In LBT 2 we see two grownup threehorns coming to the rescue at the sinking sand (it would make sense for the other threehorn to be Cera's mother though it is never stated explicitly). In LBT 2, 3, and 4 we often see threehorns who seem to be a bit younger or (in case of LBT 4) older than Cera who might well be siblings of her. Then there is the undetermined origin of Dinah and Dana in LBT 6. It is not sure if the "auntie" Cera is to be taken literally though as they differ from Cera and the earlier younger threehorns we have seen both in color and the fact that they sport 3 horns.
Personally, I don't think the threehorn in LBT II (who wasn't actually seen "coming to the rescue") is related to Cera. I think it's more likely that he or she was simply another threehorn who happened to be grazing nearby, whose attention was caught by the gang's cries. After all, if you heard a bunch of kids screaming for help, even if they weren't your own, wouldn't you react? Similarly, while the other young threehorns seen in the valley during the early movies could conceivably be Cera's siblings, I doubt that they are. After all, the gang's families can't be the only dinosaurs in the Great Valley who have children.
Dinah and Dana are definitely the monkey wrench in any attempted explanation of Cera's familial relationships. Given that they only appeared in LBT VI, and were never so much as referenced again, I strongly suspect they were just plot device characters whom the filmmakers introduced with little or no consideration for how the gang's families had previously been portrayed.
While Dinah and Dana's colors do differ from Cera's and every other previously seen young threehorn, that is not necessarily evidence that they are a different species. Threehorns, and indeed most LBT dinosaurs, have been shown to have extremely variable coloration, with the main characters usually being the most distinctively colored Although the filmmakers could have made Dinah and Dana the same color as Cera, there's still the matter of enabling viewers to tell one twin from another, which is probably the reason they introduced new color schemes for them. Additionally, another pair of three-horned threehorn children were shown during the introduction of LBT X, accompanied by a parent who didn't look much different from most of the background threehorns we've seen in LBT. Maybe some threehorns are just early bloomers (That's always been my assumption for Dinah and Dana).
If Dinah and Dana's horns are evidence that they are a different kind of dinosaur, then perhaps we should consider Tria, who is not only a strikingly different color from any threehorns we've seen before, but has many more epoccipitals (the small, hornlike bumps along the edge of the frill) than Cera's father (or her mother, for that matter). The fact that Tria and Topsy had a hatchling ought to be clear evidence that she is not too genetically different from him. It's still possible that that Dinah and Dana (and the LBT X threehorns I mentioned before) ARE a different species from Cera, Topsy, and Tria, but it's equally possible that they could just represent one of the many cases of peculiar individual variation among the dinosaurs of LBT.
I have a few other hypotheses for Dinah and Dana's relationship to Cera and her father, and why they are only seen in LBT VI. I can think of a few counterpoints to them, but for now I'd rather let other members make their arguments against them.
Also, if anyone thinks that I should be posting this in the Dinah and Dana thread in Character Discussion rather than here, I will gladly move it.
ï Dinah and Dana belong to another family of dinosaurs in the Great Valley, who may or may not be related to Cera's family, but are close enough to them that Dinah and Dana think of Cera and her father as their aunt and grandfather. This family had to leave the twins with Cera and her father for some reason or other, and took them back afterwards. The reason we don't see them again could be that they live in another part of the Great Valley, the valley being so large that not all of its inhabitants see each other on a day-to-day basis.
ï Dinah and Dana were lost or orphaned, and Cera and her father cared for them for a while, until either their original family was found, or a new surrogate family adopted them. In this scenario, too, they could be related to Cera and her father, or they could be an entirely different kind of dinosaur.
ï Cera and her father have farwalker relatives who occasionally visit the Great Valley. Dinah and Dana are their children, and during LBT VI, Cera and her father had to babysit them for a time. Afterwards, they left the Great Valley along with their parents. (I saw this explanation used in the fanfic
The Land Before Time Onehalf.)
By the way, isn't there already a thread somewhere discussing Cera's missing family?
