Fourmaw Sauceback

The fourmaw sauceback split from its ancestor. For some logworm saucebacks, being able to live longer as adults proved better for finding mates, resulting in an unexpected turn where some regained the ability to eat as adults. As they had lost their jaws, transitioning to being able to eat again was a slow, awkward process, but they ultimately found a solution: convergent with the long-extinct four-jawed saucebacks, the fourmaw sauceback has similarly arrived at a four-jawed mouth through elongation of some of its teeth and gums.

Each "jaw" consists of two teeth bound together by gum tissue. The spaces between the jaws each contain a single additional tooth which aids in swallowing, giving it a total of 12 teeth, which is the typical amount for the broader Dixon-Barlowe sauceback clade. The jaws can be retracted into the mouth, though the tips of the teeth remain exposed. The gums are also chemoreceptive, as they are in all beastworms, though they are mainly used for tasting while the nostrils remain in use for scent.

Adult fourmaw saucebacks are carnivores, as meat is easy to digest, and they primarily eat the larvae of other "shrewbacks". They will also eat vermees, which are in a similar ecological niche. Doing so eliminates competition for their offspring. They have a somewhat slower metabolism than other shrewbacks, so they do not starve extremely quickly and can go a few days without food. During the fall, they become excessively gluttonous, bulking up so that they may hibernate over winter and even eating the larvae of their own species. Compared to their ancestor's single-day adult life, an adult fourmaw can live as long as 3 years, though its health starts to deteriorate after only 2 due to damage to its telomeres caused by genetic drift in its ancestor. Like most saucebacks, they are blind and "see" using echolocation.

Juvenile fourmaw saucebacks are generally similar to logworms, though they can digest chitin such as that in glass flora more readily. They are ectothermic and reach their adult length before bulking up into what can be best described as a fat hairy sausage and undergoing metamorphosis in a burrow. Their "fat hairy sausage" stage is somewhat less fat than in their ancestor, however, due to their lower adult metabolism and less dire need to produce a ton of gametes. Juveniles brumate over winter and emerge as adults at different times throughout the year, generally exactly one year after the eggs they hatched from were laid.

Fourmaw saucebacks lack a mating season, but their mating practices are no less dramatic, just more spaced out. They are fertile throughout the year except during hibernation, and males will try to mate with any receptive female they encounter, identified by ultrasonic chirping calls produced using their tongues. As the need to find a mate is less dire, males no longer have giant manes, instead simply having longer feathers on the backs of their necks which are raised to intimidate one another. They will fight and sometimes even kill one another for the right to mate with a particular female, and it is not uncommon for older males to have scarred faces and torn ears. If more than two males are fighting over a particular female, however, the losers usually do not continue to fight and will instead mate with each other. Though this might seem counter-productive, it instantly reduces their aggression and hormone levels, preventing them from continuing to fight over nothing. Lone losers may instead attempt to mate with leaves or other shrewback species to a similar effect. Like its ancestor, the fourmaw sauceback offers no parental care and lays lots of eggs, though the exact number has reduced to only around 200 per mating.