Maybe I’m misinterpreting the abstracts, but those papers seem to address when the currently extant lineages began, instead of how many of the lineages of that time survived the event.
Discovery Channel said everything over twenty pounds died. Their supposition was that no large animals burrow, and only (in their supposition) burrowed species survived on land (the worldwide firestorms). They tested a representative plot of forest in blast furnace at 1500 degrees F, and ten inches below the surface the temperature was around 100 degrees or so, quite survivable.
It doesn’t give the percentage of survivors. My point was just that a variety of different lineages of both birds and mammals apparently survived the event, not just a few.
I’m confident you’re right, because you know this field, but your cite doesn’t support “not just a few”, since it talks only about modern lineages and not at all about those that went extinct. For all I know (and consistent with that paper), there were thousands of bird lineages that went extinct at the KT event, and only a small fraction survived to modern times.
Of course, I don’t know how many avian lineages there were and I assume you actually have a good idea (even if that cite doesn’t address it), so your statement is good enough for me.
By “not just a few” I mean more than two or three. Of course every species alive at the time represents a “lineage” in a sense. Since there probably were thousands of bird species extant at the time of the KT event, the ones that survived to the present do represent only a small fraction of the ones living at the time. This article indicates that there were at least 22. However, there could have been thousands of species of small non-avian dinosaurs also living at the time, and none of them made it (that we know of). So it’s a bit of a surprise why one group might have had a couple of dozen survivors, while the other had zero.
Could the sparsity of dino fossils at or just before the K-T boundary be a result of the impact and its subsequent effects, rather than an indicator of a decrease in the number of dino species extant at that time? In other words, could the impact and all the attendant phenomenon (superhurricanes and whatnot) have destroyed many of the bones that otherwise would have fossilized? For example, it could have caused severe erosion in areas that had lots of buried bones, thus preventing them from fossilizing.
Did any non-coastal, non-riverbank, megafauna survive the K-Pg extinction?
That’s probably not the reason for it. Many places show an iridium-enriched layer at the KT presumably from the asteroid (and which is one of the primary lines of evidence for an impact) that would have been laid down immediately after the impact, indicating that there would not have been a great deal of erosion post-impact.
No. Basically the only large air-breathing animals to survive the extinction were aquatic and semi-aquatic like forms like crocodilians and champosaurs. For millions of years after the event, the largest terrestrial animals were probably not much bigger than a small dog.
About finding fossils: I don’t know that much, but this is what I have read:
Yes, there’s a lot of land mass; but generally remains of animals decayed, were eaten, weathered, etc to dust. Fossils are a special case; in areas with severe sudden landslides, or rivers flowing with silt, shallow seas with silt deposits, any dead animals would be covered with mud and the bacteria would be deprived of oxygen, so decay would not set in very quickly. The result is that mud would harden to rock still containing the detectable remains.
As a result, there are a few sites where the rock formations from early silt deposits still exist. For dinosaurs, this is in areas like up and down the west coast of the ancient inland sea that ran from Texas to the Arctic. There are a few other areas also famous for the deposits where dinosaur-era fossils can be found. Most discoveries are in these few areas, so the fossil record is limited to what died and got buried quickly in certain geological situations.
IIRC, grass evolved later, so in those days erosion and silt build-up was much heavier.
All true, but in the late Campanian/early Maastrictian stages only a few million years before the K-Pg fauna, we have representative dinosaur faunas from all across the northern hemisphere and the explored parts of the southern-- North America, all across central and eastern Asia, South America, eastern Europe. Each had a diversity of species nearly double what we find in the few K-T age formations.
Well, birds are dinosaurs by a cladistic definition. See when Richard Owen came up with that term, he included two very different reptile-like animals in what he called “Dinosaurs”. If you insist the two types are both dinosaurs, then birds are then also dinosaurs. (I don’t entirely agree, the fossil evidence is not solid enough to say with certainty that birds did not evolve from archosaurs.)
wiki ;"Under phylogenetic taxonomy, dinosaurs are usually defined as the group consisting of “Triceratops, Neornithes [modern birds], their most recent common ancestor, and all descendants.”[11] It has also been suggested that Dinosauria be defined with respect to the most recent common ancestor of Megalosaurus and Iguanodon, because these were two of the three genera cited by Richard Owen when he recognized the Dinosauria.[12] Both definitions result in the same set of animals being defined as dinosaurs, including theropods (mostly bipedal carnivores), sauropodomorphs (mostly large herbivorous quadrupeds with long necks and tails), ankylosaurians (armored herbivorous quadrupeds), stegosaurians (plated herbivorous quadrupeds), ceratopsians (herbivorous quadrupeds with horns and frills), and ornithopods (bipedal or quadrupedal herbivores including “duck-bills”). These definitions are written to correspond with scientific conceptions of dinosaurs that predate the modern use of phylogenetics. The continuity of meaning is intended to prevent confusion about what the term “dinosaur” means.
There is a wide consensus among paleontologists that birds are the descendants of theropod dinosaurs. Using the strict cladistical definition that all descendants of a single common ancestor must be included in a group for that group to be natural, birds would thus be dinosaurs and dinosaurs are, therefore, not extinct. Birds are classified by most paleontologists as belonging to the subgroup Maniraptora, which are coelurosaurs, which are theropods, which are saurischians, which are dinosaurs.[13]
From the point of view of cladistics, birds are dinosaurs, but in ordinary speech the word “dinosaur” does not include birds. Additionally, referring to dinosaurs that are not birds as “non-avian dinosaurs” is cumbersome. For clarity, this article will use “dinosaur” as a synonym for “non-avian dinosaur”. The term “non-avian dinosaur” will be used for emphasis as needed."
Some small bird-like dinosaurs seemed to have been feathered. Telling them apart from some of the “primitive” group of birds would quite possibly been very difficult. The line between “bird” and “dinosaur” is fine, if it exists at all, and in the early linage, it is very hard to tell who is who and what is what, there are few fossils. Certainly it is possible that some small feathered “dinosaur/proto-bird” such as Rahonavis could have survived the KT event, then to be pushed into extinction by later “true” birds who occupied that niche better. The fossil record simply isn’t good enough to say with certainly.
But all the “big dinos” died out.
Not only that, birds are so solidly nested within a specific dinosaur lineage that keeping them out completely obliterates the whole group, not just splits it in two. You’d have to have dinosaurs (meaning only some plant eating dinosaurs), then a second group for the long-necked sauropods, dozens of groups for the off-shoots of the carnivorous theropod lineage leading towards birds, as long as you’re keen on keeping birds themselves out. If you want to define “dinosaur” in such a way as it excludes birds, then everything from T. rex to Velociraptor to Brachiosaurus can’t be considered dinosaurs either, because they’re all closer to birds than say, Triceratops or Iguanodon.
Really? All but maybe two fringe researchers in the field would not only strongly disagree with this position but have a good laugh. If this kind of fossil evidence isn’t strong enough, what would be? And what alternate hypothesis has stronger evidence?
Anyway, dinosaurs are a type of archosaur. So birds did ultimately evolve from archosaurs, via the dinosaur lineage.