The Romans didn't change the Greek alphabet, they changed the Etruscan alphabet, which in turn was derived from the Greek alphabet. Just as Greek was phonologically different enough from Phoenician that it had to modify the Phoenician script to suit its own phonology, mixing around letters so that they represented sounds in Greek, the Etruscans had to modify Greek to suit their own phonology. Phoenician, like Egyptian, does not mark vowels, and Greek used as vowels several letters used in Phoenician to represent consonants that did not exist in Greek. Likewise, Etruscan had a number of sounds that did not exist in Greek and had to be adapted. It should be noted that there was a not a single, unified Greek alphabet even in during the Hellenistic Period. The modern 24-letter alphabet, derived from the Attic alphabet as it existed in the fourth century, is not the same alphabet from which the Etruscans took their own script. The Etruscan script is derived from Western Greek, which preserved consonants that did not exist in Attic/Ionic Greek (e.g. ϝ), as well as using letters to represent sounds that they did not represent in later Attic (e.g. χ for ξ or η in its older, pre-Ionic use as the rough-breathing, which was at first not marked in Attic and then later was marked with a diacritical). In addition, Western Greek script frequently used forms that were different from those in Ionia, such as Ρ, which was written without a tail in Ionic and Attic but was frequently written R in Western Greek. The very earliest form of the Etruscan alphabet is quite conservative, making relatively few changes to the Western Greek alphabet. By about the sixth century the Etruscan alphabet had changed to reflect better the pronunciation of Etruscan. Several stops dropped out of the script, since Etruscan did not distinguish between them strongly, and an extra letter 𐌚 (whose origin is unclear) was added. The early Latin alphabet, likewise, was rather conservative to the Etruscan script, derived from Western Greek. It preserved, for example, no hard distinction between C/G/K/Q, even though Latin, unlike Etruscan, did have a distinction between those sounds, or at least some of them. Over the course of several centuries Latin slowly scrubbed out letters it did not need or changed letters that already existed. The greatest difference, indeed, between the Etruscan and Latin scripts is the consistent use of stops and the addition of the letter G.