Peninsular Thailand as a part of the Pleistocene savanna corridor: isotopic evidence of mammalian tooth enamel from the cave of Tham Phedan

<p>How climatic and environmental conditions contributed to early human migration between mainland and island Southeast Asia during the Pleistocene is one of the most hotly debated topics in paleoanthropological communities today. As Peninsular or Southern Thailand is regarded as an obligatory pathway for humans and mammals during their dispersal between these two terrestrial areas, the understanding of paleoenvironments and vegetation covers in this region is highly relevant. The hypothesis of a “savanna corridor” or a band of open vegetation (seasonal forests and grasslands) stretching from Central Thailand to Java during several periods of lowering sea level and exposed land bridges though the Pleistocene has been suggested for explaining the facilitated route of early humans and associated large mammals in migrating out of mainland Southeast Asia towards Sundaland southwards. However, the existence of savanna grasslands in Peninsular Thailand during the Pleistocene has rarely been demonstrated due to the scarcity of available proxies.</p><p>Here we reconstructed the Pleistocene vegetation and environments of the region using stable isotope analyses of mammalian tooth enamel from the channel cave deposits of Tham Phadan (Nakhon Si Thammarat Province in Peninsular Thailand) where diversified large mammal fossils were collected. The mammal fauna is tentatively attributed to a late Middle to early Late Pleistocene age according to the presence of an extirpated spotted hyaena <em>Crocuta crocuta ultima</em>. The stable carbon isotope results, ranging from -13.9‰VPDB to +4.3‰VPDB, reveal that an open vegetation/forest-grassland mosaic was dominant in this region, unlike the present-day landscapes that are mostly covered by rainforests, thus confirming the existence of a savanna corridor in Peninsular Thailand during that time. The extreme southward distribution of some grassland-related taxa (such as spotted hyaenas and Himalayan gorals), which were common in mainland Southeast Asia during the Pleistocene, reflects the habitat continuity from north to south of Thailand. However, the lack of fossil records of these two taxa in Peninsular Malaysia and the islands of Indonesia suggests that the open vegetation band did not extend far beyond the transequatorial region. Further investigations of the Pleistocene mammal faunas in the Thai-Malay Peninsula will be helpful to identify such a corridor and to examine the paleobiogeographic affinities of Southeast Asian large mammals in the future, providing empirical data for understanding the timing and pathways of human migrations into island South-East Asia.</p>

Late Pleistocene (Eemian) mollusk and small mammal fauna from Mikhailovka-5 (Kursk oblast, Central Russia)

The locality Mikhailovka-5 is situated in the northern part of the Mikhailovka quarry in the northwest of the Kursk Oblast in central Russia. A rich mollusk fauna was collected along with small mammal remains from this lacustrine deposit located between Likhvinian (= Holsteinian) fossil soils and Valdayian (= Weichselian) periglacial deposits. The small mammal fauna is diverse, and includes numerous rodents, e.g., such indicative taxa as Arvicola ex gr. sapidus and Microtus ex gr. agrestis, a significant number of Clethrionomys glareolus and various insectivores. This assemblage closely corresponds to other Mikulino (= Eemian) faunas from the Russian Plain. The mollusk fauna includes a large number of terrestrial species, some of which have currently a more southern and western distribution. Both the molluskan and mammal faunas from Mikhailovka-5 indicate temperate climatic conditions, as evidenced by the diversity of insectivores, particularly the moles. Abundant remains of rodents of the genera Clethrionomys, Apodemus, and Microtus (Terricola) and of mollusks such as Acme, Macrogastra, Ruthenica, Punctum, and Acanthinula indicate the presence of extensive woodlands of mixed or broadleaf type, which were typical for this latitude during the Eemian interglacial. The palaeontological data provided in this paper, confirm that Mikhailovka-5 belongs to the Mikulino interglacial, as previously suggested by pedological arguments.

Constructing a time scale of biotic recovery across the Cretaceous–Paleogene boundary, Corral Bluffs, Denver Basin, Colorado, U.S.A.

