Zalambdalestes

Superregnum: Eukaryota
Cladus: Opisthokonta
Regnum: Animalia
Cladus: Bilateria
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Classis: Mammalia

Zalambdalestes (meaning much-like-lambda robber) was a placental mammal living during the Upper Cretaceous in Mongolia. It is one of the oldest examples of a placental mammal known, and would have lived alongside the dinosaurs.

Zalambdalestes was a shrew-like animal with a long snout, long teeth, a small brain and large eyes. It was about 20 centimetres (8 in) long, with a head only 5 centimetres (2 in) long. It had strong front paws and even stronger rear ones, but its claws were not opposable, so it is unlikely to have climbed trees. Its diet was probably composed mainly of insects that it hunted in the forest undergrowth using its sharp, interlocking teeth.[1]
References

Parker, Steve. Dinosaurus: the complete guide to dinosaurs. Firefly Books Inc, 2003. Pg. 402

^ Palmer, D., ed (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 201. ISBN 1-84028-152-9.