On the early biogeographical history of the African placentals

The Paleocene Adrar Mgorn local fauna recently discovered in the Ouarzazate basin (Morocco) along with several significant Eocene North African faunas, has yielded the oldest known placental mammals of Africa. Contrary to those from the Eocene which are basically endemic, the Adrar Mgorn placentals display affinities with taxa from North‐Tethyan continents and indicate active faunal interchanges between Africa and Europe (and perhaps Asia) during the Cretaceous/Paleogene times. On biogeographical grounds, two dispersal events are suggested as a working hypothesis. The oldest one, exemplified by the presence of paleoryctid and adapisoriculid “insectivores”; in the Moroccan locality, possibly took place by the K/T boundary. The second dispersal event exemplified by the discovery of an omomyid primate and possible hyaenodontid creodonts may have been contemporaneous with the Paleocene/Eocene boundary during which a marine regression is also known.     

Historical biogeography of scarabaeine dung beetles

Abstract Aim (1) To review briefly global biogeographical patterns in dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae), a group whose evolutionary history has been dominated by ecological specialization to vertebrate dung in warmer climates. (2) To develop hypotheses accounting for the evolution of these patterns. Location Six principal biogeographical regions: Palaearctic, Oriental, Afrotropical, Australasia, Neotropical, Nearctic and five outlying islands or island groups harbouring endemic genera: Caribbean, Madagascar, Mauritius, New Caledonia, New Zealand. Methods Major patterns of tribal, generic and species distribution are investigated using cluster analysis, ordination, parsimony analysis of endemism and track analysis. Attempts are made to resolve biogeographical patterns with findings in the fields of plate tectonics, fossil and evolutionary history, plus phylogeny of both mammals and dung beetles. Results Because of conflict between published findings, it is uncertain at what point in time density of dinosaur dung, mammal dung or both became sufficiently great to select for specialized habits in dung beetles. However, biogeographical evidence would suggest a Mesozoic origin followed by further taxonomic radiation during the Cenozoic, possibly in response to the increasing size and diversity of mammalian dung types in South America and Afro‐Eurasia. Proportional generic distribution in fourteen tribes and subtribes showed four principal biogeographical patterns: (1) southerly biased Gondwanaland distribution, (2) Americas or (3) Madagascar endemism, and (4) northerly biased, Afro‐Eurasian‐centred distribution with limited numbers of genera also widespread in other regions. Proportional composition of faunas in eleven geographical regions indicated three principal distributional centres, East Gondwanaland fragments, Afro‐Eurasia and the Americas. These patterns probably result from three principal long‐term range expansion and vicariance events (Mesozoic: Gondwanaland interchange and fragmentation, Cenozoic: Afro‐Eurasian/Nearctic interchange and the Great American interchange). It is suggested that old vicariance caused by the Mesozoic fragmentation of Gondwanaland leads to a high degree of regional endemism at generic or tribal level across one or more Gondwanaland tracks. In contrast, it is suggested that the more recent Cenozoic range expansions occurred primarily towards northern regions leading to endemism primarily at species level. These Cenozoic radiations were facilitated by the re‐linking of continents, either because of tectonic plate movements (Africa to Eurasia in Miocene), climatically induced sea‐level change (Afro‐Eurasia to Nearctic in Miocene and Pleistocene), or similar coupled with orogenics (Nearctic to Neotropical in Pliocene). Speciation has followed vicariance either because of climatic change or physical barrier development. These recent range expansions probably occurred principally along an Afro‐Eurasian land track to the Nearctic and Neotropical and an Americas land track northwards from the Neotropics to the Nearctic, with limited dispersal from Eurasia to Australia, probably across a sea barrier. This accounts for the overall, spatially constrained, biogeographical pattern comprising large numbers of species‐poor genera endemic to a single biogeographical region and fewer more species‐rich genera, many of which show wider biogeographical distributions. In most southerly regions (Australasia, Madagascar, Neotropical), faunal composition and generic endemism is primarily dominated by elements with Gondwanaland ancestry, which is consistent with the Gondwanaland origin claimed for Scarabaeinae. In Afro‐Eurasia (Palaearctic, Oriental, Afrotropical), generic endemism of monophyletically derived Afro‐Eurasian and widespread lineages is centred in the Afrotropical region and faunal composition is numerically dominated by Afro‐Eurasian and widespread elements. In the Nearctic region, the fauna is jointly dominated by widespread elements, derived from Afro‐Eurasia, and Gondwanaland and Americas elements derived from the Neotropical region. Main conclusions Global biogeographical patterns in scarabaeine dung beetles primarily result from Mesozoic and Cenozoic range expansion events followed by vicariance, although recent dispersal to Australia may have occurred across sea barriers. Detailed phylogenetics research is required to provide data to support dispersal/vicariance hypotheses.     

