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Pterosaur Ecology Scenario

November 27, 2014

A little speculative biology tale, depicting exactly what it says on the title.

***

It is midday, at the very beginning of Autumn, in northeastern North America, where in another world would be Labrador. Dense, coniferous boreal forests spread wherever the eye can see, around the northern ragged ends of the Appalachians, stopping only by bodies of water. Glaciars can be seen on the northern mountain valleys, but otherwise snow and ice still haven’t claimed the landscape. In the few places not covered by conifers, vegetation is dominated by tones of brown, like in the clearings that sorround a lake-wetland complex in a valley.

Here, the reeds are of a deathly brown-gold, as are the the sorrounding meadows, between the woods covering the mountain sides and the waterline. Several parts of the shores are now visible, but most of the muddy substrate remains covered by adjacent plants like reeds, horsetails and shrubs. Waterfowl and other birds wade around in the water or forage around for seeds and insects, and joining them are the other group of flying sauropsids, the pterosaurs.

Upnorth, pterosaur diversity is not particularly high, as while the endothermic metabolism of the animals and their thick pelts are just as efficient on them as feathers and fur are for dinosaurs and mammals, their need to bury their eggs like most sauropsids do means that they find little suitable incubation sites, particularly on permafrost territory. Nonetheless, some have persisted, and nearly all solved this problem the same way: by giving birth to live young, just like the local lizards and snakes. For flying animals with superprecocial habits, this is not an ideal arrangement, but nonetheless it worked, and now the relatively few species that occur here do so by the numbers of individual thousands, easily the most identifiable members of the local megafauna.

One of the most prolific species around is the Gans (Xenocygnus canagica), a rather large animal with a wingspan of 3.5 meters and a height of 1.70 meters, thanks in part to its long neck. Part of the ever diverse lineage that is Ctenochasmatoidea, this animal bears the distinctive comb-like dentition iconic to these animals, lining along both the upper and lower jaws. However, it has a distinctively short snout for this clade’s standards, ending in a wide keratinous beak. As such, it has a rather diverse diet: either it dabbles on the water for aquatic plants, or grazes on land. Consequently, it’s no wonder Gans flocks are the most observable local pterosaur biota, gathering in the thousans as they forage or rest.

Overall, the Gans is a perfect example of an arctic animal: large, robust, and with short extremities. Some of its characteristics aren’t new in its clade: similarly short limbs and a huge body have been invented long ago in the Cretaceous, but these exaptations serve well regardless. It bears a thick gray or brown pelt with small gold spots along the back and a white ring around the neck and shoulders, with black wing membranes; during summer months, the males produce a pink keratinous crest that runs along the upper jaw, but they have fallen off long ago by now. The tail is about as small as it gets by pterosaur standards, though looking considerably larger due to the thick pycnofiber coat that covers like, like a flufflier version of a bear’s tail. Pycnofibers cover the arms and legs (and associated patagia, like the entire propatagium and the cruropatagia) down to the toes in thick coats, the mammalian-esque footpads being the only presence of scales as with all pterosaurs. The naked snout is of an orange color in Summer, sans for the black keratinous tips, but now its of a dull gray.

Several Gans stay on land, grazing or resting, their long necks often high in vigilance for predators, though several still still around. The water has beginning to freeze, but it does seem to bother the aquatic foragers much. Alongside the swimming Gans are several water birds like ducks and loons, as well as another pterosaur, the Northern Dewb (Anatocifer borealis). A boreopterid, the Northern Dweb reaches a slightly smaller wingspan at 3.3 meters, and is a rather less opulent animal, having the same short torso and small hinglimbs as most of its relatives. Its entire body is covered by a thick pelt, aside from the brachiopatagia, snout, eyes and footpads, coloured black in the head and tail, beige in the belly and brown in the upper torso and limbs, with the exposed wing membranes being black. The snout is of a yellowish gray tone, bearing a single bony crest on the lower jaw.

Possessing the same long, fine teeth as most of its kin, it feeds on aquatic plants, crayfish and other invertebrates, small fish and the occasional amphibian, diving its long jaws and neck to forage in the bottom while the body remains afloat like a waterfowl. Most have already departed, being among the first migrants to go, but a few still forage, perhaps youngsters that matured late or adult males still attached to their territories, building up reserves as fast as they can to compensate for the intense Summer fights. One thing is clear, though, any who remain for much longer will die soon in the extreme winter temperatures.

