Entry five of eighteen. Day 34.
These gliders, for lack of a better name, have a light, rigid bone structure which defines a half-shell of a rib cage and two, bowing, static fins which project laterally from the torso. A rudder-like tail swings horizontally behind it between two rigid projections on the rear - like noses, arching up in ridges of cartilage from the lower back. A great, wide mouth at the fore of the creature, coated in fine hairs and mucus, draws in the air required for projecting the breath through its nostrils as well as the small, microbial creatures it filters from the atmosphere.
By raising and swooping down, mouth open, it can open the channel between mouth and nostrils, using its morphology to bottleneck the air and jet it out from behind itself - while using very little energy in the process.
If alarmed or otherwise startled, the creature may inhale deeply and eject the air in a bellowing trumpet or screech, thus accelerating at great speeds.
Such creatures can grow up to sixteen feet in length, if one includes the nine feet of tail.
Neither Faraday or myself have seen any of these "gliders" upon the ground, and it would seem they would be too fragile to perch or stand. They have no external limbs, and appear to be quite comfortable to ride the thermals when not propelling across the vast prairie.
Their main predators appear to be large bracken-like lichen. Being of limited sight, we have seen these creatures become ensnared like a limp balloon - and - over a period of weeks - digested.
Faraday has collected the bones, which we intend to return in whole to the university.