Pinsyk
The Pinsyk split from its ancestor. It has developed its spikes further into hedgehog- or porcupine-like quills. They each now consist of as many as 40 elongated scales, a change allowed by the development of follicles for them to grow from. All non-quill scales, such as on the underside, are significantly smaller and are structurally somewhat similar to the reticula of Terran dinosaurs. The pair of longer quills on the head, now mobile thanks to the follicles, are frayed at the end. They have an unusual, two layered structure where the outer scales making them up are stiff and fused but the ones on the inner layer are not so much. Due to this, they have become incredibly useful sensory appendages--much like whiskers, the follicles they fit into are incredibly sensitive, to the point that a Pinsyk can tell exactly which filament at the end of the quill is being touched. In essence, it has become a bundle of whiskers on a stick.
The Pinsyk has lost the saddle in favor of more spikes. This is because, having functionally developed a new shoulder girdle, it has finally completely separated its front leg from its pelvic ring, granting high flexibility and the ability to curl into a ball. Rather than carrying its babies on its back, it will curl around them, protecting them and itself with far less risk. Its babies still are fairly helpless on the ground, especially while young. This has led to the development of more advanced nesting habits, where a mated pair will choose a safe spot, scrape a shallow burrow using the front leg like a sort of excavator, and essentially take turns being curled up around their babies while the other finds food. It is a poor digger due to its limb anatomy; as the front leg must absorb a great amount of force while running, the girdle it is on is pelvis-like rather than sliding like the front limbs of many Terran fauna, greatly limiting its flexibility and preventing the Pinsyk from making especially deep burrows.
To help it compete with arthrotheres in its environment, the Pinsyk has a fairly high metabolism compared to its ancestor. Though not quite warm-blooded, it can regulate its body temperature to some extent, allowing it to move quickly and reach food before a slower competitor can. Though its integument did not evolve as insulation, the hollow spikes unintentionally function slightly like bubble wrap and can hold in heat generated by muscle movement, assisting greatly in this development. This is part of why it was able to increase in size, in addition to its spikes making it unappetizing to large predators such as pards. Its teeth have also diverged somewhat to assist in food processing: The keratinous coating is now designed to slough off, exposing the bone core. When the bone tooth wears down, it is shed and replaced by a new tooth growing in from behind it, not unlike shark teeth. Though bone teeth are not as effective as dentin teeth, this has granted it the most effective chewing of any stinzer, enough to push it past the threshold and even pose a competitive threat to arthrotheres. Though arthrotheres still have better teeth and chewing, they are slower and have greater energy requirements due to their chitinous exoskeletons. Notably, arthrotheres would have a lot more to worry about than just competition from Pinsyk soon enough, though they are not the focus of this entry.
The Pinsyk continues to use its tail arm as a manipulator. Though ordinarily getting larger would cause tail manipulators to be selected against, it has no better option for a manipulatory appendage--its front leg is too inflexible and though its lateral mandibles, already more prehensile in its branch of evolution than in other stinzers, could probably be modified into such, the tail hand evolved its use as such an appendage first and is dramatically more useful for things such as grasping flora and dragging carcasses as a result. The greater flexibility of its body and the existing relative flexibility of its neck helps somewhat in using a tail as a manipulator, as it can more easily twist around to see what it’s doing. It is actually in a fairly unique position not reached by Terran vertebrates where it can have both a prehensile tail and a flexible neck at the same time, so it seems likely that the tail-hand will stick around for a while.
Ecologically, the Pinsyk is a generalist omnivore. Its bone teeth can rip through flesh, exoskeleton, crystals, and leaves indiscriminately. As far as meat goes, it tends to hunt prey half its size and smaller, including young arthrotheres. It consumes a lot of flora, notably more flora than meat in fact, crushing crystals and mowing down purple flora. It still does not have a stronger bite than arthrotheres, as the limitations of its jaw muscles still apply, but its flexible lateral mandibles help make up for it.
Like its ancestor, the Pinsyk must mate belly-to-belly because of its spikes, though their greater mobility has resulted in occasional experimentation. Its size increase, free hip, and higher metabolism has actually caused it to finally break the pressure barrier and give birth to more developed young; instead of being pseudo-radial everywhere behind the ears, they resemble the adults at birth, but now traits such as the tusks on the lateral mandibles must grow in as they mature. Babies are naked and pink, though not necessarily completely helpless; they can bound away from predators a few days after birth, but they still depend on their parents to defend them and bring food until their quills and lateral tusks respectively grow in. Juveniles stay with their parents until they are about 4 months old, and they reach full size at about 1 year of age.