The Bonebreaker

Aquatic molodonts which began to appear on Serina in the early Ultimocene continue to evolve and diversify during the ocean age, taking advantage of abundant food to grow increasingly large. With grinding mortar-and-pestle jaws powered by huge banks of muscle on top of the snout, most of them - with a few notable exceptions such as the rakewhale - are durophages, feeding on hard-shelled and mostly invertebrate prey. One species however has begun to adopt a more unusual dietary preference for bones, a food resource that is in no short supply in shallow seas where abundant megafauna live and die, but where no predators have sufficiently strong jaws to make use of it. Carnivores of the mid-Ultimocene sea are well-built to tear flesh from bone with all manner of sharp teeth and beaks, but then discard the hardest parts where they settle upon the sea floor where only a few small boring worms and other molluscs historically made any use of them. The bonebreaker, however, is a large vertebrate that is capable of making a living on primarily bones themselves. Specialist scavengers, they use their enormous teeth to grip and gnaw into the massive skeletons of aquatic birds and molodonts. Though they will also feed on shellfish and fresh carrion - if they can get it before more specialized carnivores - some 90% of their diet is bone, which they grind down and consume entirely, deriving most of their caloric needs from the marrow while the calcium builds their skeleton and in particular their teeth, which must grow quickly to compensate for such heavy day to day wear.

above: a male bonebreaker, showing the brighter coloration of this sex used to attract mates and demonstrate fitness. The hairless skin of these large, marine molodonts is intriguingly iridescent in the sunlight, showing a green and blue sheen like oil on water.

Directly descended from the clamcracker, the bonebreaker has increased in size significantly in the last ten million years and become even more aquatically adapted, with the hind leg now shaped into a nearly seamless, cetacean-like tail with its internal joints obscured by a heavy covering of body fat that now replaces its fur entirely. Very large by molodont standards and surpassed only by the rakewhale in size, the male bonebreaker now grows to up to 4,000 lbs and measures up to fifteen feet in length. Females are only about two-thirds as large, however, as this species still bears its young upon land and so the female must be able to haul herself ashore - this gives the young pup the best chance of survival against the gauntlet of aggressive predators lurking in the water.

Female bonebreakers give birth synchronously in colonies of several thousand, preferentially on islands just offshore but also on the mainland. Larger numbers are a better protection again land-based predators that are fewer in type than aquatic ones but still present a real danger on Serinarcta's continental beaches. It is the female's job alone to rear the young for its first three weeks, during which time the mother doesn't feed. The pup grows rapidly on a diet of a fat-rich regurgitated nutrient slurry produced by its parent, which is produced in the empty stomach from specialized glands that metabolize stored body fat directly into a milk-like nutritional fluid. At first it may seem as it the bonebreaker mother would struggle to produce such a massive load of calories from a diet of bones alone, but these animals do not only consume the hard calcium-rich exteriors; they gain the bulk of their nutrition from bone marrow, which is extremely rich in calories and fat. With huge animals dying in the sea every day and no competitors for this resource, bonebreakers easily accumulate an excess of calories on their specialist diets. So rich is their diet, in fact, that some bonebreakers can even rear two huge, rapidly-growing young at once, with twins accounting for about 10% of births. Though numbers, and ornery mothers, provide protection to the young, these colonies nonetheless can attract predators ranging from small but sneaky skuorcs, which will steal newborns right from under their mothers by merit of being much more nimble, to gigantic bumblebears which will swim across significant distances of water from the mainland following the scent of the colony and which are large enough to injure even the adult if she is caught away from the rest of the group. Giving birth on land is only a relative refuge; there is nowhere totally safe from threat.

Though only the female is readily capable of moving on land, she is not destined to be a single parent forever. Bonebreakers are monogamous animals, and each sex has adapted to take on a certain role in raising the offspring. Though he does not join them on land, once her young begin taking to the water they are met by their waiting father, who being considerably larger and highly aggressive is more capable of defending them at this life stage than their now depleted mother. As the female leaves to feed herself and refill her reserves it is now the male which becomes their primary caretaker for the next few months of their lives. Though he does not produce a specialized nutritional fluid, by now the young are able to consume partly-digested regurgitated bone marrow as well as to begin feeding themselves. The male guides his young along to food sources and keeps away carnivores until his young are almost a year old and about half their final size, at which point they can take care of themselves. After the young disperse the male returns to the coast and reunites with his partner, who is now well-fed and back in breeding condition. The two will mate and spend the duration of her next pregnancy together at sea - roughly another year - before repeating the cycle again.