: a moderate to large-sized Tomistominae indet. similar to the basalmost known tomistomines, and the small-sized basal alligatoroid cf. Diplocynodon sp. Despite its scarcity, this is the first basal alligatoroid material reported from Eastern Europe (as part of post-Soviet countries) and the easternmost record of diplocynodontines in Europe so far. An allegedly freshwater cf. Diplocynodon sp. contributes a rare faunal element to the vertebrate assemblage of the Ikovo locality, otherwise dominated by resident or facultative marine taxa. The fossil record and historical paleobiogeography of crocodyliforms from the Paleocene and Eocene of Europe are reviewed. As it has been already known, the middle Eocene fauna of crocodyliforms proves to be taxonomically diverse and complex. Its constituent lineages geographically originated in Asia or North America (Diplocynodontinae, Asiatosuchus-like crocodyloids, Planocraniidae), North America (derived alligatorines), Africa (Tomistominae), and Gondwana (ziphodont mesoeucrocodylians Iberosuchus and Bergisuchus), with possible subsequent speciation in Europe. We propose a novel hypothesis of Asian origins of European diplocynodontines, which will be explicitly tested in future studies. The revealed similarities between crocodylians and turtles from the Ikovo locality and those from Western Europe support the presence of a single Pan-European biogeographical zone during the middle Eocene, distinct from that of Asia.     

The Biogeographic South-North Divide of Polygonatum (Asparagaceae Tribe Polygonateae) within Eastern Asia and Its Recent Dispersals in the Northern Hemisphere

Eastern Asia (EA) is a key region for the diversification of flowering plants in the Northern Hemisphere, but few studies have focused on the biogeographic history within EA in the context of the other northern continents. Polygonatum is an important medicinal genus widely distributed in the Northern Hemisphere with its highest species richness in EA, and it represents an excellent model for studying the evolution of biogeographic patterns in this region. Divergence time estimation was used to examine the biogeographic history of Polygonatum based on nuclear ITS and four plastid sequences (rbcL, matK, psbA–trnH and trnC–petN) from 30 Polygonatum species and 35 outgroup taxa. The ancestral area of Polygonatum and subsequent dispersal routes were inferred using Bayes-Lagrange. Polygonatum was estimated to have originated in southern EA during the middle Miocene (14.34–13.57 Ma) with subsequent south-to-north expansion in the late Miocene. Multiple intercontinental dispersal events were inferred between EA and Europe or North America, and all of them have occurred recently in the late Miocene to Pliocene. The separation of Polygonatum into the south and north lineages and their subsequent diversifications in the late Miocene supports the existence of a biogeographic divide between the northern and southern parts of EA that also coincides with the retreat and redevelopment of the arid zone in EA in the Neogene. Our results demonstrate the complexity of biogeographic history of Polygonatum in the Northern Hemisphere including early vicariance followed by frequent and recent dispersals in the Neogene.     

A tiny stem group representative of Pici (Aves, Piciformes) from the early Oligocene of the Czech Republic

We describe a new stem group representative of Pici (woodpeckers, honeyguides, barbets, and allies) from the early Oligocene (Rupelian) of the Czech Republic. The holotype of Picavus litencicensis, gen. et sp. nov. is a postcranial skeleton with well-preserved feather remains. The new species is distinguished from crown group Pici in several plesiomorphic features and is assigned to the new taxon Picavidae, fam. nov. The absence of an elongated accessory trochlea for the reversed fourth toe shows P. litencicensis to be the most basal representative of Pici, and concerning the morphology of the distal tarsometatarsus the species represents a morphological link between Pici and their sister taxon, the Galbulae. Like all other early Oligocene piciform birds, P. litencicensis is a tiny bird, the size of the smallest extant Pici. Because all Palaeogene Pici were found in Europe and some of these are outside the crown group, an Old World origin of Pici is likely. With definitive crown group representatives of Pici being unknown before the late Oligocene/early Miocene, the fossil record does not support earlier molecular calibrations, which resulted in a late Cretaceous divergence of crown group Pici.