An omomyid primate from the Pontide microcontinent of north-central Anatolia: Implications for sweepstakes dispersal of terrestrial mammals during the Eocene

A new genus and species of omomyid primate is described from the middle Eocene (Lutetian) Lülük Member of the Uzunçarşidere Formation, Orhaniye Basin, north-central Anatolia, Turkey. This is the first Eocene primate to be reported from the vast area between Switzerland and Pakistan. The new taxon is currently represented by a single dentary fragment, limiting the scope of morphological comparisons that can be made with related taxa. Nevertheless, its dentition differs fundamentally from that of contemporary European microchoerids. The new taxon most closely resembles North American middle Eocene omomyines such as Mytonius hopsoni, and it is therefore interpreted as a member of the Asian/North American omomyine radiation. Its occurrence on the Pontide microcontinent must have resulted from sweepstakes dispersal across the intervening Tethyan barrier that separated the Pontides from adjacent parts of Eurasia during the Lutetian. Sweepstakes dispersal by various terrestrial mammal clades, especially rodents and primates, was facilitated by Eocene greenhouse climatic conditions, which promoted extreme precipitation events and frequent flooding of major river drainages.     

Middle Eocene rodents from Peruvian Amazonia reveal the pattern and timing of caviomorph origins and biogeography

The long-term isolation of South America during most of the Cenozoic produced a highly peculiar terrestrial vertebrate biota, with a wide array of mammal groups, among which caviomorph rodents and platyrrhine primates are Mid-Cenozoic immigrants. In the absence of indisputable pre-Oligocene South American rodents or primates, the mode, timing and biogeography of these extraordinary dispersals remained debated. Here, we describe South America's oldest known rodents, based on a new diverse caviomorph assemblage from the late Middle Eocene (approx. 41 Ma) of Peru, including five small rodents with three stem caviomorphs. Instead of being tied to the Eocene/Oligocene global cooling and drying episode (approx. 34 Ma), as previously considered, the arrival of caviomorphs and their initial radiation in South America probably occurred under much warmer and wetter conditions, around the Mid-Eocene Climatic Optimum. Our phylogenetic results reaffirm the African origin of South American rodents and support a trans-Atlantic dispersal of these mammals during Middle Eocene times. This discovery further extends the gap (approx. 15 Myr) between first appearances of rodents and primates in South America.     

Early Tertiary mammals from North Africa reinforce the molecular Afrotheria clade

The phylogenetic pattern and timing of the radiation of mammals, especially the geographical origins of major crown clades, are areas of controversy among molecular biologists, morphologists and palaeontologists. Molecular phylogeneticists have identified an Afrotheria clade, which includes several taxa as different as tenrecs (Tenrecidae), golden moles (Chrysochloridae), elephant-shrews (Macroscelididae), aardvarks (Tubulidentata) and paenungulates (elephants, sea cows and hyracoids). Molecular data also suggest a Cretaceous African origin for Afrotheria within Placentalia followed by a long period of endemic evolution on the Afro-Arabian continent after the mid-Cretaceous Gondwanan breakup (approx. 105-25 Myr ago). However, there was no morphological support for such a natural grouping so far. Here, we report new dental and postcranial evidence of Eocene stem hyrax and macroscelidid from North Africa that, for the first time, provides a congruent phylogenetic view with the molecular Afrotheria clade. These new fossils imply, however, substantial changes regarding the historical biogeography of afrotheres. Their long period of isolation in Africa, as assumed by molecular inferences, is now to be reconsidered inasmuch as Eocene paenungulates and elephant-shrews are here found to be related to some Early Tertiary Euramerican 'hyopsodontid condylarths' (archaic hoofed mammals). As a result, stem members of afrotherian clades are not strictly African but also include some Early Paleogene Holarctic mammals.     

