Dioscoreaceae fossils from the late Oligocene and early Miocene of Ethiopia

Dioscorea section Lasiophyton leaflets from the late Oligocene (27.23 Ma) and Tacca leaves from the early Miocene (21.73 Ma) of north‐western Ethiopia greatly expand the known fossil record of Dioscoreaceae and represent the earliest and only known records of the Afro‐Asian trifoliate, palmately veined yams (Dioscorea) and bat flowers (Tacca). Both fossils occur in volcaniclastic and clastic sediments associated with a high water table, and the palaeofloral assemblages are indicative of tropical moist forest formations. These fossils provide insight into the evolutionary history of the family in Africa during the mid‐Cenozoic and provide well‐dated taxa that can assist in phylogenetic analyses and evolutionary divergence studies for Dioscoreales and Dioscoreaceae. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 17–28.     

Middle and late Pleistocene faunas of Pinnacle Point and their paleoecological implications

The Western Cape region of South Africa is home to a unique type of mediterranean vegetation called fynbos, as well as some of the earliest sites of modern human occupation in southern Africa. Reconstructing the paleohabitats during occupations of these early anatomically modern Homo sapiens is important for understanding the availability of resources to the humans during the development of behaviors that are often considered advanced. These reconstructions are critical to understanding the nature of the changes in the environment and resources over time. Here we analyze the craniodental fossils of the larger mammals recovered from two Pleistocene assemblages in the Pinnacle Point complex, Mossel Bay, Western Cape Region, South Africa. We reconstruct the paleohabitats as revealed by multivariate analyses of the mammalian community structures. Pinnacle Point 30 is a carnivore assemblage and Pinnacle Point 13B includes early evidence of a suite of modern human behavior; together they present an opportunity to identify environmental change over time at a localized geographic scale. Further, this is the first such study to include dated Western Cape localities from Marine Isotope Stage 6, a time of environmental pressure that may have marginalized human populations. Results indicate that environmental change in the Western Cape was more complex than generalized C(4) grassland expansions replacing fynbos habitats during glacial lowered sea levels, and thus, resources available to early modern humans in the region may not have been entirely predictable.     

Miocene mammalian faunas from Wushan,China and their evolutionary,biochronological, and biogeographic significances

We report Miocene mammalian faunas from three nearby localities: Kangping, Nanyu, and Yangping, in the Wushan Subbasin, Gansu Province, China. From the Kangping locality, we identified four species, Platybelodon grangeri, Hispanotherium wushanense n. sp., Kubanochoerus sp., and Turcocerus cf. kekemaidengensis, which indicate that this fauna can be correlated with MN7/8. From the Nanyu locality, we identified Platybelodon aff. tongxinensis, which, together with the previously reported specimens of Gomphotherium wimani and Micromeryx cf. flourensianus, enables us to correlate this fauna with MN6. The Yangping locality is found to be early Miocene in age based on the presence of cf. Gomphotherium sp. This occurrence is the earliest record of proboscideans in China, and thus represents the “Proboscidean Datum Event”. Evolutionary trends of Platybelodon and Hispanotherium are figured and discussed. The possibility of a geographic boundary associated with the eastern and western differentiation of species of Turcocerus and bunodont listriodonts in China is also evaluated. This boundary was consistent with the major division of the eastern and western mammalian faunas of the middle Miocene in China. The localities in Inner Mongolia suggest a large area with transitional habitats.     

Lack of stasis in late Cenozoic marine faunas and communities, central California

