Mrs. Threehorn is a lighter shade of gray than other Triceratops seen in the series, implying that she is female. She has a few small wrinkles on her face, but it can be assumed that she is younger than her mate.
Cera's mother is seen briefly at the beginning of the first movie when Cera hatches; she later appears when Littlefoot first meets Cera, when Cera is separated from her family in the Great Earthshake, and potentially at the end of the film, when Cera reunites with her father. Outside of what may be a few small cameos in The Land Before Time II: The Great Valley Adventure, she does not appear in any of the later films, with her role as Topps' mate being usurped by Tria in The Land Before Time XI: Invasion of the Tinysauruses and onward.
- She is referred to in the 1987 script for the original film as "Mama Topps".
- The lack of clarity on whether or not she definitely appears after the Great Earthshake has led a number of fans believe that Cera's mother and sisters are deceased by the end of the original movie, with common theories regarding their hypothetical deaths involving them being attacked by Sharpteeth, or, in a less likely scenario given the film's depiction of the scene, joining Pterano's splinter herd in a flashback in The Land Before Time VII: The Stone of Cold Fire and being slaughtered by Fast Biters alongside the other unfortunate leaf-eaters.
- Though she does not physically appear in the film, Mama Topps is indirectly alluded to by Littlefoot in Invasion of the Tinysauruses when he tells Cera that Tria could serve as her new mother, which provokes an aggressive response from the young Threehorn.
- ↑ After the Great Earthshake, Cera calls out, "Mama, Daddy!"