Oldest known Varanus (Squamata: Varanidae) from the Upper Eocene and Lower Oligocene of Egypt: support for an African origin of the genus

Abstract: A large collection of lizard vertebrae from northern Africa represents the oldest unambiguous occurrence of the genus Varanus. The fossils come from late Eocene and early Oligocene freshwater deposits of the Fayum, Egypt, an area noted for many significant primate finds. The recovery and identification of this material indicate that the genus Varanus arose in Africa, before dispersing to Australia and Asia. This dispersal occurred prior to the early to mid‐Miocene, by which time fossil Varanus are known from Australia and Eurasia. Although the dispersal route remains unknown, the lizard material reported here supports the hypothesis that a corridor existed allowing freshwater and terrestrial organisms to cross from Africa to Asia.     

Out of the Orient: Post‐Tethyan transoceanic and trans‐Arabian routes fostered the spread of Baorini skippers in the Afrotropics

The origin of taxa presenting a disjunct distribution between Africa and Asia has puzzled biogeographers for more than a century. This biogeographic pattern has been hypothesized to be the result of transoceanic long‐distance dispersal, Oligocene dispersal through forested corridors, Miocene dispersal through the Arabian Peninsula or passive dispersal on the rifting Indian plate. However, it has often been difficult to pinpoint the mechanisms at play. We investigate biotic exchange between the Afrotropics and the Oriental region during the Cenozoic, a period in which geological changes altered landmass connectivity. We use Baorini skippers (Lepidoptera, Hesperiidae) as a model, a widespread clade of butterflies in the Old World tropics with a disjunct distribution between the Afrotropics and the Oriental region. We use anchored phylogenomics to infer a robust evolutionary tree for Baorini skippers and estimate divergence times and ancestral ranges to test biogeographic hypotheses. Our phylogenomic tree recovers strongly supported relationships for Baorini skippers and clarifies the systematics of the tribe. Dating analyses suggest that these butterflies originated in the Oriental region, Greater Sunda Islands, and the Philippines in the early Miocene c. 23 Ma. Baorini skippers dispersed from the Oriental region towards Africa at least five times in the past 20 Ma. These butterflies colonized the Afrotropics primarily through trans‐Arabian geodispersal after the closure of the Tethyan seaway in the mid‐Miocene. Range expansion from the Oriental region towards the African continent probably occurred via the Gomphotherium land bridge through the Arabian Peninsula. Alternative scenarios invoking long‐distance dispersal and vicariance are not supported. The Miocene climate change and biome shift from forested areas to grasslands possibly facilitated geodispersal in this clade of butterflies.     

‘Out‐of‐Africa’ dispersal of tropical floras during the Miocene climatic optimum: evidence from Uvaria (Annonaceae)

Aim African–Asian disjunctions are common in palaeotropical taxa, and are typically explained by reference to three competing hypotheses: (1) ‘rafting’ on the Indian tectonic plate, enabling Africa‐to‐Asia dispersal; (2) migration via Eocene boreotropical forests; and (3) transoceanic long‐distance dispersal. These hypotheses are tested using Uvaria (Annonaceae), which is distributed in tropical regions of Africa, Asia and Australasia. Recent phylogenetic reconstructions of the genus show a clear correlation with geographical provenance, indicating a probable origin in Africa and subsequent dispersal to Asia and then Australasia. Ancestral areas and migration routes are inferred and compared with estimates of divergence times in order to distinguish between the prevailing dispersal hypotheses. Location Palaeotropics. Methods Divergence times in Uvaria are estimated by analysing the sequences of four DNA regions (matK, psbA–trnH spacer, rbcL and trnL–F) from 59 Uvaria species and 77 outgroup species, using a Bayesian uncorrelated lognormal (UCLD) relaxed molecular clock. The ancestral area of Uvaria and subsequent dispersal routes are inferred using statistical dispersal–vicariance analysis (s‐diva ). Results Uvaria is estimated to have originated in continental Africa 31.6 Ma [95% highest posterior density (HPD): 38.4–25.1 Ma] between the Middle Eocene and Late Oligocene. Two main migration events during the Miocene are identified: dispersal into Madagascar around 17.0 Ma (95% HPD: 22.3–12.3 Ma); and dispersal into Asia between 21.4 Ma (95% HPD: 26.7–16.7 Ma) and 16.1 Ma (95% HPD: 20.1–12.1 Ma). Main conclusions Uvaria fruits are widely reported to be consumed by primates, and are therefore unlikely candidates for successful long‐distance transoceanic dispersal. The other biogeographical hypotheses, involving rafting on the Indian tectonic plate, and dispersal via the European boreotropical forests associated with the Eocene thermal maximum, can be discounted due to incongruence with the divergence time estimates. An alternative scenario is suggested, involving dispersal across Arabia and central Asia via the tropical forests that developed during the late Middle Miocene thermal maximum (17–15 Ma), associated with the ‘out‐of‐Africa’ dispersal of primates. The probable route and mechanism of overland dispersal between Africa and Asia for tropical plant groups during the Miocene climatic optimum are clarified based on the Uvaria data.     

