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> the researchers were able to approximate that about 20,000 T. rex were alive at any given time low
by vmception 6y ago
> the researchers were able to approximate that about 20,000 T. rex were alive at any given time
low
- dogma1138 6y agoYep the most endangered elephant is the Asian elephant and there are about 50,000 left in the wild right now, in total there are half a million elephants in the world of all species having only up to 20K at any given time for a species that was pretty much on top of the food chain is quite surprisingly low.
- rightbyte 6y agoMaybe the other dinosaurs were quite dangerous for the king? I mean the ones with spike tails etc.
- Sharlin 6y agoT. Rex was a predator, however, and an apex predator at that. Elephants are herbivores. That changes the expected numbers quite a bit. Prey populations typically outnumber their predators by two to three orders of magnitude.
- ALittleLight 6y agoGoogle says there are about 50,000 killer whales right now. They are apex predators and similar in mass. Of course sea creature versus land animal, but also I believe we are at a low point for killer whale population.
- dogma1138 6y agoI would put dolphins up there too and their numbers are dwindling due to humans directly fishing them for centuries and now destroying their habitats by over fishing.
- cletus 6y agoTwo issues: 1. Water covers ~70% of the Earth's surface. Whales migrate of course but can exist from the poles to the equator; 2. Of the 30% land, for pretty much any species, some portion of that is uninhabitable. Dinosaurs being reptiles likely require hot and wet environments. As predators, T. Rex would be limited by where their food could live too. The dinosaur era was largely one of a super-continent (Pangaea). A good portion of that was likely too cold or too dry to support such a large predator.
- Sharlin 6y agoNote that Pangaea had already started breaking apart a hundred million years before Tyrannosaurus rex, which lived right at the end of era of non-avian dinosaurs. Indeed T. Rex is much closer to our time than Pangaea was to T. Rex's time! They lived in what is now Western North America, but was then an island continent called Laramidia [1] so yes, they were geographically quite limited. [1] https://en.wikipedia.org/wiki/Laramidia https://en.wikipedia.org/wiki/Laramidia
- Keysh 6y agoMany dinosaurs were warm-blooded; fossils of dinosaurs have been found in Antarctica (granted, that’s from a time when the global climate was warmer and Antarctica was ice-free, but still...).
- dogma1138 6y agoThe elephant might be a herbivore but it is prey only for humans.
- Sharlin 6y agoYes, but the point is we should expect elephant population to be larger than that of an apex predator.
- aquadrop 6y agoTheir method of estimation is not far from guessing and they even say themselves, that accuracy is "low".
- Alex3917 6y agoLooking at the paper, it looks like the authors didn't correct for the fact that CO2 levels during the late Cretaceous period were around 1000pm, so at the time there would have been significantly more available calories per square mile. If each individual really did require 40 square miles, it's hard to understand how they would successfully reproduce.
- enkid 6y ago40 Square Miles is only 6.3 miles to a side. That's not that far to travel for mating.
- ardit33 6y agoThere are plenty of animals with less density, that reproduce successfully. T-Rex was probably a solitary animal, and perhaps akin to a modern Tiger in its matting patterns. The spatial distribution and population density of tigers in mountainous terrain of Bhutan "Based on our top model, the estimated tiger population size (N) was 91 individual tigers with 60 adult females and a density of 0.24 tigers/100 km2 "
- chrisweekly 6y agoAnother interesting comparison between T Rex and tigers: the diameter and crushing force of a T Rex's jaws are pretty closely matched by the killing triangle of a tiger's front paws and fangs. Citation: John Vaillant's amazing book "The Tiger: a True Story of Vengeance and Survival". (Highly recommended)