Why did pterosaurs go extinct

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These pterosaurs soared over South America during the middle of the Cretaceous period, more than a hundred million years ago. At that time a large saltwater lagoon covered the Araripe area, and the African continent lay just over the horizon, separated by a young sliver of ocean that would later grow into the Atlantic.

Among the Araripe discoveries some of the strangest have been identified by Kellner and his mentor Diogenes Campos of the Brazilian Department of Mineral Production. At his office in Rio de Janeiro, Campos pulled out one of his favorite characters, a million-year-old Araripe pterosaur that he and Kellner christened Anhanguera, or "old devil.

Still partly entombed in rock, the glossy fossil looked leaden and cold. But as I ran my fingers over the inch-long centimeter-long jawbone, tracing its curves and pits, I could imagine the Araripe pterosaurs sailing over the ancient lagoon. A solitary Anganguera takes flight, its foot 4-meter wingspan silhouetted against the sky.

The pterosaur sweeps its large keen eyes over the water, pulls its wings inward to pick up speed, and swoops low. Dropping its mouth into the water, the hunter uses its beak to slice through the waves like a black skimmer bird.

In a flash the pterosaur jerks its head up and veers skyward, gripping a wriggling fish in its teeth. Along the shore diminutive pterosaurs called Tapejara wellnhoferi pluck nuts and fruit from scrubby trees with their toucan-like beaks. Above the whole tableau soars the most impressive Araripe species, a giant called Tupuxuara, with a foot 6-meter wingspan.

This toothless pterosaur had a rounded four-foot-long 1. Paleontologists can paint this vivid portrait of Araripe pterosaurs because their bones were exquisitely fossilized, intact and uncrushed, within the quiet sediments at the bottom of the lagoon.

By comparison, the flattened pterosaurs from most other sites around the world look like prehistoric roadkill. The Araripe fossils have enabled researchers to get a better fix on what pterosaurs actually looked like and how their bones fit together. They can see, for example, how the upper arm bone, or humerus, produced the flapping motion that kept pterosaurs in the air.

The bone looks something like a hatchet: a stout shaft topped by a flared-out blade where it joined the shoulder. The wide head must have provided a broad anchoring point for the powerful chest muscles pterosaurs needed to flap their wings. The weight of these large muscles was offset by lightweight, eggshell-thin bones filled with air. Larger species had slender struts inside hollow wing bones, adding strength without many additional pounds. So even with wings almost as wide as a house Tupuxuara may have weighed no more than a child.

Hollow bones gave pterosaurs an advantage during life but were a hindrance to their immortality. Pterosaur skeletons were so delicate that they survived as fossils only when their corpses came to rest in a protected environment.

For that reason most pterosaur remains come from species that lived near the ocean—the soft seafloor ooze entombed their bodies for eternity. Even with the new discoveries, the rarity of fossils leaves major gaps in knowledge about pterosaurs. No one knows how they evolved flight, why they vanished, or exactly what they looked like.

Debate swirls around these reptiles like the air currents they once rode. Controversy has surrounded pterosaurs since the first discovery of one at the end of the 18th century. At the Bavarian State Collection of Paleontology and Historical Geology in Munich, paleontologist Peter Wellnhofer pulled out a large drawer filled with fossils and pointed out a fragile skeleton, which was no bigger than my hand. Embedded in a slab of limestone million years old, the creature lay with its mouth agape in a pose of prehistoric horror.

It has a long toothy snout, a giraffe-like neck, and lanky legs, but its most unusual feature is its forelimbs. Next to three small fingers is a fourth that extends ten times the length of the other digits. Cosimo Alessandro Collini, the first natural historian to study the fossil, was stumped when he described it in Seventeen years later the great French anatomist Georges Cuvier deduced that the animal was a flying reptile, whose fourth finger supported a wing.

Although the wing surface had not fossilized, Cuvier surmised that a membrane of skin had attached to the forelimb in life. He later named the fossil Pterodactylus, combining the Greek words for wing and finger. A few decades later the term pterosaur, or winged reptile, was coined to describe the growing list of similar fossils. In a remarkable pterosaur specimen came to light that confirmed Cuvier's deduction.

Unlike earlier fossils, this new find near the Bavarian town of Solnhofen contained delicate wing impressions, clear proof that extinct reptiles could fly. Even with more than a thousand pterosaur specimens known today, such wing impressions remain rare. Normally only bones survive the fossilization process. Material as ephemeral as skin or hair disintegrates long before an animal turns to stone.

But time was kind to the pterosaurs that died near Solnhofen because many were preserved in the sediments of a Jurassic lagoon. Wellnhofer slid open another drawer and gingerly removed a gull-size pterosaur named Rhamphorhynchus, with a wing so beautifully preserved that I could see impressions left by delicate folds of its skin.