Trans-oceanic dispersal and evolution of early composites (Asteraceae)

How did Asteraceae (the daisy family) expand from its area of origin and become so widespread? This question has challenged generations of evolutionary botanists. Molecular phylogenetic and biogeographic analyses indicate a South American origin of Asteraceae, a view supported by the recent discovery of the earliest fossils of the family in Middle Eocene (ca. 50 Ma) deposits in southern South America. The early-branching lineages in the phylogenetic tree of Asteraceae are South American and African, suggesting that the earliest successful colonization of areas outside South America may have involved long-distance dispersal to Africa. However, one particularly challenging unanswered question is how early members of Asteraceae reached Africa at a time when the Atlantic Ocean constituted a barrier between the two continents. Morphological, phylogenetic, geographic, paleogeographic, and paleontologic data have been combined to propose scenarios on possible geographical and dispersal routes and vectors of dispersion of early-branching lineages of Asteraceae from South America to Africa. Of the different scenarios proposed here, two concern alternative geographical routes: (1) via the Rio Grande Rise-Walvis Ridge axis in the South Atlantic; or (2) via Antarctica, possibly including the Subantarctic islands. Three scenarios consider different dispersal routes: (1) stepping-stones; (2) single-step; and (3) sweepstakes. Finally, three vectors of dispersion are considered: (1) birds; (2) wind; and (3) floating islands. Evaluation of these scenarios suggests that early-branching lineages of Asteraceae probably dispersed from South America to Africa along an island chain formed by the Rio Grande Rise and the Walvis Ridge, transported by birds, possibly combined with rafting and/or sweepstakes. Morphological changes typically associated with evolution on islands characterize many African carduoid descendants, providing indirect evidence for step-wise dispersal along the island chain.     

Herpetofaunas from the Upper Paleocene and Lower Eocene of Morocco

Two Upper Paleocene and one Lower Eocene localities from Morocco (Ouarzazate basin) have yielded terrestrial assemblages that stand among the rare herpetofaunas from the Paleogene of the African Plate. The collections include one of the rare frogs and the only lizards known from the Paleogene of Africa. One of the two Upper Paleocene localities, Adrar Mgorn 1, has produced an indeterminate anuran and the most diverse assemblage of squamates from the Mesozoic and Cenozoic of Africa. It has yielded the earliest known scolecophidian snake and the earliest Gekkonidae, amphisbaenians, Tropidophiidae, and perhaps Boidae from Africa. Moreover, a specimen represents either the last sphenodontian or the earliest acrodontan lizard from this continent. One of the amphisbaenians represents a very distinct new taxon, Todrasaurus gheerbranti gen. and sp. nov. Indeterminate scincomorphans, lacertilians, Madtsoidae, and Aniliidae are also present. The fauna from the Lower Eocene is less diverse than that from the Upper Paleocene, but some taxa are common to both levels. Contrary to nearly all other Paleogene herpetofaunas from the African Plate, these Paleocene and Eocene assemblages include taxa that were terrestrial, not aquatic.     

Paleobiogeography of Africa: How distinct from Gondwana and Laurasia?

