# If that meteor hadn’t killed off the dinosaurs... **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [September 13, 2013, 12:43pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761 "2013-09-13T12:43:34Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![John\_W.Kennedy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_w.kennedy/32/1031_2.png) [@John\_W.Kennedy](https://boards.straightdope.com/u/John_W.Kennedy)\ **Post date:** [September 16, 2013, 7:07pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/21 "2013-09-16T19:07:27Z")
The last I heard, all living birds descend from _one_ species of shorebird that survived K-Pg. Perhaps one colony. At the very least, there’s a very tight bottleneck there. ---
**Author:** ![bup](https://avatars.discourse-cdn.com/v4/letter/b/6bbea6/32.png) [@bup](https://boards.straightdope.com/u/bup)\ **Post date:** [September 16, 2013, 7:52pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/22 "2013-09-16T19:52:22Z")
I agree it was a tight bottleneck, but I’m pretty sure ‘they’ think that more than one species survived. There’s only one species they’ve found on both sides of the ‘divide,’ but the fossil record is too spotty to make confident predictions to the effect that it was the only species that made it (I think). On the other hand, there are several groups of birds that look a heck of a lot the same on both sides of the divide. That would be hard to do going through just one species. I admit I’m a dilettante, though, and welcome correction. ---
**Author:** ![Siam\_Sam](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@Siam\_Sam](https://boards.straightdope.com/u/Siam_Sam)\ **Post date:** [September 17, 2013, 3:01am UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/23 "2013-09-17T03:01:03Z")
> [@Siam\_Sam](#): > > I recall reading in Carl Sagan’s _Cosmos_ that whatever killed the dinosaurs killed off everything of more than 50 pounds mass. Am I remembering correctly? > [@qazwart](#): > > Didn’t kill off the crocodilians. Maybe they used to be small? ---
**Author:** ![Pazu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pazu/32/15522_2.png) [@Pazu](https://boards.straightdope.com/u/Pazu)\ **Post date:** [September 17, 2013, 3:50am UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/24 "2013-09-17T03:50:48Z")
> [@bup](#): > > I agree it was a tight bottleneck, but I’m pretty sure ‘they’ think that more than one species survived. > > There’s only one species they’ve found on both sides of the ‘divide,’ but the fossil record is too spotty to make confident predictions to the effect that it was the only species that made it (I think). > > On the other hand, there are several groups of birds that look a heck of a lot the same on both sides of the divide. That would be hard to do going through just one species. > > I admit I’m a dilettante, though, and welcome correction. Current concepts of the early radiation of modern birds (Neornithes) are rather speculative in the absence of good fossil data. While numerous fossils assigned to modern bird groups have been described from the Late Cretaceous, most of these are single bones and cannot be confidently placed in a genealogical context. In contrast, the earliest unequivocal fossils of modern birds are nearly all from the Early Tertiary (c. 55 mya). However, at least one (currently) undisputed Neornithine bird is known from the Late Cretaceous, _Vegavis iaai_ from Antarctica, which seems to be a close relative of living ducks (Anseriformes). Another fossil, _Teviornis gobiensis_ from Mongolia, also appears to be an anseriform. If these two species are in fact relatives of living ducks, then it can reasonably be inferred that there must have been at least a small neornithine radiation by the late Cretaceous, because the paleognathous birds (i.e. tinamous, ostriches, kiwis, etc.) are considered to have been the first split in the modern bird lineage. The next major branch, the Galloanserae, contains the modern landfowl (chickens, pheasants, grouse, etc.) and waterfowl (ducks, geese, screamers, etc.); thus, the former group (galliforms) also must have already diverged by the Late Cretaceous. Reference: Chiappe, Luis M. \*Glorified Dinosaurs: The Origin and Early Evolution of Birds \*. 2007. TL;DR: The definite modern birds known from the Late Cretaceous appear to be close relatives of ducks. This implies that the ancestors of landfowl, tinamous, and ratites had already diverged by that time. ---
**Author:** ![Morgenstern](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@Morgenstern](https://boards.straightdope.com/u/Morgenstern)\ **Post date:** [September 17, 2013, 1:23pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/25 "2013-09-17T13:23:56Z")
According to a show I just watched, at least a few scientist believe it was a massive methane eruption that doomed the dinos. Like a very big fart in a small room. ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [September 17, 2013, 1:41pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/26 "2013-09-17T13:41:10Z")
