Latchkey Dinosaurs May Have Created Richer Ecosystems todayheadline

Picture a baby Brachiosaurus the size of a golden retriever, hunting for food with its siblings while dodging predators. Meanwhile, its parents, towering over 40 feet tall, are dozens of miles away, completely unbothered by their offspring’s fate.

This wasn’t neglect. It was just how dinosaurs rolled.

For decades, scientists treated dinosaurs and mammals as ecological twins: the dominant land animals of their time, doing roughly the same jobs in their respective worlds. But Thomas Holtz, a geologist at the University of Maryland, thinks we’ve been missing something big. The way animals raise their young doesn’t just affect family dynamics. It reshapes entire food webs.

His new study, published in the Italian Journal of Geosciences, suggests that “free-range” dinosaur parenting may have allowed ancient ecosystems to support more diversity than our modern mammal-dominated world.

Helicopter Moms vs. Latchkey Kids

Mammal mothers are intense. They nurse, provision, and protect their young until the offspring are nearly full-grown. A mother tiger hunts for cubs as large as she is. Young elephants, already among the biggest animals on the Serengeti at birth, follow mom for years. Human teens? Well, we know how that goes.

The result: young mammals eat what their parents eat, live where their parents live, and compete with who their parents compete with. Ecologically speaking, they’re the same creature.

Dinosaurs? Different story entirely.

Fossil evidence suggests most young dinosaurs struck out on their own after just a few months or maybe a year. Paleontologists keep finding clusters of juvenile skeletons—all the same age, no adults anywhere nearby. These youngsters apparently traveled in pods of similarly sized siblings, getting their own food and watching each other’s backs.

“Dinosaurs were more like latchkey kids. In terms of fossil evidence, we found pods of skeletons of youngsters all preserved together with no traces of adults nearby.”

Modern crocodiles, among the closest living relatives of dinosaurs, do something similar. They guard nests and protect hatchlings for a limited stretch, but within months the juveniles disperse. An American alligator spends years growing from 60 centimeters to over 120 centimeters, shifting from insects to crustaceans to fish to bigger prey as it grows.

One Species, Six Jobs

Here’s where it gets interesting. A juvenile Brachiosaurus the size of a sheep can’t reach vegetation 10 meters above the ground like its towering parents. It has to feed in different areas. On different plants. It faces threats from carnivores that would never bother a full-grown adult.

As that youngster grows, from dog-sized to horse-sized to giraffe-sized to its final massive proportions, its role in the ecosystem shifts continuously. Same biological species. Totally different ecological jobs at each stage.

Holtz analyzed 18 dinosaur communities from the Jurassic and Cretaceous periods alongside 18 mammal communities from the Cenozoic era, comparing body sizes and species counts. When he counted only adults, mammal ecosystems looked more diverse. More species living together.

But when he counted independently living juvenile dinosaurs as separate functional species, which makes sense, since they occupied different ecological roles, the pattern flipped.

“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.”

A single species of large dinosaur might have occupied five or six distinct niches as individuals progressed from hatchling to adult. That’s a lot of ecological diversity packed into one species’ lifecycle.

What Fed All Those Dinosaurs?

How could ancient ecosystems support this many functional roles? Holtz offers two possibilities.

First: the Mesozoic world was fundamentally richer. Warmer temperatures and higher carbon dioxide levels made plants more productive, generating more food energy at the base of the food chain. More energy meant more animals, or at least more ecological roles that could be filled.

Second: dinosaurs might have had slightly lower metabolic rates than similarly sized mammals. If they needed less food to survive, the available resources could support more functional diversity.

“Our world might actually be kind of starved in plant productivity compared to the dinosaurian one,” Holtz suggested. A richer base could have supported more roles. And if dinosaurs had less demanding physiology, their world could accommodate more functional species than ours can.

The research doesn’t necessarily mean dinosaur ecosystems were more diverse than modern ones. Just that diversity might take forms scientists haven’t been recognizing. When you’re comparing adults-only mammals against dinosaurs with age-independent juveniles filling multiple niches, you’re not comparing apples to apples.

Holtz plans to keep exploring these patterns, looking at whether different types of dinosaur communities showed different structures. Did assemblages with lots of small carnivorous dinosaurs look different from those dominated by giant plant-eaters? The answers could reshape how we understand the world dinosaurs lived in, and how it evolved into the one we inhabit today.

“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.”

Italian Journal of Geosciences: 10.3301/IJG.2026.09