The functional view on the evolution of feathers has traditionally focused on insulation, flight and display. Discoveries of non-flying Late Cretaceous feathered dinosaurs in China however suggest that flight could not have been the original primary function. There have been suggestions that feathers may have had their original function in thermoregulation, waterproofing or even as sinks for metabolic wastes such as sulphur. Recent discoveries are claimed to support a thermoregulatory function, at least in smaller dinosaurs. While feathers have been suggested as having evolved from reptilian scales, there are numerous objections, and more recent explanations have arisen from the paradigm of evolutionary developmental biology.Theories of the scale-based origins of feathers suggest that the planar scale structure was modified for their development into feathers by splitting to form the webbing; however, the developmental process involves a tubular structure arising from a follicle and the tube splitting longitudinally to form the webbing. The number of feathers per unit area of skin is higher in smaller birds than in larger birds, and this trend indicates their important role in thermal insulation, since smaller birds lose more heat due to the relatively larger surface area in proportion to their body weight. The miniaturization of birds also played a role in the evolution of powered flight. The coloration of feathers is believed to be primarily evolved in response to sexual selection. In many cases the physiological condition of the birds (especially males) is indicated by the quality of their feathers and this is used (by the females) in mate choice. A study published in 2006 confirmed the presence of information for producing feathers in the genes of the American Alligator, but these instructions are suppressed during embryological development, causing the alligator hatchling to express only scales. The presence of a homologous trait in both birds and crocodilians indicates it was inherited from a common ancestor. This may suggest that avian feathers, dinosaur protofeathers and pterosaur pycnofibres are all variations on the same basal archosaur integument, and place the origin of feathers much further back in history than previously thought.
Several non-avian dinosaurs had feathers on their limbs that would not have functioned for flight. One theory is that feathers originally evolved on dinosaurs as a result of insulation properties; those small dinosaurs that then grew longer feathers may have found them helpful in gliding, leading to the evolution of proto-birds like Archaeopteryx and Microraptor zhaoianus. Another theory is that original adaptive advantage of early feathers was their pigmentation or iridescence, providing sexual preference in mate selection. Dinosaurs that had feathers or protofeathers include Pedopenna daohugouensis, and Dilong paradoxus, a tyrannosauroid which is 60 to 70 million years older than Tyrannosaurus rex.
The majority of dinosaurs known to have had feathers or protofeathers are saurischians, however featherlike “filamentous integumentary structures” are also known from the ornithischians Tianyulong and Psittacosaurus. The exact nature of these structures is still under study. However, it is believed that the stage 1 feathers such as those seen in these two ornithischians likely functioned in display.
Since the 1990s, dozens of feathered dinosaurs have been discovered in the clade Maniraptora, which includes the clade Avialae and the recent common ancestors of birds, Oviraptorosauria and Deinonychosauria. In 1998, the discovery of a feathered oviraptorosaurian, Caudipteryx zoui, challenged the notion that feathers were an exclusive structure of Avialae. Buried in the Yixian Formation in Liaoning, China, C. zoui lived during the Early Cretaceous Period. Present on the forelimbs and tails, their integumentary structure has been accepted as pennaceous vaned feathers based on the rachis and herringbone pattern of the barbs. In the clade Deinonychosauria, the continued divergence of feathers is also apparent in the families Troodontidae and Dromaeosauridae. Branched feathers with ranchis, barbs, and barbules were discovered in many members including Sinornithosaurus millenii, a dromaeosaurid found in the Yixian formation (124.6 MYA).
Previously, a temporal paradox existed in the evolution of feathers—theropods with highly derived bird-like characteristics occurred at a later time than Archaeopteryx—suggesting that the descendants of birds arose before the ancestor. However, this paradox was resolved in 2009 with the discovery of Anchiornis huxleyi, found in the Late Jurassic Tiaojishan Formation (160 MYA) in western Liaoning. By predating Archaeopteryx, Anchornis proves the existence of a modernly feathered theropod ancestor, providing insight into the dinosaur-bird transition. The specimen shows distribution of large pennaceous feathers on the forelimbs and tail, implying that pennaceous feathers spread to the rest of the body at an earlier stage in theropod evolution.The discovery, in 2011, of feathers preserved in amber, within samples dating to 80 mya, suggests the coexistence of theropods and birds, with both theropod and avian feather types commingled in the samples.
HEY GUYS I WAS ACCEPTED IN THE POKEMONATHÓN! \o/
Here are Squirtle, Wartortle and Blastoise. Blastoise’s design gave me a fucking headache, it took me HOURS to get it to look the way I wanted.
BTW You can keep track of this project with the tag “pokemayans”
I’ve been thinking about making prints of these guys! So let me know if you’re interested, also don’t be shy to message me if you want to commission my mayan-like interpretation of a particular pokemon, I’m thinking of:
$15 USD for a single pokemon (for example squirtle)
$25 for the pokemon + its evolution (squirtle + wartortle)
and $35 for a pokemon and its two evolutions (squirtle + wartortle + blastoise)
Let me know if that sounds good!
You can also commission pokemon I’ve already reimagined and I’ll make you a special drawing resembling mayan stelas, (I’d offer you a discount if you commissioned Eevee and all its evolutions of course xD) I’m also willing and very interested to reinvent fakemon as mayan mythical beasts :)
Other pokemayans :
Couldn’t decide what worked better. I like the bottom one more but it seems too dark.
A study of the mechanism of claw retraction in a cat, by Mauricio Antón:
“we should not talk so much about “retractable” but about “protractable” claws. Retracted is the normal, relaxed position of the claws, and active contraction of several muscles is needed for the animal to deploy its weapons.” More at Sabertooth Diaries 4: inner workings
Which do you think is more exquisitely built? The cosmos or the human form?
One is a seemingly infinite collection of various condensations of matter, all expanding outward from the same genesis, existing independently across immense distances that turn even the simplest observations into time travel.
The other is a localized collection of biological units, each dependent on the summed contributions of the whole, and even on the contributions of life beyond itself, in order to exist at all. As the cosmos does, it arises from a single genesis, but its growth and organization rely on an intensely intricate choreography of signals, relationships and cooperation across distances small enough that we don’t distinguish them from the body as a whole.
One is built out small bits of the other, but the larger, in a way, does not exist except that it has been named by the smaller.
Joe Hanson (jtotheizzoe)
I had forgotten I wrote this. I’m glad I found it. I love randomly searching through Tumblr and stumbling upon things like this. Thanks for sharing my words, you wonderful people. :)
When the Bible says Man was created in God’s image, this is what they mean. We are made on the same blueprint as spiraling galaxies and flowers, with a body and mind to create ever more complex systems. God is not to be found in the machinations of men, but the machinations of universal principles manifested in us.
Trying to disprove the logical fallacies behind religious dogma, is a losing game. You cannot argue with illogic. Move on, and discover the infinite within yourself.