A new study suggests that the babies of the largest dinosaurs to ever walk the Earth were once a crucial food source for meat-eating predators.
According to research led by a scientist from University College London, very young sauropods—long-necked plant-eaters such as Diplodocus and Brachiosaurus—played a central role in keeping Late Jurassic predators alive.
The research, published in the New Mexico Museum of Natural History and Science Bulletin, focuses on the famous Morrison Formation, a vast stretch of fossil-rich rock in the western United States dating back around 150 million years.
By combining fossil evidence with modern ecological modelling, the team reconstructed a detailed “food web” showing who ate whom in this ancient ecosystem.
Adult sauropods were almost unimaginably large.
Some were longer than a blue whale and weighed many tonnes, making them essentially untouchable for predators.
Their eggs, however, were relatively small, and their hatchlings were tiny by comparison. Once born, young sauropods would have taken many years to reach a size that offered any real protection.
Evidence suggests that sauropods did not care for their young.
Their sheer size would have made guarding nests difficult, if not impossible, without crushing eggs or hatchlings. Much like modern sea turtles, baby sauropods were likely left to survive on their own. This made them easy and abundant prey for hungry predators.
To understand how this worked in practice, the researchers focused on fossils from the Dry Mesa Dinosaur Quarry in Colorado. This single site preserves the remains of many species that lived within a relatively short time span. Among them are at least six kinds of sauropods, alongside large predators such as Allosaurus and Torvosaurus.
The team used multiple lines of evidence to work out feeding relationships. These included body size comparisons, tooth wear patterns, chemical signatures in fossil bones, and in rare cases, fossilized stomach contents that revealed what an animal had eaten shortly before it died. With this information, they built a detailed food web using software normally applied to modern ecosystems.
The results showed that sauropods were “keystone” species in the Jurassic world. They had more ecological connections than other plant-eating dinosaurs, such as Stegosaurus, which were better defended and therefore harder to hunt. While adult sauropods shaped the landscape through feeding, their young provided a steady supply of food for predators.
This abundance of easy prey may explain why Jurassic predators did not need to be as specialized as later giants like Tyrannosaurus rex. Millions of years later, when sauropods were rarer, predators faced tougher, better-armed prey such as Triceratops. This may have driven the evolution of stronger bites, sharper senses, and larger bodies in later carnivores.
By reconstructing this ancient food web, scientists can now compare dinosaur ecosystems across time and better understand how interactions between predators and prey shaped dinosaur evolution. The study paints a vivid picture of a harsh Jurassic world—one where even the biggest giants began life as vulnerable meals.