Pliocene strata in the Kettleman Hills of west-central California were deposited in the broad San Joaquin embayment as a cyclic succession of parasequences during approximately three million years. Depositional environments within each cycle ranged from relatively open marine to brackish and non-marine. Although the strata were deposited in similar, recurrent environments, the fauna changed gradually rather than during brief intervals separating periods of stasis. Although environmental gradients and community structure in the Pliocene San Joaquin Embayment and in the present-day San Francisco Bay are similar, species compositions of the faunas and of parallel communities at the two sites are markedly different. In addition, times of origination and extinction of species in the Pliocene strata of the Kettleman Hills and in San Francisco Bay do not document coordinated stasis within the Late Cenozoic. In contrast, Silurian and Devonian faunas and communities of the Appalachian Basin persisted with little change in ecological-evolutionary units that lasted for up to eight million years. Relatively brief intervals of great biotic change separate these intervals of stasis. One intriguing explanation of this pattern of coordinated stasis within an ecologic-evolutionary unit is ecological locking, in which interaction between species within the community is sufficiently strong that only major changes in the environment are able to change community and faunal composition. Probably the late Cenozoic fauna underwent rapid evolution as a result of rapidly changing environmental conditions within a complex and changing shallow, inshore marine paleogeography. In contrast, coordinated stasis in the lower Paleozoic probably resulted from negligible evolution during long periods of stable to gradually changing environments in an outer shelf setting, punctuated by brief episodes of abrupt environmental change and large-scale turnover. The independent assortment of species in late Cenozoic parallel communities indicates that ecological locking did not exist.     

Amphibians and reptiles from the late Miocene and early Pliocene of the Ptolemais area (Western Macedonia,Greece)

We herein describe the amphibians and reptiles from the Ptolemais fossil assemblage, originating from 12 nearby localities in northwestern Greece, spanning from the late Miocene (MN 13) to the early Pliocene (MN 15). Amphibians are known exclusively of anurans, with the genera Latonia and Rana being identified, the latter constituting the oldest so far known record of that lineage in Greece. Turtles are represented by the testudinid cf. Testudo, whereas numerous other indeterminate testudinoids are known. Lizards include scincids, lacertids, and at least two anguids. Among them, the material referred to scincids and the anguid Anguis constitute one of only rather few such occurrences described in the fossil record of the Eastern Mediterranean. Snakes are represented by indeterminate “colubrines” and the genus Natrix. The different ages of the Ptolemais fossiliferous localities, along with their close geographic vicinity offer the opportunity to study potential survival/extinction patterns of its amphibians and reptiles across the Mio-Pliocene boundary, a time interval that has been crucial for European herpetofaunas.     

A unique record of Cercis from the late early Miocene of interior Asia and its significance for paleoenvironments and paleophytogeography

The climatic impacts of the Tibetan Plateau since the Neogene and the phytogeographic pattern changes of formerly widely-distributed forest communities on the plateau remain poorly constrained. Today, Cercis L. (Fabaceae) is a well-known arborescent genus typically distributed in subtropical to warm temperate zones of the Northern Hemisphere, and Paleogene fossil occurrences from Eurasia and North America show a long history of the genus in mid-low latitudes of the Northern Hemisphere. Here, we describe a fossil species, Cercis zekuensis sp. nov. based on well-preserved fruits from the early Miocene of the northeastern Tibetan Plateau. Detailed morphological comparison (e.g., ventral margin with a veinless wing) of extant and fossil members of Cercis and other genera confirmed validity of the present taxonomic identity. Based on the comparison with extant relatives and their climate preferences, this unexpected occurrence of thermophilic Cercis in northeastern Tibetan Plateau indicates this area had higher temperature and precipitation in the Miocene than today. Integrated with inferred (paleo-)temperature lapse rates, this indicates a low paleoelevation of less than 2.4 km. In contrast with the present-day alpine climate here (~3.7 km), such a low elevation facilitated a more favorable habitat with comparatively high biodiversity and warm temperate forests at that time, as were evidenced by co-occurring megafossils. Moreover, the present existence of Cercis implies the genus was widespread in interior Asia during the early Neogene and shows its modern disjunction or diversification between eastern and central Asia was possibly shaped by the late Cenozoic regional tectonic uplift and consequential environmental deterioration.     

Fossil record and dynamics of Late Miocene small mammal faunas of the Vienna Basin and adjacent basins,Austria

The Late Miocene small mammal assemblages of the hinterland of Lake Pannon in Austrian Basins are represented by 99 species-level taxa and 30,400 specimens. The fossil-bearing localities can be grouped into eight intervals spanning about three million years from the Early Vallesian to the Middle Turolian. Each time slice is characterised by the occurrence and/or dominance of certain species. The retreat of Lake Pannon is reflected by a distinct diversification. This pattern may be a regional signal due to increasing habitat availability but may also be taphonomically biased due to a rather poor Earliest Vallesian record. Nevertheless, the overall community structure is quite stable throughout the Vallesian and no indication of a Vallesian Crisis can be detected. Instead, a moderate turnover occurs with the onset of the Turolian, reflected by the increasing abundance of xerophilic taxa.     

