As covered elsewhere in this atlas, Latin originally had a single letter, written V, for both the vowel sound now spelled U and the consonant sound now spelled V, inherited as one sign from Greek upsilon and, ultimately, a Phoenician sign for the sound w. Roman inscriptions used the angular V shape for both values throughout antiquity, and the rounded U familiar today is simply a cursive variant of the same letter that developed in ordinary handwriting during the Middle Ages, without at first being treated as graphically distinct.
Printers and grammarians only began to treat U and V as two separate letters, one a vowel and one a consonant, during the Renaissance; the French scholar Pierre de la Ramee, known as Ramus, is often credited with formalising the distinction in the 1560s, though the practice spread unevenly across Europe over the following two centuries, and dictionaries and typefaces did not fully separate U from V in ordinary alphabetical order until well into the 17th and 18th centuries. U therefore has no ancient graphic identity of its own distinct from V; its status as a separate letter is one of the youngest developments in the entire history of the Latin alphabet, younger even than the invention of W, which depended on doubling the older, undivided letter.