Under the microscope the surface of the wing looked corrugated, almost like corduroy. This texture comes from fine fibers only two-thousandths of an inch thick that were inside the membrane. But SOME birds, lizards, turtles, crocs and mammals survived. So, why did ALL pterosaurs die out? Phylogenetic Analysis As in dinosaurs, the pterosaurs we know from the latest Cretaceous were not the same pterosaurs living in the Triassic, Jurassic or Early Cretaceous.

All of these earlier pterosaurs became extinct, but a few genetic lines survived by evolving into the Late Cretaceous forms we know and love. The Example of Dorygnathus Analysis illustrates how the descendants of Dorygnathus changed in size and shape as they evolved into the above Late Cretaceous taxa.

Therein, l think, lies the answer to why pterosaurs were not able to continue evolving into the modern day. Figure 1. The Azhdarchidae. Click to enlarge. Setting aside the huge size differences between the two Qs and their phylogenetic predecessor, Zhejiangopterus , note that tiny TM and two other tiny pteros, No. There were no other full-size Dorygnathus present in the Late Jurassic.

Something killed every other one over a certain size. Only tiny dory descendants somehow survived. They have uses even without wings and without flight. The development of wings and flight could easily take place after the development of feathers. Feathers are a "preadaptation". The fine-tuning of feathers for flight would take place in dinosaurs who were using their feathers for all sorts of things other than flight.

None of these are Maastrichtian, and so are not relevant to the initial question. According to Wikipedia, there are three known genera of Maastrichtian pterosaurs: Quetzalcoatlus, Hatzegopteryx, and Nyctosaurus. The former two are azhdarchids, and huge. Nyctosaurus isn't in their league, but still had a 2-meter wingspan and antlers, by the way.

There may be more, but all references I find so far are to additional azhdarchids. Oh, come on! This isn't "bald. My original statement: : It appears that pterosaurs were thoroughly : out-competed by birds, and were all but gone.

If they weren't around in the late Cretaceous they're hardly relevant. But they are relevant to the question of why pterosaurs suffered in competition with birds before the Maastrichian. And you reveal just how much they had suffered below. I looked a little longer, and I see that they apparently do have ways of distinguishing between them. On page 89 there is a picture of the smallest pterosaur yet found, a juvenile with a wingspan of 7 in. The two claims could be compatible: the claim for the latter could rest on this specimen being somewhat less juvenile than this other one in the encyclopedia.

Just how juvenile, is being discussed in the blog whose url is above. Trivia: even at my age, I often get goose bumps when reading the word "Maastrichian" because I know what is coming next. Different meaning of "bald". But turkey vultures are more bald in the usual sense, not naked all over the body than this specimen was.

By the way, I've restored the full url above. Google displays ellipses at the ends of long urls but the whole thing is really there and is usable again. But when a follow-up is made, and the whole url isn't restored, the url in the follow-up stops at the ellipsis. And even with the "fully aquatic" bit, aren't the fully aquatic hairless mammals also really big?

Hesperornithiformes were big enough, but still smaller than most cetaceans. The few that survived were the huge Azdarchids. Though their size has been somewhat exaggerated, they were certainly by far the biggest organisms ever to fly. No flying bird has come close to Quetzalcoatus. Yet birds and pterosaurs apparently shared the sky for the entire Cretaceous at least Perhaps birds occupied the "small flyer" niche in a similar way that mammals occupied the "small land dweller" niche.

All birds that fly require feathers to do so. Most mammals that are bald are big whales, dolphins, elephants etc and thus not greatly affected by heat loss. The only size exceptions I know of live underground and are heat protected thereby. Thus the reason for this absense of absense seems pretty obvious.

There were birds for a long time before the KT event. They split off from the other dinosaurs quite a long time before. They AND birds were around for quite a long time at this point. The flying reptiles were not descended from or particularly closely related to dinosaurs. You are wrong about everything. Which is the part Steven addressed, and to which I addressed my reply to your response to Steven if that's not too convoluted Apparently it has more to do with how adept you are at burrowing or staying underwater for a couple of hours, at least regarding this particular event or similar ones.

I'd really like to see a cite for that. It may very well be that we find evidence of larger species more readily than smaller species. Are you more likely to notice a moose carcass in the woods or a shrew carcass? In any case, everything I've read says that the major factor in risk of extinction is the breadth of the niche.

That is, the more specialized a species in its requirements food, nest sites, what have you the more likely it is to go extinct.

Ivory-billed woodpeckers are probably extinct reports from Cuba notwithstanding but the Pileated Woodpecker seems to be doing pretty well. They're virtually identical, you know, except in their habitat requirements.