The same applies to most of the Gans, who have kept exploiting what little nourishment still remains on land, quickly vanishing as they and the birds consume whatever is left. Some groups take the advantage of the sunny weather to start the journey: a small flock of young individuals takes off, beating their wings franticly, quickly covering most of the valley before they surpass the highest trees, disappearing from sight. An old Northern Dewb follows their example: raising his wings, they come clashing against the water in a splash, starting the relatively brief but intense water-based take-off so common among its kin. In a few minutes, he is in the air, flapping his broad wings vigorously until he is some ten meters high, before soaring.

However, he chose to do this at the worse possible moment. From above, at a diagonal level, a smaller flyer dives in fast. The animal is about a third of the size of the boreopterid, rather accurately thanks to the similar limb and torso proportions, but the impact is devastating, its powerful jaws making contact with the neck in the fraction of a second, sharp and serrated teeth piercing the throat. Both animals are sent spiralling down, landing on the meadows at the edge of the forest, their fall softened by the Northern Dewb’s massive wings. Somewhat stunned by the attack and fall, the larger pterosaur puts up a fight, using his powerful wings to try to beat the attacker, but the asphyxiation and shock weaken him to a point where he can’t fight anymore. He is still alive, but the predator dislodges his teeth from the neck and begins to rip off the thick pelt of the Northern Dewb’s shoulders until the skin is exposed, and promptly begins to eat him alive.

The attacker is an American Wyvern (Amphipterus morrisii), a good example of a campylognathoidid. These pterosaurs, already specialised hawkers in the Jurassic, ultimately didn’t need to change much, aside from more extensive pneumatisation and more lethal jaws. With a snout rather superficially similar to that of avisaurid and dromaeosaurid birds, wyverns are exemplar a testament to the progressive speciation to this lifestyle, the raptors of the pterosaur world.

This is a young male, the only survivor of his brood. Spending the Summer scavenging or eating small birds and mammals, this is his first kill as a functional adult. Far from fully grown yet, this is an impressive, but extremely lucky kill, as only 1 out of 10 strikes results in a successful meal, let alone one out of a much larger pterosaur. His body is covered by a silver pelt, with dark brown patagia uppersides and a white underside. His eyes are of a diluted blue, contrasting to the blood that quickly begins cover his snout as he rips the powerful boreopterid wing muscles out. He eats as fast as he can, being unable to carry the kill away and thus being stuck on the ground with it.

Alas, such vulnerability eventually plays out for the worst. As the Northern Dewb is dead, and most of the back and left arm are decarnated, a shadow is cast from the air. It belongs to a Pied Piasa(Euamericanum leucocephalus), a massive ornithocheirid with a 6 meter long wingspan. It bears a dark brown body and wings, yellow jaws and a white head and cruropatagia. Largely a piscivore, hunting on the wing both in inland lakes and in coastlines, it is happy to scavenge, and it circles above the American Wyvern and his prey, descending slowly.

Noticing the larger predator, the young male crouches and hisses, puffing his coat and showing his wings in a rather owl-like fashion. It fails to drive the Pied Piasa away, who lands to his left, head and chest high in a confident, yet cautious exhibition. As the much larger jaws open as a threat, the wyvern has no other choice but to leave, launching himself quickly and lfying away, as the thief leisurely begins to eat. As the Pied Piasa’s powerful jaws slowly remove massive chunks of flesh, the American Wyvern gains altitude, trying one last shot at hunting in this area before migrating south.

Meanwhile, to the dense forests, another pterosaur is on the hunt. In spite of the name, the Lapp Mocho (Catha borealis) occurs in a circum-arctic distribution, across the northern forests of Scandinavia, Siberia and North America. It is a rather large anurognathid, with a wingspan of 1.5 meters. With a thick white pelt with brown jaguar-like spots that covers the entire wing membranes, it is one of the very few non-migratory pterosaurs in the region, hunting in the northern forests all year round. With its large eyes and pycnofiber facial disk, it is well adapted to hunt in the darkness.

