Ah, dinosaurs. Dinosaurs are cool. Dinosaurs even have feathers now (although that picture doesn’t).
We keep learning things about dinosaurs, and one of the most recent things we learned is about “non-avian theropods.” That’s the subset of dinosaurs the infamous Tyrannosaurus rex belongs to.
Specifically, carnivorous non-avian theropods. We’ve discovered more about how they move and how they hunt that is very interesting. Very interesting indeed.
Pursuit versus Ambush Predators
To explain this, we’ll start by looking at the two kinds of predator:
- Pursuit predators chase their prey until they are able to catch it.
- Ambush predators hide or stalk their prey then pounce.
Many of us have one or the other or both in our homes: Dogs are pursuit predators and cats are ambush predators.
Tyrannosaurus rex has long been known to be a pursuit predator. No news there. But what has changed is what kind of pursuit predator they are.
Speed Versus Persistence
The ultimate speed-based pursuit predator is the cheetah. With a top speed of 58 mph, they are the fastest land animal there is.
They sprint. If they don’t catch their prey in a brief sprint, they’re done…they have to rest, panting, until they have their breath back. They have about a 50% chance of catching their prey.
The opposite of a cheetah is a “persistence hunter.” Persistence hunters aren’t particularly fast, because they don’t need to be. Instead, they adopt a tactic of following their prey…
…and following them…
…and following them…
…until the prey falls down exhausted. So, basically, persistence hunters are this terrible B-movie monster that just won’t stop following you.
We thought Tyrannosaurus rex, with its powerful hind end, was either a speed hunter or possibly, despite its size, an ambush hunter.
We were wrong.
The bipedal gait of non-avian theropods is designed for extremely efficient walking. While the scientists talk about roaming to find prey, it’s just as likely that these giants may have been…
Want to see the most successful persistence hunter of all time?
Look in the mirror.
Bipedalism and Persistence Hunting
If T. rex was a persistence hunter then that tells us something…that persistence hunting may in fact go together with a bipedal gait.
Scientists have suspected that efficient travel over long distances is why we switched to full-time bipedalism after leaving the forest and ceasing to be arboreal like other apes.
Did that lead to us being persistence hunters because we weren’t that fast? (The top speed of a human is 28mph, compared to 58mph for a cheetah and 55mph for a highly-bred racehorse).
Or is bipedalism an adaptation for persistence hunting? If it turns out to be the latter, then the side effect of freeing our arms to hold tools is just that: A side effect. After all, crows do plenty of tool use while also walking on their hands…
Where do the Aliens Fit In?
Aliens fit in because any alien species that develops technology needs a way to manipulate that technology. That might be hands, it might be tentacles. Elephants, which are pretty intelligent, use their nose.
Having your forelimbs free to handle tools might be an important part of technology. Of course, aliens might have six or eight limbs as standard rather than four, but if they have four, then a bipedal stance is an advantage.
If the bipedal stance comes from being persistence hunters, then that may result in a good percentage of sapient, technologically advanced aliens being…persistence hunters.
And that might be to everyone’s advantage as it might affect cultural development along lines that allow for trade, communication, and a certain amount of understanding.
It’s all speculation anyway. It’s only a theory that large theropods were pursuit predators.
But if it’s true, we have more in common with them than we thought.