Horn (anatomy) - Other Hornlike Growths

Other Hornlike Growths

The term "horn" is also popularly applied to other hard and pointed features attached to the head of animals in various other families:

• Giraffidae: Giraffes have one or more pairs of bony bumps on their heads, called ossicones. These are covered with furred skin.
• Cervidae: Most deer have antlers, which are not true horns. When fully developed, antlers are dead bone without a horn or skin covering; they are borne only by adults (usually males) and are shed and regrown each year.
• Rhinocerotidae: The "horns" of rhinoceroses are made of keratin and grow continuously, but do not have a bone core.
• Chamaeleonidae: Many chameleons, most notably the Jackson's Chameleon, possess horns on their skulls, and have a keratin covering.
• Ceratopsidae: The "horns" of the Triceratops were extensions of its skull bones although debate exists over whether they had a keratin covering.
• Horned lizards (Phrynosoma): These lizards have horns on their heads which have a hard keratin covering over a bony core, like mammalian horns.
• Insects: Some insects (such as rhinoceros beetles) have horn-like structures on the head or thorax (or both). These are pointed outgrowths of the hard chitinous exoskeleton. Some (such as stag beetles) have greatly enlarged jaws, also made of chitin.
• Canidae: Golden jackals are known to occasionally develop a horny growth on the skull, which is associated with magical powers in south-eastern Asia.

Many mammal species in various families have tusks, which often serve the same functions as horns, but are in fact oversize teeth. These include the Moschidae (Musk deer, which are ruminants), Suidae (Wild Boars), Proboscidea (Elephants), Monodontidae (Narwhals) and Odobenidae (Walruses).

Polled animals or pollards are those of normally-horned (mainly domesticated) species whose horns have been removed, or which have not grown. In some cases such animals have small horny growths in the skin where their horns would be – these are known as scurs.