Dinosaurs: Feeding, Nesting and Survival in a Prehistoric Forest

An ecosystem, not a diorama

A believable prehistoric-forest simulation isn't really about drawing convincing dinosaurs — it's about giving each creature a small set of needs and behaviours and letting the population dynamics emerge from thousands of those small decisions. A herbivore roams and eats plants to keep an internal hunger value from reaching zero; it reproduces when its energy is high enough; eggs incubate for a fixed time and then hatch into juveniles that must grow before they can breed themselves. None of this needs scripted "story" behaviour — the interesting patterns (population booms, local extinctions, recoveries) come from the same kind of agent-based rules used in real ecological modelling.

What the fossil record actually tells us

Real dinosaurs lived across an enormous span of time — over 165 million years, from the Late Triassic through the end of the Cretaceous 66 million years ago — so "dinosaur" covers an immense range of body plans and behaviours, not one snapshot in time. Large plant-eating sauropods like Brachiosaurus had small heads and long necks adapted for browsing high, tough vegetation such as conifers and cycads (flowering plants didn't become widespread until the Cretaceous), while bipedal predators like Velociraptor — much smaller and feathered in reality than most popular depictions — likely hunted in a coordinated way, based on trackway evidence of multiple individuals moving together.

How dinosaurs actually reproduced

Every known dinosaur species laid eggs, and fossilised nesting sites (famous examples include Maiasaura colonies in Montana) show some species built nest mounds and returned to the same nesting grounds repeatedly, arranging eggs in careful clutches rather than scattering them randomly. Some evidence — modern bone growth analysis and nest-brooding fossils of species like Oviraptor — suggests at least some dinosaurs incubated eggs by sitting on or near the nest, much like modern birds, which makes sense given that birds are, technically, the surviving lineage of theropod dinosaurs.

egg.incubationTime = species.baseIncubation * tempFactor(nestTemperature)
juvenile.growthRate = food_available / population_density
adult.reproduces if energy > threshold and mate nearby

Why a meteor ends everything at once

The Chicxulub impact, 66 million years ago off the coast of modern-day Mexico, released energy equivalent to billions of times the largest nuclear weapons ever tested, and the mass extinction that followed wasn't caused mainly by the blast itself but by what came after: ejected debris and soot blocking sunlight for months to years, collapsing plant growth worldwide, and cascading up the food chain from plants to herbivores to predators. A simulation of that event is really a simulation of food-web collapse — remove the base of the food pyramid and every level above it starves in sequence, regardless of how well-adapted any individual species was the day before.

Why simple rules produce a forest that feels alive

None of the individual rules above are complicated — eat, grow, breed, avoid predators, respond to a shrinking food supply — but running hundreds of agents under them simultaneously produces genuinely emergent patterns: herds thin out near depleted feeding grounds and move on, population booms after a good breeding season get followed by lean years as food catches up, and predator numbers lag behind prey numbers exactly the way real predator-prey population data does. That lag and self-correction is the same underlying dynamic covered in more mathematical detail in the fox-and-rabbits population model elsewhere on this site — dinosaurs just wear more elaborate 3D models.

Frequently asked questions

Try it live

Everything above runs in your browser — open Dinosaurs and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.