“…The northern cliffs of the small continent Hatèmica are adorned with fossils ranging from small plant remains to giant petrified “trees” to bones of ancient megafauna just sticking out.
Dated back to the Recrescian epoch of the Anaktisian period between 100 and 95 million years ago, these cliffs perfectly show how life recovered after the fallout of the “great extinction”(the cause of which is still the subject of heated debate) had subsided.”
“…While the site has yielded many important fossils already, the most significant is a collection of small Eusymmetrodactyl Cryptognathan Anisospondyls that appear to be at the very base of one of the most successful Anisospondyl lineages alive: the Stauropterygia, colloquially known as X-wing(bird)s.”
“…So far, five different genera of basal Stauroptergyians have been identified. They were all found in the same layer, so it’s safe to assume they (partially) coexisted with each other. What’s interesting is that they appear to all be different stages of X-wing evolution, which probably means they carved out niches for themselves that were not occupied before.”
“…These fossils show very clearly that the X-wings ancestrally, have an zygodactyl orientation of the toes on the hind limbs, as was suspected for a long time but never truly confirmed.”
Dated back to the Recrescian epoch of the Anaktisian period between 100 and 95 million years ago, these cliffs perfectly show how life recovered after the fallout of the “great extinction”(the cause of which is still the subject of heated debate) had subsided.”
“…While the site has yielded many important fossils already, the most significant is a collection of small Eusymmetrodactyl Cryptognathan Anisospondyls that appear to be at the very base of one of the most successful Anisospondyl lineages alive: the Stauropterygia, colloquially known as X-wing(bird)s.”
“…So far, five different genera of basal Stauroptergyians have been identified. They were all found in the same layer, so it’s safe to assume they (partially) coexisted with each other. What’s interesting is that they appear to all be different stages of X-wing evolution, which probably means they carved out niches for themselves that were not occupied before.”
“…These fossils show very clearly that the X-wings ancestrally, have an zygodactyl orientation of the toes on the hind limbs, as was suspected for a long time but never truly confirmed.”
1. Eostauropteryx: To this day, this is the most basal X-wing ever discovered. Based on its arm bones, sternum and shoulder blades, Eostauropteryx has been determined to have been incapable of flight and was instead a glider. Similar to what could be expected from a primitive flyer, it still had claws on both of its free fingers. While all modern X-wings are endothermic, it’s unsure whether Eostauropteryx was too given how basal it is, but since many other Eusymmetrodactyls are mesothermic or endothermic as well, it’s possible the trait is ancestral to all.
2. Isomikopus: While todays X-wings are almost exclusively bipedal, Isomikopus with its short hind legs and sturdy front limbs proves they didn’t start out this way. Instead the earliest X-wings appear to have been quadrupedal. Using the caecal front limbs for walking while the visendal front limbs were kept retracted. It’s not clear of Isomikopus was a powered flyer or not, as the morphology of its sternum and arm bones seems in an intermediate state. Based on the fact that the interior most finger of the wings misses a claw, it is clear however than Isomikopus is more derived than Eostauropteryx.
3. Disparoclavavis: Curiously, among the many primitive Stauropterygians, a much more modern seeming one was found. Unlike the other genera in the site, Disparoclavavis was completely bipedal and in many ways already resembles modern X-wings much more than the others. Based on its sternum and its long hind limbs, it was fully powered flyer capable of liftoff from the ground. The claws of the visendal wings were also much smaller than those on the caecal wings, which might mean they were used in combat.
4. Bellatovolans: The size of a small hawk, Bellatovolans was the biggest flying vertebrate on Eryobis since the end of the Bobossic period. Based on its dentition and large talons, it was an active and fearsome predator for everything that lived in the canopy. One specimen was even found to still have the remains of its last meal inside; which appeared as if they belonged to another, smaller Stauropterygian.
5. Ischyropollex: Based on its slender sternum and the fact it retains 2 claws on each wing, it was determined that Ischyropollex was a glider and not a powered flyer. Unlike Eostauropteryx however, Ischyropollex had very powerful hind legs and strong arm muscles which probably made it a powerful jumper capable of gliding long distances.
“…The species we’ve found so far have already given a great insight into how Anisospondyls took flight the first time. We’ve only barely breached the surface of these fossil ridden cliffs, so who knows how many more will be discovered in the coming years…”
“…The species we’ve found so far have already given a great insight into how Anisospondyls took flight the first time. We’ve only barely breached the surface of these fossil ridden cliffs, so who knows how many more will be discovered in the coming years…”
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