Deltatheridium was a species of Metatherian. It lived in what is now Mongolia during the Upper Cretaceous. It was a basal metatherian, which places it near start of the linage that lead to the marsupials, such the kangaroo, koala, and opossum.
It had a length of 15 cm (5.9 in). Apart from preying on insects, its diet was also composed of small reptiles and what it could scavenge from left-over carcasses, using its sharp canine teeth.