How come not one species of dinosaurs survived?

Question

I mean not even the smallerst ones? I mean alligator, birds, roaches, etc survived?

Answer 1

Ugh...the ignorance rampant in the answers here...Crocodiles are not related to dinosaurs. Nor are Komodo dragons or any other lizard or frog or shark or what have you.

One dinosaur lineage survived, a group of animals belonging to the maniraptora. Maniraptors include therizinasours, dromeosaurs (like Velociraptor), and birds, to name a few. The modern bird was the final survivor and there are more known species of bird today than there are mammals. So I'd say dinosaurs still dominate the planet.

As for why the other lineages of dinosaur died, no one knows for absolute certain, but you have to understand that every large animal and many small animals living at the time went extinct, not just the dinosaurs. Whatever happened, it wiped out most life on earth on land and sea alike (there were no dinosaurs in the seas). The animals that survived were small, often burrowing or able to hibernate or otherwise go for long periods without food. Or, in the case of the birds, able to effortlessly travel long distances to find food.

I mostly agree with the statement above, however, mammals evolved at the same time as the dinosaurs and were not competition (except at the small scale and as egg thieves possibly). They only were able to diversify into large forms due to those niches being left empty by the already extinct dinosaur forms.

Answer 2

We are still working on that, We don't know why every Sea Reptile but the turtles died, though a good possible explanation is their willingness to be omnivores. One thing is for sure, though, they did all go extinct. How do we know for certain that Dinosaurs are extinct? The best way I can put this is,, if the dinosaurs had not gone extinct, they would have taken over the world again. In the 5, 10, 20 million years IMMEDIATELY after that extinction, well although mammals were larger, more abundant and had more variety than in the Dinosaur era,, a large chunk of the ecosystem, even/especially the very top of the food chain, was occupied,, by reptiles and birds (big raptor birds, some of whom were flightless and the next best thing to a T-rex, big reptiles like Titanoboa, and various Tertiary LAND crocodiles whose teeth (and heads) were virtually identical to raptor dinosaurs. Gradually, the mammals claimed more and more sway in the ecosystem, helped by events like the drying, cooling, becoming the 4-seasons-having world we know, but it wasn't as clear cut or immediate as we often think. Considering the fact that dinosaurs are basically halfway between reptiles and birds, it could probably be said that if the asteroid had not hit, they most likely would have still held sway, until the world started to become cold like we know it, at which time the mammals may have arisen (two of the hottest times on Earth were the Eocene, start of the mammal era, and the Mid-Jurassic).In addition, the closest thing to a complete reversal of dino and mammal fortunes, roles, sizes was in the Mesozoic polar regions, which were like British Columbia now. As I said, in a nutshell, if dinosaurs had NOT gone extinct, they would have taken over the world again, or at least, the world that came to exist/existed immediately AFTER the impact. We can say with reasonable certainty that they did, because in the K-T aftermath we see iguanas the size of men, NOT Iguanadons.

Answer 3

I reckon this is a really good question. I guess the bottom line is that no one really knows so all we can do is have a good guess.

Assuming the extinction of the dinosaurs was driven by a sudden catastrophic event leading to a prolonged climatic shift etc it is reasonable to assume that organisms that would survive would be the smallest most adaptable species. This is reasonable as following catastrophic events in the world today (usually caused by us) the first to suffer are the largest species. Large dinosaurs would need huge amounts of food and a fairly constant climate to sustain what is thought to have been a fairly active life. Crocodilians and other large reptiles can undergo prolonged fasts by cutting down on their levels of activity and this ability may have enabled them to see through some tough times.

Fossil evidence would seem to suggest that a lot of the dinsaurs, even the smaller ones, were fairly specialist and at a tough time this may have given the opportunist early descendants of mammals a competitive advantage. The mammals may have had a further advantage as they are much more likely to get through a cold spell.

Ofcourse there's a compelling argument that some of the smallest of the bird-hipped dinosaurs didn't die out but are the ancestors of modern birds.

Hope that helps.

Answer 4

Sharks, crocodiles and alligators are not closely related to dinosaurs. Birds are the only surviving descendant of dinosaurs, having evolved from feathered dinosaurs (maniraptorans), via dino/bird enantiornithians and later primitive proto-birds ornithurians.

Dinosaurs rebounded from several mass extinction events, including major extinctions at the close of the Triassic and Jurassic. But the mass extinction event at the close of the Cretaceous killed them all. A major reason that dinos did not rebound from the K/T mass extinction (65 million years ago) was the rise of the mammals, which began to seriously diversify 83 million years ago. When there is competition during a mass extinction event, very few competitors survive. The November 2007 issue of Discover Magazine has a nice account of the rise of the mammals.

Answer 5

Wiggy's basically spot on, except that birds are dscended from the _lizard-hipped_ dinosaurs, not (oddly enough) from the bird-hipped dinosaurs (the theropods are all saurischians). All those people who are claiming that alligators, crocs, etc. were dinosaurs are wrong. Dinosaurs were a particular type of reptile, but quite different from the others. Your question is a very good one, but I think we'll never know the answer for certain. Keep in mind, though, that dinosaurs were just one of many groups that got hammered at the end of the Cretaceous. That was one of the biggest mass extinctions we know about. Personally, I think they were just unlucky.

Answer 6

Think about what you just said, those big lizards, like alligators and crocodiles, but also including species like the Komodo dragon and the Gila monster, they're basically a kind of dinosaur. Birds too- you heard of Archeopteryx, the feathered dinosaur? It seems quite a few other dinosaurs had feathers, and birds are in fact their relations. Someone mentioned sharks, they're right, sharks are basically unchanged since they first evolved, they were around even before a lot of the dinosaurs.

Don't let the number of dinosaurs on the fossil record blind you to the ones that did make it through. Sure, if they found even bigger dinosaurs hiding out in the Amazon or the Congo it'd be great too...

Answer 7

Dinosaurs diverged from the reptiles and are very different from them. The descendents of the dinosaurs are the birds which are from a particular branch of dinosaur. 99% of all species that have ever lived on this planet are extinct. The dinosaurs are just one of the many extinct groups.

Answer 8

I've identified your problem. So, evolution, isn't it? If so, please,
take this question out of science and mathematics > Zoology
and back to the book worship folks in Culture and Groups.
The only idol worshiped here is science.

Answer 9

Sharks, Alligators, Croc's. Read up on them. There are other smaller creatures and fish deep in the ocean that are considered 'fossil fish' as well, thought long extinct but alive and kicking.

Answer 10

Well all the plants started dying, the veggie dinos couldn't survive. The meaties could eat their bodies but I think that their was no water and they died from dehydration. But crocodiles look like dinos to me.