This is a silver-backed chevrotain, aka "mouse-deer," from Vietnam.
Until this and other camera trap photographs were taken in the last two years, no scientific evidence of the rabbit-sized animal had been collected in three decades. From Nature:
The animal was first described in 1910 from four specimens, but since then only one verifiable record exists, from the early 1990s. The Red List of Threatened Species maintained by the International Union for Conservation of Nature classifies the silver-backed chevrotain (Tragulus versicolor) as 'data deficient'.
Indigenous people living in the Nha Trang forest suggested where the scientists should place their camera traps to get the animals on film.
"To these local people our camera-trap evidence that the silver-backed chevrotain survives in Vietnam is not new," says (Global Wildlife Conservation scientist Andrew) Tilker. "But to the wider scientific community, we are comfortable saying that our findings constitute a rediscovery."