Recently, a man in Bellevue, Michigan (U.S.A) accidentally discovered the bones of a mastodon, burie

Recently, a man in Bellevue, Michigan (U.S.A) accidentally discovered the bones of a mastodon, buried in his own back yard. At first they discovered a blackened rib, but they soon unearthed 42 bones.Michigan’s fossil record represents a slew of Pleistocene animals, including giant beavers, peccaries, a great diversity of ungulates, and the occasional walrus. But the most common find is ‘Mammut americanum’, the American Mastodon. To date, over 330 American Mastodon sites have been discovered in Michigan; more than any other Pleistocene animal.Why are we finding so many bones from this one, gigantic animal? The mastodons must’ve been greatly outnumbered by the various species of voles and squirrels, etc, not just in terms of individuals, but in terms of biomass, or in terms of total number of bones. If mastodons were a minority during their time, then why are the majority of the bones mastodon bones?The answer was a mystery, until Margaret Skeels Stevens published a comprehensive summary of all the Mastodon sites found in Michigan. She found that mastodon bones were invariably preserved under similar topographical conditions.As the glaciers that covered Michigan retreated, they left lakes of melt water, which gradually drained into the ocean, leaving wetlands in their place. One type of wetland the lakes left was the “quaking bog”. A quaking bog features a two or three foot layer of peat moss across the top. A person can walk across it, but if they do, the surface will jiggle and quake, hence the name. During the last glacial melt, when Northern Michigan was still submerged under the premodern Great Lakes, bloated with glacial melt water as they were, Southern Michigan was drying up, but it was still covered with hundred of “kettle” ponds. (A kettle pond is exactly what it sounds like; a pond with the same drainage as a medium saucepan, vis à vis, zero drainage.) The Southern Michigan kettles would inevitably fill up with sediment, often becoming quaking bogs as they did. Many an unfortunate American Mastodon strayed onto the surface of these quaking bogs, possibly mistaking their surface for more safe, solid ground, or possibly knowingly risking the danger for the sake of delicious semi-aquatic flora, but instead faced an untimely death.Incidentally, quaking bogs, like all peat bogs, are highly acidic, and that acidity, over many centuries, will blacken bones. This is why so many mastodon bones are found more or less darkened. Due to the large number of mastodon bones discovered in the state, Michigan made mastodon bones the state’s fossil in 2002.Further Reading: http://othello.alma.edu/~lopez_isnard/mastodon/site/High%20School/Documents/mastodons%20and%20mammoths%20of%20michigan.pdfPicture credit for fossilized mastodon: e_monkhttps://www.flickr.com/photos/e_monk/Colter -- source link

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