Unless I miss my guess, thats a mainly reabsorbed twin. Mammalian twins compete for nutrients in the maternal supply; sometimes one absorbs the other completely. This happens occasionally (rarely) in humans, too. As to precise cause, who knows?
We dont fully understand what causes twinning, or even the prenatal growth of singletons. We cant explain it; it just happens.
Enjoy your paper and the beautiful country it serves.
Dr. Paul S. Sussman
I have seen another in Indian Beach where I had lived for two years. Last winter I had a young buck around the house who at first I thought had been shot, but as I started to feed him I noticed he had a displaced jaw, with some dark deep makings along it. It was not from a gunshot but an abnormal growth.
I know I should not feed the wildlife but this guy came every day at the same time. I was feeding the birds as I always do and the feral rabbit some family left behind. Also, he started coming for the food too. I was worried about him making it through the winter.
Glenda L. Hill