"Animals of the Past" by Frederic A. Lucas is a scientific publication written in the early 20th century. The work explores the history of extinct species, focusing on the formation of fossils, early vertebrates, and the various animals that once roamed the Earth. With contributions from notable artists for its illustrations, the book promises to blend technical information with engaging visuals that make paleontology accessible to a wider audience. The opening of this work sets the stage for a deep dive into the subject of paleontology, highlighting the rising public interest in the ancient life of Earth and the ongoing expeditions to discover fossil remains. Lucas introduces the concept of fossils, explaining how they are formed and the conditions necessary for preservation. He discusses various types of fossils, including impressions and natural casts, and emphasizes the difficulty in defining when and how these remains come into existence. Overall, the beginning of the book piques curiosity about the lives of early creatures, promising a blend of science and storytelling that aims to captivate both lay readers and enthusiasts of natural history. (This is an automatically generated summary.)