TALES FROM TODAY
|Arthur Bibbins was struck by a car on a Baltimore street in 1936. He died a day later (Anonymous, 1936). By this time, of course, all iron mining was a thing of the past, although some of the pits like those around Muirkirk were kept open as brick clay and paint pigment mines, even to the present day. Records of the mine names were lost and most filled with water, becoming ponds (Fig. 12). Fossil dis-coveries all but ceased.
There were occasional discoveries. For example, a small part of a meat-eater was found in 1898 while workers were digging a sewer on Capitol Hill; the leg of a sauropod was found in 1942 during construction of a water filtration plant; a tooth came into a collector's possession in the 1950's; and a bone fragment was discovered in the clay pits by a foreman in 1974. The old sites were so well known to Marsh, Hatcher, and Bibbins that they saw no reason to mark their locations when they labeled their finds, which are now part of the Smithsonian collections. It is possible that they did not mark their sites on a map to protect them from other collectors, or if they made such a map it has been lost. When I tried to find these locations in the mid-1980's, I learned that many were completely unknown to the current curators at the Smithsonian, and those that could be found were overgrown ponds (Fig. 12) or dump sites. Over the years with the help of Singewald's Iron Ores of Maryland and the knowledge of George Smith, an 80+ year old building engineer and present resident of the Muirkirk area, I have been able to locate most of the sites (Fig. 9). Mr. Smith remembered their names from when he played and fished in the old mines as a boy.
Figure 9. Map of fossil sites associated with iron ore pits in the Muirkirk area. Locations of former Muirkirk Iron Works and the proposed Dinosaur Park are also shown. (base map courtesy State Highway Administration)
|KEY TO FOSSIL SITES SHOWN ON FIGURE 9:|
|Sites from which the National Museum of Natural History, Smithsonian Institution, holds dinosaur fossils:|
|Bladensburg||Bladensburg East Branch of the Potomac River; location unknown.|
|(B?) Branchville||Number 248-250 of Singewald (1911) are associated with Branchville.|
|C? Contee||Numbers 224-235 of Singewald are associated with Contee.|
|Coffin's Old Engine Bank||See Swampoodle.|
|Coffin's Engine Bank||See Swampoodle.|
|D Duvall's Bank||Singewald no. 234|
|(F) F and First St., SE, D.C.||Sewer excavation, not an ore pit.|
|H? Henson's Bank||Presumed to be on the property of Thomas A. Mitchell|
|I Island Bank||Presumed to be part of the Tyson Banks; Singewald no. 237.|
|(J?) Jessup||Probably Linthicum ore banks; Singewald no. 210.|
|L? Latchford's Dump||Possibly O'Brien's Bank; Singewald no. 228.|
|(M) McMillan Reservoir (First and
Channing St., NW, D.C.
|Construction site, not an ore pit|
|S? Shea's Bank||Property is south of Beaver Dam Rd.; location uncertain|
|S Swampoodle||Singewald no. 243|
|Sites from which there are reports of dinosaur fossils, but with which no museum specimens can be linked:|
|a Ashland Bank||Singewald no. 239.|
|b? Blue Bank||According to George Smith, part of Tyson's Bank; Singewald no. 237.|
|(h) Hobb's Bank||Singewald no. 189|
|m Millbrook Bank||Singewald no. 235; L. F. Ward refers to this as Blue Bank.|
|(s) Soper Hall Bank||Singewald no. 194|
|(t) Timber Neck Bank||Singewald no. 201|
|(w) Welch's Bank (or Welsh)||Singewald no. 220|
|? Question mark indicates probable location.
( ) Parenthesis indicates site is outside the map area.
