The Adams Mastodon: Uncovering An Ice Age Behemoth!

Discovery, Excavation and Conservation

On July 7 a road crew working near Adams Road and M-59 were amazed to see a large limb bone fall from the shovel of their backhoe. Members of the Oakland County Road Commission (Bill Macentee and Jim Persinger) and the crew from Dan’s Construction Inc. stopped their project, searched and removed additional materials from the sediments, including a tooth and partial tusk that suggested that they had discovered the remains of the American mastodon (Mammut americanum), a shaggy haired elephant-like animal that roamed Oakland County at the end of the last glacial period, before becoming extinct roughly 10,000 C-14 years ago.

A team from the Institute was called in to confirm and assess the find and continue the excavation with the support of the construction crew and road commission. The following Monday, July 10, Institute staff members, Director and archaeologist Mike Stafford and geologist John Zawiskie, removed the remaining mastodon bones, associated plant and invertebrate fossils and documented the geological context of the find, naming the animal the Adams Mastodon in the process.

Mike Stafford and John Zawiskie excavating Adams mastodon.

Many local residents and members of the media watched in awe as the massive bones and associated plant fossils were progressively unearthed. A flurry of local and national media attention documented the findings in newspaper, radio and television reports. The excavation was remarkable as it was an excellent example of “rescue paleontology” where the Road Commission and construction firm cooperated with local scientists to save the fossils for science and to inspire the public with a sense of place for their community and the ice age world just beneath their feet.

The road crew discovered another bone at the site on while shifting sediments on 7-26. Then on August 3rd a group of 7th and 8th graders enrolled in the Institute’s summer geology field camp discovered more of the mastodon’s bones and associated fossil plants from sediments that had been hauled from the original site and temporarily stored at a local gravel pit near the town of Holly. Their activity was captured on film by PBS as part of the program Get Up and Get Out airing on 8-25 (5:00 PM) and 8-26 (9:00 AM).

The next phase of the project involved the cleaning and treatment of the fossils supervised by Institute paleontologist Mark D. Uhen and his paleontology prep-lab team. Much of the conservation work was done outside the museum and on the exhibit floor giving thousands of visitors and local media an opportunity to see the process and get a close up view of the find.

Mark Uhen preparing mastodon bones on the Institute exhibit floor.

What Was Found?

Roughly 30% of the animal is now known including the following: shoulder (scapula) and front limb (humerus, ulna and radius); part of the hind limb (femur, patella, ?partial tibia); ankle, toe and foot bones; vertebrae from the neck (including atlas and axis), back and tail, numerous ribs and neural spines; a molar tooth and partial tusk; portions of the skull, occiput and brain case. Plant fossils (mostly spruce cones) and wood were recovered from the bone-bearing layers and invertebrates (mollusks: clams and aquatic snails) from the overlying layers.

Some of the limb bones and scapula of the Adams mastodon.

The bones indicate that the Adams mastodon was likely a large male that stood 8’ high at the shoulders and weighed between 8 to 10 tons, very similar in proportions to the mastodon reconstruction on the exhibit floor at the Institute and about the size of a large African elephant!

Restoration of the American mastodon at CIS; same size as Adams mastodon.

Geologic Setting and Age of the Adams Mastodon

The Adams mastodon was recovered from postglacial sediments deposited on and adjacent to a glacial landform called the Inner Defiance moraine (see map PDF1). The moraine formed during late glacial times around 14,000 C-14 years ago when the terminus of a melting continental glacier was present in the area. Ice wedge polygons in aerial photos and information from other local sites indicate that permafrost and polar desert conditions (with mean annual temperature 20°F colder than present) existed before tundra and eventually spruce forest and the mastodon community moved into Oakland County as global warming accelerated. The sediment layers containing the Adams mastodon bones and abundant white spruce cones (See stratigraphic section PDF1) were deposited in a small lake that formed in an ice block depression on the glacial landscape (kettle lake), probably more than a thousand years after the ice front receded from Oakland County. The lake eventually evolved into a bog as a boreal coniferous forest (spruce followed by pine) progressively surrounded its drainage area. Judging from the radiocarbon dates of wood and cones from other local sites the Adams mastodon is likely to be between 12,000 and 10,500 C-14 years old. The excellent surface condition of the bones indicates that the carcass did not undergo extensive exposure and degradation but more likely subsided rapidly into a tomb of sandy lake clay until it was unearthed by the backhoe on 7-7-06!

