Eastern horseshoe bat skull

Educational value

• The eastern horseshoe bat ('Rhinolophus megaphyllus') is a tiny, locally common bat found in coastal areas of eastern Australia. It roosts in small groups in warm humid caves, tunnels, abandoned mines and crevices in rocks, roots and buildings. Like all bats, it is a placental mammal and births its young in spring in dedicated maternity roosting sites. It is a nocturnal hunter of insects, especially moths, which it captures in its jaws during flight, often close to the ground.
• The eastern horseshoe bat has long soft grey-brown fur and a paler underside, although some individuals may exhibit a temporary red-brown colour phase. It has large widely separated ears, small eyes and membranous wings. The eastern horseshoe bat has a distinctive horseshoe-shaped nose-leaf, a fleshy area around the nose used to direct sonar, or echolocation, signals. This bat is 45-53 mm long and weighs up to 13 g.
• The skull shape and teeth of bats are highly variable. The insectivorous bats, such as the one represented here, have very sharp teeth for piercing the armour of insects and, as seen in the image, they often have sharp W-shaped grooves on their molars. Some species are born with slender backward-curving 'milk' teeth, which they use to hold onto their mother, but in this family of bats the milk teeth are absorbed before birth.
• Placental mammal skull and dentition arrangements vary considerably according to the type of food consumed. Placentals generally have two sets of teeth, the first 'milk' teeth being replaced by a second set later in life. Only anteaters and some whales lack teeth. Typically placentals have four premolars and three molars on each side in both the upper and lower jaws. They also have incisors (often three pairs in the upper and lower jaws) and canines (usually one pair in each jaw).
• The mammal skull is a complex fusion of around 34 bones, in three main parts: the braincase which encloses the brain, the rostrum including the snout and upper jaw, and the lower jaw or mandible. The mammal skull is distinguishable by the presence of three bones in the middle ear used for hearing (not visible in the image). It also has a unique jaw joint in which the single lower jaw bone connects with a small skull bone (the squamosal), resulting in a distinctive jaw movement.
• There are three types of existing mammals: the placentals, the marsupials and the primitive monotremes. Placental mammals give birth to live young after extended nourishment from a placenta in the mother's womb, marsupials are characterised by the presence of a pouch for rearing the young, and monotremes are egg layers. There are many shared characteristics between these three groups and some important distinctions, especially in the skull and dentition arrangements.

Year level

5; 6; 7; 8; 9; 10; 11; 12

Topics Alphabets (Writing systems) Culture Bats Jaws