Ferhat Kaya

An ecometric analysis of the fossil mammal record of the Turkana Basin

Although ecometric methods have been used to analyse fossil mammal faunas and environments of Eurasia and North America, such methods have not yet been applied to the rich fossil mammal record of eastern Africa. Here we report results from analysis of a combined dataset spanning east and west Turkana from Kenya between 7 and 1 million years ago (Ma). We provide temporally and spatially resolved estimates of temperature and precipitation and discuss their relationship to patterns of faunal change, and propose a new hypothesis to explain the lack of a temperature trend. We suggest that the regionally arid Turkana Basin may between 4 and 2 Ma have acted as a ‘species factory’, generating ecological adaptations in advance of the global trend. We show a persistent difference between the eastern and western sides of the Turkana Basin and suggest that the wetlands of the shallow eastern side could have provided additional humidity to the terrestrial ecosystems. Pending further research, a transient episode of faunal change centred at the time of the KBS Member (1.87–1.53 Ma), may be equally plausibly attributed to climate change or to a top-down ecological cascade initiated by the entry of technologically sophisticated humans. This article is part of the themed issue ‘Major transitions in human evolution’.

The rise and fall of the Old World savannah fauna and the origins of the African savannah biome

Despite much interest in the ecology and origins of the extensive grassland ecosystems of the modern world, the biogeographic relationships of savannah palaeobiomes of Africa, India and mainland Eurasia have remained unclear. Here we assemble the most recent data from the Neogene mammal fossil record in order to map the biogeographic development of Old World mammalian faunas in relation to palaeoenvironmental conditions. Using genus-level faunal similarity and mean ordinated hypsodonty in combination with palaeoclimate modelling, we show that savannah faunas developed as a spatially and temporally connected entity that we term the Old World savannah palaeobiome. The Old World savannah palaeobiome flourished under the influence of middle and late Miocene global cooling and aridification, which resulted in the spread of open habitats across vast continental areas. This extensive biome fragmented into Eurasian and African branches due to increased aridification in North Africa and Arabia during the late Miocene. Its Eurasian branches had mostly disappeared by the end of the Miocene, but the African branch survived and eventually contributed to the development of Plio–Pleistocene African savannah faunas, including their early hominins. The modern African savannah fauna is thus a continuation of the extensive Old World savannah palaeobiome.Savannah faunas developed in a spatially and temporally connected palaeobiome that flourished in the mid Miocene, before fragmenting into Eurasian and African branches in the late Miocene.

Systematics and dental microwear of the late Miocene Gliridae (Rodentia, Mammalia) from Hayranlı, Anatolia: Implications for paleoecology and paleobiodiversity

New finds of Gliridae (Mammalia, Rodentia) from the late Miocene of Hayranlı, located in central eastern Anatolia, are described. These specimens include Microdyromys koenigswaldi De Bruijn, 1966, and Myomimus maritsensis De Bruijn et al., 1970. The morphological overlap between Myomimus and Peridyromys makes it difficult to distinguish between the two genera. The last appearance of Microdyromys was previously recorded in Ampudia 3 (MN 10, Duero Basin, Spain), but the Hayranlı collection from the middle Turolian extends its spatiotemporal occurence. Dental microwear analysis indicates that these species of dormice had a diet that involved a combination of insects, fruit, seeds, and grasses, which could point to the development of a more generalist behavior adapted to the seasonal availability of foods. Environmental changes, occurring from the middle Miocene to the late Miocene in Europe and the Eastern Mediterranean, caused a drastic decrease in the number of species of Gliridae adapted to an arboreal lifestyle and a warm and humid climate. There is a significant faunal exchange from forest dwellers to ground dwelling species, which is characterized by the increase in Myomimus finds from a number of localities during the late Miocene − probably attributable to the vegetational shift from predominating forested wetland environments to open woodland and steppe-like environments. Considering the large herbivore-omnivore mammal collection of Hayranlı the mean hypsodonty value (=1.6) depicts a relatively humid woodland and shrubby paleoenvironment. Ferhat Kaya. Department of Geosciences and Geography, University of Helsinki, PO Box 64 (Gustaf Hällströmin katu 2a), 00014 Helsinki, Finland, ferhat.kaya@helsinki.fi Nuretdin Kaymakçı. Department of Geological Engineering, Middle East Technical University, Ankara 06531, Turkey, kaymakci@metu.edu.tr

Magnetostratigraphy and paleoecology of the hominid-bearing locality Çorakyerler, Tuglu Formation (Çankiri Basin, Central Anatolia)

ABSTRACT Ouranopithecus turkae, from the late Miocene of Çorakyerler in Central Anatolia, is considered one of the last known occurrences of great ape in the eastern Mediterranean. The Çorakyerler fauna has previously been correlated with MN 11 to early MN 12 on the basis of biochronology, and its faunal composition has been found to contrast with those from contemporaneous sites. In this paper, we present the magnetostratigraphy of the Çorakyerler site and an expanded interpretation of its paleobiogeographical and paleoecological contexts. The paleomagnetic results reveal two intervals of normal polarity and an intervening interval of reversed polarity in the main fossiliferous section. Of the three likely age correlations spanning 8.13–7.15 Ma (MN 11-MN 12), we favor correlation with chron 4n, with a possible age range of the fossiliferous deposit between 8.11 and 7.64 Ma (late MN 11). The geographic distribution of genus-level faunal similarity and mean hypsodonty show that Çorakyerler is a typical representative of the Pikermian chronofauna with a wide range of faunal similarity, including late Miocene localities from the eastern Mediterranean, eastern Asia, and eastern Africa. Lithological and sedimentological characteristics of the fossiliferous horizon, however, indicate a lacustrine depositional environment and relatively humid local conditions within the more arid regional context. This special setting could explain the unexpected occurrence of a hominid primate at Çorakyerler.

Author Correction: The rise and fall of the Old World savannah fauna and the origins of the African savannah biome

In the version of this Article originally published, each of the five panels in Fig. 5 incorrectly contained a black diagonal line across the plot. This has now been corrected.