Why so big???
1+1 = 2 instead of (1+1)/2 ?
Hybrid vigor.
In tigers, the gene for growth regulation is supplied by the male. In lions, it's from the female. Since this animal has a tiger for a mother and a lion for a father, it didn't get the gene from either parent. (Heard this on Discovery the other day.)
Hybrid vigor.
When I look at the picture where it is standing on it's legs, it seems to have a body type more of the tiger than the lion.
A Siberian tiger is about 650 lbs, which is quite a bit bigger than the lion.