Although Africa was south of the Tethys Sea and originally belonged to the Gondwana, its paleobiogeographical history appears to have been distinct from those of both Gondwana and Laurasia as early as the earliest Cretaceous, perhaps the Late Jurassic. This history has been more complex than the classical one reconstructed in the context of a dual world (Gondwana vs. Laurasia). Geological and paleobiogeographical data show that Africa was isolated from the Mid-Cretaceous (Albian-Aptian) to Early Miocene, i.e., for ca. 75 million years. The isolation of Africa was broken intermittently by discontinuous filter routes that linked it to some other Gondwanan continents (Madagascar, South America, and perhaps India), but mainly to Laurasia. Interchanges with Gondwana were rare and mainly “out-of-Africa” dispersals, whereas interchanges with Laurasia were numerous and bidirectional, although mainly from Laurasia to Africa. Despite these intermittent connections, isolation resulted in remarkable absences, poor diversity, and emergence of endemic taxa in Africa. Mammals suggest that an African faunal province might have appeared by Late Jurassic or earliest Cretaceous times, i.e., before the opening of the South Atlantic. During isolation, Africa was inhabited by vicariant West Gondwanan taxa (i.e., taxa inherited from the former South American-African block) that represent the African autochthonous forms, and by immigrants that entered Africa owing to filter routes. Nearly all, or all immigrants were of Laurasian origin. Trans-Tethyan dispersals between Africa and Laurasia were relatively frequent during the Cretaceous and Paleogene and are documented as early as the earliest Cretaceous or perhaps Late Jurassic, i.e., perhaps by the time of completion of the Tethys between Gondwana and Laurasia. They were permitted by the Mediterranean Tethyan Sill, a discontinuous route that connected Africa to Laurasia and was controlled by sea-level changes. Interchanges first took place between southwestern Europe and Africa, but by the Middle Eocene a second, eastern route — the Iranian route — involved southeastern Europe and southwestern Asia. The Iranian route was apparently the filtering precursor of the definitive connection between Africa and Eurasia. The relationships and successive immigrations of mammal (mostly placental) clades in Africa allow the recognition of five to seven phases of trans-Tethyan dispersals between Africa and Laurasia that range from the Late Cretaceous to the Eocene-Oligocene transition. These Dispersal Phases involve dispersals toward Laurasia and/or toward Africa (immigrations). The immigrations in Africa gave rise to faunal assemblages, the African Faunal Strata (AFSs). All successful and typical African radiations have arisen from these AFSs. We recognize four to six AFSs, each characterized by a faunal association. Even major, old African clades such as Paenungulata or the still controversial Afrotheria, which belong to the oldest known AFS involving placentals, ultimately originated from a Laurasian stem group. Africa was an important center of origin of various placental clades. Their success in Africa is probably related to peculiar African conditions (endemicity, weak competition). Although strongly marked by endemicity, the African placental fauna did not suffer extinctions of major clades when Africa contacted Eurasia. The present geographic configuration began to take shape as early as the Mid-Cretaceous. At that time, the last connections between Africa and other Gondwanan continents began to disappear, whereas Africa was already connected to Eurasia by a comparatively effective route of interchange.     

Tectonics,climate and the diversification of the tropical African terrestrial flora and fauna

Tropical Africa is home to an astonishing biodiversity occurring in a variety of ecosystems. Past climatic change and geological events have impacted the evolution and diversification of this biodiversity. During the last two decades, around 90 dated molecular phylogenies of different clades across animals and plants have been published leading to an increased understanding of the diversification and speciation processes generating tropical African biodiversity. In parallel, extended geological and palaeoclimatic records together with detailed numerical simulations have refined our understanding of past geological and climatic changes in Africa. To date, these important advances have not been reviewed within a common framework. Here, we critically review and synthesize African climate, tectonics and terrestrial biodiversity evolution throughout the Cenozoic to the mid-Pleistocene, drawing on recent advances in Earth and life sciences. We first review six major geo-climatic periods defining tropical African biodiversity diversification by synthesizing 89 dated molecular phylogeny studies. Two major geo-climatic factors impacting the diversification of the sub-Saharan biota are highlighted. First, Africa underwent numerous climatic fluctuations at ancient and more recent timescales, with tectonic, greenhouse gas, and orbital forcing stimulating diversification. Second, increased aridification since the Late Eocene led to important extinction events, but also provided unique diversification opportunities shaping the current tropical African biodiversity landscape. We then review diversification studies of tropical terrestrial animal and plant clades and discuss three major models of speciation: (i) geographic speciation via vicariance (allopatry); (ii) ecological speciation impacted by climate and geological changes, and (iii) genomic speciation via genome duplication. Geographic speciation has been the most widely documented to date and is a common speciation model across tropical Africa. We conclude with four important challenges faced by tropical African biodiversity research: (i) to increase knowledge by gathering basic and fundamental biodiversity information; (ii) to improve modelling of African geophysical evolution throughout the Cenozoic via better constraints and downscaling approaches; (iii) to increase the precision of phylogenetic reconstruction and molecular dating of tropical African clades by using next generation sequencing approaches together with better fossil calibrations; (iv) finally, as done here, to integrate data better from Earth and life sciences by focusing on the interdisciplinary study of the evolution of tropical African biodiversity in a wider geodiversity context.     

