Dromolopes

Dromolope anatomy is fairly typical for an endognathan vertebrate. Note that endognathans have yellow blood, unlike Terran land vertebrates, as they use the cobalt-based oxygen carrier coboglobin rather than iron-based hemoglobin. Coboglobin binds to fewer oxygen molecules than hemoglobin, which is why endognathans have a binary vascular system with two hearts to pump coboglobin around their bodies. Endognathans breathe through a spiracle located just below their eyes, and lack lungs or air sacs — the Melidoran atmosphere is so oxygenated that they can just simply breathe through diffusion. Large crests, made out of beta-sheet polymers (the same material that dromolope teeth are made out of) are present in most dromolope species and are typically used for signaling purposes. The figure at upper right depicts a dromolope with its outer jaw open, revealing the three-part jaw anatomy.

The Domehead is a typical species of Dapsilis Planitia in Lamarckia. Like Terra's bighorn sheep and extinct pachycephalosaurs, Domeheads engage in head-butting rituals as a show of dominance. Their heads are padded with a thick cushion-like material that absorbs the force of impact. However, they need not worry about damaging their skulls as much as a Terran creature would, for their brains are actually located in their chests.

Temperate woodlands are home to species like the Shovel-snouted Dromolope of northwestern Ys. This little creature is a voracious eater, and is particularly fond of one type of tenucaulian, the Corsair. By eating Corsairs, the Shovel-snouted Dromolope performs a beneficial service for the forest tenucaulian community, as Corsairs have a nasty habit of grafting themselves onto the root networks of other tenucaulians and stealing nutrients from them.

Some dromolopes have even managed to colonize the northern polar regions, like the Bowhorn. A thick filamentous integument, similar to the downy feathers of Terran birds, acts as an insulating blanket, trapping heat and allowing it to remain warm through the coldest of polar winters. As polar summers can be extremely hot and humid, the Bowhorn sheds its winter coat with the onset of spring to avoid overheating.

Dromolopes are Melidora's principal group of terrestrial herbivores. They are comparable in dominance and diversity to the extinct Terran hadrosaurs.

Taxonomically speaking, dromolopes are members of a large clade of Melidoran land vertebrates called Endognatha ("nested jaws"). Like all endognathans, they have two jaws. The outer visible jaw consists of three mandibles arranged in a triangular shape. The inner jaw is similar, but it is nested inside the throat and has "teeth" made from strong beta-sheet polymers similar to those found in the silk produced by Terran spiders.

Dromolopes use their toothless outer jaws to pull apart tenucaulian leaves. Once swallowed, the leaves travel to the inner jaw, with is lined with flat, crushing "teeth". There, the leaves are ground to a thick pulp.

The pulp is further broken down in the foregut, a chamber analogous to the stomach of Terran tetrapods. Here, symbiotic colonies of cellulose-digesting microbes extract sugars from the tenucaulian pulp, providing the dromolope with energy.

Eventually, the symbiotic microbes squeeze all the nutrients out of the pulp. The waste material that remains is then excreted through a tube-like organ that terminates near the base of the dromolope's neck.

Dromolopes have evolved a very efficient digestive system for a herbivorous Melidoran land vertebrate, and this has allowed them to thrive and radiate into a variety of forms.