ABSTRACT The Cretaceous–Paleogene (K–Pg) boundary interval represents one of the most significant mass extinctions and ensuing biotic recoveries in Earth history. Earliest Paleocene fossil mammal faunas corresponding to the Puercan North American Land Mammal Age (NALMA) are thought to be highly endemic and potentially diachronous, necessitating precise chronostratigraphic controls at key fossil localities to constrain recovery dynamics in continental biotas following the K–Pg mass extinction. The Laramide synorgenic sedimentary deposits within the Denver Basin in east-central Colorado preserve one of the most continuous and fossiliferous records of the K–Pg boundary interval in North America. Poor exposure in much of the Denver Basin, however, makes it difficult to correlate between outcrops. To constrain fossil localities in coeval strata across the basin, previous studies have relied upon chronostratigraphic methods such as magnetostratigraphy. Here, we present a new high-resolution magnetostratigraphy of 10 lithostratigraphic sections spanning the K–Pg boundary interval at Corral Bluffs located east of Colorado Springs in the southern part of the Denver Basin. Fossil localities from Corral Bluffs have yielded limited dinosaur remains, mammal fossils assigned to the Puercan NALMA, and numerous fossil leaf localities. Palynological analyses identifying the K–Pg boundary in three sections and two independent, but nearly identical, 206Pb/238U age estimates for the same volcanic ash, provide key temporal calibration points. Our paleomagnetic analyses have identified clear polarity reversal boundaries from chron C30n to chron C28r across the sections. It is now possible to place the fossil localities at Corral Bluffs within the broader basin-wide chronostratigraphic framework and evaluate them in the context of K–Pg boundary extinction and recovery.

Constructing a Timescale of Biotic Recovery across the Cretaceous–Paleogene Boundary, Corral Bluffs, Denver Basin, Colorado

ABSTRACTThe Cretaceous–Paleogene (K–Pg) boundary interval represents one of the most significant mass extinctions and ensuing biotic recoveries in Earth history. Earliest Paleocene fossil mammal faunas corresponding to the Puercan North American Land Mammal Age (NALMA) are thought to be highly endemic and potentially diachronous, necessitating precise chronostratigraphic controls at key fossil localities to constrain recovery dynamics in continental biotas following the K–Pg mass extinction. The Laramide synorgenic sedimentary deposits within the Denver Basin preserve one of the most continuous and fossiliferous records of the K–Pg boundary interval in North America. However, poor exposure in much of the Denver Basin makes it difficult to correlate between outcrops. In order to constrain fossil localities across the basin, previous studies have relied upon chronostratigraphic methods such as magnetostratigraphy. Here we present a new high-resolution magnetostratigraphy of 10 lithostratigraphic sections spanning the K–Pg boundary interval at Corral Bluffs located east of Colorado Springs in the southern part of the Denver Basin. Fossil localities from Corral Bluffs have yielded limited dinosaur remains, mammal fossils assigned to the Puercan NALMA, and numerous fossil leaf localities. Palynological analysis identifying the K–Pg boundary in three sections and two independent but nearly identical206Pb/238U age estimates for the same volcanic ash, provide key temporal calibration points. Our paleomagnetic analysis has identified clear polarity reversal boundaries from Chron C30n to Chron C28r across the sections. It is now possible to place the fossil localities at Corral Bluffs within the broader basin-wide chronostratigraphic framework and evaluate them in the context of K–Pg boundary extinction and recovery.

MIDDLE PLEISTOCENE SMALL MAMMAL fAUNAS Of EUROPE: EVOLUTION, BIOSTRATIGRAPHY, CORRELATIONS

The paper is concerned with the small mammal fauna evolution in Europe in the Middle Pleistocene. The information on the faunas of the end of the Early Pleistocene has been also taken into consideration. The data available made possible identifying several stages in the small mammal evolution. Not all intervals within the Middle Pleistocene are provided with sufficient information for recognizing individual stages; that is particularly true for the cold periods of the Middle Pleistocene – the Donian and the Okian glaciations (=Elsterian, =Anglian). Based on the studies of small mammal localities, the biostratigraphic scheme has been developed, the principal phylogenetic lineages of Arvicolinae were traced, and maps of the Middle Pleistocene small mammal localities have been compiled

Mammals of the Saracá-Taquera National Forest, northwestern Pará, Brazil

The Amazonian rainforest harbors one of the most diverse mammal faunas found anywhere in the world, although this fauna is still poorly known. Inventories are essential for the understanding of the biology and ecology of species, and provide basic data for conservation. Over 15 years of sampling in the Saracá-Taquera National Forest, we recorded 72 species of small (nonvolant), medium, and large mammals belonging to 30 families in 10 orders. These taxa included 29 species endemic to the Amazon biome, and 14 classified as threatened with extinction. Overall, the mammalian species richness recorded in the present study was equal to or greater than that recorded in other Amazonian studies, reflecting high levels of diversity on a biogeographic scale. This reinforces the importance of this national forest for the maintenance of the region's mammalian fauna. Some of the species were recorded in the region for the first time, thus extending their known geographic distribution.