Fossil Teeth Reveal That Dinosaur Parents Fed Their Young Special Meals — Just Like Modern Birds
It turns out that being a caring parent is not a new invention — it may be one of the oldest behaviors in the history of life on Earth. A new study of fossilized dinosaur teeth has revealed that a species called Maiasaura peeblesorum, a duck-billed dinosaur that roamed North America about 75 to 80 million years ago, likely fed its young softer, more nutritious food than the adults themselves ate. The finding pushes the origins of bird-like parental care deep into dinosaur history.
The researchers, led by John Hunter, an associate professor at The Ohio State University, analyzed the dental wear patterns — the microscopic scratches and impressions left on teeth by different types of food — of both juvenile and adult Maiasaura fossils. Think of this like reading clues left behind on a cutting board: a board used to slice soft bread will look different from one used to chop hard carrots. Juvenile Maiasaura teeth showed significantly more crushing wear, the kind produced by eating soft, low-fiber foods like fruit. Adult teeth, by contrast, showed more shearing wear, which comes from tearing through tough, fibrous plant material like stems and leaves.
This difference strongly suggests that adults were actively sourcing and delivering more nutritious, easier-to-eat food to their young rather than simply letting the babies find their own meals. Today, this same behavior is characteristic of altricial birds — birds whose chicks are helpless and nest-bound after hatching, such as robins and eagles, where parents make constant food deliveries. Hunter described the urge to feed a youngster as "a very old behavior," one that his study suggests may stretch back even further than the origin of birds themselves — possibly all the way to the origin of dinosaurs as a group.
The study also found that this specialized diet likely had a powerful effect on how fast baby Maiasaura grew. Researchers believe the high-nutrition, low-fiber diet may have caused juveniles to grow at a remarkably fast rate during their first year of life, which would have helped them reach a size where they were less vulnerable to predators much more quickly. In the mammal world today, a similar pattern of dental wear differences can be spotted when comparing horses or cows, which graze on tough grasses, with animals like tapirs, which prefer softer plant foods — just like the adult and juvenile Maiasaura, respectively.
The researchers also considered alternative explanations. Maiasaura parents might have partially regurgitated — brought back up from their stomach — softer, pre-digested food for their young, another behavior still common in modern birds. It is also possible that some juveniles left the nest to forage on their own, a behavior seen today in some herbivorous lizards. However, Hunter and his team believe juveniles were most likely nest-dependent and helpless in the first weeks after hatching, making dedicated parental feeding the most probable explanation.
Maiasaura has long been an important species for understanding dinosaur family life — its name even means "good mother lizard" in Greek. Extensive nest fossils found in Montana first hinted at its strong parental instincts decades ago. This new dental evidence adds another layer to that picture, showing that the social and family systems of dinosaurs were far more sophisticated than many once assumed. As Hunter put it, "Even among closely related dinosaurs, there is probably still quite a bit to learn about them." The study was published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.
Source: The Ohio State University / Phys.org