Bryce Canyon Was Never Known for Fossils. A 2022 Survey Found 59 New Sites.

In its first hundred years Bryce Canyon National Park never became known as a fossil park. Then, in the 2022 field season, a new paleontology team went looking and found 59 new fossil sites in a single season, including the first dinosaur footprints ever recorded there.

Tut Tran, an ACE Epic Paleontologist Fellow at the park, wrote this account for the Spring 2023 Park Paleontology News, as the park marked its 100th birthday.

The edge of the Paunsaugunt Plateau seen from the Under the Rim Trail. NPS photo by Peter Densmore.

A park of hoodoos beside a fossil-rich neighbor

Over 61 million people have visited since the park began as Bryce Canyon National Monument, drawn by pink hoodoos of Eocene age. Southern Utah's geology as a whole keeps a nearly unbroken record of environmental change from the Late Cretaceous (100 to 66 million years ago) into the early Cenozoic (66 to 34 million years ago). Grand Staircase-Escalante National Monument (GSENM), next door, is famous for abundant and varied Cretaceous dinosaurs, including many new kinds. Bryce shares much of that geology, yet it has a documented fossil record of its own, and the potential for far more.

1988 to 2013: Dr. Jeffrey Eaton's surveys

For most of the park's history, paleontology stayed out of public view and amounted to a few fossils that visitors picked up now and then. The richest period of rigorous study was led by Jeffrey Eaton, now Professor Emeritus of Geosciences at Weber State University. From 1988 to 2013 he and several groups of students surveyed much of the rugged terrain and found over 170 sites in all the fossil-producing rock formations: the hoodoo-forming Eocene Claron Formation, the mostly terrestrial Cretaceous Wahweap and Straight Cliffs Formations, and the deep-marine Cretaceous Tropic Shale. Their finds include fish, sharks, frogs, turtles, crocodilians, mammals and some dinosaurs, along with plants, snails and clams, and trace fossils such as feeding traces and burrows.

They concentrated on Cretaceous microfossils, mostly teeth of mammals and reptiles. A large and varied sample of small fossils, collected by screen-washing rock and examined under a microscope, gives a fuller picture of an ancient ecosystem than a handful of dinosaurs can. Eaton compared the small mammals from Bryce's Cretaceous rocks with those of the same age at GSENM and found distinct groups with few species in common, which suggests environmental differences across the Cretaceous landscape of southern Utah.

He also found four holotypes, the single specimens that define new species:

• a rodent-like multituberculate mammal, Dakotamys shakespeari
• a skink-like lizard, Monocnemodon syphakos
• two sawfishes, Columbisia deblieuxi and Texatrygon brycensis

Eaton, though retired, still studies fossils from in and around the park, now the Paleocene-Eocene floodplain life preserved in the Claron Formation.

After his last survey in 2013, paleontological work in the park paused for nearly ten years. The exception was an emergency fossil salvage during road construction along SR12, carried out by Eaton, Utah State Paleontologist James Kirkland and monitors from an environmental consulting firm. The incident showed the Resource Management Division and the Superintendent that the park needs an active paleontology management program.

Figure 1. Fossil leaves found in Bryce Canyon. Scale bars are in centimeters. NPS photo.

2022: the first in-house team

In June 2022 the park's first internal paleontology team, Tran (then a Physical Science Technician) and a Scientists-in-the-Parks intern, began a paleontological resource management plan. The first task was to relocate and assess Eaton's earlier sites, recording any new ones met along the way.

New sites came faster than expected: at the start of the season, up to three a day. By the end of the field season in November, 59 of the 105 documented sites were new. The fossils matched Eaton's: snails, trace fossils, plants, turtles, crocodilians and dinosaurs. Highlights included:

• well-preserved fossil leaf and petrified wood sites
• a fossil wasp or bee burrow network
• sites full of freshwater and marine snails, oysters and even ammonites
• several large crocodilian fossils
• a partial juvenile hadrosaur tail
• the first dinosaur footprints recorded in the park's 100-year history

Figure 2. Marine invertebrates found in Bryce Canyon, including ammonites (A and B) and a cluster of rudist bivalves (C), the primary reef-builders at that time in the Cretaceous. NPS photo.

The hadrosaur tail vertebrae lay on the surface at one site. They are juvenile because their sutures are unfused and unbroken; in adults the sutures fuse to the neural spines. Isolated skull and limb pieces nearby suggest more of the animal may still be in the ground. The footprints are sandstone casts, not impressions in the rock: the animal likely walked on soft mud, and sand later buried and filled the prints. That is common for hadrosaur tracks in this part of southern Utah.

Figure 3. Juvenile hadrosaur tail vertebrae found on the surface of a single site, with unfused sutures visible. NPS photo.

Figure 4. Close-ups from the hadrosaur tail site: a tail vertebra, a partial skull (frontal) bone, and microfossils including bowfin fish vertebrae, snails and a hadrosaur tooth. Scale bars equal one centimeter. NPS photo.

What comes next

The park has to work out how to protect these non-renewable fossils from erosion and from disturbance, and whether to collect them or leave them in place. The dinosaur tracks are too big to collect, so digitizing them with photogrammetry is probably the best way to preserve them. The park is also working with its law enforcement rangers and interpretive staff, and with outside paleontologists such as Eaton and Kirkland.

Storage is a problem. Zion National Park serves as the museum repository for four parks and monuments (Zion, Bryce Canyon, Cedar Breaks and Pipe Spring), so space for future finds is limited. Eaton's discoveries are kept at the Natural History Museum of Utah. For now, most of Bryce's fossils are safest where they have been for eons, in the ground.

The park's centennial runs across two anniversaries: the monument was established in 1923 and became a national park in 1928.

Sources

• Tut Tran, ACE Epic Paleontologist Fellow, Bryce Canyon National Park, "One Hundred Years of Bryce Canyon: Over Fifty Million Years of Fossils," Park Paleontology News, Vol. 15, No. 1, Spring 2023, National Park Service (https://www.nps.gov/articles/000/one-hundred-years-of-bryce-canyon-over-fifty-million-years-of-fossils.htm); a work of the United States government. The author's words are paraphrased, and a picture that names an intern is left out; rewritten in hubnx's own words.