Scutocephala

Scutocephalians are one of the four major clades of the order Bilatera. With an efficient segmented bodyplan, they are among the most succesful of all clades on the entire history of Nispe. they get their name from their head, usually the most protected or prominent part of their exoskeleton, which in most groups covers the entire body. there are many variations of the basal form, ranging from multi-legged land forms, walking stilt-legged ones, swimming ones, worm-like burrowing ones and even sessile ones, which testify to the high diversity of the clade. however, all groups still possess shared traits: a beak, a pair of simple eyes (except for the earliest forms), the ability to molt, and a soft and boneless inside. all scutocephalans are sexually differentiated, and most species (save for land ones) share the same larval form, unique to this clade.

While the forms and anatomy of each group is unique, there are still macro typings in which classify each of them: Slithering, Swimming (with two unique forms), Crawling, Walking and Sessiles.

### **History**

The history of the scutocephalans is very long, with the first species dating back to the later stages of the Cloacian. During the Benician, most of the main groups evolved, and the clade consolidated their daptive success by covering many vital, but mostly lowly tiered niches. the Chodician saw the first land forms (being the very first land animals as well), alongside the further diversification of marine ones, particularly Stilt Sgrabs. with the Orchidian, the clade starts to evolve many unusual forms, diversifying even more the niches and adaptations it can have.

### **Groups**

#### **Basal Scutocephalans**

The definition of basal scutocephalans groups all the bottom-dwelling, slithering forms which are only provided of a singular "foot" on their underside. most of the species in this grouping are also provided of a "rasping-type" beak, which only consists of a sharp rasping organ (the beak proper) and a mouth with various denticles that disgregate the food coming in. Scallop crabs, the earliest known species of the clade, compose an **archaic** group in itself. it's direct descendant, the shallow crab, and most of it's own descendants are classified as **Neoscutocephalans**, differing from the predecessor for the presence of eyes and a fully-covered body (where the scallop crab only possessed plates on the head segment). another big clade of the basal morphs are **Chitocephalans**, composed of most descendants of the Pesky Sgrab as well as the Trap Crabs, which evolved in parallel with the latter despite their notable differences. generally adapted for a wider range of meals, they are also recognizable for their rounder shapes, with a shell more adapted for straight defense than digging. finally, **Ambusher** scutocephalans are a one-off clade that diverged from a lineage close to the trap crabs, but retained more archaic characteristics alongside new ones, like a flexible shell and a sharp tail used for defense. while this type of scutocephalan has been widespread thorought most of Nispe's history, only the neoscutocephalans alone survive as of the Orchidian.

#### **Swimming Crabs**

While a rare occurence, swimming in scutocephalans evolved twice during Nispe's history from two different lineages. the first were the **Arrowgnats**, evolved from freshwater crabs during the later Chodicene, repurposing their tail-end as a full-blown fin. the head, with it's characteristic shape, aided in stabilization. aside from that, they retained many characteristics from their ancestors. true **Swimming Crabs**, however, evolved in the early Orchidian, exclusively in the Middle Sea, from the Skate Crabs. originally making use of water-repellent secretions, evolved from their ancestor's sand-running oils, to take off from the sea floor, eventually they also evolved fins by leaving more space for the softer tissues in the shells. later forms even managed to evolve a rudimental notochord, in order to further support the whole body and the nervous system. however, due to habitat and food loss, both these forms died in their own age's mass extinction respectively, but it's not to exclude the re-emergence of swimming in the future.

#### **Halluciscutans**

Originally an offshoot of chitocephalans, **Stilt Sgrabs** became in the Chodicene one of the main scutocephalan groups thanks to the wide ranges of adaptation and biomes occupied. originally, stilt sgrabs only moved by contracting their whole body, while using the stilts to stabilize (a trait retained, and repurposed in a most succesful way, by the quirk sgrabs), but later species evolved the ability to move the stilts independently, allowing them to archieve an even greater mobility and potential. from the halluciscutans also evolved two of the most bizarre forms of scutocephalians: one of them are the **Nematoscutans**, which have completely repurposed their bodies for a burrowing lifestyle, becoming similiar to the bicephalian worm-like forms in the process.

#### **Freshwater Scutocephalans**

despite seeing their heyday in the Chodicene, the ancestor of the freshwater scutocephalians evolved in the benicene with the deadman sgrab, a species that adapted to the extreme environement of the Eastern Lake at the time. as it turned to a much more livable state, however, the species started to adapt and diversify to fill the new niches. freshwater scutocephalians are most notable for being the first ever animals adapted to live on land, with a few species that evolved to specifically feed on the plants that were spreading everywhere near their place in the era. the swimming Arrowgnats also evolved from this group. eventually the jump to full-blown terrestriality was made by the **Milli Grubs,** an offshoot of the group that evovled various adaptations to definitely leave behind the water, like shelled eggs and fully developed broncoles, and eventually spawned the podocephalan group. as these latter outcompeted all amphibious crabs, freshwater scutocephalans now survive only in their original state as bottom feeders of Holean lakes and rivers.

#### **Podocephalans**

Podocephalans are the most widespread land lifeforms in the world, almost beating plants themselves in biomass. thanks to their great adaptability, they have managed to live even where nothing could grow, spreading on much of Labia's surface. characterized by the presence of many soft legs, with which they crawl at faster speed than their ancestors, some forms even adapted at jumping by repurposing their tail as an extremely strong pad to propel themselves with. while most podocephalans are generalists, some adapt to specific foods in particular, and some families even evolve further to feed on it, like the parasitical sap gnats.