Dragons are amongst the oldest races on Equis, with fossils predating back to the time of dinosaurs. Equestrian scientists have been able to piece their lineage back in time. Some had argued that they were descended from dinosaurs themselves and this was a long accepted theory. With recent advancements in technology and re-examining fossils, scientiests have concluded they are descended from the Crocodylomorpha Superorder, sometime around the Early to Mid Jurassic. The species Dracofallax nanus, which was first thought to be a crocodilian mimicking draconic features, has now been confirmed as the first of the dragon lineage. This of course pushed back the lineage's original thought date from the Early Cretaceous to the Early Jurassic. Unlike many would believe, dragons are naturally warm blooded for the most part. This has lead to some speculation that they should be considered mammal like reptiles.

Current dragon relations are mixed as dragons don't have established nations. Dragon relations across the globe vary to individuals and species, with some having 'rogue' status which makes many wary of them.

Dragon

Dragons are the most well known of the Draco Order and the most wide spread. They are the general icon when it comes to this family. Dragons are known for their excessive greed, being only outmatched by their earthern kin. The reason for this greed is down to a genetic level. They are able to get nutrients from the gems, which helps keep their scales nice and hard as well as keep them inherently healthy. You can tell a dragon's health by how shiny a scale is as it's hard to see fat or such underneath their thick hide.

As well, dragon size dictates a dragon's hoard as they are tied said size, especially earlier in their lives. Larger dragons need a more reliable source of nutrition as well as to stave off smaller dragons. If a smaller dragon were to come across a large horde, their instincts would naturally trigger a 'flight' response since it would indicate a large and healthy dragon as well as the overpowering aroma.

Dragons are naturally aggressive. In fact, they are the most aggressive of the draconic order. They have an innate greed that helps fuel their growth as well as their aggression. Even if a dragon doesn't pose a threat, they will go out of their way to kill any competition, whether it be family or children of other dragons.

The hoards are usually kept within caves and other enclosures and rarely left unguarded aside from hunting trips. However, females will leave their nests every fifty years to find a mate. They can wait this long given the inherent longevity of dragons, with some having lived as far back as the dawn of Equestria, some ten thousand years ago. Males during this time will willingly shift behavior, using their hoards to decorate the outside of their lair. This display helps show they can support and feed a receptive mate and show off their strength. A dragon's courtship is dangerous however. Many dragons are severely wounded or even killed during this process, so males have to be wary when attracting larger females.

These 'nests' they share are normally found around rivers and lakes, allowing males to fish. Places rich in platinum are prime locations for dragons as the rock helps ignite their fire. This is why ponies and most other species avoid platinum deposites, making the mineral rare in many locations until advancements in weaponry have made it possible to ward them off. As well, fish carries a fair amount of calcium, which the female needs when carrying her eggs. Dragons don't mate for life, given their aggressive natures. With clutches of about three to a dozen, they will care for the young for about five years before the female leaves. She will not risk her young, especially her sons, to stay around a male dragon. Males have been known to kill offspring on occasion, mostly sons, to thin out future competition.

Dragon hide is naturally impervious to most small arms and can only be cut by the sharpest of blades, most of which need magical assistance in order to cut through. This of course makes them an unmitigated threat to most people, with only the largest magi cannons able to effect them. This is also due to the dragon's naturally resistance to magic. Very few mages are strong enough to actually damage a dragon with magic, aside from lucky eye shots. Their hides are also impervious to extreme bouts of heat, allowing them to actually swim through lava without being in danger.

While they are rather heavy, dragons are fast and nimble in the air. They are often referred to as 'Lords of the skies', though many flying races are disgruntled by this title. {Especially the pegasi.} There are several breed of dragons, but fire dragons are the most common. Each dragon type is able to spew a certain variety of 'breath' whether it be fire or ice or other such thing. They also have a natural immunity to their respective elements. However, fire dragons are the most versatile and hardiest of the lot, which is why they're the most common dragons across the globe. Dragons, in relation to their crocodilian ancestors, have a special palate at the back of the mouth which covers their throat when they breath fire or other materials to stop back tracking of their breath and self harm.

Dragon relations with others are the most stressed as their natural aggression is higher then the other species. They will routinely raid and plunder settlements across the globe freely and without remorse. This is why most dragons are hunted as soon as they are spotted, though most attempts end in failure.

Sea Serpent

Sea Serpents were originally their own family as there hadn't been much evidence to support their inclusion. {Even though some, including Starswirl himself, had proposed this theory in the past.} As well, sea serpents openly despise other dragons. There hasn't been a clear reason as to when this animosity sprung up, but scientists have attributed it to their aggressive dragon genes from their ancestors. Of course, it wasn't until the genetic structure of sea serpents and dragons were mapped out, and recent fossil finds, did similarities arise.

Akin to the relationship between pegasi and sea ponies, dragons and sea serpents can be derived from coastal populations. We can see some similarities in some coastal dragons who have a semi-aquatic lifestyle. Sea serpents have taken this life a step further. Sea serpents are the top predators of the sea. They easily outsize most other carnivorous aquatic creatures and their intelligence gives them a keen edge. Though, their solitary lifestyles do put them at a disadvantage when compared to family oriented species, such as Orcas.

