Hornitos Formation, Chile, 82 million years ago

No part of planet Earth is endless. Every vast stretch of dry land is bound to be interrupted by some form of water, just as the reverse is true. Even the deepest, darkest depths of the oceans eventually end in the sea floor. The closest the world has is a part only visited by a few: the sky.

It appears as an eternal, ethereal expanse of pure, translucent blue, reaching as far as the eye can see. The mid-day sun stands prominently amidst this sapphire backdrop, radiating light with a sharp intensity. Golden-yellow beams shimmer off the crisp edges of cool gray puffs.

Made up of cold air, these clouds appear in varying numbers, shapes, and sizes across the heavens. Each gently drifts at a leisurely, barely noticeable speed. Occasionally, wisps of vapor curl and dance around these masses, caught in the unseen winds of the high altitude.

Few forms of life have achieved the ability to reach these heights even in our modern day. Here in the Late Cretaceous, this space belongs to something unrecognizable to human eyes. Their forms serve as relics of this long-forgotten period of Earth's history. With occasional, thunderous wingbeats, they glide through the air as if floating through the ocean. They're not birds as would be seen today, but rather reptiles.

This is a pair of Thanatosdrakons, a type of pterosaur that roams the skies above South America. They specifically belong to a peculiar family within this famous order of flying reptiles, the azhdarchids, as signified by their pointed, spear-like beaks and sinuous, serpent-like necks. Although still young, their massive, membranous wings spread out to 20 feet in length. On the tops of their heads and behind their obsidian black beaks are proportionately small, semi-circular crests. Their eyes are large, deep-set, and piercing, with rich amber irises. Much of their bodies are covered in solid black, fur-like pycnofibers with a collar of white. Their feet, necks, and heads are devoid of such plumage, exposing their rustic red, scaly skin. As they're both males, their crests are painted in a much brighter shade of crimson.

Once, Thanatosdrakons reigned across the South American skies. Unfortunately, these aerial titans have been on the decline in the past few million years. Thus, these brothers, Rafael and Gabriel, are among the last of their kind.

Their only goal now is to simply survive. To do that, they'll need to find resources like food and water, something vital to maintaining their colossal size. Such needs won't be met in the serene realm of the sky. Their search demands they descend beyond the veil of clouds, revealing the world that lies below.

***

Emerging from the heavens reveals the western edge of South America. Here lies what will one day be the country of Chile. Where Rafael and Gabriel are soaring will be a dry expanse of rocky desert, salt flats, and barren hills in the shadow of the Andes Mountains to the east. The few remaining plants are sparse and drought-resistant, adapted to the hyper-arid, near-rainless Atacama. Wind and the occasional flash floods would engrave canyons and valleys out of much of the terrain. Temperatures in the area would regularly rocket past 95 degrees Fahrenheit.

The land that the Thanatosdrakons are reaching is drastically different. The scenery is much lusher, dominated by an array of ferns, cycads, seed ferns, horsetails, and araucaria trees. Despite still being warm, cooler, humid air permeates this semi-tropical landscape. Connected rivers and lakes snake across this verdant environment.

It's at one of the larger ponds that these airborne brothers descend. Gently, Rafael and Gabriel land on the stony edge of the freshwater reservoir. The thunderous flaps of their wings fade to silence as they fold them backward. Upon touching the ground, flight immediately transforms into steady walking.

Now on all fours, both Thanatosdrakons leisurely tread to the fringe of the lagoon. They dip their long beaks part-way into the water before pulling upward, taking in whatever bit of water they can at a time. The process repeats as both brothers refresh themselves with pure hydration, an essential routine for these titanic travelers on their grandiose journeys.

Their drinking, like the environment around them, is calm and serene. Quickly, this quiet is terminated as Gabriel makes an unwitting mistake. His beak only touches that of his brother, but it's enough to prompt Rafael to recoil. The two Thanatosdrakons exchange these beak clacks and a few honks before Gabriel backs off. These brothers are the same in both age and size, yet Rafael has time and time again proven himself to be the more dominant of the two. All Gabriel can do is simply wait for the moment he may finally escape the shadow of his sibling's supremacy.

From where they stand, the Thanatosdrakons gain a glimpse of the diverse array of wildlife that dwells here. Below the sparkling surface of the freshwater, fish swarm and float about, sucking up any bits of algae or insect larvae they can find. The air above is the domain of several winged insects such as flies, dragonflies, and beetles. Hidden by the forest floor, crickets make their presence known through constant chirping while millipedes silently forage for food. Shimmering silk webs rest on a few of the many trees, spiders sticking to them in wait for prey.

