In the 1990s, a pair of Yale archaeologists discovered a graffiti-covered cliff wall at the Wadi el-Hol (Gulch of Terror) in Egypt. Most of the inscriptions were in systems they could recognize, but one of them was unfamiliar. It looks like an early transition from a hieroglyphic to an alphabetic system, but it hasn't yet been deciphered.
2. CRETAN HIEROGLYPHICS
The excavations on Crete also revealed a third type of writing system, with symbols that looked more picture-like than those of the linear scripts. Some of these symbols are similar to elements in Linear A. It is assumed that the hieroglyphic script developed into Linear A, though the two systems were both in use during the same time period.
The Olmecs were an ancient Mexican civilization best known for the statues they left behind: the so-called "colossal heads." In 1999, their writing system was revealed when road builders unearthed an inscribed stone tablet. The tablet shows 62 symbols; some look like corn or bugs, and some are more abstract. It has been dated to 900 B.C., which would make it the oldest example of writing in the Western Hemisphere.
There once was a giant engraved slab made of sandstone at the mouth of the Singapore River. It had been there for 700 years or so when, in 1819, workers uncovered it while clearing away jungle trees. A few scholars got a look at it before it was blown to bits in order to make space for a fort to protect the British settlements. The parts that didn’t end up in the river were eventually used for road gravel, though some fragments were saved. The script hasn't been deciphered, but there have been various suggestions for what language it might represent: ancient Ceylonese, Tamil, Kawi, Old Javanese, and Sanskrit.
When missionaries got to Easter Island in the 1860s, they found wooden tablets carved with symbols. They asked the Rapanui natives what the inscriptions meant, and were told that nobody knew anymore, since the Peruvians had killed off all the wise men. The Rapanui used the tablets as firewood or fishing reels, and by the end of the century they were nearly all gone. Rongorongo is written in alternating directions; you read a line from left to right, then turn the tablet 180 degrees and read the next line.
This ancient writing system was used more than 5000 years ago in what is now Iran. Written from right to left, the script is unlike any other ancient scripts; while the proto-Elamites appear to have borrowed the idea for a written language from their Mesopotamian contemporaries, they apparently invented their own symbols—and didn't bother to keep track of them in an organized way.
Source: Mentalfloss