The Inglewood Mammoth (Prince George's County, Maryland) (Slightly Revised 07 March 2015)

The Inglewood Mammoth Site

(Prince George’s County, Maryland)

(2nd draft, slightly revised 07 March 2015)

G. HaynesAnthropology DepartmentUniversity of Nevada, Reno

Maryland’s first (and probably only) dated mam-moth died about 24,000 calendar years ago. Based on dental measurements, the taxon is considered to be Mammuthus columbi. The bones were recovered by a Smithsonian team led by Dennis Stanford in 1982, after initial exposure by heavy equipment the year before. This paper provides information about the excavations and results of preliminary analysis.

THE INGLEWOOD MAMMOTH

(PRINCE GEORGE’S COUNTY, MARYLAND)Gary Haynes

Anthropology DepartmentUniversity of Nevada, Reno

In the second half of 1981, heavy equipment ex-cavated a “sediment control outfall ditch” in a planned commercial park just east of the Capitol Beltway, in Prince George’s County, Maryland (Fig. 1). The exca-vators leveled the bed of the ditch to about 10-15 feet (~3-4.5 m) below the surface of the gently sloping sur-rounding field (and possibly 4-6 feet (~1.2-1.8 m) be-low the level of an existing natural drainage way), and smoothed the sloping banks. The ditch drained towards an unnamed stream paralleling the Capitol Beltway; this small stream in turn joined Southwest Branch, which joined Western Branch, which joined the Patuxent Riv-er to the southeast. Not far west of the site is the Ana-costia River; the mammoth site is very near the water-shed separating that drainage from the Patuxent system.

Fig. 1: Google Earth view of the site area in 1993. A first draft of this report incorrectly identified the stream at the bottom of the photograph as the drainage ditch con-taining the mammoth bones, which were in fact north of the stream in the central open area, now built over.

Information here about the first discovery mainly comes from the Washington Post of 25 March 1982 (pp. A1 and A10; author M. Kernan). Dana D’Aria, a University of Maryland undergraduate student, dis-covered the mammoth bones on 14 March 1982 while looking for fossils to fulfill a geology class assignment. He may have been alerted to the existence of fossils at the site by his brother, a cement truck driver, who per-haps had been to the construction site. On D’Aria’s first visit he collected a mammoth rib, a scapula, one half of a mandible with a tooth in it, and a tusk fragment. Un-able to reach the Smithsonian Institution by phone to tell someone about the find, he made a second visit with family members who dug up more ribs, teeth or tooth plates, an unknown number of vertebrae or vertebral fragments, a 16-inch-long (~40 cm) fragment of tusk, and half the pelvis (Fig. 2). D’Aria and his University of Maryland geology professor Dr. Peter Kranz finally suc-ceeded in contacting staff at the Smithsonian Natural

History Museum.

In the newspaper article Kranz states a piece of tusk “several feet long and six inches thick” was recovered, but the piece is not in the current collection, which might suggest other large elements had been present and collected at one time, but not recorded. D’Aria confirmed the bones he found were located exactly where the main bone cluster was later mapped.

On 18 March, a team of staff and volun-teers from the Smithsonian Institution’s Natural History Museum began salvage work at the site, led by Dennis Stanford of the Anthropology Department. Frank Whitmore, a vertebrate paleontologist for the U.S. Geological Survey with an office in the museum’s Paleobiology Depart-ment, made a preliminary sketch map after the first stakes of a grid system had been set in, but before excavations had be-

gun in earnest (Fig. 3). Within a few days, the Smithso-nian crew and volunteers had completed the excavation of the bone cluster (Fig. 4) where D’Aria had found the first elements in the ditch.

Fig. 2: 1982 snapshots of the first discovery of the bones in the ditch (source: Dana D’Aria).

Fig. 3: The late Frank Whitmore making a sketch of the few bones he could see before excavations started.

G. Haynes returned to the site on 1 and 2 May to collect sediment samples and draw stratigraphic pro-files. The original overburden may have been a fair-ly thick Collington alluvium (fine sandy loam) over a heavy dark Cretaceous deposit, which the buried bones

rested upon or had been pressed into. The bones ap-peared to be in stream-laid or re-deposited fluvial sed-iments in a slight depression that had eroded into the Cretaceous layer. The water-laid sediments may have been 50 inches (127 cm) to >4 feet (>122 cm) thick originally.

A sandy layer was below the loamy alluvium, 2-4 feet (~ 61-121 cm) above the water level in the ditch; and the water level in the ditch was about 6 inches (~15 cm) above the bone level. The sandy sediment was an effective aquitard, almost impermeable. Along with abundant rounded pebbles and scattered cobbles (see Fig. 5), small and large sandstone concretions were as-sociated with the bones.