These creatures share this ecosystem with a larger, more prominent group of animals. They've spread all across the world, ruling for nearly 120 million years. These dominant lifeforms would go on to be known as the dinosaurs.

The smallest of them is a type of two-legged herbivore named Gasparinasaura. These Labrador-sized dinosaurs have compact, streamlined bodies built for speed and agility. Long, powerful legs add to this, aiding them in their swift, bounding strides across the forest floor. Relatively short yet flexible arms are present too, ending in three fingers with small, slightly curved claws. Stiff, lengthy tails are held out behind them, acting as a counterbalance during their movements. Their necks are lengthy and graceful, giving them an elegant, almost bird-like posture. Atop them are sleek, narrow heads with slightly rounded snouts. Large, deep amber, almond-shaped eyes dominate their face, gleaming with alertness and curiosity. Strong yet slender jaws are tipped with a keratinous beak and lined with small, leaf-shaped teeth, perfect for slicing up vegetation. Their skin is primarily covered in dark gray, bird-like scales with little patches of brighter, golden brown around their eyes. Their heads and torsos are a slightly iridescent muddy green, with males having tall crests of this plumage atop their skulls.

Joining them in their browsing are herds of Secernosaurus. These are a type of "duck-billed" hadrosaur, a family that although widespread is rarely seen outside of Asia and North America. It's only thanks to a temporary land bridge to South America that it and other members of this famous group have been able to populate the continent.

Their bodies are lean and lightweight, growing up to 16 feet in length. The rear legs are long and powerful, built for rapid movement when on two legs. The front ones are much shorter yet still just as strong. While the back legs end in the traditional three toes of many dinosaurs, each of their front ones ends in a keratinous, hoof-like nail. Lengthy, rigid tails help provide balance to their overall forms. Short, gently curved necks connect their bodies to slightly elongated heads. They taper into a gently rounded snout with a smooth, keratinous beak and mouth filled with large, tightly packed, diamond-shaped teeth. Two expressive eyes rest atop these heads, framed by a faint ring of dark scales. The majority of their skin is primarily a sandy brown with mottled spots and horizontal stripes of rust with a dull gray underbelly. Males stand out with bright blue staining their noses.

Normally, both Secernosaurus and Gasparinasaura would be more commonly seen further east in nearby Argentina. However, seasonal droughts in their usual habitats have forced these herds to migrate, seeking refuge wherever they can. Northern Chile, with its verdant ponds and forests, has become one such sanctuary, a short-term haven in a time of scarcity.

But among these visitors are residents that remain here year-round. They're also the largest animal here aside from the Thanatosdrakons. These are Arackar, a type of long-necked sauropod whose name comes from the Kunza word for "skeleton." At up to 21 feet in length, they'd easily be outsized by the many other whale-sized sauropods of South America. It's isolation in these forests and the surrounding harsher landscapes that have stunted their growth, allowing them to require less food and water per day to survive.

Their bodies are compact and rounded, their rib cages swelling outward to house enormous lungs and digestive organs. Four robust, pillar-like limbs support their bulk with ease, ending in broad, circular feet with small, blunt, clawed toes. Their tails are long and tapering, acting as a counterbalance as they gently sway back and forth. Long, S-curved necks rise gracefully from their shoulders, lifting their small, stream-lined, wedge-shaped heads over 8 feet off the ground. This posture allows them to reach the many tree branches around them, stripping them with their rows of slender, peg-like teeth before swallowing. Atop their angular skulls are subtle ridges above large, vigilant eyes. Their scaly, weathered skin is mainly gray-brown with a lighter, dull underbelly.

Indeed, many herbivores have claimed this as a sanctum from the harsher world around them. In the process of feeding on the plentiful vegetation, they add a variety of sounds to the forest ambiance, in addition to snaps and munches. Gasparinasaura produce soft coos and trills while Secernosaurus produce honks and grunts and Arackars make several rumbles, booms and creaking groans.

However, not all is perfect in this Cretaceous Eden. On the horizon, the Thanatosdrakons see a distant yet dreadful sign. A haze of thick, black smoke rises into the air, merging with the clouds above. The residents of these forests instinctively know what it means and therefore keep a far distance from the origin of this shroud. While the Gasparinasauras, Secernosaurus, and Arackars may flee from this growing smog, Rafael and Gabriel are allured by it. Thus, having hydrated themselves, they flap their wings and take off, flying towards the shadowy clouds like moths to a flame.

***

Soaring past the Chilean forest and its surrounding freshwater, the Thanatosdrakons spot the origins of the smoke. It's a natural force capable of both cleansing and destruction. An element that's at this point, beyond control: fire.

Flames have consumed the edges of the forest, decimating all in its path. Any signs of vibrant greenery behind the blaze are entirely absent. In its place is scorched earth covered in black ash and a handful of leafless trees.

