The Mastodons and Mammoths of Michigan
Skeels, Margaret Anne, Michigan Academician
Editor's Comments. Margaret (Skeels) Stevens produced this paper while a student at the University of Michigan. She was a productive scholar and teacher at Lamar University in Beaumont, Texas, before her recent retirement. This is the seminal paper on the mastodonts and mammoths of Michigan. It not only details the known records of these animals in the state, but discusses aspects of their taphonomy (mode of death, burial, and fossilization) and biology. The idea that Skeels put forth--that the deep muck and peat and floating mats of vegetation ("quaking bogs") in the late Pleistocene were natural traps that these heavy animals would have broken through--is still accepted as primary taphonomic event involved in the fossilization of these proboscideans. The fact most fossil proboscideans in Michigan have been excavated from former shallow basins of kettle bog sites attests to this hypothesis.
Nevertheless, the fact that these animals are almost always found as scattered parts rather than whole skeletons indicates that other taphonomic events occurred. Several of these have been addressed by Daniel C. Fisher of the University of Michigan (e.g., Fisher 1984a,b). It is quite possible that the animals merely become stuck, rather than completely buried in bogs. Here they could have died of starvation and been scavenged by humans (see Barondes' 1996 report on the St. Johns, Michigan mastodont excavated by Daniel Fisher and Fisher 1987); or weakened ones could have been killed by human hunters. Then the animals could have been butchered at the site, the edible portions carried away, and the remaining parts discarded in the boggy areas in which they were found. There, fossilization would have occurred.
The lack of smaller vertebrate fossils from proboscidean sites in Michigan was attributed by Skeels to the possibilities that, because of their smaller size, their remains might have been overlooked, considered recent intrusions, or because they look "... very much like pieces of branches or roots that are sometimes present in muck or peat." Since Skeels (1962) many sites have been carefully excavated by professional vertebrate paleontologists, and there is still no question that small vertebrates are exceedingly rare at these localities. I suggest that at least one part of the problem is due to the fact that the highly fibrous plant matrix in which Michigan proboscideans are found is almost impossible to dissociate, thus standard wet-screening methods do not work; and that another part of the problem may be do to the erosion and eventual loss of small vertebrate bones due to the highly acidic conditions of bogs and bog remnants. Most of the C14 dates in this paper are too young.
Fossil mammals are known only from the Late Pleistocene of Michigan. If earlier Cenozoic deposits ever were present in Michigan they were destroyed by glacial ice that four times overrode the state. The American mastodon and Jefferson mammoth were the largest Pleistocene animals to walk on Michigan soil. Most of the information concerning these large mammals in the state must be sought in newspaper reports of individual finds. However, O.P. Hay (1923) reported upon all Michigan Pleistocene mastodon and mammoth remains known to him. Case and others (1935) reported the occurrences of the Jefferson mammoth from Glacial Lake Mogodore in Cass County. Later in the same year, Case and Stanley (1935) reported on the Bloomfield Hills mastodon. Archie MacAlpin (1940) summarized all known finds of the American mastodon in Michigan but did not publish on the mammoths. The purpose of this paper is to place on record all known occurrences of both the American mastodon and Jefferson mammoth in the state, including those discovered since 1940, and to make available to the citizens of Michigan an account of these interesting mammals.
Most of the fossil remains of these animals found in the state have occurred in swamps and bogs. …