The Leporid Datum: a late Miocene biotic marker

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Differences between the late eocene foraminiferal faunas in western und eastern Europe

During the Late Eocene two marine provinces existed in the epicontinental Europe: a West European province with a warm water foraminiferal fauna of Tethyan character and an East European province with a cold water fauna. The boundary between these provinces was situated in Poland. The main dispersion routes of the Late Eocene foraminiferal faunas coincide with some important tectonic features.     

Systematics of early and middle Miocene Old World monkeys

New information about the early cercopithecoids Prohylobates tandyi (Wadi Moghra, Egypt) and Prohylobates sp. indet. (Buluk and Nabwal, Kenya) is presented. Comparisons are made among all major collections of Early and Middle Miocene catarrhine monkeys, and a systematic revision of the early Old World monkeys is provided. Previous work involving the systematics of early Old World monkeys (Victoriapithecidae; Cercopithecoidea) has been hampered by a number of factors, including the poor preservation of Prohylobates material from North Africa and lack of comparable anatomical parts across collections. However, it is now shown that basal cercopithecoid species from both northern and eastern Africa can be distinguished from one another on the basis of degree of lower molar bilophodonty, relative lower molar size, occlusal details, symphyseal construction, and mandibular shape. Results of particular interest include: 1) the first identification of features that unambiguously define Prohylobates relative to Victoriapithecus; 2) confirmation that P. tandyi is incompletely bilophodont; and 3) recognition of additional victoriapithecid species.     

New data on late Miocene mammals of Kohfidisch, Austria

Cervids and bovids of the Early Turolian mammalian fauna of Kohfidisch (Austria) are reviewed. A new species, Micromeryx mirus sp. nov. (Moschidae) is described.     

Upper Eocene to Middle Miocene ostracode faunas and paleo-oceanography of the North Coastal Belt,Jamaica, West Indies

The ostracode fauna of the Montpelier Group (Upper Eocene-Middle Miocene) exposed in the western part of the North Coastal Belt of Jamaica contains representatives of three paleo-environments. Allochthonous shelf and littoral species, characterized by abraded carapaces and eye tubercles, and a diverse group of archibenthal (slope) forms are present throughout. Species restricted to the World Ocean Psychrosphere (> 1000 m), notably Bradleya dictyon, Australoecia tipica, Agrenocythere hazelae and Macrocypris spp., first occur in sediments of earliest Miocene age (planktonic foraminiferal zone N4). Their presence establishes a minimum age for the entry into the Cayman Trench of frigid (<8–10°C) water masses drawn from the Atlantic thermohaline stratification.Upper Eocene and Oligocene assemblages are dominated by smooth, blind genera such as Krithe, Messinella and Bythocypris and lived in lower thermospheric conditions (10°C) at or near the base of the thermocline (700– 900 m). During the Early Miocene, downfaulting of the north island slope of Jamaica in response to southward tilting of the Nicaraguan Rise brought the Montpelier depositional site into contact with progressively deeper and colder water-masses. This subsidence culminated in the late Early Miocene; faunas of this age contain large numbers of Bradleya dictyon, Agrenocythere hazelae, Macrocypris sp. 1, Bairdia oarion and Bairdoppilata cassida. They suggest paleodepths of 1500–2000 m and the local presence of a 3–4° water-mass tentatively identified as the North Atlantic deep water. If this interpretation is correct, then the maximum sill-depth and water-mass configuration of the Miocene Cayman Trench have persisted to the present. Middle Miocene assemblages indicate a return to paleodepths of 1000–1500 m heralding the pronounced Upper Miocene to mid-Pleistocene tectonism which elevated Montpelier strata above sea level. An alternative view attributes the Miocene ostracode succession in the Montpelier to episodes in the development of the Atlantic circulation as recognized in the northeast Atlantic.Montpelier deposition took place either on a broad step intervening between the northern edge of the Clarendon Platform and the abyssal basins of the Cayman Trench or on a Tertiary analog of the existing north island slope. These results have emphasized the value of detailed taxonomic and morphologic studies of deep-sea ostracodes in geohistorical reconstruction.     

