Was the world of the dinosaurs really more dangerous than the current evolutionary period?

Factual Questions
61

Let me put it another way. How would a crocodile fare against an equally weighted carnivorous mammal? What about one 75% of its weight? 50%? 25%?

The predatory terror bird roamed free in South America 65 million years ago, well after the age of the dinosaurs. But when North America joined up with South America, that formerly apex predator was pushed to extinction. And it wasn’t arthropods that did them in.

I’m guessing that a world of 100 foot long crocodiles would be fairly manageable, though yeah more dangerous than the current day. I’m less sure I’d want to deal with nine foot carnivorous ostriches who hunt as a team.

62

At least one member of the group, Titanis, was able to colonize North America and compete with placental carnivores until about 5 million years ago or later.

63

I’m pretty sure 65 million years ago was when the dinosaurs were rendered extinct. So not well after the age of the dinosaurs, more like immediately after, but I bet you meant a different date.

64

The Phorusrhachidae, or Terror Birds, first evolved about 62 million years ago, shortly after the age of dinosaurs, but survived until about 5 to 2 million years ago.

65

I wonder how humans would smell to dinosaur predators. Food? Tiny animals not worth hunting? Rival predators who must be driven out of one’s territory immediately? Is the diet of our humans (e.g. whether they eat meat) an important factor.

Would the higher oxygen levels be bad for human health, short-term and/or long term? Would firearms still function properly, or would one need special bullets with a propellant designed for a high-oxygen atmosphere?

66

Firearms don’t use atmospheric oxygen. You can fire a gun underwater, or in space.

But high oxygen levels would lead to thin blood, I think, the reverse of how people at altitude develop thick blood.

67

It’s a good question - though it’s also a question of how much they relied on smell as opposed to movement, shape, coloration, etc.

Making modern comparisons one of the reasons people are advised not to run away from bears is that it makes them think of you as prey - if you’re running away, you’re afraid and if you’re afraid, you must know the bear is stronger, therefore you’re a good snack. Standing your ground is no guarantee of safety, but is generally the better strategy.

And great whites are believed to attack humans when they mistake us for seals based on shape and silhouette. When they bite and find out we don’t taste right, they let go and move on. If they hadn’t made the mistake, we’d have been safe except from the hungriest sharks willing to eat anything.

So it would not surprise me at all if a dinosaur predator saw us, sniffed around, decided they weren’t hungry enough to tangle with an unknown creature and then moved off.

68

But the predator population is kept artificially low by humans. We destroy habitat, hunt predators and their prey, and generally exist. It seems the larger predators that actually might be a threat to us are disproportionately affected, too. Perhaps it’s better to compare the danger of the Mesozoic Era (or whatever time you want to use) to the danger of modern times where humans are interested in eating you too.

Alternatively, do we have any idea how much of a danger predators were to humans when we were in small groups and hadn’t had a significant effect on the world?

Possibly making all of this irrelevant, couldn’t predator biomass (or whatever is used to measure the “units” of predators) be distributed in a way that’s more dangerous for humans? You could have 100 foxes or 10 leopards. We evolved according to what (reasonably well) suits the dangers posed by modern predators. It seems unlikely, to me, that we’d be equally as good at surviving predators that are completely alien to us.

69

Based on what I’ve read reading the world’s remaining hunter-gatherers and large predator attacks on humans, when humans are in a group they’re pretty safe. Very few animals will take on a group of humans, and those aren’t necessarily predators. Elephants - which also travel in groups - will confront a group of humans, especially if the elephants have gotten into alcohol (they’ve been known to steal it). There are records of whales attacking the whalers attacking them, which, strictly speaking, is self-defense and not the whales initiating hostilities. Single predators, even large ones like tigers, will retreat rather than take on a group of humans.

Remember, predators act aggressively mostly to eat, they don’t want to get hurt.

From accounts I’ve read of the Kalahari H-G’s, most predator attacks occurred at night, like a lion dragging a single person off in the dark. Predators will attack lone humans, even relatively small predators like coyotes. Infants, children, and women walking alone are the typical human prey of large, man-eating cats. Just about anything carnivorous will go for a severely wounded or disabled human if it thinks it can do so without getting hurt.

Large lizards, which may or may not be good models for dinos, such as crocodiles or komodo dragons don’t focus on humans as a major prey though they’ll take one if the opportunity arises. Again, though, they’ll pick off an individual. They don’t seem inclined to confront a group of humans on alert.

I’m going to take a wild guess and say the biggest danger to our time travelers won’t be the large, presumably single predators like T-rex. It will be the smaller, pack hunters that will be a danger to a group of humans because they can work in a coordinated fashion. Even so, after the first few confrontations they’ll be cautious.

Single humans, especially the young, the feeble, and the injured will, of course, be fair game for anything that finds them.

70

That’s all true of other prey animals though- a lion is going to try to find a zebra or antelope that is alone, sick, small, or otherwise vulnerable.
Whether dinosaurs were more crocodilian or birdlike, anything the right size that moved likely got sampled at least once… and humans are soft and juicy with no shell or spines.

So stay together! And keep those torches lit!

71

I’d think large pointy sticks might work better than torches. But, to be sure, take both!

72

Hummmm.
What was the rate of naturally occurring fire, ( lightning strikes & stuff. ) that the dinos would be instinctively fearful of?

High O2 but wetter conditions, type of ground cover that would burn well? Hummmm

I have no idea if big lizards even now are afraid of fire. Enough so that a torch would be enough or would it have to be a really big fire?

73

FWIW, T. Rex seems to have had very large olfactory bulbs, implying a sophisticated sense of smell.

74

I wouldn’t be so sure of that.

I had a ball python while I was in high school. It would eat rats, but not mice. This was something of a hassle because he wasn’t a very big snake and so we had to make sure to get small rats - small enough that they weren’t much bigger than an adult mouse. But he just plain refused to consider mice as food.

My current snake is a Mexican red tail boa. While he will eat just about anything that moves and is the right size, he can tell the difference between species. For a while, we were feeding him gerbils (a local school had an explosion in gerbil babies and we did our part to help out.) If you put a mouse in his cage, he flicks his tongue and slowly stalks them, taking his time in the hunt. But a gerbil? Forget stealth or tracking, he’s all over a gerbil as quick as he can get there; any mice can wait. So gerbils taste/smell better than mice, clearly, and he’d never waste time hunting mice if there were enough gerbils in the area.