Studying Fossil Horses

The horse has frequently been used as a classic example of long-term evolution because it possesses an extensive fossil record. This book synthesizes the large body of data and research relevant to an understanding of fossil horses from perspectives such as biology, geology, paleontology.

This book provides an update on the phylogeny, systematics and ecology of horses in South America based on data provided over the past three decades. The contemporary South American mammalian communities were shaped by the emergence of the Isthmus of Panama and by the profound climatic oscillations during the Pleistocene. Horses were a conspicuous group of immigrant mammals from North America that arrived in South America during the Pleistocene. This group is represented by 2 genera, Hippidion and Equus, which include small species (Hippidion devillei, H. saldiasi, E. andium and E. insulatus) and large forms (Equus neogeus and H. principale). Both groups arrived in South America via 2 different routes. One model designed to explain this migration indicates that the small forms used the Andes corridor, while larger horses used the eastern route and arrived through some coastal areas. Molecular dating (ancient DNA) suggests that the South American horses separated from the North American taxa (caballines and the New World stilt-legged horse) after 3.6 - 3.2 Ma, consistent with the final formation of the Panamanian Isthmus. Recent studies of stable isotopes in these horses indicate an extensive range of 13C values cover closed woodlands to C4 grasslands. This plasticity agrees with the hypothesis that generalist species and open biome specialist species from North America indicate a positive migration through South America.

Everything you were taught about evolution is wrong.

During the last ZO years great progress has been achieved in our understanding of both earth history and vertebrate evolution. The result is that climatic/tectonic events in earth history can now be placed in a more precise and global time frame, that permit their evaluation as abiotic causal factors which might trigger extinction and dispersal events in vertebrate history. Great strides have also been made in genetics and cell biology, providing new insight into phylogenetic relationships among many vertebrates. These new data, along with data on chronologie resolution of earth history, provide tests of previous interpretations regarding ancestral-descendant relationships based solely on the fossil record. It is fitting and proper that a volume on European Neogene mammal chronology is produced at this time, to ensure that new interpretations of vertebrate evolution and chronology are based on the most accurate and current data. Vertebrate paleon tologists believe that the fossil record is the only secure data for measuring the actual course and tempo of vertebrate evolution. Knowledge of the fossil record must keep pace with advances in other areas of science so that inferences on vertebrate evolu tion are accurate and meaningful.