Neogene hyperaridity in Arabia drove the directions of mammalian dispersal between Africa and Eurasia

The evolution of the present-day African savannah fauna has been substantially influenced by the dispersal of Eurasian ancestors into Africa. The ancestors evolved endemically, together with the autochthonous taxa, into extant Afrotropical clades during the last 5 million years. However, it is unclear why Eurasian ancestors moved into Africa. Here we use sedimentological observations and soluble salt geochemical analyses of samples from a sedimentary sequence in Western Iran to develop a 10-million-year long proxy record of Arabian climate. We identify transient periods of Arabian hyperaridity centred 8.75, 7.78, 7.50 and 6.25 million years ago, out-of-phase with Northern African aridity. We propose that this relationship promoted unidirectional mammalian dispersals into Africa. This was followed by a sustained hyperarid period between 5.6 and 3.3 million years ago which impeded dispersals and allowed African mammalian faunas to endemically diversify into present-day clades. After this, the mid-Piacenzian warmth enabled bi-directional fauna exchange between Africa and Eurasia, which continued during the Pleistocene.

Pleistocene Mammals from Pampean Region (Argentina). Biostratigraphic, Biogeographic, and Environmental Implications

The Pampean Region contains sedimentary sequences with abundant mammal fossil records, which constitute the chronological outline of the Plio–Pleistocene of South America. These classic localities have been used for more than a century to correlate with other South American regions. Throughout this time, a series of misinterpretations have appeared. To understand the stratigraphic significance of these localities and the geochronological situation of each unit referring to the Pleistocene, a critical historical study of the antecedents was carried out, evaluating the state of each unit. The biostratigraphic studies of the Pampean Region’s mammalian faunas improved the understanding of biogeographic changes taking into account the environmental fluctuations of the Pleistocene.

First mammal from the Willow Creek Formation: a new early Paleocene ptilodontid (Mammalia, Multituberculata) from near Calgary, Alberta, Canada

Although multituberculates are among the best-represented mammals of the Late Cretaceous and early Paleogene in North America, their evolution during the first several tens to hundreds of thousands of years following the Cretaceous–Paleogene (K–Pg) impact event is largely obscure. A better understanding of the early Paleogene record of multituberculates is crucial, for their dominance in early Paleocene mammalian faunas is unquestionably a result of rapid evolution during the immediate post-impact interval, and they accordingly played an important role in the evolution of mammalian communities more generally. I report on a new multituberculate from the early Paleocene of southwestern Alberta, in rocks of the Willow Creek Formation, the first such occurrence in this otherwise poorly known unit. The new multituberculate, Aenigmamys aries gen. et sp. nov., most closely resembles the ptilodontid Kimbetohia campi in comparable parts of the dentition and sheds light on the early evolution of Ptilodontidae, one of the major cimolodontan families that diversified during the Paleocene. The presence of Aenigmamys in mammalian faunas that lived soon after the K–Pg boundary implies a still-deeper evolutionary history for Ptilodontidae that may have extended into the Late Cretaceous. Aenigmamys is part of a new mammalian fauna from southwestern Alberta, the taxonomic composition of which includes a diversity of multituberculates, cimolestans, primates, and condylarths. The fauna correlates with those of middle Puercan age from other parts of the Western Interior of North America, and its high taxonomic diversity further corroborates previous hypotheses that multituberculate recovery — and mammalian recovery more generally — occurred relatively quickly after the K–Pg extinction event.

First discovery of Stegodon (Proboscidea) in Malaysia

A cheek tooth of Stegodon, an extinct genus of Proboscidea, had been discovered in a cave in Gopeng, Perak. The discovery represents the first fossil of Stegodon ever found in Malaysia. Embedded in lithified cave infillings are the associated dental remains from at least three or four other different taxa of fossil mammals commonly found among Southeast Asian Pleistocene-Holocene faunas. The finding provides a unique chance for investigations into the evolution dynamics of Stegodon in this part of Southeast Asia and the species diversity of Proboscidea in prehistoric Peninsular Malaysia. Fossil mammal assemblages from different phases of Pleistocene-Holocene period collected from karstic caves in Peninsular Malaysia, when considered with similar assemblages from other parts of Southeast Asia, have the potential to contribute to our understanding of prehistoric faunal migrations and species compositional changes among the biogeographic (sub)divisions in Southeast Asia. This may ultimately lead to a better knowledge of the possible paleoenvironmental and paleoclimatic fluctuations that influenced patterns of migration and adaptive responses of mammalian faunas in Quaternary Southeast Asia.

Time constraint on Danangou and Dongyaozitou mammalian faunas in the Nihewan Basin, North China

<p>Nihewan Basin is one of a series of well-developed East Asian Cenozoic basins, located in Hebei Province, North China. It has abundant gullies developed along both banks of the Sanggan River during and after the demise of Nihewan paleo-lake, creating a number of outcrops of the Nihewan Beds of fluvio-lacustrine origin, which are underlain by the Pliocene eolian Red Clay and overlain by the late Pleistocene loess. The fluvio-lacustrine sequence is rich sources of mammalian faunas and Paleolithic sites, thus providing unique insights into our understanding of land mammal biochronology and early human settlements in East Asia. Among the Nihewan Fauna (sensu lato), the Danangou (DNG) and Dongyaozitou (DZ) faunas are two of the important Pleistocene and Pliocene mammalian faunas in the Nihewan Basin. Except for a biostratigraphy, precise age control on the DNG and DZ faunas remains unavailable. Here we report a high-resolution magnetostratigraphic results that stringently constrain their ages. Rock magnetism and thermal demagnetization results show that magnetite and hematite dominate the remanence carriers in the DNG and DZ fluvio-lacustrine sequences. High-resolution magnetic polarity stratigraphy indicates that the DNG sequence recorded the Brunhes normal chron, the Matuyama reverse chron and the late Gauss normal chron, yielding the fossil-rich layers of DNG fauna with an age of ca. 1.95 Ma to 1.78 Ma during the Olduvai normal subchron. The DZ sequence was located at the late Gauss normal chron, leading an age of ca. 3.04−2.58 Ma before the termination of the Kaena reverse subchron. This result, together with previously published magnetochronology data obtained in the eastern basin, constructs a precise age constraints on the chronological framework of the Nihewan faunas and Paleolithic sites, especially during the Plio-Pleistocene transition.</p>