New York City Mastodons: Big Apple Tusks

Abstract

Unlike some cities, New York is not known as a locality for fossils, and for good reason, they are few and far between, especially if you exclude the treasure trove of fossils embedded in the dimension stone of facades, lobbies, and rest rooms. It is easy to understand why New York City offers such a paucity of naturally occuring specimens when you consider that most of the city’s bedrock is composed of high-grade metamorphics—gneiss, marble, and schist—1.1 billion to 435 million years old (Baskerville 1994). Any fossils that may have existed in the original parent rock have been destroyed by ensuing high-grade metamorphism, a process by which rocks are altered by heat and/or pressure. The only exposed sedimentary rocks are Cretaceous-age clays and sands. In the past, they have yielded plant fragments including lignite and a few invertebrates (Hollick 1908) and some microfossils, but these exposures are substantially diminished with continuing urbanization. However, almost the entire city has been glaciated, and in places the veneer of glacially transported rocks yield a variety of Paleozoic invertebrate fossils delivered from north and west of the city (Hollick 1893). But it also turns out that late glacial and/or early post glacial sediments contain relatively rare fragments of mastodon skeletons—the ice-age elephant (Mammut americanum)—and finding them is a hit-or-miss undertaking. I have chosen the mastodon for this discussion, focusing on New York City as an unusual locality, because mastodon fossils are well distributed throughout North America, its fossils have been collected by the thousands (Haynes 1991), and mastodons were the rage long before dinosaurs were discovered. The fact that these animals roamed what is now Broadway is an excellent example for starting a discussion on climatic change as well as the hot topic of what caused the demise of the charismatic late Pleistocene megafauna and, as we will see, introducing some aspects of the history of paleontology. Another purpose of this paper is to show that the study of paleontology and evolution can and should be interdisciplinary and multidisciplinary. Often, it is the secondary aspects of these subjects that can excite students and gain their interest. Based on the plant material associated with mastodon fossils in northeastern United States, the mastodons clearly lived in spruce forests and open spruce woodlands containing swamps and bogs. Although the stratigraphic record is not very good for New York City localities, it can be assumed that they lived in a similar vegetation zone, an environment so different than the eastern deciduous forest that exists now in New York City. Today, there are remnants of this forest still extant, not only altered by many introduced species, but also not a true virgin forest because during the occupation by British and Hessian armies during the American Revolution the forests were entirely cut down on Manhattan Island to provide firewood and construction materials. The forest of the present time reestablished itself in many places with the withdrawal of the foreign troops. As most of the glacial deposits are covered by buildings or located in the adjacent waterways that make New York City an archipelago, finding fossils requires diligence at construction sites where, in general, the focus has been on Evo Edu Outreach (2008) 1:204–209 DOI 10.1007/s12052-008-0042-y