Eosimias is a genus of early primates, first discovered and identified in 1999 from fossils collected in the Shanghuang fissure-fillings of Liyang, the southern city of Jiangsu Province, China.

[5] E. sinensis was tiny, as small as the smallest monkey presently, the pygmy marmoset (Cebuella pygmaea) of South America, and could fit in the palm of a human's hand.

Due to its highly primitive nature, some paleontologists consider E. sinensis to be evidence that higher primates may have originated in Asia rather than Africa.

Biostratigraphic evidence also suggests these fossils are younger than E. sinensis, which is consistent with the anatomy of eosiimids because the dentition of E. centennicus is slightly more derived than that of E.

E. sinesis was originally described on the basis of fragmentary fossils, but with the discovery of E. centennicus and a complete lower dentition, Eosimias can more definitively be described as an early anthropoid.

[9] Analysis of these remains has led to the conclusion it was the largest of the known species of Eosimias, yielding a body mass ranging from 107 to 276 grams (3.8 to 9.7 oz).

The best estimate for NMMP 23 includes an overall mean weight of about 111 grams, which places it in the upper-sized end of Eosimias fossils discovered.

The presence of eosimiid in Myanmar, as well as a high species diversity found in China leads to an apparent conclusion that they had a relatively wide distribution.

[10] A new species of eosimiid primate, Eosimias paukkaungensis, from the latest middle Eocene of Pondaung, central Myanmar, was discovered in the early 2000s.