Until now, juvenile dinosaurs were thought to have eaten smaller prey, such as insects in the case of carnivores, and fruits or shoots for plant-eaters. But exactly how the young ones’ nutrition varied from that of their adult parents has remained unclear.
Now, a new study of fossilised teeth of the duck-billed dinosaur Maiasaura peeblesorum, which lived about 75 to 80 million years ago, has revealed what juvenile plant-eaters ate.
These large herbivorous dinosaurs lived in herds and were thought to have been highly social creatures.
A closer analysis of their dental wear patterns show that while juvenile Maiasaura teeth had significantly more crushing wear, adults exhibited more shearing wear.
The findings suggest that adult Maiasaura parents brought softer, higher-protein food to their children than they themselves ate.
This proves that the urge we see in birds to feed their offspring is a “very old behaviour”.
“What we’re providing is that evidence for that behaviour probably goes much further than the origin of birds, perhaps to the origin of dinosaurs,” said John Hunter, an author of the study published in the journal ‘Palaeogeography Palaeoclimatology Palaeoecology’.
Researchers now believe juvenile Maiasaura ate more nutritious low-fibre foods like fruit, while their caretakers consumed a greater proportion of tougher, nutritionally poor high-fibre plant parts.
The diet followed by the young ones may have caused them to grow particularly fast in their first year.
The tooth marks found in the study among adult Maiasaurs were similar to patterns seen even in mammals today, where shearing wear is more likely present in grazers like horses, antelopes and cows. On the other hand, low-fibre diet eaters like tapirs have dental marks similar to those of young dinosaurs.
Shifts in diet during adolescence likely played an important role in the early growth and development of dinosaurs, the study suggests.
The research also hints that dinosaurs may have fed their young partially regurgitated food, another behaviour now common in birds.
Dinosaur young ones were likely dependent on their parents to feed them during the first weeks after hatching, scientists say.