New paleontological research shows that prehistoric animals, including dinosaurs, supplemented their diets with marine matter like seaweed washed up on ancient beaches. This practice, known as marine subsidization, occurs today when terrestrial organisms turn to ocean resources during food shortages, such as droughts. Lead researcher Clayton Forster, a geologist at the University of Arkansas, demonstrated that this exact phenomenon occurred during the greenhouse climates of the Cretaceous period.
The Discovery
Scientists evaluated carbon isotope ratios, known as delta 13C, which track light C-12 and heavy C-13 carbon signatures passed from food into tooth enamel. While living animals usually display an upward shift of 11 to 13 parts per thousand in enamel relative to their diet, dinosaur teeth frequently yielded mysterious, higher-than-expected values. Because land plants carry lower delta 13C values than marine plants, researchers realized coastal dinosaurs were likely consuming sea life or prey that fed on oceanic material.
What Scientists Found
The team examined fossilized tooth enamel from coastal and landlocked regions along the ancient Gulf of Mexico and the Western Interior Seaway, an inland sea that divided North America around 100 million years ago. Their analysis revealed several key findings:
- Coastal fossils from the early Albian period (113 to 107 million years ago) and early Cenomanian period (100 to 96 million years ago) had higher delta 13C values than inland fossils.
- This chemical signature was shared across the coastal food chain, from fish to massive plant-eating dinosaurs, across various latitudes and timeframes.
- Seaweeds, or marine macroalgae, were identified as the primary low-chain food source providing this unique carbon trace over millions of years.
- Dietary choices varied by species; for instance, the large Cretaceous herbivore Tenontosaurus tilletti showed values matching a strict land-plant diet.
Why It Matters
Published in the journal Frontiers in Ecology and Evolution, the study is the first to identify marine subsidization in ancient ecosystems. It highlights that terrestrial and marine environments have been deeply intertwined for hundreds of millions of years, reinforcing the crucial nature of protecting environmental linkages across time and space.
Source: prehistoric animals new study - BingNews · Published October 03, 2026 · Photo by Steff Hanson on Unsplash