The bonebed thickness in the main area, labeled squares J98 and J99, was 0.26 m to 0.32 m. Deepest bones were at almost the same level in all squares. A sandstone boulder had been exposed in a downstream area not far from the bones, but a layer of cobbles and dense pebbles was also present upstream. A 1 x 10 inch (2.54 x 25.4 cm) piece of sandstone had been found ear-lier in same area where bones clustered, and small and occasionally large rocks were not rare in the bone locus. Around the main bone concentration were many sand-stone concretions with irregular shapes and a few fist-sized and smaller round grey sand concretions. Small round quartz pebbles (fingernail sized) were abundant where the bones were closest together, along with oc-casional larger pebbles/small cobbles (<10 cm x 5 cm and smaller) in a 3 inch (7.62 cm) thick layer which the bones mostly overlaid. A grey stratum rich in clay and sand lay over and in places under the pebbles, partly cemented into platy lumps, forming thin laminae.

Field visits to record the stratigraphy continued

Fig. 4: Part of the final map of excavated materials, also listing some elements that had been removed earlier.

into early May, when a few more small bone fragments were found by G. Haynes and P. Krantz. Sediment sam-ples collected from the site included twigs and roots, some of which were identified as from estuarine and ex-tinct tree species, including Cretaceous and Quaternary taxa, the latter being spruce, pine, and Composite taxa, according to Dr. Thomas Ager of the U.S. Geological Survey.

INVENTORY OF RECOVERED BONES Recovered bones were mapped and recorded in three dimensions in the field. Only mammoth bones were found in the excavated levels above the Cretaceous sediments, all belonging to single individual (Mam-muthus columbi.) in its early teens (Fig. 5). One rib had a healed fracture in mid-shaft, a common occurrence in living and extinct proboscideans (Haynes and Klimo-wicz, 2014, Proceedings of the VIth International Confer-ence on Mammoths and their Relatives, Scientific Annals,

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School of Geology, Aristotle University, Thessaloniki, Greece, Special Volume 101:68-69). Currently a bovid element is curated as part of the collection in the Paleo-biology department of the Smithsonian’s Natural Histo-ry Museum. This bovid bone was not found during the SI excavations. Also recorded were pre-Pleistocene (cf. Cretaceous) faunal fragments (Fig. 6).

Mammoth elements recovered in excavations and surface collection: Scapula - 1 left Innominate - 1 Vertebra arches - 9 Thoracic zygopophyses - 3? centra - 9 epiphyseal plates for centra - 17 complete - 1 Thoracic and 2 Sacral Tooth plate (including 2 upper?) - 21 Rib - 11 right, 8 left [one rib had a swelling in midshaft that appeared to be a healed fracture]

Mandible - 1 nearly complete, but fragmented Cranium - fragments only Hyoid - 1 stylohyoid Tusk – 1, side unknown, and fragments Limb bone - 2? (possibly 1 tibia and 1 unknown)

Missing from the mammoth skeleton are: max-illa and upper teeth, 1 tusk, 1 scapula, 7 larger limb bones, and foot bones. It is possible that these elements were removed by the heavy equipment which dug out the ditch, or had been collected earlier before the Smithsonian excavations, or washed away before the excavations. It is also possible, but not likely, that these elements long ago had been dispersed from the rest of the mammoth skeleton, perhaps by trampling animals or scavengers, although no recovered bones show clear signs of carnivore gnawing or trampling damage. All recovered bones are excellently preserved, with no ev-idence of subaerial weathering, and must have been at least partly articulated and probably connected by soft tissue at the time of burial.

Fig. 5: The Inglewood mammoth’s refitted mandible and lower M3 and M4 teeth (also known as dp4 and M1) in place, indicating the animal was in Laws AEY (African El-ephant Years) age group XI/XIA, around 12-15 years old at death. Frank Whitmore considered the taxon to be M.columbi,

SEDIMENT STUDIES (UNFINISHED) Profiles were drawn and described of six cut fac-es, and sediment samples were taken at six points across the ditch, and sent to D. Whitehead (University of In-diana) for pollen and sediment analyses. No results are on record, and it is assumed the analysis did not take place after the site was determined to be non-cultural with at least partly reworked sediments.

Fig. 6: Pre-Pleistocene (probably Cretaceous) fossils from the Inglewood site.

SUMMARY OF EXCAVATIONS Squares J98 & J99 (both measuring 2 x 2 m) were troweled and water-screened, and all exposed bones were mapped in situ – 59 mapped bones in J98, and 32 mapped pieces (including 31 bones and 1 cobble appearing below the bone level) in J99 Square I98 (also 2 x 2 m) was shoveled and trow-eled, not screened – 1 bone was mapped in situ Square I99 (2 x 2 m) was shoveled only – 3 bones were mapped in situ Approximate location of Square I100 – not mea-sured, shoveled only by P. Kranz while profiling –1 bone was found and mapped in roughly estimated place Squares K98 and K99 (both 2 x 2 m) were shov-eled only – no bones were found

DATING Collagen from one mammoth rib –20,070+265 14C yrs BP (SI-5357) [~24 k yrs BP, calibrated] Collagen (ultrafiltration) from mammoth tusk fragment – 20,270+70 14C yrs BP (Beta-388177) [~24.3 k yrs BP calibrated] Bulk sample, dark sediment containing twigs and roots – 29,650+750 14C yrs BP (SI-5408) (~33.5 k yrs BP calibrated]

INTERPRETATION The bones were very well preserved, unweath-ered, with no signs of carnivore gnawing. They were found in a relatively tight cluster, about the same size as the animal’s original carcass would have been, and some vertebrae and ribs were in anatomical position and semi-articulated. The bones must have been buried rather quickly after death about 24,000 calendar years ago in an anaerobic sediment that was an aquitard, keeping the bones from drying out. It seems likely that ligaments still connected many if not all the elements during burial by alluvial sediments. The animal’s cause of death is unknown, and other than the one example of a probable healed broken rib (quite common in probos-cideans), no other pathologies were noted. The death occurred in the Last Glacial Maximum, when environ-ments in the area may have been rather open and step-pelike or grassy, accounting for the presence of a mam-malian taxon generally thought to be a grazer.