This is an old female, resting on the branches of a spruce. She does not mind hunting during the day, as she has done throught the Summer, but for now she simply waits, eyes semi-closed as she hangs on to her roost. Cautiously, she stretches one of her wings, quickly closing it as to avoid drawing attention to herself. She is most definitely not safe from aerial predators, avian or pterosaurian, until the snow starts falling and she is the largest aerial predator around.

Predictably, revealing herself does not end well. Beneath her, a pair of Krawos (Dracocorvus corax) begins hissing and screeching, puffing up their coats. The Krawos is a species of rather typical scaphognathine, primarily black in colour except for the bright yellow eyes. Omnivorous and opportunistic, the two males were drinking sap from a hole left by a woodpecker, but now they interrupt this as a very real threat to their survival is nearby. One of them hops his way squirrel-style up the trunk, until he is near the Lapp Mocho’s branch, agressively hissing and puffing.

The anurognathid hisses and puffs back, and this prompts the other male to take off and land on her branch. Before she can react the other strikes, biting her wing and then retreating, forcing her to take off. The two chase after her, biting her wings and back, until they cease to chase after her and return to their tree. Not seriously injured, the Lapp Mocho looks for a better roost.

She finds one in the slopes of a mountain, where the trees rarify before the upland meadows, where an old cypress offering a large hole which she uses to hide herself in. Before her, another spectacle takes place: a flock of Montane Camox (Capralagopus vulgaris) is foraging on shrub twigs and berries. These pterosaurs are tapejarids, well adapted to life in the cold with their thick pelts that cover even their wing membranes. During Spring and Summer, this coat is of various shades of brown, but now it is pearly white, with a few brown spots on some individuals, contrasting against their black beaks and headcreasts.

During this time of year, both sexes exhibiting massive headcrests and a long yellow-cream beard, bellowing and clapping the beak, as they execute their mating rituals. Both sexes engage in extensive mate competition, seeking to form pairs that will last throught the Winter, before disbanding in Spring. It is thought to be a strategy to survive the harsher part of the year, the gravid female being supported by her partner until she gives birth in the Spring, lending then the flaplings to the male to raise for the first few weeks. The Montane Camox is one of the few pterosaurs that doesn’t migrate, instead simply moving from their home in the highlands to the forest valleys, where they will spend the winter feeding on bark, twigs and needles.

A female spots a partner at the edges of the flock, browsing on a birch shrub. Coming towards him, she bobs the head up and down, clapping the beak. He responds with the same gesture, and both beging jumping in circles around each other like goats, beginning their courtship dance. However, a larger male flies in their direction, attacking the smaller one by grabbing on to his shoulders with the beak and kicking with the forelimbs. The female intervenes, attacking the intruder, biting the back and beating her wings. He releases her partner, biting her face and eventually gouging out her right eye. The other male joins the fight, biting the wing membranes of the attacker and pushing violently, starting to causing bleeding.

Suddenly, the rest of the Montane Camoxes fly off, as the American Wyvern flies above. Circling the distracted trio, the quickly dives, closing his wings and falling rapidly, opening them only when he is one meter away from the central target.

He falls on the attacking male, his body landing on his torso. Before he can react, the predator’s jaws are on the nape, and the teeth bury into the throat. The other Montane Camoxes hiss and stomp the ground agressively, but he doesn’t pay attention, until the female bites his tail. The American Wyvern hisses, and the two tapejarids launch away, resuming their courtship elsewhere. After they leave, the young male looks around, and drags the carcasse uphill, into the wide, open space away from forest predators. He takes off with the corpse, and lands a few meters above in a rocky outcrop, where he proceeds to eat.

When the Sun sets a few hours later, the carcasse is a bloody and torn mess, the head and neck largely intact but the limbs utterly decarnated and torn, the torso opened and hallowed out and chunks of ligaments covering the reddened bones. The Krawos made their way here, but they don’t dare to leave the safety of the forest canopy, huddling instead against each other.

The Lapp Mocho leaves her hole, and takes off. She didn’t notice her former tormentors, and probably forgot about them by then, instead starting what she will do for the next six months.

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