Sea serpents, like most vertebrates, are four limbed with two of their appendages being atrophied over time. However, said atrophied limbs are to be found in different places in the species. The more commonly seen Sea serpents lost their front limbs. Their wings have thus evolved into make shift flippers. Some species still have the ability to fly for short distances, but most never use it more then to glide over the waves. This causes some confusion as they are sometimes mistaken for plesiosaurs when under the waves. This convergence in appearance and life style has allowed them to outcompete plesiosaurs in some areas. Sea serpents are still tied to land, so they will comunially come to shore to lay their eggs. This puts them at risk from predation as they are, mostly, easy targets as well as the eggs which they will leave once laid. Once hatched, the surviving younglings will form large pods for protection until they are old enough to go out on their own.

The other type, the more primitive river serpent, lost it's wings as it didn't need them for river travel. Instead, they use their arms to help pull them through rivers and through thick plant life. Of course, over generations, they have adopted a serpentine body and 'hair' like scales around their head. Sea serpents are also known to have these structures, but river serpents take them to another level. It is unknown why they have evolved as they do, though some scientists argue that they are for attracting mates. This, like their sea cousins, have caused some confusion as they are sometimes mistaken for Loongs.

River serpents have much better temperaments than most dragon species. They are known to be jolly and helpful, though rather timid creatures despite their size. It is considered good fortune to find a river serpent on a journey as they will happily help you cross rivers, take you up stream quickly, and help with directions.

Both species have lost their insatiable lust for jewels that other species of dragon have. This is mostly because their lifestyles don't benefit from this desire so they've grown out of it through the ages. Of course, sea serpents are picky when it comes to 'gastrolith's' which they used to help them grind up tougher meals.

Terran

Terran have been described as aspects of the earth and have been noted through several corpses and conversations to have lifespans that easily dwarf any other dragon. They are known to be rather mellow in nature, but still hold the same territorial aggression that most other dragon species have. However, unlike dragons of the air who use pre-existing shelters to house their treasure troves, Terrans create them theirselves. This is down to their digging expertise, being coined as 'earthworms' by Starswirl the Bearded.

He was almost swallowed hole by a Terran shortly after coining it.

However, the description is apt. Like many digging species, such as Diamond Dogs and Tatzleponies, Terrans find their homes underground. They can cut through just about any substance, even the hardest of metals with ease. As well, their hide is even thicker then Dragons. This makes them almost impervious to any attack aside from nothing short of a demi-god. Over the last few centuries, engineers have been trying to counter this impervious armor or even to replicate it. Not much has been found in this area, though some advancements have been made.

With all of this, Terrans are easily the strongest creatures on the planet. They can lift weights several times their own mass with ease. However, Terrans have been known to be slow on land. Their combined weight makes running long distances difficult, so Terrans are known to be better ambush predators. They dig out dens and fill them out over themselves with only the top of their head present, which is camoflagued. This is why their nostrils and eyes are located higher up on their skull. They have been known to wait for years, before making a kill. This plays into their mellow nature.

Of course, like most dragon species, their biggest threat is other dragons. With every race, besides Loong, cannibalism and eating other dragon species is rather common. This helps keep populations in check and route out potential rivals. Terrans don't have large clusters of eggs like most other dragons, instead having just 1-3, depending on the species. This means more care is given to select offspring and are raised for longer intervals. Males and females have been known to form life long bonds and given their lifespans, this is saying something.

Loong

As Dragons are lords of the air, Terrans lords of the earth, and sea serpents lords of the sea, Loong's are lords of magic. Loong's are creatures fueled by magic, which is why they can float in the air without the use of wings. They can create magical constructs and spells so powerful, that very few beings alive can even hope to match a regular Loong's. It has been said one Loong is the equivalent of a demi-god. Thankfully, Loong's are rather peaceful and are happy to share their vast knowledge.

Loong's crave knowledge themselves and they will happily trade gold, skills, or whatever they can find to know something new. Whether it be a riddle, book, or even a recipe. They crave it as much as most other dragon species crave jewels. Yes, Loong's do collect jewels as well as consume them, they don't do it as readily. It's more of a staple diet. This is mostly because of how their hide is constructed. Dragons and other species need readily available sources of jewels to keep healthy. Their hides depend on them to be kept hard as they are known to soften if dragons are deprived of their jewels. Loong's have evolved softer hides, so while they do need jewels for sustenance, they don't need it as badly. Instead, their scales have elongated, mimicking theropods and their proto-feathers. This adaptation has allowed them to dominate northern climates, where dragons are few in number.

Their serpentine form leads them to sometimes be mistaken for river serpents when they takes baths in rivers and lakes. Loong's find this a great insult and have been known to curse individuals who say such a thing. However, they are quick to forgive and the curse itself won't last long. Kitsune, the masters of illusion and curse magic, are said to have been told by the most ancient of Loong. Many believe it to be true, given how close the two species are with each other.

