For decades, scientists have compared dinosaurs to modern mammals as if they were just oversized versions of today’s animals. We’ve imagined T-Rex hunting like lions, herds of Triceratops living like elephants, and baby dinosaurs snuggled up to their mothers like baby bears. But what if we’ve been getting this fundamentally wrong?
Thomas R. Holtz Jr., a principal lecturer at the University of Maryland’s Department of Geology, has spent years studying dinosaur ecosystems. His recent research published in the Italian Journal of Geosciences challenges one of our most basic assumptions about how dinosaurs actually lived. The answer isn’t in their teeth or their size or their speed. It’s in how they raised their babies.
“A lot of people think of dinosaurs as sort of the mammal equivalents in the Mesozoic era,” Holtz said. “But there’s a critical difference that scientists didn’t really consider: reproductive and parenting strategies.”
The Helicopter Parent Problem
Here’s the thing about mammals. Whether it’s a tiger, an elephant, a whale, or a human, moms stick around. They hunt for their cubs. They teach them how to survive. They protect them until they’re basically adults. This long-term parental investment means young mammals share the same food sources, the same habitats, and the same ecological roles as their parents.
“You could say mammals have helicopter parents, and really, helicopter moms,” Holtz explained. “A mother tiger still does all the hunting for cubs as large as she is. Young elephants, already among the biggest animals on the Serengeti at birth, continue to follow and rely on their moms for years.”
This parenting strategy fundamentally shapes how ecosystems work today. When you count up the number of different species in a savanna or a rainforest, you’re mostly counting distinct adult niches. The babies are just smaller versions of their parents, eating similar food in similar places.
Dinosaurs didn’t operate this way at all.
The Latchkey Kids of the Mesozoic
Dinosaurs laid eggs, often massive clutches of them. Once those eggs hatched, juvenile dinosaurs separated from adults relatively quickly. Within months or about a year, they formed groups with other youngsters their own age and fended for themselves. No parental feeding. No protection from predators except whatever basic nest guarding might have happened initially.
Modern crocodilians offer the closest comparison. Crocodile mothers defend nests briefly, but hatchlings quickly disperse into the world to survive on their own.
The fossil evidence backs this up. Paleontologists have found pods of dinosaur skeletons, all youngsters roughly the same age, preserved together with no adult remains nearby. These kids were literally living on their own, traveling in packs, finding their own food.
“Dinosaurs were more like latchkey kids,” Holtz said.
Imagine a baby Brachiosaurus no bigger than a golden retriever. While its parents, towering 40 feet tall, continue their lives with zero involvement in the youngster’s daily survival, this little dinosaur searches for low vegetation alongside its siblings. It faces predators its massive parents would never encounter. It eats plants its parents can’t reach. It’s not just smaller. It’s fundamentally different.
The Ecological Game Changer
This is where things get wild. A juvenile Brachiosaurus couldn’t reach leaves 10 meters above the ground. It would feed on lower vegetation, occupy different spaces, face different predators. As it grew from dog-sized to horse-sized to giraffe-sized to absolutely enormous, its place in the ecosystem shifted at every single stage.
“While adults and offspring are technically the same biological species, they occupy fundamentally different ecological niches,” Holtz explained. “So, they can be considered different ‘functional species.’”
Think about what this means. If you count juvenile dinosaurs as separate functional species from their parents, the total number of distinct ecological roles in ancient dinosaur communities suddenly explodes. Scientists who study modern science have generally assumed mammal-dominated ecosystems today are more diverse because we see more different species living together. But when you recalculate dinosaur ecosystems with this new framework, the functional diversity jumps dramatically.
“The total number of functional species in these dinosaur fossil communities is actually greater on average than what we see in mammalian ones,” Holtz said.
How the Ancient World Actually Worked
This raises an obvious question: how could ancient environments support all these distinct ecological roles when modern ones can’t?
Holtz suggests two factors. First, the Mesozoic climate was warmer with higher carbon dioxide levels. Plants grew like crazy. The energy available at the base of the food chain was substantially richer than what we have today. Second, dinosaurs probably had lower metabolic demands than similarly sized mammals. They needed less food to survive.
“Our world might actually be kind of starved in plant productivity compared to the dinosaurian one,” Holtz suggested. “A richer base of the food chain might have been able to support more functional diversity.”
So dinosaur communities might not have been “better” or “more diverse” in some absolute sense. They were just structured completely differently. A world where young and old animals occupy separate ecological niches could theoretically pack in more functional roles than a world where parental care keeps everyone in similar habitats and niches.
Holtz emphasizes he’s not claiming ancient dinosaur ecosystems were definitively more diverse than modern mammal ecosystems. But he is saying we’ve been measuring diversity wrong. We’ve been comparing apples to oranges and not even realizing it.
Still Capturing the Full Picture
The deeper insight here is that we’ve been making dinosaurs in our own image. We imagine them as scaled-up versions of animals we know today because that’s how our brains work. We pattern-match. We default to what’s familiar.
“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.”
This research opens doors. If we’ve been wrong about parenting strategies shaping entire ecosystems, what else have we misunderstood about how dinosaurs actually lived? Maybe our whole mental model of Mesozoic life needs rethinking. Maybe those giant sauropods weren’t just bigger versions of modern animals. Maybe they operated according to ecological rules we’re only just beginning to understand.
The next time you see a documentary about dinosaurs raising their young in happy family groups, remember: those filmmakers are probably imagining mammals in costumes, not the wild, independent creatures that actually roamed ancient Earth.
