Sylvia was a female giant ground sloth who was cut from the first Ice Age film, but can be found in the deleted scenes of the 2-Disc DVD release and in the Ice Age movie novelization. She was voiced by Kristen Johnston.
Sylvia was shown waylaying Sid into traveling with her. Sylvia eventually found him again, after two days, though this time, she found him laying in the mud alone, after been kicked by two female sloths. Sid agreed, telling her that he would leave her for a moment to get some turnips so as to stuff their cheeks to migrate the many miles, but it was only a distraction to let him escape without her knowing it. Not fooled for long, Sylvia followed Sid, finding him in the jaws of Diego, the saber-toothed cat. However, She did not believe that Sid was truly dead as she sees him breathing, and after angrily looking at Diego who nervously shrugged,. It is presumed that after that, she left Sid alone. Sylvia had red-colored fur and red, untidy hair.
According to the Ice Age DVD commentaries, the scenes with her were cut because of two reasons. The first reason was for timing purposes; although the scenes with her were funny, they took up a lot of time and didn't focus on the main plot. The second reason was because of Sid's behavior towards her, considering that the creators of the movie were still experimenting with Sid's personality, they found out that Sid was acting a bit mean towards her during these cut scenes and decided to take them out, to not reveal any cold hearted nature. Also according to these commentaries, there was an alternate ending to the first movie. After Sid and Manny's friend Diego dies and they give the baby back to his father/herd, they head south and met up with the other animals (they headed south without Diego because in earlier drafts of the movie Diego died and never came back). In this alternate ending Sid sees Sylvia again he was a bit nicer to her and asks her to be his mate.
Even though she was a cut character, she was cut from the movie fairly late. Most of the sequences with her were completely animated and rendered (and usually when it comes to animated films scenes usually get cut in the storyboard phases). Sylvia was also seen in earlier trailers of the movie as well as early ads and posters.