ALBERTA, Canada – A groundbreaking study published in PLOS One has revealed the first definitive evidence of mixed-species grazing among dinosaurs. The discovery, made at the Skyline Tracksite in Alberta’s Provincial Park of the Dinosaurs, sheds new light on dinosaur social behavior, suggesting they moved and grazed together in groups, much like modern African mammals.
Dinosaur Footprints Rewrite Social Behavior Theories
New evidence from Alberta, Canada, suggests dinosaurs grazed in mixed herds, challenging previous assumptions about their social lives.
Key Takeaways:
- First direct evidence of mixed-species grazing among dinosaurs found.
- Footprints suggest coordinated group movements, possibly for defense or resource access.
- New techniques are transforming the study of fossil footprints.
An international team of paleontologists, led by Brian Pickles of the University of Reading, Phil Bell of the University of New England, and Caleb Brown of the Royal Tyrrell Museum of Paleontology, unearthed the fossilized footprints. These tracks paint a picture of life from 76 million years ago, documenting how different dinosaur species interacted and traveled together.
What exactly did the study find? The Skyline Tracksite yielded fossilized tracks indicating at least five different dinosaur species. Among them were ceratopsids like *Styracosaurus albertensis*, a probable ankylosaur known as *Euoplocephalus*, two large tyrannosaurids, and a small theropod. The arrangement of these tracks suggests ceratopsids walked in parallel, with the ankylosaur moving among them, indicating gregarious and coordinated behavior.
“This rock edge seemed crushed mud between the fingers of my feet, and immediately intrigued me,” said Phil Bell, who has spent nearly two decades collecting fossils in the park. The consistent orientation of the tracks supports the idea of a directed movement, perhaps toward a watering hole.
Defense or Forage: What Drove Mixed Herds?
The parallel tracks of tyrannosaurids moving alongside the herbivore group suggest that mixed-species grazing might have served as a defense mechanism against predators. However, scientists caution that more evidence is needed to confirm this hypothesis.
The discovery of an isolated small theropod footprint adds another layer to the site’s fauna. It hints at the complex ecosystem where various species shared the same territory.
The excavated area spans 29 square meters. Researchers employed meticulous techniques like grid mapping, photogrammetry, and differential GPS to document each footprint’s precise location and shape, enabling a detailed 3D reconstruction of the site. This discovery is particularly significant as it was made in the Dinosaur Park Formation, one of the most intensively studied fossil sites globally, yet one that is only now revealing its full potential for footprint discoveries.
New Techniques Unlock Ancient Secrets
The identification of natural footprint molds, known as concave epireliefs, proved crucial. These preserved impressions, showing sediment displacement, have allowed paleontologists to uncover new sites previously thought scarce due to erosion in the badlands geology. This breakthrough opens a transformative path for studying fossil footprints in this rich region and beyond.
“It was incredibly exciting walking following the traces of the dinosaurs 76 million years after they left them,” said Brian Pickles, highlighting the thrill of connecting with the ancient past. The new techniques have also aided in finding other fossil sites, promising more discoveries about dinosaur interactions and behaviors.
“This discovery demonstrates how much there is yet to discover in dinosaur paleontology,” emphasized Caleb Brown. “Dinosaur Park is one of the most studied fossil sites in the world, but only now are we beginning to understand its full potential for footprint discoveries.”
Phil Bell also pointed to the overlooked abundance of footprints, an aspect often overshadowed by bone fossil research in the area. “The traces of the tyrannosaur give the feeling that they were really watching the pack, which is disturbing, although we don’t know for certain if they really crossed,” Bell commented, alluding to the potential predator-prey dynamics.
The study emphasizes the global rarity of such detailed dinosaur footprints and reinforces the idea that their regular, parallel arrangement signifies herd behavior. The simultaneous presence of predator and herbivore tracks strongly supports the theory of mixed groupings as a survival strategy, mirroring resource use and defensive tactics seen in contemporary large mammals.
The article also noted the absence of hand impressions in the footprints of ceratopsids and ankylosaurs. This is likely due to how these dinosaurs distributed their weight, with their hind legs likely overprinting their front footprints, a phenomenon observed in other quadrupedal dinosaurs.
The combination of natural mold identification and advanced search techniques marks a significant advancement for footprint studies in the Dinosaur Park Formation and other badlands areas. The research from the University of Reading underscores the value of ichnological records, which provide crucial data on fauna composition, behavior, and preservation, even in thoroughly explored paleontological formations.
