Trio of Paleontologists discover remarkable tracksite in Alaska's Denali park proving multi-generational herds thrived in ancient ecosystem

DALLAS, TX (July 8, 2014) – A trio of paleontologists from the Perot Museum of Nature and Science, University of Kansas and Hokkaido University Museum has discovered a remarkable new tracksite in Alaska’s Denali National Park filled with duck-billed dinosaur footprints – technically referred to as hadrosaurs – that demonstrates the animals not only lived in multi-generational herds but thrived in the ancient high-latitude, polar ecosystem. The paper also provides insight in the herd structure and paleobiology of northern polar dinosaurs in an arctic greenhouse world.

The scientific paper – entitled “Herd Structure In Late Cretaceous Polar Dinosaurs – A Remarkable New Dinosaur Tracksite” – will be published in Geology, the flagship journal produced monthly by the 126-year-old Geological Society of America (GSA) and regarded as the world’s premier scientific publication for the industry. Anthony R. Fiorillo, Ph.D., the Perot Museum’s curator of earth sciences and a Fellow of the GSA, is the lead author. Stephen Hasiotis, Ph.D., of the University of Kansas’ Department of Geology – also a Fellow of the GSA – and Yoshitsugu Kobayashi, Ph.D., of the Hokkaido University Museum, are the co-authors. To view the article, which is now available online at Geology’s website, go to:

It all began in 2007, when the three paleontologists went on a survey sponsored by the U.S. National Park Service. At that point, the Upper Cretaceous Cantwell Formation in the Alaska Range of Denali had not been explored. On the last day, perched precariously on the steep side of the mountain, Fiorillo said the three men were giddy – somewhere between giggling and crying – when they came upon the wealth of tracks.

“Without question, Denali is one of the best dinosaur footprint localities in the world, but what we found that last day was incredible – so many tracks, so big, and so well preserved,” said Fiorillo. “Many had skin impressions so we could even see what the bottom of their feet looked like. And there were lots of invertebrate traces – the tracks of bugs, worms, larvae and more – which were important to us because they showed an ecosystem existed during the warm parts of the years.”

Hasiotis adds that the findings told them a lot about how hadrosaurs lived as families within the warmer-than-expected Arctic climate.

“The Denali tracksite is extremely significant to the reconstruction of this Cretaceous high latitude polar ecosystem as it demonstrates higher annual temperatures compared to the present-day climate. The hadrosaur tracks show specifically where they lived and how they acted as an extended family. The burrows and trails of mud-loving beetles, mole crickets, midge fly larvae, and other sediment-dwelling beasties demonstrate that the whole cast of characters left their traces of life in the river bank sediments during the warm summer months—frozen in time, waiting to be discovered!”

Over the next several years, the three returned to the excavation site again and again. Because the fossils were so well preserved, Fiorillo, Hasiotis and Kobayashi were able to accurately measure and analyze the footprints, which showed that four different age classes of Hadrosaurids – adults, sub-adults, juveniles and very young individuals – lived together in a large social group. The team’s research also suggests that the Hadrosaurid dinosaurs – affectionately known as the “cows of the Cretaceous” – experienced a period of rapid growth in their life history.

“This is one of the greatest dinosaur tracksites in the world in terms of size, number, and quality. We could see how hadrosaurs walked, ran, or slipped on muddy surface. Footprints were so vivid that we almost could see and smell them,” said Kobayashi. “We were so excited when we found tiny, baby footprints, because we instantly knew this was the evidence to support the polar hadrosaurs survived through winters and lived as a herd to protect each other like other mammals do.”

They initially thought they had five stair-stepped layers of rock on the side of the mountain. In 2009, after a helicopter hovered over the site providing an aerial view, they realized it was instead a single bedding plane – and it was at risk. If an earthquake occurred – as what happened in 2002 when a major earthquake rocked a nearby region of Denali – the extraordinary tracks would crumble and slide down the mountain into a nearby river. Denali National Park officials immediately recognized the potential danger and acted quickly to help the paleontologists remove and preserve the specimens.

The molds were then transported to the Perot Museum of Nature and Science in Dallas and handed off to Ronald S. Tykoski, Ph.D., fossil preparator at the Perot Museum. Tykoski then began meticulously crafting casts of the tracks, which are now on permanent display in the Museum’s T. Boone Pickens Life Then and Now Hall, along with videos documenting the paleontologists’ journey. The large epoxy casts are lit from below to spotlight the exquisite detail that was captured.

Fiorillo, who departed yesterday for Alaska and will conduct research in Denali National Park through late July, is thrilled that the team’s work is being recognized in Geology.

“Geology receives submissions from across the world but publishes fewer than 300 papers a year, so it’s an enormous honor to be chosen for inclusion,” said Fiorillo. “It demonstrates that the discovery was significant not only to us but to our peers in the scientific arena.”

He also credits the National Park Service and specifically the staff at Denali National Park.

“Without their cooperation, none of this would have happened,” said Fiorillo. “They were incredible, really crucial partners, and we’re very, very grateful.”

This isn’t Fiorillo’s first venture into Alaska. He and Tykoski have published manuscripts announcing a number of Alaskan discoveries – a new pygmy tyrannosaur named Nanuqsaurus hoglundi announced in March 2014, a new horned dinosaur species called Pachyrhinosaurs perotorum announced in 2011, and a part of a juvenile Pachyrhinosaurus perotorum described in 2013.

“Every year we learn something new from our digs in Alaska. To find evidence of a big dinosaur population proves once again that the ecosystem of ancient Arctic was a very different place than we might once have thought, and it challenges everything we know about dinosaurs,” said Fiorillo.

The duck-billed dinosaur tracksite specimens are on view at the Perot Museum of Nature and Science, located at 2201 N. Field St, Dallas, Tex., 75201. For tickets and more information, go to Visitors are strongly encouraged to purchase tickets online and in advance.

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