They border the horizon, so far away from this watering hole, yet their presence cannot be denied. Ashes choke the sky, but also nourish the ground, allowing a small bosque of conifers to prosper around the water. This is a godsend to the local dinosaurs: sauropods travel far and wide across the desert, stopping here for a drink. Ornithischians and tritylodontid synapsids are smaller herbivore guilds, permanent and scarcer, watching for the careless bulk of the giants. Following their herds is a Dilophosaurus, laying in the shade, observing the herbivores relaxing in the pool, while a lone Kayentasuchus rests on the bank, the sourrounding animals giving its meat-slicing jaws a wide berth.
But flying above this scene are the by far most common animals, the pterosaurs. Flocks gather here, having flown great distances, their fluttering and calls drowning the air in a strange symphony. Several land in between the sauropod giants, their groups matting the ground and risingin multicoloured clouds each time a dinosaur comes near, while others climb the trunks like ancient squirrels - and not at all unlike the haramiyidans that they share their trees with. A few swim in the lake, bathing and removing excess dirt from their pelage, launching with vapid and rapid wing beats, joining the others above or in the ground. The vast majority, however, flies above, either to move from between roosting places or to arrive or leave.
Pterosaurs have greatly diversified in the Jurassic, producing a large variety of species from the terrestrial dimorphodontids to the hawking campylognathoidids. The ashes of the Triassic cataclysms opened up a myriad of new possibilities, and these flying animals wasted no time taking advantage, reclaiming old niches and claiming brand new ones. Size has also increased, some species reaching wingspans of 2 meters or more.
One species, however, dwarfs them all.
It starts as a shadow, soaring in the horizon, just closer than the mountain range, flying in from the southwest. It glides effortlessly in the desert thermals, much like the other pterosaurs, and it quickly speeds in, its wing beats sporadic and powerful. As it approaches, however, something seems off. Smaller pterosaurs get in the way, and they seem much, much smaller as they dart beneath the newcomer.
Eventually, it approaches the watering hole, and its full bulk is evident. Its wings shadow the open canopy, their span eclipsing even the sauropods aside from the very largest. Its arrival is met by a launching of many of the smaller pterosaurs, tiny flies compared to the newcomer. Dinosaurs and mammals eye it with caution, several of the smaller herbivores darting for safety. Even the Kayentasuchus is wary, bearing its jaws at the sky.
The giant circles the watering hole, looking for a good place to land. It eventually finds a fault in the tree line, just wide enough, and it descends, flapping its wings vigorously as it falls, its hindlegs absorbing the impact as the wilds fold, massive gorilla-like arms touching the ground while the wing-fingers rise as masts. As soon as it is grounded, it begins walking, surprisingly gracefully in an alien hopping motion, before crouching above the water. It wastes no time laying its toothed jaws on the surface.
This is a nomadic traveller, having flown far and wide across the globe. It has travelled over these arid lands for a while, and it sees fit to replenish its water supplies. Ideally, it would continue flying to the northeast until it reaches the Arctic coastline; this time of the year, the beaches are full of ammonite corpses, which vagrants like this tend to take advantage off. The migrant itself has flown over there many times over the years, the route well carved into its brain.
For now, however, it rests: after drinking its fill, it retreats to the shadow, laying cumbersomely on its side, wings and legs free to stretch. The Dilophosaurus is not far, and even at its massive size the pterosaur is vulnerable, though far from defenseless. The dinosaur begins to rise, but the flyer flashes its toothed jaws, prompting it to sit down again. Relaxed again, the pterosaur grooms its pelage with the long and thick teeth. The tail flaps on the ground, leaving small puffs of dust.
Above, smaller pterosaurs begin gathering. They begin threat displays, various hisses and tail swipes, some even landing on the ground to bite the giant's tail. They begin also piling up on the Dilophosaurus, pecking at its tail and sides. Already nervous, the theeropod rises and runs away, prompting a chain reaction and leading more pterosaurs to chase after it, leaving the resting giant alone. It, however, can't stick around for much longer, as the dinosaur outruns its aerial pursuers.
Slowly and deliberately, the massive pterosaur rises once more, balancing itself with its powerful forelimbs. Its tail swats a smaller harasser, and it walks away. If landing was difficult, launching will be even more so. It walks up to the borders of the bosque, a small elevation granting it convenient - though not necessary - high ground. Crouching, it vaults. It takes a few tries, but several pushups with its massive arms eventually propel the animal out of the ground, a high enough stroke clearing room for the massive wings to flap and immediately ascend the animal's bulk.
All of this happens in the span of a few seconds, the titan once again airbone. It circles above the watering hole one last time, rising in the thermals, before it finally flies towards the northeast, its size quickly decreasing again as it glides towards the horizon.
Then a bomb detonates and kills everyone. Amen.