Deer Dentition

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“My deer is so old it has no top front teeth!”  I have heard this many times, and each time the person is surprised to learn that no deer have upper incisors.  It is strange indeed that deer have lower incisors with no uppers to chew against.  The lower incisor-like teeth are pressed against a hard upper pad, or palate, to pinch and tear off plant parts.  The 8 lower “incisors” are actually 6 incisors with an outside pair of lower canines.  Through evolution, these lower canines have moved forward in the jaw to look and function as incisors. The lower jaw also has 3 premolars and 3 molars on each side that mate with their counterparts above to grind and regrind food.  Fawns are born with all 8 lower incisor-like teeth, all 3 premolars, and 1 molar on each side of the jaw.  All incisor-like teeth and premolars are replaced with adult teeth before the age of 2 years, which provides biologists and others a method of ageing deer according to their tooth eruption and replacement patterns.  After 2 years, all adult teeth are present and ageing is accomplished by looking at the wear on the teeth.  There is too much variation in wear patterns to place all deer accurately into the correct single-year category, but this method still allows managers to pool age classes together and define the relative age structure of the population.  For example some states group deer into age categories of 1.5, 2.5, 3.5 to 5.5, 6.5 to 8.5, and 9+ years.     

The fact that elk have upper canine teeth or “ivories” is well known, however, few people realize that on occasion deer can also grow upper canine teeth.  These canines growing out of the maxillary bones of the skull are vestiges from a time in deer evolution when they had well pronounced fangs.  In fact, the black spots on each side of the lower jaw (called the ‘labial patch’) is though by some to be a remnant from the days when this black patch accentuated large white canine tusks.  The percentage of deer possessing maxillary canines is low, generally 0.05 – 18% in populations where these teeth have been documented.  When present, these canines are not large, but generally small peg-like teeth just breaking the gumline.  Some canines would not be seen even upon inspection because they are so small that they don’t break through the skin and are not visible by simply looking in the mouth.

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Antlers: Armaments or Ornaments?

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Megaloceros giganteus

The original function of antlers has been debated with several theories being proposed, including heat radiation, protection against predators, scent dispersal, armaments for fighting other males, and display/intimidation.  The most popular and obvious explanation for the origin and function of antlers is their use as weapons to battle rival males for access to breeding females.  Antlers harden just before the breeding season and drop off afterward, they occur in only males (except in caribou), antlers of all species end in sharp points, and they are used extensively for fighting and ritualized antler to antler shoving matches.  Besides their use as weapons, antlers are thought to also serve as visual cues to potential rivals.  Since the size of the antlers depends on age, nutrition, and genetics; the larger the antlers, the older, better nourished, and genetically superior the body which produced them.  With antlers as an index to health, a females can also select a visibly superior individual to mate with and perpetuate her genes.  The great diversity in antler shapes and sizes provides strong evidence that more than one factor was involved in shaping antlers throughout the evolution of the deer family.  If antlers served only one purpose in all deer species throughout their evolution, it seems one shape would prevailed as the most efficient.

Welcome to DeerNut’s Blog!

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Welcome to Deernut’s Blog!  I’ll share what I think are interesting pieces of information about the most glorious animal on earth!  Watch for the launch of The DeerNut Podcast coming soon.  For more information about deer, or to get an autographed copy of my book “Deer of the Southwest,” go to WWW.DEERNUT.COM.