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Dinosaurs of the Mason Dixon Line

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New Find Enhances Record

Richard D L. Fulton

There was a time when Frederick and Adams counties looked more like an alien world than that which exists today.

A primordial lake (dubbed Lake Lockatong) existed from Rocky Ridge, growing in size towards the northeast, as it sprawled through Pennsylvania, New Jersey, and into New York State. Some believe that this great lake covered an area equivalent to the presently existing Lake Tanganyika in Africa, at some 20,000 total miles in size.  Often, vast mud flats bordered the huge freshwater lake, giving way to conifer forests (based on fossil evidence gathered outside of Rocky Ridge).

This was during a period of time classified as the Late Triassic, some 220 million years ago.

Based on fossil excavations in Rocky Ridge and another nearby site, fossils recovered indicate that the lake teemed with fish, mostly those related to the present-day gars, sharing the water with five-to-six-foot coelacanths (whose ancestors gave rise to land vertebrates), and an ancient aquatic gator-like (but unrelated) reptile called Apatopus.

It should be noted that the reptiles and dinosaurs discussed are known only from their tracks, with the exception being Rynchiosauroides (noted below) whose body impressions have also been recovered at Rocky Ridge.

Hundreds of two-to-three-foot-long lizards (called Rynchiosauroides) patrolled the shorelines, diving into and paddling their way within the shallows in search of snails, clams, and freshwater shrimp, while prehistoric crickets, beetles, and millipedes scurried about the mudflats.

The lizards were occasionally joined by at least one species of dicynodont reptiles in their quest for more food. The dicynodonts, though reptiles, were also ancestral to the first mammals, and those of Rocky Ridge apparently established that these unique animals survived longer than previously assumed before,  themselves, becoming extinct.

But the local evidence of the beginning of the rise of another group of animals in the Late Triassic —the dinosaurs—can be found a little further north in Adams County.  Most of the dinosaurs during this period of time in the Mason-Dixon area ranged from a few feet in height or length to 12 feet.

The latest evidence of the local presence of dinosaurs occurred on June 9, 2012, when a remarkable bed of dozens of dinosaur tracks was found at an undisclosed, secured site located on private property, southwest of Gettysburg (for security purposes, The Catoctin Banner agreed not to reveal the exact location of the ongoing excavation, although the reporter was permitted to visit the site).

The discovery was initially made by Brian Cole, a member of the Franklin County Rock and Mineral Club, while hunting for crystals in the limestone deposits. Cole stated that the collectors he was with started finding fossil mud cracks and gathered up several specimens to take home. He later discovered one of the slabs had a clearly defined dinosaur track on it.

The find resulted in return trips to the site, which ultimately resulted in the discovery of dozens of dinosaur tracks, along with non-dinosaurian  reptile tracks. To date, more than 40 tracks have either been removed from the site or still remain on-site. How many remain to be found? Only time and further exploration will reveal.

The site in question consists of limey layers of rock which likely represents the shoreline of Lake Lockatong. Aside from the reptiles Rynchiosauroides and Apatopus, the new site added the tracks of two more (non-dinosaur) reptiles to the list, Desmatosuchus (which bore some resemblance to a crocodile with prominent spikes on its back and heavy back armor) and two different species of  Brachychirotherium.

The primary dinosaur present at the site has been identified as Grallator, also known only from its tracks, but it is believed to be related to better-known Coelophysis, whose skeletal remains have been found in New Mexico. There may be what turns out to be species of Grallator at the site, one larger than the other.  The much more plentiful smaller tracks may represent a different species of Grallator than the scarcer larger version.

The Grallator were bipedal carnivores, potentially ranging up to more than nine feet in height, and apparently hunted in packs. Over two dozen tracks were found on one layer at the site, all heading in the same direction. If Grallator was as Eastern Coelophysis, it could have had “feet (with) three main claws and a fourth, smaller claw positioned further up the foot,” and “The arms (that) were adapted for grasping and holding prey but are not thought to have been particularly powerful, a long and thin head, with jaws containing “around 50 small, sharp teeth,” according to Activewild.com.

Grallator and Coelophysis are among the oldest known dinosaurs, and it is generally held that they primarily ate insects and other small animals. As has been demonstrated by finds made at the Rocky Ridge site, there was no shortage of insects and small reptiles living in the area during the Late Triassic Period.

In 1895, James A. Mitchell, a graduate student at Johns Hopkins University, found nearly two dozen, 220-million-year-old dinosaur footprints on two flagstone (shale) slabs found in the pathways leading up to Saint Joseph’s Roman Catholic Church in Emmitsburg, thus making them reportedly the only dinosaur tracks that had been found in Maryland from this period of time (the Triassic Period).

The tracks appeared to have been those of Grallator. One of the two slabs that were found by Mitchell is presently on display at the Maryland Science Center.

But the first “mother lode” of dinosaur tracks, which also included non-dinosaurian reptile tracks, including dicynodont, occurred in Adams County in Trostle’s Quarry near York Springs when the tracks were discovered by Elmer R. Haile. Haile made his discovery in the summer of 1937 when he and some associates were gathering stone for the Civilian Conservation Corps to be used in a bridge; they were building the bridge on South Confederate Avenue over Plum Run.

