Fona herzogae, a recently discovered dinosaur from Utah, likely lived partially underground, as evidenced by its anatomical adaptations and frequent fossil preservation in burrows, reshaping our understanding of Cretaceous life. Credit: Jorge Gonzalez
The discovery of the burrowing dinosaur, Fona herzogae, from the mid-chalk period reveals a complex ecosystem with dinosaurs occupying underground niches. This highlights the diversity and ecological adaptability of dinosaurs, expanding our understanding of their roles in the ancient environment.
The age of the dinosaurs was not just spent above ground. Newly discovered ancestor of Tecelosaurus reveals that these animals spent some of their time in underground burrows. This new kinds adds to our understanding of life during the mid-Cretaceous, both above and below ground.
the new dinosaur Background [/Foat’NAH/] herzogae lived 99 million years ago in what is now Utah. At the time, the area was a large floodplain ecosystem located between the shores of a massive inland ocean to the east and active volcanoes and mountains to the west. It was a hot, humid, muddy environment with many rivers running through it.
Paleontologists from North Carolina State University and the North Carolina Museum of Natural Sciences found the fossils—and other specimens of the same species—in the Mussentuchit Member of the Cedar Mountain Formation beginning in 2013. The preservation of these fossils, along with some distinctive features, alerted them to the possibility of excavation.
Physical features and evidence of burrowing
Background was a small, herbivorous dinosaur about the size of a large dog with a simple body plan. It lacks the bells and whistles that characterize its highly decorated relatives such as horned dinosaurs, armored dinosaurs, and crested dinosaurs. But that doesn’t mean Background it was boring.
Background shares several anatomical features with animals known for digging or burrowing, such as large biceps muscles, strong muscle attachment points on the thighs and legs, fused bones along the pelvis—probably to help with stability when digging—and hind limbs, which are proportionally larger than forelimbs. But this is not the only evidence that this animal spent time underground.
Fona’s 3D printed skull. Credit: Lindsay Zano
“The fossil bias is toward larger animals, mainly because in floodplain environments like the Mussentuchit, small bones on the surface will often be dispersed, rotted, or scavenged before burial and fossilization,” says Haviv Avrahami, Ph.D. student at NC State and digital technician for the new Dueling Dinosaurs program at the North Carolina Museum of Natural Sciences. Avraami is the first author of the paper describing the work.
“But Background it is often found whole, with many of its bones preserved in the original postmortem position, chest down with forelimbs spread, and in extremely good condition,” says Avrahami. “If it was already underground in a hole before death, that would make this type of storage more likely.”
Lindsey Zano, associate research professor at NC State, head of paleontology at the North Carolina Museum of Natural Sciences and corresponding author of the paper, agrees.
“Background skeletons are much more common in this area than we would have predicted for a small animal with fragile bones,” Zano says. “The best explanation for why we find so many of them and find them in small groups of multiple individuals is that they lived at least part of the time underground. Essentially, Fona has done the hard work for us by digging into this entire area.
Although researchers have not yet identified the underground holes of Backgroundthe tunnels and chamber of its nearest relative, Oryctodromeus, have been found in Idaho and Montana. These findings support the idea that Background also used holes.
Fona herzogae. Credit: Jorge Gonzalez
Cultural and Scientific Significance of Fona
The name of the genus Background comes from the creation story of the ancestors of the Chamorro people, who are the indigenous people of Guam and the Pacific Mariana Islands. Fo’na and Pontan were sibling explorers who discovered the island and became earth and sky. The species name honors Lisa Herzog, manager of paleontological operations at the North Carolina Museum of Natural Sciences, for her invaluable contributions and dedication to the field of paleontology.
“I wanted to honor the local mythology of Guam, where my Chamorro ancestors are from,” says Avrahami. “In the myth, Fo’na became part of the earth when she died, and from her body sprang new life, which for me is associated with fossilization, beauty and creation. Background it was most likely covered with a down coat of colorful feathers. The species name is for Lisa Herzog, who has been integral to all of this work and has discovered one of the most outstanding Background specimens from several individuals preserved together in what is probably a burrow.
Background is also a distant relative of another known North Carolina fossil: Willo, a Thescelosaurus neglectus a specimen currently housed in the museum and also believed to have adaptations for a semi-fossorial – or partially subterranean – lifestyle, research published in late 2023 by Zano and former postdoctoral researcher David Button of NC State.
“T. neglect was at the end of that line – Background is its ancestor from about 35 million years ago,” says Avrahami.
The researchers think Background is key to expanding our understanding of Cretaceous ecosystems.
“Background gives us an idea of the third dimension that an animal can occupy by moving underground,” says Avrahami. “This adds to the richness of the fossil record and expands the known diversity of small-bodied herbivores that remain poorly understood despite being incredibly integral components of Cretaceous ecosystems.”
“People tend to have a myopic view of dinosaurs that doesn’t keep up with the science,” Zano says. “We now know that dinosaur diversity ran the gamut from small arboreal gliders and nocturnal hunters, to sloth-like herbivores and yes, even underground denizens.”
Reference: “A new semi-fossorial Thescelosaurus dinosaur from the Cenomanian Mussentuchit Member of the Cedar Mountain Formation, Utah” by Haviv M. Avrahami, Peter J. Makovicky, Ryan T. Tucker, and Lindsay E. Zanno, 09 Jul 2024. The anatomical record.
DOI: 10.1002/ar.25505
