Paddle-Finned Muscossum
Evolved from Pseudospathula concavens is the Paddle-Finned Muscossum (Pseudospathula muscossum). Although it appears rather similar to its ancestor, it has developed one new feature that gives it an edge over other similar canetodes: The two inner muscles of the leg have been strengethened by increasing the concentration of muscle fibers, providing more support to the leg and allowing it to exert more force than before.
The Paddle-Finned Muscossum is named after its muscles that function similarily to suppporting bones, though the similarities end there, as they are not hardened or ossified like actual bone. This is useful for the Paddle-Finned Muscossum as it can produce longer, harder strides which enables it to actually run away from its dominant predators (Thalassaraptor fundatus, Thalassaraptor gallicorpus, Thalassaraptor kokovajilotus) for the first time. Muscle-Frilled Needleworms (Acutognathus acidonenum) and Blattealimax panivore will also attempt to predate on members of the species, but are not typically fast enough to keep up with them and instead settle for the smaller young. Paddle-Finned Muscossums have a top running speed of four to five miles per hour (4-5 mph). This doesn't sound fast compared to other terrestrial organisms, but it is enough to outmaneuver large predators such as wyverns in settings with dense vegetation.
Like its ancestor, the leg muscles of the Paddle-Finned Muscossum are anatomically similar to the extrinsic muscles of a tongue. Each leg is composed of four muscles that extend outward from their hollow, cartiligous "backbone" and connect at the tip of the leg. The outer muscles are primarily responsible for moving the leg forwards and backwards, while the inner muscles provide pull towards the body. The Paddle-Finned Muscossum is able to tense up its strengthed inner muscles, which are manipulated by the outer muscles, giving the ability to stand more upright for shortened periods of time. This allows it to move more efficiently in short bursts in order to escape predators.
The Paddle-Finned Muscossum uses its six limbs to locomotate in a sequence in which movement of the left first limb, right second limb, and left third limb are synced with the other limbs back-and-forth and vice versa. It holds them in a sprawled-outwards stance that slopes downwards from the body to reduce its belly's drag on the ground, using support by the muscle within to travel in a semi-erect posture. When it detects a predator, it will quicken and hasten the pace of its limbs to move faster.
Like its ancestor, the Paddle-Finned Muscossum feeds on the stems of Aruraherba caesicoles, Heavy Tuftweed (Aruraherba haberefortis), and Aruraherba wetrilli by swallowing them whole. They sleep and forage in three-hour (3-hr) shifts with no preferred time for activity, although they are faster in warmer temperatures due to their ectothermy. They have no instinct that enables them to hibernate and they instead deal with winter by trying to endure the cold and scooping their heads around to find polyphs to consume.
Paddle-Finned Muscossums grow to twenty centimeters (20 cm) in length and take seven weeks (7 wks) to mature due to the stronger development of the leg muscles. They lack sexual dimorphism and so they will reproduce internally with other members of the species. Males deposit sperm while females keep the eggs inside them to be laid once fertilized. Females will lay approximately thirty (30) eggs and are capable of reproducing once a month (1 mo).
