A dragon is any one of the extinct species of the large reptiles in the family Draconidae. Known around the globe, dragons were the last surviving species of dinosaurs. The engravings, drawings, and sculptures that survived history are records, first hand accounts of people that lived alongside dragons and fought them.
Dragons are often held to have major spiritual significance. One example of them in religion would be some biblical references that seem to hint that the dragon is a type of archangel, one of which by the name of Lucifer, rebelled against God to become known as the seven-headed red dragon called Satan. Some take this as a sign that dragons are an evil force, however other parts of the Christian Scriptures (depending on the version) seem to indicate that God created multiple dragons, not all of whom rebelled. As a note, not all religions have dragons so morally in question. In many oriental cultures, they were a being to be revered, and were representative of the primal forces of nature and the universe.
Most species of dragon possessed wings. The dragons' chest was very powerful and heavily muscled. They also had a massive heart because the chest muscles needed large quantities of oxygen-rich blood to maintain a steady wing beat. The bones were perfectly designed for flight too, with an internal structure very specialized, being honey-combed, which is strong but very light weight. All of these adaptations are general characteristic of powered flight, but their wings still couldn't generate enough lift to get an animal of a dragon's size off the ground.
A dragon's wing span measured under 20 feet with an initial weight of 900 pounds. Dragons possessed a pair of leathery organs, resembling a second pair of lungs within their chest cavity. The tissue walls of these organs were thin and elastic, designed to expand. They were storage sacs. They held gas composed predominantly of hydrogen, which is 14 times less dense than air. Fill a balloon with hydrogen, it rises and when the organs were filled with hydrogen the principle was the same. The organs were the dragon's "flight bladders". All creatures contain bacteria in their gut that help break down food and in the process the bacteria release metabolic byproducts as gas. The bacteria inside dragons released hydrogen that was channeled into the two storage sacs, the dragon's "flight bladders". Along with a super-light skeleton the gas filled flight bladders were the key to the dragon's flight capability.
Another evolutionary adaptation was the dragon ability to "breath fire". The inner surface of a dragon's mouth was almost armor plated. At the back of throat there was a fleshy valve. This flap was similar to the false palate found in crocodile throats used to stop their lungs from flooding when grabbing prey under water. Dragons used the false palate to prevent a back draft of fire from scorching their lungs.
Dragons had both incisors (meat ripping teeth) and flattened molars (grinding teeth). The molars were used to pulverize platinum into powder that remained on the surface of the enamel. Dragons used the platinum as a catalyst to trigger a chemical reaction. The reaction of platinum with hydrogen would ignite the hydrogen to combust, producing fire. A dragon's flight and fire apparatus was a binary system, both relied on the stored hydrogen in the flight bladders. Dragons became naturally attracted to reflective objects because they were conditioned to look for shiny platinum deposits and dragon territories were formed around platinum deposits.
Mountain dragon biology
Mountain dragons had lines of defense against the cold. A heat exchanging circulatory system and a highly stratified layer under their scales help minimized heat loss. And from their marine ancestors they inherited a blood protein similar to that of polar fish. These specialized proteins prevented the formation of ice crystals in the bloodstream so the blood continued to flow and the dragons could remain active even in freezing temperatures. This genetic inheritance proved vital to mountain dragons as they retreated to ever more remote areas. As another adaptation to the coldest environments, the dragons would go into suspended hibernation for the coldest months of the year, slowing their metabolism. This survival strategy left them exposed to dragon hunting humans. All their usual functions were placed on emergency status and their hydrogen reserves fell to almost zero. Another adaptation for life in the cold climate was that dragon wings soaked up heat like solar panels.
Dragons first appeared during the Cretaceous period, from the crocodilian line. The primary enemy of the prehistoric dragon was probably the Tyrannosaurus rex. In addition to the land dragon, towards the end of the Cretaceous period there evolved a marine dragon alongside the land dragon. Over time flight bladders became swim bladders, reduced wings developed into fins, and the powerful tail became a rutter.
65 million years ago, at the peak of the prehistoric dragon success, a curtain came crashing down on the Cretaceous period. A meteorite the size of Mount Everest wiped out nearly all life on Earth.
The cataclysm of the six mile wide meteor unleashed one of the greatest mass extinctions in the history of our planet. The age of dinosaurs was brought to a crashing halt. On land nothing larger than a cat survived. But in the sea life found a way.
