Glossary

airfoil — a streamlined surface such as a wing or gliding membrane that produces lift (or down force depending on the application) when air flows around it.

angle of attack — the angle the wing makes with the direction of the oncoming airflow. The amount of lift generated by a wing is directly related to the angle of attack, with greater angles generating more lift (and more drag as it increases the frontal area); this remains true up to the stall point, where lift starts to decrease again because of airflow separation; at zero degrees, the front of the airfoil is pointed directly into the stream; at 90° it is pointed straight up and down.

angle of descent — the angle descent from the launch point to the landing point; measured from point of the launch to the horizontal; the smaller the angle of descent the greater the gliding distance.

anterior — situated at the front of.

arboreal — adapted to living and moving about in trees.

bank — a turn during a glide of 90° or less.

basal — associated with the base of an organism or structure.

biogeography — the science that seeks to explain the distribution of species, and higher taxa, on the surface of Earth.

cartilaginous — of, relating to, or consisting of cartilage.

caudal — pertaining to the tail or posterior or hind part of a body.

cavity — a tree hollow or tree hole is a semi-enclosed cavity which has naturally formed in the trunk or branch of a tree.

cloaca — the posterior opening that serves to eliminate urinary and faecal waste and the opening for the reproductive organs.

dentition — the teeth of an animal.

digipatagium — gliding membrane or patagium between the digits of the paws.

dipterocarp — trees of the Family Dipterocarpaceae, which are chiefly tropical Asian trees with two-winged fruits.

distichous tail — the arrangement of the hairs in two rows on opposite sides of the tail and thus in the same plane, which makes it look like a feather.

diurnal — active during the day.

dorso-ventral — top to bottom.

drag — the sum of all the aerodynamic forces on an airfoil in the direction of the external airflow. It therefore acts to oppose the motion of the object.

femoral — pertaining to the femur or thigh bone, the most proximal (closest to the centre of the body) bone of the leg in tetrapod vertebrates.

folivore — an animal that feeds mainly on plant leaves.

glide — the movement in air, especially at a downward angle, as a result of gravity or momentum already acquired. Species that glide descend at an angle less than 45° to the horizontal, while those that parachute descend at an angle greater than 45°.

glide ratio — the ratio between the glide distance and the distance travelled; the greater the glide ratio, the greater the gliding efficiency.

gliding efficiency — the performance of a glide and includes the angle of descent and the glide ratio; the lower the angle of descent or the greater the glide ratio, the greater the glide efficiency.

induced drag — this is produced as a result of frictional forces, and is a result of the pressure differential generated by the wing as it creates lift; it is compromised of two components that include parasite drag that is incurred by the body while profile drag is incurred by the wings. Induced drag results from wings producing lift by creating a pressure differential between the top and bottom of the wing, and from the limited wing span. Induced drag is inversely proportional to aspect ratio.

lift — consists of the sum of all the aerodynamic forces on an airfoil perpendicular to the direction of the external airflow around that body.

melanistic — a dark colouration of the skin, hair or fur of the animal because of an excessive amount of melanin.

mesophytic — a land plant that grows in an environment having a moderate amount of moisture.

metatarsal — a group of five long bones in the foot located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes.

morphology — the form and structure of organism.

mya — million years ago.

myrtaceous — trees relating to, or belonging to the Family Myrtaceae, mostly tropical and subtropical trees and shrubs having oil glands in the leaves.

nocturnal — active during the night.

oestrous cycle — the phase when the female is sexually receptive.

olecranon — a bony projection of the ulna (part of the forearm) that projects behind the elbow.

paramyids — extinct rodents of the Family Paramyidae.

patagium (pl. patagia) — gliding membrane of mammals that consists of skin with two layers bound together tightly by connective tissue composed of muscles and nerves between.

pectoral — a thick, fan-shaped muscle, situated at the chest on the anterior of the body.

pelage — the coat of a mammal, consisting of hair, fur, wool or other soft covering, as distinct from bare skin.

pisiform — a small knobbly, pea-shaped wrist bone.

pitch — rotation of the glider around an axis through each side.

plagiopatagium — a gliding membrane or patagium that extends from the forelimbs to hind limbs and is connected to the sides of the body.

polyestrous — Having several oestrous cycles during a single breeding season.

posterior — the end of an organism, opposite to its head.

propatagium — a gliding membrane between the neck and the forearms.

quadrupedal — form of land animal locomotion using four limbs or legs.

roll(ing) — rotation of the glider around an anterior—posterior axis.

rudimentary — of a primitive kind.

spur — a spiked projection growing on the bone.

stall — when an excessively high angle of attack causes loss of lift, due to a disruption of airflow, usually resulting in a loss of elevation.

staminate cones — cones having male parts (stamens) but no female parts.

styliform cartilage — a cartilaginous projection that originates from the pisiform bone in the wrist. The extended cartilage increases the size of the plagiopatagium, stiffens and supports it and helps unfold its lateral leading edge.

sympatry — two species or populations that occur in the same area and are able to encounter each other.

taxon (pl. taxa) — a taxonomic group of any rank, such as genus, family or class.

taxonomy — the theory and practice of classifying organisms.

tectonic — relating to movement of Earth’s crust.

type locality — the location where the first specimen from which a species was described, and given a scientific name, occurs.

ulna — one of the two long bones in the forearm, the other being the radius.

unciform cartilage — a cartilaginous projection that originates from the olecranon process of the ulna in the forearm (near the elbow) and helps support the leading edge of the plagiopatagium.

uropatagium — a patagium that extends from the hind limbs to the tail.

ventral — related to the abdomen or stomach.

vestigial — having retained a simple structure and reduced size and function during the evolution of the species.

wing loading — the amount of weight per square metre that has to be overcome to provide lift.

winglets — small vertical extensions on the tips of some wings of aeroplanes and many gliding mammals that reduce lift induced drag; they improve the efficiency of the wing or gliding surface by increasing the effective wing length.

yaw(ing) — rotation of the glider around a vertical or dorsoventral axis.