Picture her standing in front of you: She’s a whopping 18 feet tall. If you were in the second story of your house and peaked out the window, you’d be eye-to-eye. And what an eye: It’s believed to have been bigger than a tennis ball, with a binocular field of view wider than a modern hawk’s.
But you’re probably staring at her teeth right now, aren’t you?
They’re sharp as swords and as long bananas. Her legs can send her sprinting at speeds of up to 25 miles per hour. And she can rip off 220 pounds of flesh in a single bite.
She is the Tyrannosaurus Rex. “Tyranno” meaning tyrant and “saurus” meaning lizard in Greek; and “rex” meaning “king” in Latin. Which makes T-Rex the king of the tyrant lizards.
Is it possible that she and her tyrant brethren could have been domesticated? And if so…how much would it cost to keep a T-Rex as a pet? Richard Kissel, PhD is here to help us figure it all out.
Richard: The T-Rex skull itself is a sports car of reptilian anatomy. It’s sleek, yet strong and robust, with these massive teeth sticking out of its frame at different lengths because of the continual replacement. It must have had a gnarly smile.
Behind Dr. Kissel is a collection of dinosaurs on bookshelves. But it’s his shirt that catches my attention: It’s light blue with a repeated pattern of old-school red roller skates. A delightful fit for his job.
Richard: I am here in San Antonio, Texas at The DoSeum. It is a children’s museum and I am the Vice President of Education here. For my graduate work I actually did pursue paleontology through the departments of geosciences, and then went up to Toronto Ecology and Evolutionary Biology.
It’s no coincidence that our best friends, dogs and cats, are carnivorous creatures.
Doug: Based off what you’ve learned about the T-Rex over the years, do you think it would have been possible for us to have domesticated it?
Richard: Short answer: yes. Simply because domestication is such a broad term. Domestication of plants, domestication of animals, basically any kind of process where we’re adapting wild plants or animals for human use falls within that umbrella of dominance.
Okay, so the short answer is yes, as long as you could get a few T-Rex together, as long as you could get them to successfully reproduce. And if you were intentionally choosing individuals to reproduce, to continue the traits that you wanted to continue, then yes, technically, boom. You are domesticating a T-Rex.
The natural extension of that is, well, how far could you go in that process? And could you basically have T Rex as a pet, for example?
Doug: Do you think it would be possible?
Richard: That depends. How much patience do you have?
Mankind has quite the patience when it comes to domesticating animals. We’ve been doing it for a while, after all. Just look at the 30,000 years since a wolf approached our fire and we were like, “Hey buddy, what do you say we team up? Maybe start hunting together? Then in a few thousand years or so we’ll dress you up in cute holiday sweaters and treat you like a fluffy little human? How’s that sound?”
Richard: You got to go all in if you want to domesticate an organism, especially one with a slightly longer lifespan. Because you’re going to need that generation after generation after generation of reproduction to shape the animal how you want it, or to use a more technical phrase, artificial selection. And with T-Rex having a decent lifespan of about 30 years, and this is more of a guess, but probably reaching sexual maturity between the ages of 10 and 20. They had pretty quickly turned over generations.
If you want to not only domesticate a T-Rex, but also have one as a pet, there are three questions you have to answer.
Number one: How much time and patience do I have?
Richard: What kind of capacity does that organism have to be domesticated?
It’s no coincidence that our best friends, dogs and cats, are carnivorous creatures. They typically tend to be, just to put it bluntly, a little brighter than their herbivorous cousins. And there are multiple reasons for that. Obviously, if you’re a herbivore, eating grass, you don’t really need to be strategic about eating that grass. But if you’re a big cat on the savanna, and your prey also has a brain and can move quickly (and it’s often bigger than you), you need to have some strategy built in there.
And so just being carnivorous tends to lend itself toward a greater capacity for intelligence. Plus, meat is much more rich in calories than eating strictly plants, which helps feed and permit the evolution of a larger brain.
If you look at what was happening with the T-Rex brain, based on the cavity that’s in the skull, very large olfactory bulbs, so a really strong sense of smell. More so than anything, the vision was probably quite good as well as we can tell by just the shape of the skull and the way the eyes are positioned forward for that stereoscopic vision. And so T-Rex was no doubt a keen predator based on those little puzzle pieces that we have. And as we connect those puzzle pieces and we try to see see what the picture looks like (even though we’re probably missing 75% of the puzzle pieces), we can see T-Rex as a predator had to have some level of smarts associated with it. And so you could probably have it do some learned behaviors, I would guess, as they like to call them now.
And the third and final question you need to ask yourself before jumping off the Jurassic deep end and trying to make a T-Rex your pet: What’s your budget? Cuz that ain’t gonna be cheap.
Let’s start with space for romping around with that big head and tiny arms.
DOUG: If we have the T-Rex as a pet, and we have an idea of its speed and its size, can we calculate how much space it would need to be happy? How big is that yard?
Rich: Or ranch, probably. There was a study that came out I want to say earlier this year or late last year, and they were asking the question, just how many T-Rex have ever lived?
So we know their geologic timeframe. We know their general distribution. And they were looking at a formula that I believe was developed for the population density of mammals. The example that they used was that in an area the size of Washington, DC, could sustain two T-Rex. The state of California would be between 3,000-4,000 T-Rex.
Richard: And so they needed quite a bit of room to roam, at least according to this model. They also have pretty specific environmental needs.
At the end of the Cretaceous period, when the T-Rex was living large, you could find them in sticky, stinky, sweat-inducing swamp regions. And again, it is a model and models carry assumptions, but it’s still data-driven. And it’s still a great question to ask and an even more fun answer to try to find.
