Dinosaurs living near ancient coastlines may have scavenged marine material that storms pushed onto land, according to research reported by Futurity. A team examining carbon isotope traces in fossilized teeth and bones from coastal-dwelling dinosaurs found a chemical signature that could point to seafood in their diets. The findings also underline how long land and ocean ecosystems have been linked.
The study was coauthored by Lindsay Zanno, an associate research professor at North Carolina State University and head of paleontology at the North Carolina Museum of Natural Sciences, with Clayton Forster, a geologist at the University of Arkansas, as first author. Futurity published its report on the work on October 23, 2026.
Why it matters
The research suggests that the flow of nutrients from sea to shore is not a modern phenomenon. Storms carry marine material onto land, where land-dwelling animals can eat it, a process known as marine subsidization. According to Futurity, this happens today in coastal ecosystems, particularly when land-based food is scarce, such as during droughts.
Zanno framed the finding in broad terms. "As it turns out, what happens in the sea doesn't stay in the sea," she said, per Futurity. The team reports that coastal land animals in the greenhouse climates of the Cretaceous depended on ocean-derived resources to top up their diets, in a manner similar to modern organisms, according to Forster.
The study also speaks to how extinctions in the sea can ripple onto land. Zanno said the work clearly shows that climate-driven extinctions in Mesozoic oceans would have had effects that moved up the food chain into the terrestrial world. She added that the research is an important step toward understanding how ancient land and sea animals were connected, which she described as key to identifying what drove biodiversity loss during past periods of climate change.
A chemical fingerprint in tooth enamel
The analysis rests on carbon isotopes. Plants contain both a lighter form of carbon, C-12, and a heavier form, C-13. The ratio between them, written as δ13C, acts as a chemical fingerprint that passes from food into the body of whatever eats it. When an animal feeds, the δ13C value is built into its tooth enamel, shifted upward relative to the value of its food. In living animals, Futurity reports, that gap in tooth enamel runs between 11 and 13 parts per thousand.
Dinosaur teeth have posed a puzzle. The offset recorded in them has consistently come out higher than expected, and their δ13C values also exceed what would be predicted for animals eating only land plants, which carry lower δ13C values than most marine plants. If dinosaurs, or the prey they ate, consumed marine material, that could account for the mismatch.
To test the idea, the researchers used powder from fossils collected at sites that were once coastal as well as at landlocked locations. They found that the δ13C value in fossils from coastal sites was higher than in fossils from inland sites. The coastal values also held steady across sites regardless of latitude or age.
Because the distinct carbon value turned up in both plant-eaters and meat-eaters, the team concluded that the marine food source must have sat low on the food chain. Seaweed was the most likely candidate, according to Futurity.
Forster said the researchers can trace marine resources as they move along the food chain and end up locked into the minerals of bones and teeth belonging to dinosaurs, crocodiles, turtles and fish.
What to watch
The results add to the picture of coastal ecosystems as places where ocean and land food webs overlap, and they give researchers a chemical tool for probing ancient diets. Further work on fossil chemistry from coastal and inland sites could sharpen the case for marine material as a regular part of some dinosaurs' menus.
