67 million years ago, five triceratops died. The cause of death will always remain partly a mystery, but the heavy rains in North America at the time most likely led to flooding and drowning. Millions of years later, paleontologists can excavate and use the bones to discover more about the life and behavior of triceratops. Researcher Jimmy de Rooij from Naturalis has published an article on what they have discovered so far and how they found it.
Tan enamel lasts for years
Why is this place exactly like uslearn a lot about triceratops, while this dinosaur species already seems so familiar? This mass grave contains many well-preserved teeth. “If a Triceratops eats certain plants or drinks water, some of its components end up in the tooth enamel,” says de Rooij. “As in many other animals, a new layer of tooth enamel forms every day, creating a time course in a tooth.” In this way, a Triceratops feeding in several places collects an impression of what food and water it ingested in a single tooth. “Tooth enamel is so hard that it can be preserved for millions of years as a kind of time capsule. By looking at the composition of the tooth enamel, scientists can find out (with isotopic analysis) what and in what environment the triceratops ate in the last days to months before their death.”
The triceratops by the stream
The components of the tooth enamel of these Triceratops changed very little over time. So it seems that these animals mostly got their food from the same place. This is very important information because it matters triceratops did not migrate, but could spend some time in the same place. And how was this place? The water that the Triceratops drank from the mass grave turns out to be from a freshwater river. The triceratops probably ate the vegetation that grew nearby. This is similar to the composition of the tooth enamel of other animals found in the mass grave, viz caiman pike and crocodile-like champsosaurs who lived in rivers.
Everyone has their own niche
The mass grave also tells something about the ecosystem from 67 million years ago. “If you look at the teeth of an herbivore, you will see that the teeth and the shape of the jaws are adapted to eating certain types of plants. We also saw this in the composition of the tooth enamel, because it can vary greatly between different herbivorous dinosaurs. For example, we first thought that the herbivores Hadrosaurus lived by rivers, while triceratops supposed to have lived in interior forests. But now we find evidence of it triceratops also lived by the river, and the habitats of Hadrosaurus and triceratops to overlap strongly. Very interesting because we have strong evidence that these dinosaurs existed at the same time. They may have avoided competition for food because the species focused on plants that grew at different heights. so could Hadrosaurus reach low-hanging trees, while triceratops was limited to grazing what grew on the ground.”
On your own or in a group?
Analysis of the tooth enamel indicates that the five triceratops-individuals ate the same kinds of plants and drank the same water. “It suggests that here we are dealing with several animals that were together during their life and death and may even have formed a herd. It is not yet clear whether we are really dealing with a herd. To answer this question, further research into precipitate takes place around the mass grave.”
- The entire article is published in Palaeogeography, Palaeoclimatology, Palaeoecology and can be read online at Elsevier.
Text: Lieke Ruven and Jimmy de Rooij, Naturalis Biodiversity Centre
Photos: Nadia de Waal; Megan Hulscher