When the argusraptor complex evolved, they were extremely efficient predators. This resulted in the local extinction of the plehexapod in areas where the two species coexisted due to sticking out like a sore thumb. However, populations of plehexapods would enter the Darwin Chaparral where these predators are absent. Over time those populations that entered this habitat would begin to rapidly adapt and soon became a distinct species known as the spinebutt plexos. From there, the species would spread further and diverge into two distinct subspecies.
Spinebutt plexos are generalistic in feeding habits, feeding on a wide variety of shrews, dundis, worms, and purpleflora. They often dig up their burrowing prey with their “wing-legs", which have become thicker to better support their weight and assist with exposing prey hiding in burrows. The arms of the spinebutt plexos do still assist with digging, but primarily using them to instead help with manipulating food.
Spinebutt plexos still retain the waxy coat on their photosynthetic skin to avoid desiccation and provide insulation. Meanwhile, the thorns on the “tailstril” have become much bigger and more abundant to act as a better defense against most of its predators. Saucebacks, however, can pretty much ignore these spines and so the spinebutt plexos have to instead rely upon the spikes on their “wing-legs” to lash out at threats since they can’t outrun most of their predators.
The spinebutt plexos, however, only use these defenses as a last resort and instead primarily rely on their camouflage to avoid being detected by threats. This is where the main differences between the two subspecies present themselves. The golden spinebutt plexo (P. o. aurorus) is native exclusively to the Darwin Chaparral and as such carotenoids and anthocyanins are used to give them their gold and purple patterns to blend into their environment. They also have a slightly larger spike on their “wing-legs” and bigger head as they have less cover compared to the other subspecies and thus rely upon their defenses more often.
The second subspecies is the shadow spinebutt plexo (P. o. noctis), which despite appearing different at first glance are not too distinct from the golden spinebutt plexo. This is due to the subspecies having the majority of their populations being anthocyaninistic where they have an overabundance of anthocyanin in their tissues and thus have their patterns much darker. Due to these darker patterns, they’re able to do quite well in Darwin’s Woodlands and Rainforests and as such are much more widespread than the golden spinebutt plexo. Compared to the other subspecies, the shadow spinebutt plexo relies much more upon its camoflauge.
Just like their ancestor, both subspecies of spinebutt plexo have a large throat pouch where their offspring are retained where oxygen is brought in to help the young breath. These babies will poke their heads out of the female’s mouth and beg for food that the male spinebutt plexo brings. The entire time the female does not feed, relying on the fat reserves she built up from eating excessive amounts of food beforehand while the young are inside the pouch. Once the young start to become too big and unwieldy to safely carry, the mother will essentially vomit up the juvenile spinebutt plexos, her jaw being able to unhinge to make the task easier.
The Golden Spinebutt Plexo. Artwork by OviraptorFan