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NewsFona herzogae lived approximately 99 million years ago during the Cretaceous period in what is now Utah. At that time, the area was a vast floodplain ecosystem nestled between the shores of an enormous inland ocean to the east and active volcanoes and mountains to the west. The environment was characterized by warm temperatures, high humidity, and muddy terrain, with numerous rivers crisscrossing the landscape.
This unique habitat provided an ideal setting for a diverse array of plant and animal life, including the newly discovered Fona herzogae. The floodplain’s rich soil and abundant water sources supported lush vegetation, which in turn sustained herbivorous dinosaurs like Fona herzogae and its relatives. The presence of both aquatic and terrestrial ecosystems in close proximity created a complex food web and allowed for the evolution of various survival strategies among the resident species.
Paleontologists from North Carolina State University and the North Carolina Museum of Natural Sciences began unearthing the fossil of Fona herzogae — along with other specimens from the same species — in the Mussentuchit Member of the Cedar Mountain Formation in 2013. This discovery marked the beginning of a fascinating journey into understanding the life and habits of this ancient creature.
The Mussentuchit Member, known for its fossil-rich deposits, has been a treasure trove for paleontologists studying Late Cretaceous fauna. The sedimentary layers in this formation have preserved a remarkable record of the diverse ecosystems that existed in North America during this period, providing crucial insights into the evolution and adaptation of various dinosaur species, including Fona herzogae.
The exceptional preservation of these fossils, coupled with some distinctive anatomical features, alerted the researchers to the possibility that Fona herzogae engaged in burrowing behavior. This realization opened up new avenues for understanding the ecological roles and survival strategies of small herbivorous dinosaurs in the Late Cretaceous period.
Fona herzogae was a small-bodied, plant-eating dinosaur approximately the size of a large dog, with a relatively simple body plan. Unlike its more flamboyant relatives such as horned dinosaurs, armored dinosaurs, and crested dinosaurs, Fona herzogae lacked the ornate features that often capture the public’s imagination. However, this apparent simplicity belies the fascinating adaptations and behaviors that made Fona herzogae a unique and important member of its ecosystem.
Despite its unassuming appearance, Fona herzogae possessed several anatomical features commonly associated with animals known for digging or burrowing. These adaptations included large bicep muscles, which would have provided the strength necessary for excavating soil and creating burrows. The dinosaur also had strong muscle attachment points on its hips and legs, indicating powerful limbs capable of generating the force required for digging.
Another notable feature of Fona herzogae was the presence of fused bones along its pelvis. This fusion likely enhanced the stability of the dinosaur’s body while engaged in digging activities. Additionally, the hindlimbs of Fona herzogae were proportionally larger than its forelimbs, a characteristic often observed in burrowing animals that use their hind legs to brace themselves and push soil out of their burrows.
However, these anatomical adaptations are not the only evidence suggesting that Fona herzogae spent time underground. The preservation state of the fossils themselves provides compelling support for this hypothesis.
Haviv Avrahami, a Ph.D. student at NC State and digital technician for the new Dueling Dinosaurs program at the North Carolina Museum of Natural Sciences, explains, “The bias in the fossil record is toward bigger animals, primarily because in floodplain environments like the Mussentuchit, small bones on the surface will often scatter, rot away, or become scavenged before burial and fossilization.”
This bias typically makes it challenging to find well-preserved fossils of smaller dinosaurs. However, Fona herzogae defies this trend. Avrahami continues, “But Fona herzogae is often found complete, with many of its bones preserved in the original death pose, chest down with splayed forelimbs, and in exceptionally good condition.”
The remarkable preservation of Fona herzogae fossils suggests that these animals were protected from the usual processes of decay and scavenging that affect surface-dwelling creatures. Avrahami proposes, “If it had already been underground in a burrow before death, it would have made this type of preservation more likely.”
Dr. Lindsay Zanno, associate research professor at NC State, head of paleontology at the North Carolina Museum of Natural Sciences, and corresponding author of the work, concurs with this assessment. She notes, “Fona herzogae skeletons are way more common in this area than we would predict for a small animal with fragile bones.”
The abundance of well-preserved Fona herzogae fossils presents a puzzle that the burrowing hypothesis elegantly solves. Dr. Zanno explains, “The best explanation for why we find so many of them, and recover them in small bundles of multiple individuals, is that they were living at least part of the time underground.”
This behavior would have provided significant advantages for Fona herzogae. Burrows offer protection from predators and harsh environmental conditions, such as extreme temperatures or storms. They also provide a stable microclimate that can help conserve energy and water. For a small herbivorous dinosaur like Fona herzogae, these benefits could have been crucial for survival in the dynamic and sometimes challenging environment of the Late Cretaceous.
Dr. Zanno humorously adds, “Essentially, Fona herzogae did the hard work for us, by burying itself all over this area.” This self-burial behavior has inadvertently provided paleontologists with a wealth of well-preserved specimens to study, offering unprecedented insights into the life and ecology of these small dinosaurs.
While the researchers have yet to identify the actual subterranean burrows of Fona herzogae, evidence from its closest relative, Oryctodromeus, supports the idea that Fona herzogae also used burrows. The tunnels and chambers of Oryctodromeus have been found in Idaho and Montana, providing a tangible example of burrowing behavior in this group of dinosaurs.
Interestingly, Fona herzogae is also a distant relative of another famous North Carolina fossil: Willo, a Thescelosaurus neglectus specimen currently housed at the North Carolina Museum of Natural Sciences. Willo is also thought to have had adaptations for a semi-fossorial — or partially underground – lifestyle, suggesting that this behavior may have been a successful strategy employed by multiple members of this dinosaur lineage over millions of years.
Avrahami provides context for this evolutionary relationship, stating, “Thescelosaurus neglectus was at the tail end of this lineage — Fona herzogae is its ancestor from about 35 million years prior.” This connection highlights the enduring success of the burrowing adaptation in thescelosaurines throughout the Late Cretaceous period.
The researchers believe that Fona herzogae is key to expanding our understanding of Cretaceous ecosystems. Avrahami explains, “Fona herzogae gives us insight into the third dimension an animal can occupy by moving underground. It adds to the richness of the fossil record and expands the known diversity of small-bodied herbivores, which remain poorly understood despite being incredibly integral components of Cretaceous ecosystems.”
This discovery challenges traditional perceptions of dinosaurs and highlights the diversity of adaptations and behaviors that these ancient creatures developed. Dr. Zanno emphasizes this point, saying, “People tend to have a myopic view of dinosaurs that hasn’t kept up with the science. We now know that dinosaur diversity ran the gamut from tiny arboreal gliders and nocturnal hunters, to sloth-like grazers, and yes, even subterranean shelterers.”
The study of Fona herzogae and its burrowing behavior opens up new avenues for understanding the complex interactions and survival strategies of dinosaurs in their ancient ecosystems. It reminds us that there is still much to learn about these fascinating creatures and that new discoveries continue to reshape our understanding of prehistoric life.
The work detailing the discovery and analysis of Fona herzogae appears in the scientific journal The Anatomical Record, providing the paleontological community with valuable insights into the life and behavior of this unique dinosaur species.
