The thylacine was relatively shy and nocturnal, with the general appearance of a medium-to-large-size dog, except for its stiff tail and abdominal pouch similar to a kangaroo's, and dark transverse stripes that radiated from the top of its back, reminiscent of a tiger.

The thylacine was one of only two marsupials to have a pouch in both sexes: the other is the water opossum. The pouch of the male thylacine served as a protective sheath covering the external reproductive organs.

Copyright:

https://en.wikipedia.org/wiki/Thylacine