Tertiary Mammal Horizons of North America is a book written by Henry Fairfield Osborn and published in 1907. The book is a comprehensive study of the mammalian fossils found in North America during the Tertiary period, which is the time period between 66 million and 2.6 million years ago. The book is divided into two parts. The first part provides an overview of the Tertiary period, including the geological and climatic changes that occurred during...