Wyvern

Wyvern's are considered proto-dragons and none of the other species will ever want to associate with them. This is because of how primitive wyverns are on an evolutionary scale. They are ancient throwbacks to the Cretaceous period and they haven't changed much since then. They lack any sort of sapient thought, combined with a dragon's aggression, and this leads to possibly a deadly combination. It's advised to never approach a wild wyvern because they will always go for the kill if they view their territory is in danger.

Wyverns are the only species of dragons to be cold-blooded, which restricts the species to warmer climates. This hasn't stopped them from being incredibly prosperous. They are known to be quick breeders and in some lands where other larger predators are scarce or driven off by sapients, they can easily become a deadly pest. Wyverns are rather sociable so they can sometimes form flocks that help hunt and locate larger prey over long distances. These packs don't have any real leader so squabbles over food are inevitable. This aggression leads to a number of deaths within the flock, but given their year round breeding cycle, they can easily make up for these losses.

Wyverns have been domesticated over the centuries. The ancient pegasi culture have been reported to have tamed wyverns over twelve thousand years ago. For the most part, wyverns are used as war mounts and to break enemy lines. Their aggressive nature makes it hard to do much else. However, some nobility have gone through great strains to domesticate some breeds to be rather docile or at least more tolerable to be around. This has had mild success, though wyverns are still used primarily for modern military units. Dragons and other species have no comment on this process, though it is polite to not ride wyverns while in their presence.

Kur

Said to be the oldest and most powerful dragon species in existence, Kur are shrouded by mystery. Only sparse information about them is known, mostly from Time Charger records, but what is known is rather terrifying. In prehistoric times, back before Equestria and rational pony thought, Kur were the dominate species on the planet. They were known to be massive, with some growing so large they could fit a whole Terran drake into their mouths and swallow them whole. By accounts, the Kur were a technologically advanced race able to conquer the stars. They were able to warp matter into anything they want and bend the laws of physics like a toy. Their empire was said to be limitless, but it is agreed that they were stationed here as their homeworld. Some have speculated that most dragon species owe them as their ancestor. As well as their hardiness, since it was said that Kur were impervious to most anything, even being able to survive the vacuum of space.

Kur held six eyes, each of which could see spectrums of light un-see-able by most creatures. It was nearly impossible to fool them with any bit of illusion as they could see right through it. Kur were said to have a great dislike for magic, which can be seen in many dragons today. Which is why upon meeting the ancients alicorns and their growing empire, war was inevitable. {It should also be noted that both sides were instigators, since Time Charger's assure us that alicorns were an incredibly expansionist race.} This war was said to have shaked the heavens and the very core of existence. The Kur's technology was able to match the alicorn's magic evenly and neither side would back down. Time Charger scholars have said that if the war had gone on any longer, all of existence would be destroyed.

Finally however, the war ended with both races being destroyed. The Kur had lost Equis, their homeworld, some ages ago, so life has been able to evolve well enough without them. We wouldn't know of them if not for the last Time Charger refugees from the war. With everything said and done, the species of Equis have much to be thankful. It seems that our world has been so saturated by magic, that the Kur would be cleansing it if they found it. We can rest in peace knowing that they are gone.

However, there are some concerns that not all the Kur had died out. Alicorns have of course been reborn on Equis and the ancient beast 'Nidhoggr' is believed to perhaps been a Kur. This is just speculation, but if it is true, then he still slumbers somewhere in the world. No one knows where, or if the story is true. That the World Tree keeps him at bay. Some say Celestia knows, but she avoids the question. Of course, no one dares to press our beloved Sun Goddess, who rules over us with benevolence, for questions she does not think worth answering. We must trust her judgement when she says that these fears will never come to pass.

Yet, there are reports of massive earthquakes during great upheavals in Equestria's history such as Nightmare Moon's betrayal or Discord's reign. The screaming that some claim to have heard was maddening and full of nothing but rage. I hope these are just rumors.

By Celestia, I hope they are just rumors.

{Sorry for the wait. Dragons were a tricky subject to tackle and I hope I did it well enough. Comment on feedback and if you found this helpful.}

This all so very fascinating, you're really put ton of effort into building this world. A few more things,

Is Spike a Terran dragon?

Which is why upon meeting the ancients alicorns and their growing empire

Wait, alicorns come from a different planet? Also I can't wait to hear more about the Time Chargers.

5167839 Spike is a Terran dragon. I never liked the theory that he'd grow wings. I know it's a world of magic, but that's pushing it. As well, there were plenty of earth dragons in mythology.

They did and thank you for the feedback.

5167856 You're welcome.

5167856 This is awsome. End of story.

5167647
how big/tall was the average Kur?

6105573
Average? The average could fit a full grown dragon in their mouth and swallow them whole.

6105662
I mean in metric height. Something like a 1,000 or whichever

6105678
Depended on the populations on some planets/systems. Usually, they would be around 800 - 1000 meters in length. Some were smaller and a rare few were even bigger.

So the Kur are basically dragon Daleks...

I really, really hope they're all gone. I mean, it's not like you'd have any need to bring them back, right?

Right?