The Gettysburg Times reported on August 3, 1937, that three dinosaurs who left their tracks in the quarry were identified by Arthur B. Cleaves, state junior geologist and paleontologist, as Anchisauripus exsertus, Anomoepus scambus, and Grallator tennis, all three being bipedal (standing upright on two legs). The newspaper also reported in December 1937 that approximately 150 tracks were recovered.

The two blocks containing the dinosaur tracks that made it into the top layer of stones on the Plum Run Bridge have been identified as Atreipus milfordensis, a plant-eating dinosaur that walked on all four legs, and Anchisauripus sillimani, another bipedal meat-eater. The Trostle’s Quarry tracks have been dispersed over time to such places as the Smithsonian Institute, the William Penn Museum, the Carnegie Museum in Pittsburg, the Adams County Historical Society, and the bridge on the Gettysburg Battlefield (where they remain exposed and unprotected). 

As an aside, the species names of the dinosaurs (and reptiles) noted in the article can, and may have, changed over time. Paleontology, or the study of prehistoric life, is a constantly evolving science, in and of itself, and as more is learned about a given prehistoric species, sometimes new findings can result in name changes.

Grallator

Adams County Grallator tracks (new site).

Photo Courtesy of Robert Weams (USGS retired).

Illustration Courtesy of National Park Service.

The Grallator were bipedal carnivores, potentially ranging up to more than nine feet in height, and apparently hunted in packs.

atreipus

Atreipus tracks (Plum Run Ridge).

Photo by Rick Fulton.

Illustration Courtesy of Columbia University.

Atreipus, a plant-eating dinosaur that walked on all four legs.

Not All Dinosaurs Were Huge, Some Were Shrimps

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James Rada, Jr.

Hundreds of millions of years ago, dinosaurs walked the earth, and hundreds of millions of years before that, prehistoric clams filled a vast lake that covered all of Central Maryland and a mud flat that stretched from North Carolina to Connecticut. The lake, known as the Lockatong, sat in the middle of Pangaea, an immense, C-shaped supercontinent.

Then came the drastic climate change that dried the lake, leaving the clams, fish, and other creatures laying in mud where they died. Small land animals moved across the mud flats, seeking water and leaving behind their prints in the mud.

Today, a portion of the former lake is a lush, green farm owned by John and Linda Ballenger in Rocky Ridge. Although the lake is gone, a small stream runs through the property bordered by layers of shale that are slowly yielding their secrets.

Although the Ballengers call their property Buck Forest Farm, among geologists, archeologists, and research papers, the property is referred to as The Fulton Site.

In 1994, John Edwards with the Maryland Geological Survey told Linda Ballenger that there might be dinosaur tracks on her property. Linda examined the area Edwards identified, but didn’t do anything with the information for ten years. That’s when she read an article by Richard D. L. Fulton about an Emmitsburg quarry where fossils had been found. Linda contacted Fulton and told him that her farm might have dinosaur tracks.

Fulton came out to the farm and confirmed what Linda had been told. He then asked permission to begin studying the farm for other prehistoric fossils. Since 2004, his search has yielded thousands of reptile tracks, skin impressions and bones, millipede and insect tracts, plant fossils, and fossil freshwater shrimp and fish.

The site has also attracted attention from researchers in the United States and abroad. Most recently, a group of graduate students from the University of Nebraska toured the site on May 13. They picked at the shale with their hammers and studied the pieces through loupes to see what had been unseen for millions of years.

Jean Self-Trail, a geologist with the U.S. Geological Survey, led the group, which was touring geological sites from North Carolina to Pennsylvania.

“This is part of a field course for these students to look at different types of geology,” said Self-Trail. “They usually go someplace like England or Spain, but, this year, we wanted to study the East Coast.”

In between digging at some of the sites, the students are engaged in various study exercises.

The visit to The Fulton Site was productive in that some additional fossils were unearthed. Robert Weems of the U.S. Geological Survey found fossils of tiny prehistoric shrimp called Cacostrian (or freshwater clam shrimp) that made faint half-moon impressions in the shale.

“We hit pay dirt both literally and figuratively,” Weems said, as he held up the find. Some researchers believe the clam shrimp found on the property to be a unique species.

Some of the other finds at the site include a nicely preserved imprint of a fish about four inches long. The fins, teeth, and scales can all be seen. Paul Olsen of Columbia University said that it represents the oldest dinosaur-age fish found to date east of the Mississippi River. The head of a second smaller fish appears to be jutting out of the head area of the four-inch fish, suggesting it may have been in the process of being eaten by the larger one.

The footprints of two types of reptiles, resembling dicynodonts—one a mouse-size species and the other a larger animal, about the size of a cat—have been found as well, along with the fossils of coelacanth scales.

Following the exploration of The Fulton Site, the group traveled up to the Fairfield Quarry in Fairfield, Pennsylvania, to view the dinosaur tracks that were found there decades ago.

“Today typifies the experience we have had doing research at this site for eight years. We can seem to get twenty Nebraska university students from 1,000 miles away to work on the site, but haven’t even been able to get but one Maryland university student from some 50 miles away to work on the site,” said Fulton, who is the lead lay-professional paleontologist.

Dino Bones 1

Photo by James Rada, Jr.