S. David Webb

Spatial Response of Mammals to Late Quaternary Environmental Fluctuations

Analyses of fossil mammal faunas from 2945 localities in the United States demonstrate that the geographic ranges of individual species shifted at different times, in different directions, and at different rates in response to late Quaternary environmental fluctuations. The geographic pattern of faunal provinces was similar for the late Pleistocene and late Holocene, but differing environmental gradients resulted in dissimilar species composition for these biogeographic regions. Modern community patterns emerged only in the last few thousand years, and many late Pleistocene communities do not have modern analogs. Faunal heterogeneity was greater in the late Pleistocene.

The isotopic ecology of late Pleistocene mammals in North America: Part 1. Florida

Mammoths and mastodons are common in Pleistocene deposits, yet these proboscideans and many other animals disappeared suddenly ≈10,000 years ago. In this study, we reconstruct the diets of proboscideans and associated mammals through isotopic analysis of carbonate in tooth enamel apatite in order to test nutritional hypotheses for late Pleistocene extinction. We analyzed specimens from six sites in Florida, ranging from full glacial (>21,000 BP) to late glacial (14,750 to 10,000 BP) age. The oxygen isotope composition of mammalian apatite covaries with meteoric water composition, which in turn varies with climate. Consequently, oxygen isotope analysis can be used to assess the potential for time-averaging or mixing of specimens from different geographic regions within fossil assemblages. The carbon isotope composition of an herbivore is controlled by the isotopic composition of the plants that it ingests. Carbon isotope analysis reveals that mastodons ate chiefly C3 plants, presumably trees, shrubs and herbs, whereas mammoths consumed chiefly C4 grass. Several nutritional hypotheses for late Pleistocene extinction entail the assumption that extinct taxa had specialized diets. The resource partitioning and focused feeding preferences of Floridas proboscideans corroborate this assumption, but they do not, in themselves, prove that nutritional stress was the cause of the late Pleistocene extinction.

Tracking mammoths and mastodons: Reconstruction of migratory behavior using strontium isotope ratios

Variations in the strontium isotope ratio ( 87 Sr/ 86 Sr) of tooth enamel are used to examine the migration patterns of late Pleistocene mammoths and mastodons from Florida. An animal’s 87 Sr/ 86 Sr ratio tracks the ratios of its environment, which vary with differences in bedrock and soil. Consequently, the environmentally controlled differences in 87 Sr/ 86 Sr ratio recorded in mineralized tissue, such as tooth enamel, may be used to reconstruct the movement patterns of an individual. We map variations in local 87 Sr/ 86 Sr ratios across modern Florida and Georgia through analysis of rodent teeth, plants, and surface water, then use this map to interpret the movement patterns of extinct mammals. Mastodons from northern and central Florida have higher 87 Sr/ 86 Sr ratios than both modern environmental samples from Florida and fossils from nonmigratory species, suggesting that mastodons migrated north into Georgia. Mammoths display ratios similar to those of environmental samples and resident species, suggesting that they did not migrate outside Florida.

ON THE ORIGIN OF LAMINE CAMELIDAE INCLUDING A NEW GENUS FROM THE LATE MIOCENE OF THE HIGH PLAINS

Abstract The fourth radiation of Camelidae in North America produced both living tribes of Camelidae: the Camelini of the Old World and the Lamini of South America. This paper focuses on the origin of Lamini. It places on record a new genus and species, Pleiolama mckennai, from the middle Miocene of Nebraska and Texas, and assigns to that genus the species P. vera (Matthew, 1909) from the late Miocene of the High Plains. Pleiolama is distinguished from four other extinct genera of Lamini recognized in North America. The nominal genus and species, Pliauchenia humphresiana Cope(1875), traditionally thought to be an early representative of Lamini, is shown to be a nomen vanum.

Richard Stone: Mammoth: the resurrection of an Ice-Age giant

One hardly knows what to make of such a nice little book on such a huge subject. By comparison, volume two of the Proboscidea, Henry Fairfield Osborn’s great posthumous tome on Elephantidae, outweighs this by one and a half pounds to the ounce. The style of this trade book is journalistic and its focus is just one species, the woolly mammoth. When it’s all said and done, the book is more about the insatiable curiosity of Homo sapiens than about the paleobiology of Mammuthus primigenius. This book has a curious, mostly symbiotic, relationship with the Discovery Channel’s frozen mammoth story. Members of the television audience who witnessed the slow thawing of the Jarkov Mammoth and its scrutiny by a select international team of scientists, will enjoy this book as it inquires more deeply into the past, present, and future of woolly mammoth studies in Siberia. There is one really major difference between mammoth science as perceived by the book and that of the TV team organized by Bernard Buigues and filmed by the Discovery Channel. The latter were primarily investigating hypotheses about the extinction of arctic mammoths. This book, however, invests nearly equally in the concept of resurrection, a more dramatic but more remote possibility. As stated in the introductory chapter ‘‘Explorers and scientists are racing to raise the dead . . . For some the finish line spells doom; for others, the start of a spectacular drama.’’ Four of the twelve chapters in this book explore the current and expected technology for cloning, resurrecting, and ultimately repatriating a viable herd of woollies. The drama of arctic exploration is very well told here. The possible science of resurrecting extinct species is also probed effectively. Surprisingly, two vital subject areas were virtually ignored. One is the phylogenetic and geographic sweep of elephantid evolution. And the other concerns the tusk analyses of life history that Dan Fisher is pursuing. More than any other current research avenue tuskology seems worthy of attention and indeed was featured in the televised version. If one accepts that this book is intended for a broad audience, it is a laudable adventure in lyrical reading. If one already has a stake in mammoth paleontology, it may strike a slightly jarring tone. As two paleontologists of different generations we both recommend this for young paleontologists and avocationalists. The limited number of illustrations implies that you should read this nice little book after you see the TV show and meet the real researchers tramping through the remnants of the mammoth steppe.