Forget the idea that dinosaurs matured the way modern mammals do—new research suggests young dinosaurs lived radically separate lives, changing how scientists understand prehistoric ecosystems.
According to new research from the University of Maryland, young dinosaurs played very different roles in their environments than adults did, a finding that changes how scientists interpret Mesozoic ecosystems and the role reproduction played in shaping them.
The research was detailed in a new study, published in the Italian Journal of Geosciences, which suggests that juvenile dinosaurs behaved as distinct functional species, thereby increasing the diversity of ancient habitats in which dinosaurs thrived long ago.
A Different Approach to Parenting
Dinosaurs are often compared to modern mammals since both groups were the dominant land animals of their time. However, Thomas R. Holtz Jr., a principal lecturer in the University of Maryland’s Department of Geology, points out a key difference in the way each group raised its young.
“A lot of people think of dinosaurs as sort of the mammal equivalents in the Mesozoic era, since they’re both the dominant terrestrial animals of their respective time periods,” Holtz said in the release. “But there’s a critical difference that scientists didn’t really consider when looking at how different their worlds are: reproductive and parenting strategies.”
Modern mammals depend on extended maternal care. Young tigers, elephants, and primates stay with their parents until they reach almost full size, eating the same foods and filling the same ecological roles. As Holtz put it, “You could say mammals have helicopter parents, and really, helicopter moms.”
In contrast, dinosaurs only provided brief parental care before their young became independent. “Dinosaurs were more like latchkey kids,” Holtz said. This pattern has been supported by the discovery of fossil beds containing groups of juveniles without any adult remains present.
Crocodiles offer a modern comparison. They guard nests and protect hatchlings for a short time, but juveniles quickly move on and live independently of their parents within months of hatching.
One Species, Many Roles
As soon as young dinosaurs left their parents, their lives diverged sharply from those of the adults. A hatchling started out tiny, only to shift into a very different creature as it grew. What it could eat changed, the animals that hunted it changed, and the terrain it could safely move through changed as well.
“The key point here is that this early separation between parent and offspring, and the size differences between these creatures, likely led to profound ecological consequences,” Holtz explained.
For example, a juvenile Brachiosaurus could not reach treetop leaves like its parents and instead had to feed at ground level, making it more vulnerable to predators that would not attack adults. As the animal grew, its ecological role also changed.
“If we count young dinosaurs as separate functional species from their parents and recalculate the numbers, the total number of functional species in these dinosaur fossil communities is actually greater on average than what we see in mammalian ones,” Holtz stated.
Ways to Support Additional Life
To support this range of ecological roles, Mesozoic ecosystems required enough energy to sustain animals of many sizes and metabolic needs. Holtz offers two possible explanations for how this was possible.
First, the climate during this period was warmer and had higher carbon dioxide levels, which would have increased plant growth. A more productive plant base could support a wider variety of ecological roles.
Second, dinosaurs may have had lower metabolic rates than mammals of similar size, so they needed less energy each day. The combination of lower energy requirements and abundant vegetation available could have supported a greater variety of ecological niches.
A New Framework for Dinosaur Diversity
Holtz notes that this model does not mean dinosaur ecosystems were necessarily more diverse than those of today. Instead, it suggests that Mesozoic diversity took forms that paleontologists have not always recognized. Functional diversity shaped by age and growth may have been a key feature of dinosaur-dominated environments.
“We shouldn’t just think dinosaurs are mammals cloaked in scales and feathers,” Holtz said. “They’re distinctive creatures that we’re still looking to capture the full picture of.”
Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds a Master of Business Administration and a Bachelor of Science in Business Administration, as well as a certification in Data Analytics. His work combines analytical training with a focus on emerging science, aerospace, and astronomical research.