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A28 SCIENCE
Wednesday 13 March 2019
Dinosaur tracks make fresh impression at Valley Forge park

on Park Service land are
still where they were dis-
covered, in the original
bedrock location. But oth-
ers were moved by human
activity, including a set of
burrows from an ancient
species that appear on the
rock facade of a visitor's
center bathroom at Valley
Forge. Those rocks originat-
ed outside the park.
There also happens to be a
significant Ice Age fossil lo-
cation beneath the Valley
Forge park, the Port Ken-
nedy bone cave. First dis-
covered in 1871, it has pro-
duced fossils that include
giant tapirs, ground sloths
and saber-toothed cats.
Port Kennedy is considered
one of the most important
mammal fossil sites in North
America, with some find-
ings having been displayed
at the park visitor center,
although most are at the
Academy of Natural Sci-
ences in Philadelphia. That
750,000-year-old site was
lost after a quarry was filled
In this Feb. 28, 2019 photo combination shown are fossilized dinosaur footprints and a non-dinosaur reptile, lower right, a relative of
the modern crocodile, on paving stones at the Valley Forge National Historical Park in Valley Forge, Pa. — partly with asbestos —
Associated Press before being rediscovered
by scientists in 2005. It is not
By MARK SCOLFORO bumps in the sandstone kilometers) to the west. sources are protected, but accessible to the public.
Associated Press rock, with the largest about Most of the tracks left in not where to find them. The There are at least 35 Park
VALLEY FORGE, Pa. (AP) — 9 inches long. On a recent what were once muddy 5-square-mile (13 square ki- Service properties known to
The national park on the weekday, hikers, joggers flats consist of three-toed lometer) park has about 30 have fossil tracks of ancient
site where George Wash- and dog walkers used the foot impressions from the miles (48 kilometers) of trail. vertebrates, and vandal-
ington and the struggling trail, oblivious to the marks early days of dinosaurs, al- The dinosaur footprints ism and theft have been a
Continental Army endured of prehistoric animals be- though Stack also found Stack found are not unique problem. Federal law pro-
a tough winter during neath their feet. footprints from a non-dino- or even particularly rare, hibits visitors from disturbing
the American Revolution Those marks drew the at- saur reptile, a relative of and don't add to the body park elements.
boasts a new feature that's tention of Tom Stack not the modern crocodile. The of scientific knowledge A park spokesman said
a couple of hundred million long after he began work- largest would have been a about the creatures, said there have been prelimi-
years old — dozens of fos- ing as a volunteer park am- bipedal theropod that was National Park Service pale- nary discussions about de-
silized dinosaur footprints bassador at Valley Forge in 6 (1.8 meters) to 9 feet (2.7 ontology program coordi- veloping an interpretive
discovered on rocks used 2017. meters) long and 4 (1.2 me- nator Vince Santucci. They program to give visitors in-
to pave a section of hiking Stack, who has a back- ters) to 6 feet (1.8 meters) date from later in the Trias- formation about the trace
trail. ground in geology and high. sic period and before the fossils. Stack said the park
The trace fossils, as they paleontology, recognized "They're subtle, they're not Jurassic era that's so famil- should consider removing
are known, are scattered the approximately 210 mil- easy to spot, but once you iar to moviegoers. rocks that contain the best
along a winding trail at Val- lion-year-old rocks known learn the characteristics of "There's no question that fossils, to prevent damage
ley Forge National Historical as argillite as being similar them, given the right sun- they are" dinosaur trace or theft.
Park, on slabs purchased in in age and type to fossil- light angle and, at times, fossils, said Santucci, who "I would think they are of
2011 from a nearby com- bearing rocks used to con- the moisture on the rock, examined them in person value as an educational
mercial quarry. struct a 1930s-era bridge then they are easier to last April. "They're consistent tool," said Helen Delano,
To the untrained eye, they on the Gettysburg battle- identify," Stack said. with the tracks that occur a senior scientist with the
appear as indistinguishable field, about 100 miles (161 There are also distinctive in equivalent-age beds all Pennsylvania Geologic Sur-
patterns in the rock thought over the East Coast." vey. "Dinosaurs are a won-
to be caused by the crack- More than 270 National derful way to hook people
ing of dried mud, and from Park Service properties into paying attention to the
the ripples of a lake or river. contain some sort of pale- geological environment.
The National Park Service ontological resource, from Every kid loves dinosaurs."
requested the exact lo- Dinosaur National Monu- Stack said the rocks are
cation of the rocks not be ment in Colorado and Utah abundant, cheap and du-
publicized, to help protect to the fossils scattered in rable, so they have long
them from being damaged rock used to build the Lin- been used for paving, side-
or removed. Officials said coln Memorial and Capitol walks, garden walls and
visitors will be told about Reflecting Pool in Washing- similar features in the Phila-
the rocks and how park re- ton, D.C. Most fossils found delphia area.q