Fortunately for the wider woodlands, the inferno has already begun to die down. As each pyre of flame diminishes, the overall rate of burning decreases dramatically. Wildfires like these are somewhat common, allowing for the local plant life to eventually be reborn stronger and healthier from the ash.

These fiery episodes may be temporary, but they're a symptom of a more permanent part of this environment. Outside the borders of this idyllic forest and its bodies of water lies a much harsher landscape. It's one dominated by nature's most destructive superpower, one that is powered by the blood of the earth itself: lava.

Beyond the lands of lush vegetation, volcanoes rule over a charred, arid landscape. Periodically, they spew ash and magma from their exposed summits, crowding the atmosphere with deadly greenhouse gases. Settled mountains are also the start of lahars, flows of mud, water, and rocky debris that veer onto the ground below as rivers of ashen gray. Those still active spill tons of glowing red lava onto the landscape.

These rivers of molten igneous twist across a scarred, black terrain. Solid basalt stone rests among fields of ash and pebbly dirt. Some of these rocks, shaped like termite mounds are known as hornitos. These pipe-like structures are formed by lava spewing from the crust, with some still leaking it long after hardening.

Much like the forests that were visited by the Thanatosdrakons, lakes are present, albeit in smaller quantities and sizes. The water is also drastically different, being muddy and cloudy. This coloration mixes with bits of white around the edges of these pools. Only a high volume of sulfuric acid can shape these puddles in such a manner. Doing so also heavily increased their acidity, making them highly toxic to most living things. Only small microorganisms can live in these extreme bodies of liquid without the risk of burning. The same water is shot out of nearby geysers, sending it 10s of feet into the air at a boiling 400 degrees Fahrenheit.

Amidst the hazy, smog-ridden sky above, Rafael and Gabriel can still be seen soaring through. Even in such a hazardous hellscape, these brothers aren't turned away from their goal. What lures them here isn't any life but rather death.

At random parts of these volcanic fields are the corpses of Arackar. In failing to escape the erupting mesas, they succumb to both burns and toxic gases. All that remains of them are charred, inanimate husks of flesh and bone. Most corpses that aren't already swallowed up by magma are small scraps of their former selves.

On the rare occasion, there'd be one Arackar body almost completely intact. Their presence serves as a reminder of the deadly, natural power behind this Chilean landscape. For the brothers, they serve a different purpose: food.

Like most other pterosaurs, Thanatosdrakons primarily eat meat. Often, they'd get such sustenance from fish or smaller land animals. Though in trying times when their species is dying and food is harder to come by, Thanatosdrakons like Rafael and Gabriel are more than willing to resort to scavenging. Thus, once they find an intact Arackar, they immediately begin to descend towards it.

Growing closer to the corpse reveals that another carnivore has spotted it as well. Called Aucasaurus, it's a member of the abelisaur family of two-legged, theropod dinosaurs. The group as a whole is highly common throughout the southern hemisphere, this species in particular is primarily known from western Argentina. Despite its outside origins, even it is drawn to this volcanic range by the stench of decay.

At 20 feet long and weighing one-and-a-half tons, its robust, stocky form is medium by the standards of other abelisaurs. Long, powerful hind legs help support its compact, barrel-shaped body. As with all abelisaurs, its backward-facing arms are small and stubby, bordering on vestigial. A lengthy, tapering tail helps provide a counterbalance to its sturdy build. Supported by a thick, muscular neck is a heavy, blunt, wide head with a deep snout that suddenly rounds at the tip. Hidden by its lips are jaws lined with short, thick, serrated teeth, perfect for gripping and slicing fresh. Small, bony crests rest above each of its piercing, golden-yellow eyes. Its skin is primarily a mosaic of brownish-gray non-overlapping scales interrupted by black, randomly placed, conical studs.

With an easy meal in sight, the Aucasaurus leisurely draws closer to the dead Arackar. Its salivated jaws creep open, preparing to bite into a mass of plentiful flesh. Suddenly, its approach is paused upon witnessing Rafael and Gabriel drop in front of it.

The Thanatosdrakons attempt to scare away the rival meat-eater by clacking their beaks and honking at it. Staring upward, the Aucasaurus lets out a series of growls and grumbles. For a while, both sides remain undeterred by one another.

Eventually, the brothers' imposing size and sharp bills prove to be too much for the Aucasaurus. Thus, the predator backs away before turning around. In its retreat, the wandering dinosaur vanishes into the smoke permeating the environment.

At last, the Thanatosdrakons have succeeded in claiming the corpse. Now the two are free to feast on their heart's desires. Gabriel is the first to attempt digging his beak in the dead Arackar, eager to taste the barbecued meat inside. Instantly, his bite is halted as he gets knocked away from the remains.

