JINAN, May 15 -- Chinese archeologists have discovered new forms of the earliest Chinese characters and rare human skull oracle bones in their latest study of thousands of ancient inscribed animal bones and tortoise shells, they announced on Thursday.

The discoveries include new forms of two Chinese characters, Gou and Shou, and special tortoise shells with military tokens, said Song Zhenhao, a researcher with the Chinese Academy of Social Sciences (CASS).

Archeologists also found two rare pieces of human skull oracle bone, an oracle bone recording a sacrifice ritual with 300 cattle, and a large tortoise back shell measuring 48 cm in length, said Song at a seminar in Jinan, capital of east China's Shandong Province.

The findings were made in a joint research and conservation project between the Shandong Museum and the CASS.

Staffers have handled 7,541 inscribed animal bones and tortoise shells since the program started in December. The project will last four to five years.

With a collection of 10,588 inscribed animal bones and tortoise shells, Shandong Museum is one of the most important institutions in the research of such materials.

Oracle bones were first unearthed in the late 19th century among the ruins of Yin (Yinxu) in Anyang, capital of the Shang Dynasty (1600 BC-1046 BC). Yin was the ancient name for the Shang Dynasty. The ruins were listed as a UNESCO World Heritage Site in 2006.