If there is no symbol, refer to notes at right
|References: Frye, 1993; Hopkins, 1878a, 1878b, 1894; Singewald, 1911; Vokes, 1949; Ward, 1892, 1893, 1894, 1902.|
Present day excavations, largely for road and building construction, occasionally expose "Arundel" clays. When this happens, if I become aware of the exposure, I try to examine it for dinosaur fossils. The only regularly producing exposure that exists at the time of this writing is at the brick clay pit of Cherokee Sanford Co. south of Contee Road and east of U.S. 1, Muirkirk, Maryland. Virtually all of the modern discoveries have come from this pit. Dinosaur and other fossil vertebrates and invertebrates are common in a layer of dense clay charged with lignite, a layer known to the old miners as "blue charcoal clay." The layer also contain iron ore lumps, some of considerable size.
On the Sunday, May 19, 1991, four days after attending a lecture I had given to the Natural History Society of Maryland in Baltimore, Arnold "Butch" Norden took his two children to hunt dinosaur bones in the Cherokee Sanford clay pit. Mr. Norden noticed some bone fragments and reported his find to the Smithsonian. The excavation by a Smithsonian crew the following day retrieved the largest dinosaur bone ever found on the East Coast (Meyer, 1991; Fig. 10). It was a femur of Astrodon, a sauropod. Although the proximal end was missing, its length was more than a meter and its weight more than 40 kilograms (approximately 90 pounds). When whole, the femur may have been twice that size. Despite its size, my students and I, who had visited the site twice the preceding week, had totally missed observing it, which illustrates how significant a role chance plays in dinosaur hunting.
Figure 10. Astrodon femur, currently the largest dinosaur bone known from the East Coast of the United States: (a) femur being cast in plaster for removal from Muirkirk clay pit by Dan Chaney (left) and Peter Kroehler (right) of the National Museum of Natural History in May, 1991; (b) in the laboratory at the National Museum of Natural History, March, 1996; shown at approximately 1/10 size; note hammer for scale; (c) sketch of an Astrodon family.
On one occasion in May, 1992, I was more fortunate. I had taken a seven-year old prodigy to the site to hunt dinosaurs. The experience lived up to (or exceeded) my expectations, because he found three teeth in less than an hour. I was even more successful, discovering lower leg bones and ribs from what has been tentatively identified as a large ornithomimid or "ostrich" dinosaur.
This discovery is highly significant because the fossils are the first associated dinosaur bones known from the Potomac Group. ("Associated" indicates all bones are probably from one individual animal.) (Several other collectors and I had found an articulated and nearly complete skeleton of an undescribed turtle several years earlier.)
The most significant fossil find in the pits in recent years was in April, 1990, when I found the tooth of a new and as yet unnamed dinosaur (Fig. 11). (Almost all dinosaurs have but a single type of tooth in their mouths. These, however, differ from species to species. Thus, an unknown tooth indicates an unknown dinosaur.) Most paleontologists who have seen the tooth believe it belonged to a dryosaur, a kind of ornithopod, although some think it may be a cerotopsian. If the former, it is one of the latest; if the latter, one of the earliest. Regardless, this is an important discovery. (Dr. David Weishampel of the Johns Hopkins University Medical School believes the tooth may belong to a juvenile tenontosaur (personal commun., 1995).
Figure 11. Multiple views (top) of painted cast of dinosaur tooth, showing (left to right): buccal (cheek side), mesial, and lingual (tongue side) faces (approximately 2.5' enlargement). Tooth was found by the author at Muirkirk clay pit in April, 1990. Below, three possible sources of the tooth: (a), a dryosaur (late Jurassic); (b), a tenontosaur (early Cretaceous); and (c), a ceratopsian dinosaur (late Cretaceous). Time periods given for the dinosaurian candidates are typical for that type. The illustrated tooth is Early Cretaceous in age. Dinosaurs not to same scale. (Dinosaur silhouettes by Gregory S. Paul.)
The dinosaur from which the tooth came is still very poorly understood, it is not a named dinosaur. Thus for identification purposes, I tentatively propose the unoccupied name Magulodon muirkirkensis, meaning "Cheektooth of Muirkirk."