He swerves his head to his left to find the culprit of such a blow: Rafael. As the dominant brother, it's he who gets a bite of any food they find. Thus, as the lesser sibling backs away, Rafael begins to poke his beak into the seared flesh.

Suddenly, his feast ends as Gabriel shoves him away. The Thanatosdrakons lock eyes with one another, each sending out a series of hostile honks. Even as each subsequent combative call increases in volume and frequency, neither brother flinches from their stance.

As these savage sounds fade into silence, Rafael and Gabriel's conflict quickly becomes physical. Using their sharp bills, each one stabs and bites at the other. Many of these strikes are dodged by the brothers, but often narrowly. Small gashes and cuts form on the skin of their faces and necks, blood slightly leaking from these exposed wounds.

Finally, Gabriel attacks his rival sibling with a massive shove. Caught off guard, Rafael tumbles backward, kicking up dirt and ash upon landing on the ground. Standing over his fallen adversary, Gabriel honks aggressively at his once-dominant brother. These threatening sounds persist until Rafael takes off away from the corpse.

At last, Gabriel is victorious. Now this Thanatosdrakon will be able to feast on the dead Arackar, free of his brother's authority. He relishes this moment by gorging down on the body's contents, ravenously consuming as much as he can fit in his mouth.

Unfortunately, this youngster's troubles are far from over. Gabriel's ears pick up an ominous sound, one of deep, thunder-like flaps. They're the same as heard whenever he or his brother are flying, but these are a much lower sound. A gigantic shadow also travels across him, entrapping him in darkness. The traveling silhouette pauses as a loud honk appears behind Gabriel followed by a massive thud.

Shaken by these signs, he slowly turns his body around. Glancing upward reveals the source of such a foreboding presence: an adult Thanatosdrakon. Named Maximo, this male towers over Gabriel at a height of 20 feet and a wingspan of 30. Such size and intimidating presence easily earns him a species name that means "dragon of death."

Upon seeing the younger Thanatosdrakon, Maximo lets out another honk, seemingly deafening all other sounds around him. Gabriel doesn't move an inch, paralyzed with fear. Only once the adult snaps his bill at his younger adversary, he jumps backward. Standing over the dead Arackar, Maximo asserts his authority once more by fending off his younger rival with more honks and beak clacks.

Alas, Gabriel's efforts have gone to waste. He can't even fight back as taking on an adult Thanatosdrakon alone would be suicide. Now, all he can do is watch as the mature male devours parts of the carcass.

Maximo's beak stabs the charred flesh with ease, the sickening sound of tearing meat filling the air. Chunks vanish into his throat, each swallow punctuated by a deep gulp.

Amidst these guttural sounds, another sound starts to be heard. At first, they appear faint and distant but grow louder with each passing second. Maximo turns to his left as the sounds hit their peak, but is met by the sight of another young Thanatosdrakon: Rafael.

Preemptively, the larger male honks, only to suddenly be knocked back as the returning brother lands on his body. Maximo easily pushes Rafael away with a single swipe of his left wing. Meanwhile, on the right, Gabriel attacks as well, biting and spearing the titan's membrane. The adult turns again, honking and clacking at the younger flyer. As he does, Rafael attacks once again, snapping his beak at the giant's vulnerable neck.

Maximo's body shakes and turns all around, forcing both brothers off him. Though the attack has been brief, he's left with all sorts of small cuts and gashes on his neck and right wing. Although still towering over the two, his presence doesn't deter either Rafael or Gabriel. Together again, it's they who start shooing him away with honks and beak clacks. Injured and outmatched, Maximo shoots the brothers one last, smoldering glance flapping his arms. Laboriously, he flies away, remaining low due to his injuries. The flapping sounds of his departure fade into silence as he disappears in the smog-ridden clouds above.

At last, the dead Arackar belongs to Rafael and Gabriel once again. Tired and bruised, the brothers shift their attention to one another. This time, they don't bicker, honk, or clack their beaks. Rather, they begin to feast on separate parts of their reclaimed carcass. Once starting, they don't hesitate in rapidly gulping down any meat they can stuff down their gullets.

Sibling rivalry is an often-intense conflict that persists even in the natural world. The urge to survive and prove one's strength creates a perfect storm of conflict for those like the young Thanatosdrakons. In the end, the mutual goal is to pull through in this harsh landscape allowing Rafael and Gabriel to rise above their rivalry. Until they're old enough to travel on their own, only working together can ensure the shared survival of these brothers in wings.

Chapter art by u/Spinosaurenjoyer on Reddit