If you know your dinosaurs you’ll know that there were two different types – the meat eaters, like Tyrannosaurus rex or allosaurus, and the vegetarians, like brontosaurus, triceratops or stegosaurus. That’s not surprising. Animals today follow similar diets. Lions hunt zebra and wildebeest which are herbivores. Foxes take rabbits and hares, herbivores again. And ladybirds eat aphids which graze on plants. It’s a fact of life – carnivores eat herbivores.
For a long time it was assumed that carnivorous dinosaurs hunted plant-eating ones. That seems to be true – save for one small detail. The herbivores weren’t entirely vegetarian. A recent study, published in the scientific journal Scientific Reports, has found that they occasionally dined on shellfish and other invertebrates.
So, how can we tell what dinosaurs ate? The biggest clue is their teeth. Tyrannosaurus, for example, had sharp, dagger-like teeth similar to those of a lion or other predators. Herbivorous dinosaurs have flatter, grinding teeth like those found in cattle and other plant-eaters. But there is another way to find out a dinosaur’s diet – look at its poo.
Some fossilised dinosaur droppings were found in Utah in the USA. They belonged to a 75 million-year-old duckbilled dinosaur. Due to the shape of their teeth, we’ve always thought that these were vegetarians which fed on conifers and ferns. But what they’ve left behind shows something different. They did indeed eat plants, which made up the vast majority of their diet. But they also ate crabs and insects.
Perhaps they ate the animals by mistake? Could they have swallowed them by accident along with a mouthful of tree? Well, along with crab shells and insect parts the poo also contained quite a bit of wood. This couldn’t be digested by dinosaurs which suggests that duckbills went hunting for crabs which had taken refuge in piles of rotting wood.
It’s not all that surprising really. The dinosaurs’ closest living relatives are birds and they rarely eat a 100% vegetarian diet. Even birds who feed primarily on seeds or berries will happily eat the odd insect. They’re a valuable source of protein and not to be sniffed at. Little wonder then that the ancestors of birds behaved in a similar way to how their descendants behave today.
If you like dinosaurs then Nature Matters is the place for you. We have loads of articles on science, including several on dinosaurs like this one which looks at whether or not tyrannosaurs had feathers. There’s so much just waiting for you to discover. Go on – take a look.