Reconstruction of Oakland County 12,000 years ago, courtesy of J. Shoshani.

Mastodons and Mammoths: The Mega-fauna

Mastodons are members of the order Proboscidea that also includes elephants and the extinct mammoths. It is thought that mastodons originated 35 million years ago in Africa and first entered North America 15 million years ago via Asia. The American mastodon (Mammut americanum) evolved from this ancestral stock around 4 to 5 million years ago and is found only in North America, ranging from Alaska to Mexico to the eastern continental shelf, with the highest concentration of finds in the eastern and Great Lakes regions. Their conical tooth structure and isotopic composition, geologic and environmental context and the other animals they are found with indicate that the American mastodon was a browsing herbivore eating a mix of coniferous trees (particularly spruce), swamp and shrub plants. They likely required 300 to 500 pounds of vegetation per day and probably undertook seasonal migrations in search of food. They are especially linked with the boreal spruce and parkland Taiga habitat during the end of the last glacial period. The American mastodon (Family Mammutidae) is a distant cousin of the modern elephant and extinct mammoth (Family Elephantidae) having last shared a common ancestor over 30 million years ago!

Mammoths possessed very different high crowned teeth with a flat chewing surface more suitable for a grazing life style and were better adapted for more open grassland habitat being only rarely associated with mastodons, supporting the notion of ecological habitat differences for these two giants. Mammoths also originated in Africa and four species are known to have inhabited North America, with the earliest finds being roughly 2 million years old. The mammoths also became extinct in North America with the mastodons and other large animals (mega-fauna) around 10,000 C-14 years ago. The mega-fauna extinction in North America is still a mystery but a growing body of evidence implicates an abrupt climate reversal (Younger Dryas) and Paleo-Indian hunting as contributing factors.

Oakland County Mega-fauna and Cranbrook History

Over 211 well-documented sites for the American mastodon are known in Michigan and 45 for the mammoth. The mastodon was officially named the state fossil in 2002. The Adams find is the 16th American mastodon site and 17th individual discovered in Oakland County (see mastodon map PDF2). Two individual mammoths known from isolated teeth (Mammuthus jeffersoni) have been found in the county, one of which is in the Institute collection.

In terms of completeness the postcranial skeleton of the Adams mastodon is the best so far discovered in Oakland County. The Shelton mastodon site worked during the early 1980s in Brandon Township near Pine Knob (partially sponsored by Cranbrook and under the direction of former Institute Research Associate Hezy Shoshani; current staff geologist John Zawiskie interpreted the geologic setting) is by far the most intensely studied reference locality with numerous radiocarbon dates and other related documentation of additional late glacial vertebrates, invertebrates (diatoms and mollusks) and plant macro- and microfossils (pollen and spores). All of the material from the Shelton site is currently stored in the Institute collections.

Former CIS Director Robert Hatt with baby mastodon jaw from Pontiac.

Other local Michigan mastodon finds in the collection and on display at the Institute include: two specimens from the Pontiac area recovered in the early 1960s, one of which is arguably the smallest known mastodon jaw in the world (from a baby less than one year old at death); Troy mastodon, a jaw dredged from a branch of the Rouge near Long Lake and Coolidge in the early 1970s; Cranbrook mastodon, a scapula found by the Cranbrook grounds staff (Keith Ellsworth) on the campus near the Vaughn Rd. entrance in the mid-1970s; Lake Orion mastodon, a pair of tusks; and the Rappuhn mastodon, recovered during a detailed excavation headed by former Institute archaeologist Warren Wittry on the bean farm of Gotlieb Rappuhn in Lapeer County during the early 1960s (Institute staff member Robin Odle participated in the excavation). Also of note is a partial mastodon skeleton called “Elmer” (from the Groleau – White Lake Township site) that was mounted by Hezy Shoshani with an associated mural at the Oakland Community College Highland Lake Campus.

What’s Next?

With respect to the science the next step will involve radiocarbon dating of wood and cones from the Adams site and a study of the plant macro- and microfossils and the invertebrates. Analysis of the carbon isotope composition of the tooth enamel will reveal the relative amount of grasses versus other vegetation in this individual’s diet and the oxygen isotopes and growth bands in the tusks will give information about climate, the age and season of death of the Adams mastodon. The findings from this site will join a growing data base that allows us to understand how life responded to the global climate changes at the end of the last glacial period and serves as a piece of the puzzle of the large scale extinction of large animals during that time.

