groundhog skull

In this post I will talk about my groundhog skull, and why I think it was young.

the groundhog dental formula is:

I : 1/1   C : 0/0   P: 2/1   M: 3/3 = 22    (11x2=22)

or

upper: 2 ; 0 ; 4 ; 6

lower: 2 ; 0 ; 2 ; 6

which means:

a groundhog has 1 incisor, 0 canines, 2 premolars and  3 molars on each side of the top jaw, so they have 2 incisors, 0 canines, 4 premolars and 6 molars on the top jaw. (12 teeth)

they have 1 incisor, 0 canines, 1 premolar, 3 molars on one side of the upper jaw therefor has 2 incisors, 0 canines, 2 premolars and 6 molars on the entire bottom jaw. (10 teeth)

ground hogs have 22 teeth.

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Unfortunately, I do not have the lower mandible of the groundhog. But the cranium has room for all 12 teeth (some fell out post-mortem, but all the teeth have grown) I have one incisor, 6 molars, and 2 of the premolars on my skull. There are only 3 teeth missing.

Compared to my groundhog bottom jaw (not from the same animal) this skull has sharp teeth, suggesting this skull is young and\or the other animal from which I have the jaw was very old.

the 'sharp' teeth on my groundhog skull

the jaw from older groundhog

On this skull, the auditory bullae (inner ear bones), the back of the brain case and the nasal bones are missing.  I know that in deer, when the back of the brain case is missing it is a sign the animal was young. Also, the bones are not fused, which in most animals, means the animal was not fully grown. (It is possible that the brain case has been crushed, but because of the lack of fusion in the bones and sharp teeth I think it is more likely it is missing because the groundhog was young and the piece of bone just fell off.)

The pictures show the missing auditory bullae and braincase. In the first picture,  you can clearly see the bones that are not fused.

In conclusion, this groundhog had all it's teeth, but they where not worn down. That means that the animal was not as old as my groundhog jaw. The bones are not fused, causing the brain case and auditory bullae to detach and no longer be on the skull, And that happens to young animals. And that is why I think the skull was from a young groundhog.