For a brief time in the Permian period, humans evolved wings and flew all over the world. We lost them from atrophy after humankind stopped flying, likely due to the nuisance of the TSA. (Triassic Security Administration)
How did feathered dinosaurs finally take to the air? When did they become birds? This dramatic transition didn’t happen all at once, as Dinosaurs Among Us demonstrates. The evolution of feathers and flight-ready brains was just the beginning. And those awkward in-between stages include some of the most fascinating animals that ever lived: bushy, feathered tyrannosaurs; birds with lizard-like tails, teeth and claws; and even some small, leaping creatures with four wing-like limbs.
Found only on birds, feathers are some of the most complex integumentary (skin) structures found in vertebrates.
There are two primary types of feathers: flight and down. Some birds, such as peacocks and birds-of-paradise, also have display feathers.
Flight feathers come in two categories of their own: remiges (wing feathers), and rectrices (tail feathers). These strong feathers are what allow most birds to fly. They have strong midline ridges, called the shaft (or rachus). The rachus is mostly covered in the fluffy-but-structured extensions, what most people think of as the “feather”, called the vane. At the bottom of the rachus, below the vane, is the bare quill (or calamus). Each extension on the vane is covered in many hooks and hooklets (also called barbs and barbicels), which is what birds are putting back into place when they preen - gotta keep everything in order to fly well!
Down feathers don’t have the hooks or the rachus of the flight feathers. There are many types of down feathers, but all of them serve the same basic purpose, which is temperature regulation. They trap air close to the bird’s body, which insulates it from the cold. When a bird puffs up in the middle of winter, it’s creating a bigger insulating layer to trap body heat, so that it doesn’t cool off as quickly.
To replace their feathers on a regular basis (to remove damaged or correct for lost feathers), birds undergo a process called moulting. Depending upon the species, this can happen all at once, be staggered over the course of a year, or happen gradually over several years. Many species undergo moulting during breeding season, to show off their flashy plumage.
Moulting is regulated by the pineal gland and circadian rhythms in most birds, though in pet birds, a somewhat-constant slow moult (punctuated by one or two “big moults” a year) is found, as a result of artificial lighting.
How did feathered dinosaurs finally take to the air? When did they become birds? This dramatic transition didn’t happen all at once, as the new exhibition Dinosaurs Among Us demonstrates. The evolution of feathers and flight-ready brains was just the beginning.
This early almost-bird, named Anchiornis huxleyi, appears right on the cusp of flight. Its feathered proto-wings couldn’t have kept it aloft for long, but they might have provided enough lift to help it leap to safety, pounce on prey, parachute down from heights, or run up steep slopes. Whatever the function of these early wings, they represent one of the last evolutionary stages before true modern flight evolved.
How did feathered dinosaurs finally take to the air? When did they become birds? This dramatic transition didn’t happen all at once, as the new exhibition Dinosaurs Among Us demonstrates. The evolution of feathers and flight-ready brains was just the beginning. And those awkward in-between stages include some of the most fascinating animals that ever lived: bushy, feathered tyrannosaurs; birds with lizard-like tails, teeth and claws; and even some small, leaping creatures with four wing-like limbs.
“During the first years of the sixteenth century, Leonardo da Vinci made careful observations of the Black Kites, larks, and other species common to the Italian countryside, jotting down his ideas in a private notebook that came to be called Codex on the Flight of Birds. Leonardo’s designs for flying machines included a now-famous illustration of a primitive helicopter, as well as a flapping Icarus-style flier, but the most important pictures in the book may be a series of small birds sketched casually in the margins. They look like pigeons in flight, showing a variety of postures and depicting the birds with lines of air passing under and over each wing. Combined with his text on the "thickness” and “thinness” of air, these pictures make plain that Leonardo had begun to intuit the importance and function of airfoils.“
Thor Hanson, Feathers: The Evolution of a Natural Miracle.
Yeah, 1992 was a crap year for non-avialaen dinosaur discoveries… and avialaen dinosaur discoveries. I gotta scrape at the barrel for this. Still, Sinornis is a pretty cool dinosaur, all things considered. It lived about 135 million years ago, in the Valanginian age of the Early Cretaceous. It was found in the Jiufotang Formation at Liaoning, People’s Republic of China. It was about the size of a sparrow, and it was a transitional form between the very primitive early bird Archaeopteryx and modern forms. It lent much insight into the evolution of flight in modern birds, since Archaeopteryx did not have many of the features of modern birds with regards to flight and perching. It, like many early birds, had a mouth fully of teeth; most of its advanced characteristics were related to flight and perching. Based on its breastbone and shoulder structures, it was capable of flight similar to modern birds (and had the muscles necessary for it;) it had modified wrist bones that would allow the wrist to bend sharply back to tuck the wings during flight or rest. It had reduced claws, and small hands with a steady middle finger to allow for flight feather anchorage. It had separate finger bones, well adapted for flight, which in combination with its small form made it easier to fly. It was also capable of perching and climbing. It lived in a primarily arboreal habitat, and probably inhabited an ecological niche similar to sparrows.
Been playing with my tablet, time for some original content!
The False Dragon (Anolis draconis) is a product of the
diversification of the anolis genus of lizard in the post-human era. This is one of the earliest false dragons and the
common ancestor of what would grow to be a large group of flying
reptiles sharing the name false dragon tens of millions of years after
the extinction of humanity. While this one is small, only slightly
larger than your average anole, its descendants would come in a variety
of shapes and sizes and reclaim the skies for reptiles after the decline
of most species of diurnal flying bird. This particular false dragon
first appeared around four million years after humans and would have
been a very common sight throughout the Americas, though mostly in the
now-expanded tropics. Seen here is a male perched upon a branch and
displaying his dewlap. This behavior is unchanged from that of his anole
ancestors with him flapping the dewlap open and shut and bobbing his
head to attract mates. At this point in their evolution proper powered
flight is not possible due to the small wingspan, exothermic tenancy, and long tail, but by
nine million years after humans large flocks of his ancestors will soar
through the canopy eating insects and on occasion cooperating to take
down small vertebrate: usually another anole descendant or small mammals
such as mice. The false dragons are more social than their anole
ancestors and usually live in groups of 30-50 individuals, but sometimes
they may live in groups as large as 80 or more. They care for their
young initially, but because they develop quickly this period doesn’t
last long and as soon as hatchlings can glide their parents more or less
abandon them. These social groups, called flights, are mostly for
“strength in numbers” and little social interaction actually occurs, but
they will band together to fight off larger predators that threaten the
flight or other flights that encroach on their hunting grounds.