Why did 'the dinosaurs perish' but our ancestors did not?
Assuming that dinosaurs were cold blooded (like today's reptiles - not certain to be the case, last I heard) and that birds which survive to this day are not dinosaurs.
(which I think they are)
Here is perhaps why.
The reason the dinosaurs perished but we (i.e. our small rodent-like ancestors - mammalia) did not, may have had more to do with their body temperatures and the amazing adaptive evolutionary capabilities of fungi (which was illustrated on the Mir space station where in conditions of high radioactivity and high humidity the space station's resident commensal fungi evolved the ability to eat electrical insulation and some say even plastics and metal, leading to a dangerous situation and fire.) than anything else, on a cooler planet where some temporary blip in the climate caused a sudden increase in fungal growth, which led to widespread die off or many animals, especially the large reptiles, and the same reason may be why mammals survived to rule the earth, because our own body temperatures were much hotter than ambient temperatures fungi evolved in, at that time, while reptiles's cooler bodies were not, and so we were immune to fungal infections that dinosaurs were not at that time, its possible that we survived for that reason, says a scientist, Arturo Casadevall.
But all bets may be off if the average ambient temperatures here on Earth rise to near our body temps. Then fungi may likely evolve the ability to invade our bodies much more than they have now, and given a chance, they might be successful in killing us off in large numbers!
Especially if a sudden die off of a great many trees (from volcanism, as it has in the past, or a meteor, or not unlikely, a combination of both, as a really large meteor may cause the Earth to ring like a bell and suddenly erupt in volcanic activity, especially at the opposite point on the Earth to where the meteor had struck, as the oblate spheroid shape of the Earth might act a bit like a lens to focus the mechanical stress on its opposite side.
Suppose that happened, large numbers of plants and animals would die, and "return into dust".
Indeed, it seems that this has happened almost planet wide on multiple occasions, (however each time some portions of the planet escaped the massive die off despite the fact that some huge shift seems to have killed a great many animals almost everywhere else..) Its quite possible the thing that killed them, which wouldnt survive in any way we could record now, were toxins produced in large quantities by fungi in order to kill other fungi, with ourselves and reptiles and other animals being 'collateral damage'.
Spores, and toxic fungal metabolites would fill the atmosphere and all the planet, except maybe some islands, with immune system suppressing mycotoxins (dead trees = fungi to eat those dead trees, which produce a witches brew of dangerous chemicals, including hundreds of toxic mycotoxins -including abundant respirable quantities of ergot alkaloids closely related to the drug LSD- which cause symptoms best known as those which caused humans to believe themselves to be possessed by demons, leading to the witch burnings of the Middle Ages, (caused by eating ergot contaminated bread). (The ergot alkaloids are a virulence factor produced by aspergillus fumigatus, the 'most successful' pathogenic fungi in existence today, when it sporulates, its a very common fungi that eats decaying wood.) It also produces large amounts of bacterial toxins, (such as endotoxins) and also a large amount of glutathione depleting mercury vapor would be liberated from those trees by the process of decay which produces heat putting the mercury vapor into the atmosphere where it then condenses onto the next thing it can find once the temperature and water vapor pressure allows it to.) The dangerous state of toxicity created might last a very long time. Under those conditions, survival would be difficult even without the rapid evolution of fungi to contend with.
How about for 'locational diversity'. It only takes one big rock hitting the earth to wipe out all of mankind. If we are to survive, we need locational diversity. In other words, don't be here when it happens. Or at least have multiple locations.
The dinosaurs were around for about 185 million years and were well adapted for their environment - right up until a big rock came through the atmosphere.
Inevitably, a similar event will happen to the human race.
Amoeba the unicellular organism has lived for 185M, longevity period of dinosaurs+ the period till date.So have the
rest of multicellular species belonging to various biological divisions of zoology and botany.
We can employ another set of arguments that is -Since rest of the creation with stood and survived that adverse period, humans
being can survive an identical repeat catastrphe.
Why can we not?