Snail faunas in the early stages of a chalk grassland succession

Snail faunas from 10 sites in chalk grassland on the South Downs are described. The sites represent a range of early stages in the succession of grazed chalk grassland to scrub. The faunas of the later stages sampled, with vegetation 12–45 cm high, are substantially different from those of the earlier stages (2.5–10 cm high), lacking most xerophil species, and having much higher proportions of species typical of woods and hedgerows.
The results are discussed in relation both to those from other studies of existing faunas, and also to the environmental interpretation of buried faunas from geological and archeologtcal studies.     

Late Miocene insular mice from the Tusco-Sardinian palaeobioprovince provide new insights on the palaeoecology of the Oreopithecus faunas

Oreopithecus bambolii is one of the few hominoids that evolved under insular conditions, resulting in the development of unique adaptations that have fueled an intensive debate. The palaeoenvironment associated with this great ape has been the subject of great controversy as well. On the one hand, palaeobotanical data indicate that Oreopithecus likely inhabited mixed mesophytic forests interrupted by swamps; on the other hand, an abundance of hypsodont bovids points towards the existence of dry and open environments. Here, we provide a new approach based on the ecomorphology of the extinct endemic Muridae (rats and mice) of the so-called Oreopithecus faunas. Our results show that the successive species of endemic insular murids (Huerzelerimys and Anthracomys) evolved a number of adaptations observed only in extant family members that include significant proportions of grass in their diet. While this fits the pattern exhibited by large mammals, it contrasts with the available palaeobotanical information, which indicates that grasses were minor components of the vegetation. This contradiction may be explained because these endemic murids may have been adapted to the consumption of particular food items such as hard parts of aquatic plants (as shown by some extant murid species). However, because it is unlikely that the remaining herbivore mammals were adapted to this diet as well, we favour an alternative hypothesis that takes into account the peculiar ecological conditions of insular ecosystems leading to a density-dependent selective regime with strong competition. Such a regime would promote the selection of dental adaptations to increase feeding efficiency and durability of the dentition (such as hypsodonty) as seen in some fossil insular ruminants. This hypothesis requires further testing, but may partly account for parallel evolution of dental traits in phylogenetically unrelated insular mammals.     

A late Miocene low-nutrient window for Caribbean reef formation?

Miocene and Pliocene reef tracts of the Caribbean were less common and smaller than older Oligocene and younger Pleistocene to Recent reefs. In the present study, samples from the Arroyo Bellaco exposures in the Cibao Valley, northern Dominican Republic were analyzed for ⁸⁷Sr/⁸⁶Sr to refine the age for a rare, well-developed Mio-Pliocene reef sequence. A mean age of 6.2 million years old (Ma) was determined for the reef. This age places the reef in the latter part of the late Miocene Messinian stage. The reef originated in a low-nutrient window at the end of a global cooling event and sea level lowstand, coincident with a period of decreased upwelling intensity from 6.2 to 5.8 Ma. Reef demise is attributed to a latest Miocene transgression and an associated pulse of marine siliciclastic deposition.     

Warm and humid Trans-Himalaya during the late Miocene: plant fossil evidence

Neogene fossil records from the Indus Basin sedimentary rocks (IBSR), deposited in the Indus Tsangpo Suture Zone (ITSZ), are very rare, but are important to understand the history of plant diversity and paleoclimate in the Himalaya. We report fossil wood ascribed to Ebenoxylon siwalicus Prakash from late Miocene sediments of the Karit Formation belonging to ITSZ. The anatomical details of the fossil wood, such as small to medium-sized vessels occluded with tyloses, scanty paratracheal to diffuse-in-aggregate axial parenchyma, 1–3 seriate homo to heterocellular rays, bordered intervessel pits with lenticular apertures and simple perforations, suggest its close affinity with Diospyros Linnaeus of the family Ebenaceae. Further anatomical details suggest a close resemblance with extant D. ehretioides Don and D. macrophylla Blume. The present fossil, along with previously known fossil records of Lagerstroemia (Lythraceae) and palms, indicate that the Trans-Himalaya was warm and humid during the late Miocene, quite different from the modern cool and dry climate in the study area.     