You can find a few scientists who believe any wild theory you care to name. The problem is that any theory that only focuses on why non-avian dinosaurs died is most likely wrong. There were lots of animal types that went extinct at the K-Pg boundary, and any comprehensive explanation has to account for at least most of them. ---
**Author:** ![Tom\_Tildrum](https://avatars.discourse-cdn.com/v4/letter/t/e95f7d/32.png) [@Tom\_Tildrum](https://boards.straightdope.com/u/Tom_Tildrum)\ **Post date:** [September 17, 2013, 2:32pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/27 "2013-09-17T14:32:41Z")
> [@Irishman](#): > > What’s with this “K-Pg event”? I’ve always heard of it as the “K-T” event. It’s actually now the “KPMG event.” What with cuts in university funding, many scientists are turning to product placement. Along similar lines, the GMC Triceratops has been reclassified as a sport-utility dinosaur. ---
**Author:** ![bup](https://avatars.discourse-cdn.com/v4/letter/b/6bbea6/32.png) [@bup](https://boards.straightdope.com/u/bup)\ **Post date:** [September 17, 2013, 3:01pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/28 "2013-09-17T15:01:38Z")
> [@Darwins\_Finch](#): > > You can find a few scientists who believe any wild theory you care to name. The problem is that any theory that only focuses on why non-avian dinosaurs died is most likely wrong. There were lots of animal types that went extinct at the K-Pg boundary, and any comprehensive explanation has to account for at least most of them. Right, of course. But the question I see is not why non-avians died out (that was the default thing to do at the K-Pg boundary), but (if the fossil record supports this, which it’s looking like it doesn’t yet), why did several species of birds survive? If 4 soldiers survived in a battle from an entire division that was otherwise killed, and they all had one thing in common (where they were, or what their armor was, or something), the question arises why they survived. Of course the answer could be dumb luck, but it’s at least a question worth asking. ---
**Author:** ![Floater](https://avatars.discourse-cdn.com/v4/letter/f/dc4da7/32.png) [@Floater](https://boards.straightdope.com/u/Floater)\ **Post date:** [September 17, 2013, 3:33pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/29 "2013-09-17T15:33:02Z")
I read just the other day that the survivors were mainly small critters that could hide somewhere and fresh water dwellers. ---
**Author:** ![jack](https://avatars.discourse-cdn.com/v4/letter/j/cc9497/32.png) [@jack](https://boards.straightdope.com/u/jack)\ **Post date:** [September 18, 2013, 9:28pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/30 "2013-09-18T21:28:19Z")
> [@qazwart](#): > > However, dinosaurs as a clade weren’t doing so well a million or so years before the _KT event_. That event certainly didn’t help, but the rate of dinosaur evolution was slowing down. Meanwhile, mammalian evolution was starting to pick up and larger and larger mammals started to appear. Still, by the KT boundary, there was no doubt that dinosaurs were still the dominant clade. An excellent point. Most dinosaurs species were already extinct by 65 MYA, and in general, it’s rare for species of large land animals to last more than a couple of million years. We talk about dinosaurs going extinct but have you noticed how many frickin’ birds there are out there? This isn’t like the monotremes where we have what maybe three genera, a handful of species and a limited number of individuals in a small geographic range. That’s a lineage that’s not doing well. Dinosaurs, they’re doing fine. ---
**Author:** ![jack](https://avatars.discourse-cdn.com/v4/letter/j/cc9497/32.png) [@jack](https://boards.straightdope.com/u/jack)\ **Post date:** [September 18, 2013, 9:43pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/31 "2013-09-18T21:43:40Z")
> [@Siam\_Sam](#): > > Maybe they used to be small? No. The crocodiles of the Cretaceous looked a lot like modern crocs, and some of them grew quite large (30+ feet in length). I don’t know of any fossil crocs since then that reached that size. I’m not sure that the largest crocs of the Cretaceous were still around though at the end of the Cretaceous, but I think I am safe in saying that crocs as big as modern crocs survived. The quote that started this off may have meant that no large terrestrial-only animals survived. ---
