Z has the unusual distinction of having been both an original member of the Latin alphabet and a later re-import. The earliest Etruscan-derived Roman alphabet included a letter descended from Greek zeta in the seventh position, matching zeta's own place in the Greek sequence; but early Latin had little practical use for the sound, and the letter fell out of use, with its old seventh-position slot eventually reassigned to the newly invented G, as covered elsewhere in this atlas.
Centuries later, during the late Republic, Rome reintroduced Z directly from contemporary Greek, this time to transliterate Greek loanwords that used the sound, and placed the reborrowed letter at the very end of the alphabet, alongside the similarly reintroduced Y, rather than restoring it to its original seventh position.
Z's zigzag shape, essentially unchanged from Phoenician zayin through Greek zeta, was carried over intact in this second borrowing, and the letter therefore preserves an ancient Semitic outline while occupying one of the newest, most recently assigned positions in the entire Latin sequence, having effectively started at position seven, been dropped, and ended up refiled at position twenty-six.