More Mastodon Mania!

So, if you missed out on the mastodon mania this summer come visit us this fall! The Adams mastodon bones will be on display in our lobby area at the Institute starting on Labor Day and extending at least until early December. Don’t miss Thanksgiving weekend when we’ll augment the mastodon material on display with additional rarely seen specimens from our collections in the most extensive mastodon display in the history of the Institute!

More than anything else the Adams find gives a whole new generation their very own inspirational memories of an engaging, exciting scientific moment, right in their own backyard and reminds others of discoveries past!

Michigan Mastodons and Mammoths Resources

Abraczinskas, L. M. 1993: Pleistocene Proboscidean sites in Michigan: new records and an update on published sites Michigan Academician Vol. XXV, No. 4: 443-9.

Also see special volume on Michigan Mastodons and Mammoths: Michigan Academician September 2003 issue.

Shoshani, J, Fisher, D.C., Zawiskie, J.M., Shoshani, S.L., Benninghoff, W.S. , Zoch, F.H. 1989, The Shelton Mastodon Site: Multidisciplinary Study of a Late Pleistocene, (Twocreekan) Locality in Southeast Michigan: Contribution from the Museum of Paleontology, University of Michigan, Vol. 27, no.14, p.393-436.

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Global Climate Change
in Southeast Michigan:
Ice House to Hot House!

The landscape of Oakland County formed when giant continental ice sheets last covered the region around 14,000 years ago during the late Pleistocene epoch, near the end of the last glacial period. So how much colder was it? Direct evidence for the former existence of permafrost in southeast Michigan is being documented by Institute geologist John Zawiskie and his colleague Nina Misuraca of the Oakland County PEDS environmental stewardship program, who are mapping the distribution of patterned ground (relict ice wedge polygons) visible in aerial photos of Oakland County. The presence of these features indicates that the mean annual temperature was at least 15° to 20° F cooler than present during late glacial times!

For the last 10,000 years (Holocene Epoch) the Earth has been in a warm interglacial climate state characterized by sometimes abrupt and dramatic changes. During the Holocene climate has been influenced by such factors as: the rate of volcanic eruptions; variations in solar activity and the tilt of earth’s rotational axis; changes in atmospheric circulation (El Nino –La Nina) and deep ocean circulation; and in recent decades the increasing concentration of atmospheric greenhouse gases.

The instrumental temperature record demonstrates that the earth has warmed by roughly .7°C since the mid- to late 19th century and studies have now shown that the pace of warming and the melting of the ice sheets covering Greenland and Antarctica have increased in recent years. Is there evidence regarding the late Holocene climate in Oakland County before the instrumental record and the modern warm period?

One of the world’s leading tree ring researchers, Dr. Edward Cook of Lamont-Doherty Earth Observatory (Columbia University), has used the pattern of tree ring widths since 1700 AD to analyze the history of drought conditions across the United States, with particular emphasis on the western part of the country. As a data point in their geographic data base Dr. Cook’s team assembled a tree ring chronology for White Oaks growing along the southern margin of Orchard Lake in Oakland County Michigan (Orchard Lake Nature Sanctuary). The tree ring chronology from this site spans the 402-year period 1581 to 1983 AD. The public domain Orchard Lake White Oak data are currently archived at the International Tree Ring Data base in World Data Center-A for paleoclimatology under the file name Cranbrook Institute of Science.

Cook’s analysis did not include the 16th and 17th century portions of the Orchard Lake tree ring data. The Institute’s John Zawiskie downloaded and graphed the public domain data (see LIA PDF). The growth indices clearly show periods of extreme prolonged stress for the White Oak population during parts of the 16th to 19th century that were unrivaled in the 20th century portion of the Orchard Lake record. For example, 11 of the 12 most severe individual summers, with 30% or more reduction from mean growth, occurred prior to 1840 with none in the 20th century. 1591 was the single most severe summer in the entire record with more than 40% reduction in growth index. Elsewhere the middle to late 16th and early 17th century were typified by horrible multi-decade mega-droughts in the western USA and along the eastern seaboard. The Orchard lake data set suggests that these climate conditions may have extended into southeast Michigan as well.