Fire and fire-adapted vegetation promoted C4 expansion in the late Miocene

Large proportions of the Earth's land surface are covered by biomes dominated by C(4) grasses. These C(4)-dominated biomes originated during the late Miocene, 3-8 million years ago (Ma), but there is evidence that C(4) grasses evolved some 20 Ma earlier during the early Miocene/Oligocene. Explanations for this lag between evolution and expansion invoke changes in atmospheric CO(2), seasonality of climate and fire. However, there is still no consensus about which of these factors triggered C(4) grassland expansion. We use a vegetation model, the adaptive dynamic global vegetation model (aDGVM), to test how CO(2), temperature, precipitation, fire and the tolerance of vegetation to fire influence C(4) grassland expansion. Simulations are forced with late Miocene climates generated with the Hadley Centre coupled ocean-atmosphere-vegetation general circulation model. We show that physiological differences between the C(3) and C(4) photosynthetic pathways cannot explain C(4) grass invasion into forests, but that fire is a crucial driver. Fire-promoting plant traits serve to expand the climate space in which C(4)-dominated biomes can persist. We propose that three mechanisms were involved in C(4) expansion: the physiological advantage of C(4) grasses under low atmospheric CO(2) allowed them to invade C(3) grasslands; fire allowed grasses to invade forests; and the evolution of fire-resistant savanna trees expanded the climate space that savannas can invade.     

Faunal change in the Turkana Basin during the late Oligocene and Miocene

Faunal evolution over the last 65 million years of earth's history was dominated by mammalian radiations, but much of this era is poorly represented in Africa. Mammals first appeared early in the Mesozoic, living alongside dinosaurs for millions of years, but it was not until the extinction of dinosaurs 65 myr ago that the first major explosion of mammalian taxa took place. The Cenozoic (65 Ma to Recent) witnessed repeated and dynamic events involving the radiation, evolution, and extinction of mammalian faunas. Two of these events, each marking the extinction of one diverse fauna and subsequent establishment of another equally diverse fauna, both involving advanced catarrhine primates, are recorded in sites in the Turkana Basin, despite the poorly represented record of Cenozoic faunas elsewhere in sub-Saharan Africa. The first of these events occurred at the Oligocene-Miocene transition and the other at the Miocene-Pliocene transition.     

Occurrence and paleocologic significance of Halimeda in late Miocene reefs,southeastern Spain

Facies mapping of a late Miocene reef complex near the town of Níjar (Almería Province, southeastern Spain) demonstrated that Halimeda-rich beds compose about 20% of the proximal-slope sedimets. Halimeda segments are unbroken, preserved as molds, randomly oriented to layered, and concentrated in beds that commonly contain few fossils other than Halimeda. The associated biota (a laminar form of the coral Porites, articulated bivalves, small gastropods, and in-situ branching coralline algae) and sediment texture suggest possible insitu formation of the Halimeda.Repetitive stratigraphy characterizes the proximal reef-slope sediments at Níjar. Each repetition consists of the following idealized succession: an eroded base, mixed-fossil hash, Halimeda-rich beds, and mixed-fossil beds that contain little if any Halimeda. Although Halimeda beds do not dominate in the proximal-slope environment, their local abundance may signify changed environmental conditions.The concentration of Halimeda in beds suggests spatial segregation of Halimeda from many reef-dwelling organisms. The repetitive stratigraphy suggests temporal segregation as well.Episodic upwelling may have been responsible for the repetitive stratigraphy. The occurrence of Halimeda-rich beds in reef complexes of similar age throughout the Spanish Mediterranean region, and the occurrence of possibly correlative cyclic basinal sequences, is consistent with an upwelling mechanism. If responsive to upwelling episodes, Halimeda beds may represent event strata of regional significance.