This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Storms routinely wash marine material ashore, providing food for land animals and other organisms. This is known as marine subsidization (MS).
Today, MS is particularly common in coastal ecosystems and is especially important to animals when land ecosystems produce less food than usual, such as during droughts. A new Frontiers in Ecology and Evolution study has shown that dinos and their prey, too, may have eaten seafood washed onto beaches. "We show that coastal terrestrial organisms in the greenhouse climates of the Cretaceous relied on marine resources to supplement their diets in a similar way that modern organisms do," said first author Dr.
Clayton Forster, a geologist at the University of Arkansas. "We can identify that marine resources are passed along the food chain and incorporated in the minerals of bones and teeth of dinosaurs, crocodiles, turtles and fish." Plants contain "light" (C-12) and "heavy" (C-13) carbon isotopes. The ratio of these isotopes, expressed as δ13C, is a chemical "fingerprint" that passes from food into a consumer's body.
When an animal eats, the δ13C value is incorporated into its tooth enamel, where it is higher than in its food. In living animals, this difference is 11–13 parts per thousand. In dino teeth, however, this difference has consistently been higher, creating a mystery around their carbon signatures.
Their δ13C values were also higher than expected for animals that eat only land-growing plants, which have lower δ13C values than most marine plants. If dinos or their prey snacked on marine matter, however, that could explain the discrepancy. "By determining the carbon isotope composition of dinosaur, fish and crocodile tooth enamel, we can determine what their primary dietary source was and if they were different between regions," Forster explained.
To do so, the researchers used fossils from sites that were once coastal along the Western Interior Seaway—a vast inland sea that split North America into two landmasses around 100 million years ago—and the ancient Gulf of Mexico coastline. They also included fossils from landlocked sites. These sites formed during the early Albian (around 113–107 million years ago) or early Cenomanian (approximately 100–96 million years ago).
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