Mitochondrial DNA structure in the Arabian Peninsula

Background  

Two potential migratory routes followed by modern humans to colonize Eurasia from Africa have been proposed. These are the two natural passageways that connect both continents: the northern route through the Sinai Peninsula and the southern route across the Bab al Mandab strait. Recent archaeological and genetic evidence have favored a unique southern coastal route. Under this scenario, the study of the population genetic structure of the Arabian Peninsula, the first step out of Africa, to search for primary genetic links between Africa and Eurasia, is crucial. The haploid and maternally inherited mitochondrial DNA (mtDNA) molecule has been the most used genetic marker to identify and to relate lineages with clear geographic origins, as the African Ls and the Eurasian M and N that have a common root with the Africans L3.     

Historical biogeography of amphibian parasites, genus Polystoma (Monogenea: Polystomatidae)

Aim  The present-day geographical distribution of parasites with a direct biological life cycle is guided mostly by the past dispersal and vicariance events that have affected their hosts. The Amphibia– Polystoma association (which satisfies these criteria) also exhibits original traits, such as host specificity and world-wide distribution. This biological model was thus chosen to investigate the common historical biogeography of its widespread representatives.
Location  North and South America, Eurasia and Africa.
Methods  We investigated the phylogeny of 12 species of neobatrachian parasites sampled from North and South America, Eurasia and Africa. Hosts belonged mostly to hyloids and ranoids of families Bufonidae, Hylidae, Leptodactylidae, Ranidae and Hyperoliidae. Phylogenetic reconstructions were inferred from maximum likelihood and maximum parsimony analyses from complete ITS1 sequences.
Results  The group of American species appeared paraphyletic with one species at the base of a Eurafrican clade, within which two lineages were seen: one composed of only Eurasian species, and the other of European and African species, with the two European species basal to an African clade.
Main conclusions  The route of Polystoma evolution is deduced from the phylogenetic tree and discussed in the light of host evolution. We conclude that Polystoma originated in South America on hyloids, after the separation of South America from Africa. The genus must have colonized North America in Palaeocene times and Eurasia by the mid-Cainozoic, taking advantage of the dispersal of either ancestral bufonids or hylids. Africa, however, appears to have been colonized more recently, during the Messinian period.     

On the origin of northern and southern hemisphere grasslands

The origin of the grassy habit during the Eocene and the development of C4 grasses during the Miocene/Pliocene boundary are discussed before the origin of primary and secondary grassland in Eurasia and North America are discussed. A comparison shows that both Northern and Southern hemisphere primary grassland originated due to climatic changes to drier conditions during the end of the Eocene, and that modern grassland vegetation types can be traced back to the Oligocene. The Eurasian steppes becomes more fragmented towards the west and south and relicts of primary grassland exists only in the most xerothermic localised habitats in central and western Europe. Secondary grassland clearly due to manmade deforestation, started with the spread of Neolithic husbandry. Southern African grasslands were however not only determined by droughty conditions, but cooler conditions at high altitudes are one of the major driving forces that prevent colonisation by trees of a generally tropical origin.     

Neogene–Quaternary Mammalian Paleobiogeography of the Indian Subcontinent: An appraisal

A biostratigraphic evaluation of the Indian subcontinent Neogene–Quaternary mammal genera at 1 Ma intervals reveals a strong correlation between faunal turnovers (first and last appearances and immigrations), diversity and major tectonic and climate-induced sea level and vegetation changes at 23–22, 20–18, 17–16, 15–14, 11–10, 9–8, 3–2 and 1–0 Ma. The Early Miocene collision of Afro-Arabian and Eurasian Plates, followed by the Middle Miocene Climate Optima and the presence of evergreen rainforests, most likely facilitated the dispersals into and out of the subcontinent from the west along the coast and included African proboscideans, primates, creodonts, thryonomyid rodents and Asian chalicotheres, rhinos, suids, anthracotheres, carnivores and muroid rodents. The Late Miocene and Early Pleistocene cooler and drier conditions, the spread of grasslands and sea level drops may have influenced the exchange of African monkeys, Eurasian carnivores, bovids, equids, camelid, and South Asian suids, leporids and murids. Immigrations from the east (East and SE Asia) occurred mostly during the Miocene and involved primarily small mammals.     