Fig. 7: Inglewood mammoth stylohyoid showing differen-tial staining.

Differential staining of bone surfaces (Fig. 7) had resulted from post-burial contact (and in many cases post-fracturing contact) with variable sedimenta-ry units while still unexposed and enclosed in a satu-rated matrix (Fig. 8) Breakage of some elements was a mixture of what appeared to be fresh- and not-so-fresh-bone fragmentation, with linear fracture edges inter-secting curvilinear/spiral fracture edges. The breakage was a result of the heavy excavating equipment riding over the sediments that enclosed the bones during con-struction of the drainage ditch. This is supported by the presence of deformational sediment structure in the site profiles (see Fig. 13 below). Equipment such as Cat-erpillar Bulldozers and Gradalls typically range from 7 tons to 15 tons and sometimes much more, with a rel-atively small footprint, concentrating the huge weight, and that sort of intense vertical and lateral pressure on

waterlogged sediments encasing well preserved bones surely would have distorted and broken some buried el-ements.

Fig. 8: Inglewood mammoth bones atop thick pebbles, part-ly pressed into the Cretaceous sediment. Bones in this mass included, among others, two vertebral centra, two ribs, a fragment of cranium, a long bone shaft fragment, and a possible part of a tibia epiphysis,

The Inglewood mammoth is a noncultural site, without verifiable trace of human activity (except for the 1981 and 1982 actions that exposed and later re-moved the bones). As it may be Maryland’s only dated mammoth bone site, it has an important place in the faunal history of the mid-Atlantic region. More analysis and publications about the materials are planned.

NEXT PAGES: Fig. 9 is the final map of excavated bones; Fig. 10 shows activity at the site; Fig. 11 is a field record of one day’s recovery from a 2-m square; Fig. 12 shows D. Stanford mapping at the site; Fig. 13 shows two pro-files from the site.

Fig. 9: Final bone map from Smithsonian excavations (note that several elements and fragments had been removed before excavations, and are not on this map; see Fig.4 above).

Fig. 10: Joe Brown, Jim Rancier, and Dennis Stanford as-sembling a water pump at the Inglewood site, 1982. In the background is the drainage ditch.

Fig. 11: Example of a field record of one day’s finds in square J99.

Fig. 12: Dennis Stanford during bone mapping at the Ingle-wood site, 1982.

NEXT PAGEFig. 13.: Profiles of two north walls; at top, on the south side of the drainage ditch; at bottom, on the north side. These have been re-drawn from original field sketches, with modifications to an earlier published figure (see Haynes, 1991, Mammoths, Mastodonts, and Elephants, Cambridge University Press, p. 236), based on field notes re-discovered in 2014.

ACKNOWLEDGMENTS

Dennis Stanford of the Smithsonian Institution orga-nized and led the salvage work at the Inglewood mam-moth site, assisted by Jim Rancier. I thank Dennis for more than his leadership on just this one project – he supported me for several years and generously shared his knowledge, his home in Front Royal, Virginia, his data, and his office space. No amount of thanks can ever pay him back; I am grateful beyond words.

I also thank the late Frank Whitmore for his patience and openness, and many other Smithsonian people who gave help and encouragement over the years, including Mildred and Waldo Wedel, Betty Meggers, Joe Brown, and my dear friend Jean Fitzgerald. During the Inglewood project and later work, Robert Stuck-enrath provided essential help from the Smithsonian Radiocarbon Lab.

I thank Max Wiener, Land Development Manager of McCormick Properties, Inc., in 1981 and 1982, who kindly provided copies of the Inglewood Business Community’s soil boring reports and the plans for rough grading and sediment control.

I should also thank Dana D’Aria, whom I haven’t seen since 1982. He made every effort to tell Smithso-nian scientists about the Inglewood site, and donated mammoth bones found at the site to the Smithsonian’s Paleobiology Department.

I thank the Zimbabwe National Parks and Wildlife Authority for allowing me to study elephants and ele-phant bones in the field for over 30 years.

I am also deeply grateful to the many colleagues who allowed me to study mammoth bone collections and who taught me much about extinct proboscideans, no-tably Piotr Wojtal in Poland, and Nikolai Vereshchagin and Vadim Garutt in Russia, both long deceased.

I thank Janis Klimowicz for her many years of vital help.

Mammoth skeleton (from O.P. Hay, 1911).