Richard: As far as the environment goes, because that’s the next connection, if you’re going to start a T-Rex farm, where do you want to start it?
We find their fossils in the northwest, South Dakota, Montana, very good places for finding a T-Rex. They find them as far north as Alberta. There’s questionable stuff from Big Bend over here in Texas, but it’s not confirmed to be T-Rex specifically. But that area, North or South Dakota, Montana, what that looked like at the end of the Cretaceous period was really kind of like Louisiana, southern Louisiana, that Mississippi Delta type environment. And so you want a pretty lush, pretty humid, pretty wet environment for these things if you wanted them to be perfectly feeling at home.
An area the size of Washington, DC, could sustain two T-Rex.
Lions, the range they have in the wild compared to what we have them in zoos, for example, is very, very different as well, too. If you were feeding them every day, if they didn’t have to worry about finding the food, I’m sure they would be happier in a much smaller space than what we were just talking about. Again, kind of using that modern comparison of looking at the large predators today in the wild, and looking at their range versus what they can do in a more captive environment, to make sure that they’re still healthy and fit both physically and mentally, of course.
Doug: I imagine they needed quite a bit of food to keep going. How much did they eat per day?
Richard: Some folks say 40,000 calories a day would be all they needed. And then another study says they basically needed the equivalent of 80 adult humans. So if you want to say 2,500 calories per human, you’re looking at 200,000 calories per day. And with protein having four calories per gram, fat having about nine calories per gram…if you average those out, presuming they’re eating pure protein and fat, you’re looking at about 70 pounds per day.
Let’s say you’re feeding them whole chickens, which are about $1.28 per pound. That’s $89.60 per day. And you’re starting small with just 3 T-Rex at your ranch. That’s $268.80 per day or $98,112 per year. To sum it up: To feed three T-rex over a 30-year lifespan is going to run you $8,830,080.
These dudes were constantly munching. In their teenage years, their massive caloric intake led to impressive growth spurts. But how do scientists know this?
Richard: By looking at the growth rings within some of the fossils we have. The more spacing you have between the rings, the more growth you had that year. And you see the greatest spacing in their teenage years, when they were putting on about 1500 pounds per year. So that’s about four pounds per day, which is quite a growth spurt.
My time with Dr. Kissel was winding down, but there were still two more things I needed to know before he skated on out of our Zoom chat. Before I could ask them, he dropped this bomb of pure ecstasy on me about T-Rex breeding.
Feeding three T-rex over a 30-year lifespan is going to run you $8,830,080.
Richard: Over many, many, many generations, if you kept selecting for smaller and smaller individuals to reproduce, could you get a teacup T-Rex that you could push in a stroller or carry in a bag and take on an airplane? I think so.
It might be a little snippy and not quite as quote-unquote “intelligent” as a dog or cat. But I think you could get there and at least be somewhat satisfied with what you have.
So…about those two things I needed to know.
Doug: This is a long shot. But I am curious if, based on creatures nowadays who may be similar in the animal kingdom to a T-Rex, can we infer anything about its personality?
Richard: So using their evolutionary relationships, looking at that family tree, that phylogenetic tree, and that’s why I love these evolutionary trees because you can actually use them to predict, they just don’t tell you how things are related, but they help fill in those missing gaps. T-Rex is pretty close to the raptors, which are pretty close to what you would say are our birds. And I think really what you probably do is look at living birds today to see what kind of potential personality you get in a T-Rex. And here in San Antonio, we have these wonderful birds called grackles. And I just love them because they have so much personality to them.
Could you get a teacup T-Rex that you could push in a stroller or carry in a bag and take on an airplane? I think so.
And they kind of have the personality of a cat. They kind of don’t care. They’ll just walk over and take your food and they won’t scurry away. They’ll just kind of eat it in front of your face. And so it’s funny every time I see these grackles which have wonderful, wonderful calls of beeps and whistles, I always think that’s probably what a little dinosaur would have looked like. Kind of got a little edge to it, slightly annoying, kind of knows it’s got the run of the place. It’s going to push the boundary more than it’s going to be careful about the boundary.
Doug: Would you take the job as a T-Rex trainer?
Richard: I don’t know if I’d try to get a traveling circus going with my cap and my horn and doing the three-ring circus thing. But I could see myself retiring with quite a bit of acreage, and having a few T-Rex out there on the ranch and just kind of appreciating them from a safe distance, or within an armored vehicle. Just kind of doing their thing.
Every time I see these grackles…I always think that’s probably what a little dinosaur would have looked like. Kind of got a little edge to it, slightly annoying, kind of knows it’s got the run of the place. It’s going to push the boundary more than it’s going to be careful about the boundary.
Could we have domesticated a T-Rex? Dr. Richard Kissel thinks so—if you could acquire the patience and abundance of resources it would take.
There are tons of other considerations we didn’t even touch on, like how much are vet bills? And what happens if your T-Rex eats the vet? What’s the going rate for a T-Rex sitter when you’re out of town? What’s poop cleanup like? (That last one wouldn’t be much of a problem if you had a teacup T-Rex. Can you imagine that teeny fella roaming your backyard and letting out little screeches as it chases squirrels and drops miniature poo?)
All fantasies aside, the reality is that we know so little about the king of the tyrant lizards. We’ve mainly focused on their savagery, their identity as primitive beasts, since we first discovered a partial T-Rex skeleton in 1902. We’re just beginning to understand them as animals.
120 years. In the vast spindle of time, that’s hardly a tug at the thread. The puzzle pieces are fractured. Our knowledge is limited. But as long as we keep asking questions, we’ll continue dusting off information that’s been in hiding for over 60 million years.