Lagomorpha

This Order originally was classified as a suborder of Rodentia. It has been shown that fossil forms of both orders date back to the Paleocene, and were even then distinct from each other. The two orders have probably evolved independantly of each other and have resulted in one family in the order known as Leporidae. With 4 species of Leporidae found in the Britain and Ireland consisting of two genera, Oryctolagus and Lepus.

Lagomorpha are relatively defenseless on the whole and form a very important part of the diet of nearly all carnivorous mammals and birds. There only defence being flight. As some protection they are predominantly nocturnal although rabbits can be seen at almost any time and some seem to be crepuscular in their habits. Rabbits that are seen out during daylight tend not to venture far from the safety of their burrows, which provide them with safety from all predators apart from several members of the mustelid family which are small enough to follow then down underground.

Lagomorpha are gnawing animals and can be characterised by the nature of their teeth, especially the incisors. These incisors are chisel shaped and coated with enamel that is thickest at the front but covers all aroung the tooth unlike that of rodents. The dentine,which is softer then the enamel forms the bulk of the tooth, wears away quicker than the enamel and leaves behind a sharp cutting edge formed from the enamel. These teeth are long and set in very deep sockets from which they grow continually in order to compenste for the wearing action of chewing on the rough grasses. The sharpness and shape of the tooth are determined by the waering action that it receives. There are two pairs of incisors in the upper jaw. The second pair is very much smaller than the first and are set in behind them as opposed to the side as in other mammals. There are no canines present and instead they have a gap between the incisors and the cheek teeth known as the diastema. The cheek teeth are very short but wide and have a pattern of transverse ridges. There are 6 in each side of the upper jaw and 5 in the lower. The upper jaw is wider than the lower, so that when the jaw is shut the lower jaw cheek teeth lie inside the upper, and the jaw is moved in a crossways or rotary movement to grind down the food. There are also three upper milk molars and two lower on each side. These preceed the other molars and are correspondingly premolars. The incisors are also preceeded by milk teeth, the first upper and lower ones by rudiments that never break the gum and are absorded before birth. The second milk incisors are functional but are lost at about three weeks after birth, the same time as the milk molars.

Oryctolagus contains only one species in Britain and Ireland and that is the rabbit Oryctolagus cuniculus.

Lepus on the other hand has two distinct species, the Brown Hare Lepus europaeus occidentalis and the Blue Hare Lepus timidus with a third, the Irish Hare Lepus timidus hibernicus, although this is in reality a sub species of the Blue Hare. Apart from the black ear tips and larger size of the hares, there are also other differences in their anatomies.

In the skull the Lepus genus has a short palate, it is actually shorter than the width of the posterior nares, the post orbital process is broad and triangular and the sutures of the interparietal bone are fused in the adult. The opposite of these pionts is found in a rabbit skull. The young at bieth in rabbits are born naked and blind in the nest whereas hares are born fully furred and with their eyes open.

[top]

back to mammals