**Author:** ![jack](https://avatars.discourse-cdn.com/v4/letter/j/cc9497/32.png) [@jack](https://boards.straightdope.com/u/jack)\ **Post date:** [September 18, 2013, 11:57pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/32 "2013-09-18T23:57:14Z")
> [@Jamicat](#): > > If mammals worked so well…why are there still eggs? > > How come chickens don’t have pouches of little chicks about? > > Reptiles had the same amount of time to evolve and adapt, why didn’t the warm blooded mammalian life style take to them? > > What the hell is fishes? 1. We still have eggs. We don’t have hard egg shells and we keep our eggs inside our women (except for the monotremes). Both strategies have advantages and disadvantages, but only mammals (and curiously enough the Red Martians, if I recall my DC comic books correctly) get to have belly buttons. If we laid eggs though, man the abortion debate would be quite different. A woman could just tell Operation Rescue: “You want to raise this egg? Fine, you incubate it.” Fish and amphibians hatch from an egg laid in water and can take of themselves from the start. Turtles, snakes and crocs are in an egg surrounded by a shell and hatch as mini-adults who don’t need a lot of care. Young birds are pretty undeveloped at birth, like lots of mammal species that have large litters. On the other hand, the advantage for mammals is that for large mammals that graze over a wide area (think elephants or cattle or whales), by not laying eggs, the calf can be pretty fully developed at birth (and the species I mentioned usually have one calf at a time). They’re likely to be pregnant for a long time, but a baby whale can swim pretty quickly. Penguins, despite being very well adapted to an aquatic life, must come ashore to lay eggs (and for reasons different than these large animals) have one chick at a time. In short, if you lay your eggs externally, mom can’t give them food while they develop. However, it’s not necessary for mom until the eggs hatch. 1. 'Cause they aren’t marsupials. Just because we can think of it doesn’t mean we can evolve it. 2. Most likely because they evolved their own kind of warm-blooded life style. Terrestrial vertebrates are most active when their blood is warm. Some, like lizards and snakes, rely on external warming - it allows them cut down on food bills. Large dinosaurs, whether due to internal mechanisms or mass homeothermy (when you’re big, once you get warm, you stay warm). I’m surprised that their are still holdouts because the evidence seems pretty clear that at least some dinosaurs developed endothermy (internal warming). It seems to be a different system than what mammals use though in allowing much greater temperature ranges. In short, most mammals maintain a fairly constant temperature, and as a result, require ten times the amount of food that another animal of the same size, relying on external heating, would require. Birds, and perhaps dinos, have figured out how to allow internal temps to drop (say at night, when the bird isn’t hunting) and reduce metabolic needs. 3. Fishes is usually thought as indicating a number of species. “The reef has many fishes” means that it has many different species, as well as, by implication, many individuals. “That school of herring has a lot of fish” means that the school has a lot individual herring. ---
**Author:** ![jack](https://avatars.discourse-cdn.com/v4/letter/j/cc9497/32.png) [@jack](https://boards.straightdope.com/u/jack)\ **Post date:** [September 19, 2013, 12:23am UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/33 "2013-09-19T00:23:18Z")
“80 to 90 percent of sharks and other fish survived” sharks AND other fish? Cecil, say you aren’t going to contribute to the degradation of cladistics by referring to sharks as a polyphyletic group with ray-fined fish and lobe-finned fish, but with the exclusion of tetrapods. I still remember your inspiring words from thirty years ago on how to kill a vampire: “Incidentally, we’ll have none of this “preferred ways” business. There’s a right way and a wrong way to do everything. Take some pride in your work.” ---
**Author:** ![Siam\_Sam](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@Siam\_Sam](https://boards.straightdope.com/u/Siam_Sam)\ **Post date:** [September 19, 2013, 2:31am UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/34 "2013-09-19T02:31:17Z")
> [@jack](#): > > The quote that started this off may have meant that no large terrestrial-only animals survived. Could be. I was remembering a quote from almost 40 years ago. ---