Towering White Oak at Orchard Lake Nature Sanctuary, photo by Bob Gross.

John’s provisional analysis of this chronology indicates the local beginning of a climate period called the Little Ice Age (LIA) in the late 1580s and the end of the LIA summer conditions at Orchard Lake in the mid-19th century (~1846), just prior to the beginning of the instrumental temperature record and our current warm period. Many climate specialists recognize the LIA as the latest of 9 periods of cooling and climate deterioration followed by warming during the last 11,000 years. Each of these cool periods involved an abrupt change in atmospheric circulation above the Greenland ice sheet and the spread of cold ocean waters from north of Iceland to the latitude of Britain. Alpine snow lines also dropped over 100 meters below their present altitudes and glaciers in Europe, New Zealand and the southern Andes reached their most extensive development in the last 10,000 years (neo-glacial period).

Prior to the LIA, between 890 and 1180 AD, the mid- to high latitudes of the northern hemisphere experienced a warming called the Medieval Warm Period (MWP). Some tree ring studies suggest the rate of warming at the beginning of the MWP in some regions matched the 20th century trend until 1990 while temperature profiles in boreholes in ice and rock in Greenland and other northern hemisphere sites actually suggest MWP conditions slightly warmer than the 20th century; however, the spatial extent of warmth in the late 20th and early 21st centuries appears to have been unrivaled in the last 1200 years. Is there any evidence from the Holocene record in southeast Michigan for warmer conditions than today?

As noted in an earlier Science in the News update geologist John Zawiskie is participating in research projects and educational programs with the Noble Odyssey Foundation and Captain Luke Clyburn on the extreme early to mid- Holocene low stand of the Great Lakes. One project lead by biologist Dr. Doug Hunter of Oakland University centers on a drowned forest off the coast of Lexington (Sanilac Site). In an article currently in press in the journal Quaternary Research, Hunter’s team reports that the oxygen isotope composition of the wood and the patterns of tree rings indicate warmer conditions than today at the Sanilac site ~7,600 years ago. Many other sites from mid- to high latitudes in the northern hemisphere indicate warmer conditions than present between ~6,000 to 9,000 years ago, a warm period called the Holocene Thermal Maximum (HTM). Unlike our modern warm period a higher angle of tilt of the earth’s rotational axis adequately explains the warmth of the HTM.

Tree stump from the mid-Holocene drowned forest in Lake Huron, Sanilac Site, photo by Captain Luke Clyburn. Download a recent article on the Sanilac drowned forest.

One lesson from the Holocene climate record is prepare to adapt, because we’ve been darn lucky...so far! Past is indeed prologue.

Resources

Download White Oak tree ring growth index chronology data.

Learn more about the local history of the last glacial period at Cranbrook Institute of Science outdoors exhibit, A Slice of Cranbrook: A Window to the Ice Age (5-27 to 9-17-06), which details the ice age sediments exposed by recent construction on campus and the GIS map of the glacial landforms and sediments of Oakland County at: http://www.oakgov.com/peds/program_service/es_prgm/geology.html.

Alley, R.B., 2000, The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change and our Future, Princeton University Press, p. 229

Cook, E. R. et al. 1997: A new assessment of possible solar and lunar forcing of the bidecadal drought rhythm in the western USA: J. Clim. Vol. 10, p. 1343-56.

Hunter. D.R., Panyushkina, I. P., Leavitt, S. W., Alex C. Wiedenhoeft, A. C., and Zawiskie, J. M., In Press, A multi-proxy environmental investigation of Holocene wood from a submerged conifer forest in Lake Huron, U.S.A., Quaternary Research.

Osborn, J.J. & Briffa K.R., 2006, The Spatial Extent of Warmth in the Context of the last 1200 years: Science VOL. 311, 841-844.

Stahle, D.W., Cook, E.R., Cleaveland, M.K., Therrell, M.D., Meko, D.M., Grissino-Mayer, H.D., Watson, E. and Luckman, B.H. 2000. Tree-ring data document 16th century megadrought over North America. EOS, Transactions, American Geophysical Union 81: 121, 125.

Aerial photo of relict ice wedge polygons in Springfield Township, Oakland County MI.