Like Cetanthropichthyes, Pneumonobranchioceti also bear fluked tails and gills, but curiously retain their (albeit atrophying) legs and their lungs. The former fact is due to this clade recently evolving from a fully limbed common ancestor, with the legs not having yet fully disappeared in this point in time. The possession of pulmonary respiration in addition to branchial respiration, however, has a crucial advantage; these posthumans are able to submerge for shorter whiles longer by exchanging gases with the water before needing to resurface. What further distinguishes this clade from Cetanthropichthyes are their swimming maneuvers, for progression is acheived with a combination of long breast strokes and tail fluke propulsion.
Currently, this page is represented solely by the superfamily Bulbocipitoidea, united by the possession of thick, bony skulls basally taking a round, dome-shaped form to the extravagant, horn-like affairs, all serving functions of either species identification, mating displays, agonistic instruments, or a combination thereof.
To the untrained eye of its Terran ancestors, it resembles a cetacean, one of many animal groups they uneasily shared their world with. In fact, it is a somewhat conservative-looking derivation of their conquered descendants among the stars. It's bulbous head does not contain an echolocation organ like the brown, large-eyed beluga it resembles. Knowing that it's a post-human, one may be forgiven for thinking there may be a large brain inside that eerily human-like dome, one that rivals theirs in size if not complexity; truth be told, these―quite literally―are utter boneheads.
The volume of the round skull of the baby grumpy grampus, so christened for its countenance resembling a recalcitrant infant's, consists largely of thick bone. It bears large eyes for looking out for prey. With larger heads, they tend to draw attention to one another. Consequentially, it serves as an instrument for sexual selection, a fact confirmed by the crazier cranial morphologies of its more derived relatives. What's more, it appears that this sexual selection is mutual; both males and females possess such a feature, doubling it as a species recognition device.
The true bulbhead is one of the smallest of the bulbocipitoideans―and also their namesake. It is also truly bulb-headed, a configuration that, like in its closest relative, Infanticeps irritatus, functions in display and species recognition. At just about 1 meter in length, these posthumans are shallow-water bottom feeders who use their sensitive thick lips to feel around for vermiform posthumans buried in the sand. Their coloration matches that of the sand they browse through.
Also like all other bulbocipitoideans, though it respires through its gills, it can also do so with atmospheric oxygen through its lungs, and the position of the nostrils necessitates it to turn over belly side up to breathe when surfacing.
The peculiar shape of the sheephead―and not to be confused with Earthly fishes known as sheepsheads―is but a more extreme result of sexual selection, and, unlike in baby grumpy grampuses (Infanticeps irritatus), certain features such as its bumpy, bony head are sported only by males, selected for by the less prominently-endowed females, whose superb visions never fail to spot things that stand out. Moreover, the dorsal fin is taller, and the two ridges running behind it are somewhat more defined.
As is the case with other members of its clade, it propels itself with a combination of dorso-abdominal undulations aided by an increasingly sophisticated terminal fluke and powerful strokes from its pectoral flippers. Their slightly elongated, narrow jaws assist in catching fast moving prey and from within crevices in the algae reefs they regularly patrol within their range.
So far, the superfamily Bulbocipitoidea has delivered a crop of a number of absurd-looking posthumans. From the relatively tame Infanticeps irritatus (even if their facial expression appears otherwise) to the awkward Oviceps altivelum, their unusual cranial morphologies and other facial features can be attributed to the apparently arbitrary selections of mates of one or both sexes. The more divergent shapes in more derived species appear to be shaped by the preferences of females. It is through their choices that sexual selection will be ramped up to a whole new, ridiculous level, rivaling that of some of the primate relatives of their distant ancestors on Earth.
Enter the burnt goblin dolphin. This algal-reef denizen, when male, possess a head that bulges forward. Both sexes bear a pointy, goblin-like nose, though it is slightly longer in the male. Also noticeable is the presence of a beige stripe straddling the nape of its neck. Occasionally, a male will also sport freckle-like patterns on the sides of the head. These ones appear to be more successful attracting females than those without; at this current moment this is written, this was a fairly recent mutation that, within several generations, could overtake the entire species from the populations in which it is present.
Surprisingly, although modest carnivores, this species appears to have an astonishing penchant for cruelty. It sometimes engages in what resembles torture of other posthuman species to the point of death―without even eating them. Notably, there is no presence of herpetembryonid posthumans within their range; it is possible that they severed their stalks with which they attach to substrate, resulting in their deaths. Truly, then, is this species the feral cat of the Anthropomundan seas.
For hundreds of millennia, humans have sworn they found a mysterious monster from the seas wash up on the shore, one never-before-seen, one sure to captivate the human imagination, one that would feature in tales retold, in segments of local news broadcasts, and in dedicated corners on the Internet to cryptozoology. The experts, however, will then quickly point out that they were in fact the rotting remains of what are, in fact, known species.
On Anthropomundus, however, any strange beast, ultimate descendants of credulous ancestors, washing ashore is definitely not fake news. If one finds a two-meter creature of delphine appearance with a down-turned crest sprouting from its forehead and a protuberant nose, they would have found the body of a former reef baron. In life, it was, as its name suggests, the boss of the algae-reef within its range. It would either chase prey in the water column or, aided by its narrow eyes, try to search and pry prey out of rock crevices. As in other bulbocipitoids, the aforementioned crest consists mostly of bone and is a product of sexual selection by females, who lack this feature, in addition to having slightly shorter noses. What's most notable, however, is that it has the smallest hind limbs of the whole superfamily; given a few million years, they could be lost entirely, whereas curiously they remained in its other relatives, including its closest, the burnt goblin dolphin (Burnsocetus excellens), in the 25 million years since the inception of M. progenitor.
What's more, it is the most feared customer of the varying cleaner porpoises that reside in the algae-reefs of its range, for it may occasionally make a meal of them when they complete their service, clamping down on them before they exit its mouth, going away with not only a clean mouth and gills, but a free meal as well. Those that try to cheat are more likely to meet this fate. However, this dirty behavior also ends up catching impostor species of cleaner porpoise that mimic the genuine ones but make their living through treacherously feeding on the healthy tissue of their "clients."
If one has been dazzled by the dizzying diversity of the absurd, bulbous head shapes in the bulbocipitoids thus far, mirabile dictu! The trident-head is perhaps the crown jewel of its superfamily for the extremely unusual form of its head. Sharing a common ancestor with the reef baron (Bigliocetus braggadocius) fairly recently, the trident-head takes the ridiculous facial features of its cousin to a fascinating new extreme. A thin, elongated cranial crest; a pointed nose nearly as long; and a jaw that appears to nearly mirrror the shape and length of the crest create one of the most distinguished profiles in all of Anthropomundus. As a product of sexual selection, females are somewhat shorter in these proportions, and favor males with ever-longer trident "prongs." It is also the longest of all the bulbocipitoids, stretching more than 3 meters in length. The almost perfectly symmetrical shape of its head is disrupted when it pulls back its long, thin mandible to catch swift, small posthuman prey in the shallows its species prowls.
Another species of Tridenticeps exists in the much smaller lesser trident-head, T. minor, which is only a little over a meter and a half in length.