New research suggests that young dinosaurs became independent quickly, forming their own groups and occupying different ecological niches from their parents, unlike mammals with extended parental care. This distinction could reshape understandings of Mesozoic ecosystems. The study, led by Thomas R. Holtz Jr. from the University of Maryland, was published in the Italian Journal of Geosciences.
Scientists have long compared dinosaurs to mammals as dominant terrestrial animals of their eras, but a new study highlights a overlooked factor: differences in reproductive and parenting strategies. Thomas R. Holtz Jr., a principal lecturer in the University of Maryland's Department of Geology, argues in his paper that these strategies profoundly influenced ecosystems.
Mammals typically provide extended care, with offspring staying with mothers until nearly adult size, sharing diets, habitats, and ecological roles. "You could say mammals have helicopter parents, and really, helicopter moms," Holtz explained, citing examples like tigers and elephants where young rely on adults for years.
In contrast, dinosaurs followed a different path. Young dinosaurs gained independence within months or about a year, separating from adults to form groups of similarly aged individuals. Fossil evidence shows pods of juvenile skeletons preserved together without nearby adults. Holtz compares this to modern crocodilians, which protect hatchlings briefly before juveniles disperse.
"Dinosaurs were more like latchkey kids," Holtz said. This early separation, combined with size differences across life stages, meant juveniles and adults filled distinct niches. For instance, a juvenile Brachiosaurus, roughly the size of a sheep, fed on lower vegetation and faced different predators than its towering adult parents, who reached over 40 feet.
Holtz describes juveniles and adults as "functionally different species" within the same biological one, due to variations in diet, threats, and mobility. This ontogenetic niche partitioning may have increased ecological diversity in dinosaur communities beyond initial estimates, potentially exceeding modern mammalian ones when recalculated.
The study attributes this to Mesozoic conditions like warmer temperatures and higher carbon dioxide levels, which boosted plant growth, and possibly lower metabolic demands in dinosaurs. "Our world might actually be kind of starved in plant productivity compared to the dinosaurian one," Holtz suggested.
The research, titled "Bringing up baby: preliminary exploration of the effect of ontogenetic niche partitioning in dinosaurs versus long-term maternal care in mammals in their respective ecosystems," appears in the Italian Journal of Geosciences (2026; 145(2):1). Holtz plans further work on how these dynamics shaped ancient ecosystems and their transition to the modern world.