Doomzor
A group of pallazors migrated northward into the cooler regions of Hydro, where no other large fauna was yet extant. The larger they grew, the better they could cope with cold weather, warmed by their own body mass through gigantothermy. As a result, with no competitors, these pallazors grew to a full four meters in length, becoming the doomzors.
Doomzor anatomy changed very little from the pallazor, but they look quite different due to changed proportions. The body is bulkier, the limbs thicker and stronger, the torso wider and plumper, with a thick neck. They also have increased body fat to further help keep warm. The sail on the back is mostly vestigial, reduced to a few spines with little skin between them, but they are capable of extending it during summer in the temperate zone to help cool off to a minor degree. The coloration is now camouflaged against gazebo crystals and, at the underside, teal flora.
To feed their increased bulk, doomzors specialize in large crystal flora in their environment, feeding on the crystals of various gazebos along with the seeds and "caps" of slitted chandeliers. As such, they retain the ancestral specialization of gripping teeth in front and a robust array of crushing teeth in back. The lateral mandibles are strong and bulky as well, adapted for crushing chitin. Doomzors have a low metabolism and are slow-moving and slow to react, so their dietary needs are lower than their size alone would suggest.
Like the pallazor, the larvae are aquatic and radially symmetrical. Doomzors usually give birth in the spring, allowing the larvae to grow to maturity before rivers and lakes freeze over. Doomzor adults are even more bound to the land, preferring to wade rather than swim, and they have lost their ancestral finger webbing. Adult gill slits are not functional, as was already the case in the pallazor. Doomzors grow deposits of fat in their blocky heads, which fill up the area where the gill slits are, making them visible more as folds in the fat than as slits. Fatty deposits over the musculature at the base of the lateral mandibles also make for a very visible bulge.
Doomzors have lost the ability to produce males. In the pallazor, males developed in response to high population densities, which doomzors have rarely ever reached. Doomzors reproduce only by parthenogenesis, which is still triggered by "hand-holding" between two females. They have become quite genetically homogenous, with little ability for new adaptations to spread throughout the population.
Unfortunately for the doomzor, transformations in the environment of Sagan 4 would render their existence short-lived. As Hydro moved south while temperatures warmed, they increasingly overheated. Meanwhile, oxygen levels crashed, and with lungs still recently evolved, the doomzors struggled to provide enough oxygen for their large bodies. Many perished, too sluggish in the blistering heat as they gasped and suffocated. But the final blow came as further atmospheric disturbance rendered its diet unsustainable. Unable to feed themselves, the last starving doomzors drifted away into torpor and oblivion.