“Terror Birds” (Phorusrhacidae) from the Eocene of Europe Imply Trans-Tethys Dispersal

Background

Phorusrhacidae was a clade including middle-sized to giant terrestrial carnivorous birds, known mainly from the Cenozoic of South America, but also occurring in the Plio-Pleistocene of North America and the Eocene of Africa. Previous reports of small phorusrhacids in the Paleogene of Europe have been dismissed as based on non-phorusrhacid material.

Methodology

we have re-examined specimens of large terrestrial birds from the Eocene (late Lutetian) of France and Switzerland previously referred to gastornithids and ratites and have identified them as belonging to a phorusrhacid for which the name Eleutherornis cotei should be used.

Conclusions/Significance

The occurrence of a phorusrhacid in the late Lutetian of Europe indicates that these flightless birds had a wider geographical distribution than previously recognized. The likeliest interpretation is that they dispersed from Africa, where the group is known in the Eocene, which implies crossing the Tethys Sea. The Early Tertiary distribution of phorusrhacids can be best explained by transoceanic dispersal, across both the South Atlantic and the Tethys.     

海桑科的系统进化及地理分布

对海桑科植物的系统学进行了分析 ,并对海桑属的两个组进行了修订 ,即以柱头头状为主要特征的海桑组和柱头蘑菇状为主要特征的无瓣海桑组。结合海桑科海桑属植物的古孢粉学、细胞学以及古气候等资料 ,可以推论出海桑科植物的起源时间为早始新世 ,起源地点为特提斯海岸 ,3条可能的主要扩散途径是从起源中心向南沿着岛屿扩散到澳大利亚 ,向西扩散经过印度扩散至非洲 ,向北沿着海岸向日本散布。第四纪的冰川作用对海桑科植物的现代分布产生了重要的影响     

A Cenozoic time-scale — some implications for regional geology and paleobiogeography

Recent data generally substantiate the most recent incarnation of the Cenozoic time-scale (Berggren, 1969c). Newly obtained dates in the type section of the Chattian (Upper Oligocene) support a previous suggestion that a hiatus may separate the top of the stratotype Chattian from the base of the stratotype Aquitanian. The Orbulina Datum is placed at 16 my and the Globigerina nepenthes at 13.5 my. The junction of Eurasia and Africa in the early Miocene (ca. 18 my ago) and of Europe and Africa in the middle Miocene (ca. 15 my ago) markedly affected the Tethyan paleogeography and, concomitantly, the biogeographic dis tribution of larger and smaller Foraminifera, as well as various land mammal groups, including hominoids.     

Did lemurs have sweepstake tickets? An exploration of Simpson's model for the colonization of Madagascar by mammals

Aim  To investigate the validity of Simpson's model of sweepstakes dispersal, particularly as it applies to the colonization of Madagascar by African mammals. We chose lemurs as a classic case.
Location  The East African coast, the Mozambique Channel and Madagascar.
Methods  First, we investigated the assumptions underlying Simpson's statistical model as it relates to dispersal events. Second, we modelled the fate of a natural raft carrying one or several migrating mammals under a range of environmental conditions: in the absence of winds or currents, in the presence of winds and currents, and with and without a sail. Finally, we investigated the possibility of an animal being transported across the Mozambique Channel by an extreme climatic event like a tornado or a cyclone .
Results  Our investigations show that Simpson's assumptions are consistently violated when applied to scenarios of over-water dispersal by mammals. We suggest that a simple binomial probability model is an inappropriate basis for extrapolating the likelihood of dispersal events. One possible alternative is to use a geometric probability model. Our estimates of current and wind trajectories show that the most likely fate for a raft emerging from an estuary on the east coast of Africa is to follow the Mozambique current and become beached back on the African coast. Given prevailing winds and currents, transport from Madagascar to Africa is very much more likely than the reverse process. Freak transport by means of a hurricane or tornado is even less likely than rafting for mammals.
Main conclusions  Our models suggest that the scenario of sweepstakes dispersal that currently enjoys wide support is not valid at either the theoretical or the applied level when applied to the hypothetical invasion of Madagascar by African mammals. Alternative explanations should be sought.