Although the prehistoric land dragon species was completely wiped out by the meteorite, water provided marine dragons with an escape route from this deadly episode in the Earth's history. Like other creatures that endured the Cretaceous-Tertiary extinction event, dragons swam from extinction and marine dragons thrived. Then as global temperatures rose, some marine dragons returned to the coastal margins. Moving into estuaries and traveling up rivers, it wasn't long before they made their first tentative steps back on land. Although some of these species of dragons stayed in the water. The Loch Ness Monster is believed by many to be sightings of surviving marine dragons.
Those dragons that returned to land first appeared in the forests of Asia. These forest dragons evolved their fire breathing back, but still had the body of their ancestors in the water: low slung to the ground, short-limbed, long, and slender. This form remained well suited for life in the dense forests. It is these dragons that would be the Chinese dragon of legend.
Probably like their ancestors, the forest dragons of Central and Southeast Asia remained a solitary and unsocial creature that sought others of their own kind only when looking for a mate. Their wings were vestigial because flight isn't of much use when hunting in a forest. However, these dragons could move with absolute stealth. The markings on their skin served as camouflage by braking up their outline in the dappled light of bamboo forests
Forest dragons retained the ancient ability of their kind. They still carried the same hydrogen gut bacteria of their forebearers. What was swim bladders once again served as fuel stores. The flight bladders were used exclusively for fire. Fire was no longer simply a weapon but a tool, as things that could not be easily digested were simply scorched away.
Around the globe new habitats and new species evolved. The era of the dinosaurs was over and a new group of animals rose to fill the void - mammals - which provided plentiful food for dragons.
Humans and dragons
After millions of years, new species of dragons evolved that had all the features of the dragons of the Cretaceous. Throughout the age of mammals, dragons remained apex predators. They still controlled something no other creature could withstand, fire. But humans proved to be a very worthy opponent by stealing fire. Humanity recognized the abilities of fire and soon people used fire to clear forests, and to mold metal into weapons. With fire we forged our strength and over tens of thousand of years we forced all other creatures into submission, save for the dragon.
The dragons that first emerged from the waters followed the great mammoth caravans, crossing over the plains below them. Dragons inevitably became caught in the surging tide of human expansion. Environments altered to suit our needs, habitats sacrificed to fit our purposes. Those creatures that couldn't keep pace, had to find their way on the fringes of our world. By the end of the 14th century dragons were disappearing to become the rarest creatures on Earth, with only the "mountain dragon" species left. Human pressures forced dragons into the highest and remote parts of their range. The territory they patrolled was still just beyond the reach of humans.
In the mountains, females would leave their scent throughout their territory and strong winds would carry their pheromones south. Normally these female dragons were reproductive by their seventh year. When a male would pick up a female's scent the female would lead her suitor on in an aerial display. At the height of the climb, the dragons would lock talons with each other and drop out of the sky in a dazzling free fall, just like bald eagles still do today.
After mating, female dragons probably become more aggressive. Programmed by instinct to become deeply suspicious of any creature approaching the nest, even a mate.
Female dragons would set up a nest of rocks, wood, leaves, and ash all tightly packed into a cone. To keep it warm, dragons would set it on fire. The egg shells had heat resistant properties that could withstand intensely high temperatures. The developing dragon embryos inside were protected. More dangerous to them than heat exposure was a drop in temperatures. Without the seering external temperature, the dragon chicks inside the eggs would die. The rocks of the nest further shielded the eggs from direct blast, but crucially they retained the heat, releasing it over a long period and keeping the internal temperature of the nest stable. Careful and constant temperature control was essential over the thirty day incubation period.
Heat sensitive cells in a dragon's tongue allowed them to check the temperature. If it fell much below 60 degrees for any period of time the embryos would die. The incubation temperature of the eggs, like crocodile broods, determined the sex of the offspring. Cooler temperatures encouraged the development of females. Because males, even a son, would compete for territory, food, and breeding territory; many male dragons would prevent a potential rival by occasionally cooling the nest. This instinct of self-preservation was hardwired into them. However, this created an imbalance between the sexes that pushed their species further towards the brink of extinction.
Young dragons would remain with their mothers for as long as six years. Such an extended period of parental care historically ensured a high survival rate of their offspring. But with their numbers so low, over time dragons weren't reproducing fast enough to keep their population stable, the species was slipping away.
To find prey in the hostile environment of the mountains took time. Females had to find an easier supply of food to stay close by her egg. So they raided the farms of humans. In preying on the livestock of local farms, dragons made themselves an enemy in the eyes of humans.
If simple farmers failed at putting a stop to the raids, the duty of dealing with the dragon fell to the local lord. Mercenaries known as "dragon slayers" were often paid for by the local lord. People believed that dragons were born of hell's fire, an evil that must be destroyed. By the end of the 15th century dragons had fallen from reality to mythology - they were extinct.