**Author:** ![PlainJain](https://avatars.discourse-cdn.com/v4/letter/p/5daacb/32.png) [@PlainJain](https://boards.straightdope.com/u/PlainJain)\ **Post date:** [September 19, 2013, 8:38am UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/35 "2013-09-19T08:38:47Z")
QUOTH CECIL: "_As it is, human hunters wiped out numerous species bigger, stronger, and faster than themselves; chances are we’d have done the same to dinosaurs if any had lasted long enough to become our prey."_ This assumes that we could have still evolved given their existence. I’m not so sure we could have. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [September 19, 2013, 1:26pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/36 "2013-09-19T13:26:15Z")
[QUOTE=Cecil] Atmospheric oxygen levels increased significantly, peaking at about 35 million years ago. [/QUOTE] That surprised me, as I think of the Carboniferous and Jurassic as having the high oxygen levels (and the big bugs). Regarding the “no large land animals survived” idea, I saw a program on the K-Pg / Chicxulub impact that asserted that no land animal over 20 pounds survived. The implication was that the smaller animals who survived did so because they **burrowed**. (Large animals don’t tend to burrow.) The program claimed that when the impactor set the entire earth’s vegetation on fire, the ground temp would have reached 1500 degrees F; but only a few inches down, it would have been tolerable. A thought occurs to me – it may be that all the _adult_ crocodilians perished, but some (maybe all, for all I know) bury their eggs in mounds of dirt to hatch them, and those might have survived the fire and hatched, to account for large crocodilian species that passed through the barrier. ---
**Author:** ![John\_W.Kennedy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_w.kennedy/32/1031_2.png) [@John\_W.Kennedy](https://boards.straightdope.com/u/John_W.Kennedy)\ **Post date:** [September 19, 2013, 7:11pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/37 "2013-09-19T19:11:07Z")
A peak is not necessarily a global peak. ---
**Author:** ![zelskid](https://avatars.discourse-cdn.com/v4/letter/z/c4cdca/32.png) [@zelskid](https://boards.straightdope.com/u/zelskid)\ **Post date:** [September 20, 2013, 11:56am UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/38 "2013-09-20T11:56:52Z")
And then the alcohol runs out since no one is left to reorder. ---
**Author:** ![zelskid](https://avatars.discourse-cdn.com/v4/letter/z/c4cdca/32.png) [@zelskid](https://boards.straightdope.com/u/zelskid)\ **Post date:** [September 20, 2013, 12:03pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/39 "2013-09-20T12:03:06Z")
All large carnivores will shortly be extinct in the wild. ---
**Author:** ![Oldeb](https://avatars.discourse-cdn.com/v4/letter/o/ea666f/32.png) [@Oldeb](https://boards.straightdope.com/u/Oldeb)\ **Post date:** [September 20, 2013, 9:06pm UTC](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761/40 "2013-09-20T21:06:54Z")
> [@zelskid](#): > > All large carnivores will shortly be extinct in the wild. Don’t be ridiculous. Five of the seven largest terrestrial carnivores in North America have Least Concern status with the IUCN. While individual subspecies are endangered, on the whole wolves are doing okay in Canada, enough to keep them above threatened status. Coyotes are well on their way to being labeled a pest species. The cougar is roughly stable although the population has been slightly declining. The brown bear is stable and the American black bear is not only stable it’s increasing to the point where becoming road kill is a serious problem in some places. The two that aren’t of Least Concern are the jaguar at Near Threatened and largely absent from North America already and the polar bear which is considered Vulnerable. Only the polar bear is at risk of having a wild population disappear in a time frame that could be considered “short”. Furthermore even if all large carninvores world-wide did go extinct in the wild that would hardly be comparable to an extinction event any more than the loss of the dodo or the displacement/absorption of H. Neanderthalensis were. Lions aren’t going extinct because the planet can’t support them, they’re being supplanted by different species. Anyway, back to extinction events. As mammals, humans probably owe more to the Permian–Triassic extinction than anything else for the way we turned out. Synapsids (now represented by mammals) were actually the dominant group in the late Permian with Sauropsida (now represented by reptiles and birds) on the backburner. For whatever reason the Synapsids were slower to recover from the event and forced into more marginal niches. It’s likely that taking smaller, more nocturnal roles lead to these synapsids developing fur and higher metabolisms. It was the P-Tr Event that really forced the divergent paths between the two groups. [Previous page](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761.md?page=1) [Next page](https://boards.straightdope.com/t/if-that-meteor-hadn-t-killed-off-the-dinosaurs/668761.md?page=3)