I can go for either Spike, Petrie, or Littlefoot, but I'll wait until everyone else has chosen.
As for my own, I already made a herd of spikethumb (iguanodon) characters, which I'm still trying to keep as minors for the stories. Here's a list and short info on them:
Guan: first child, only brother, Hyp's age
Goanna: second child, oldest sister, two-thirds of Guan's size
Donna: third child, youngest sister, Littlefoot's age and Cera's size
Uncle Odon: uncle and teacher, Spikefoot's younger brother
Spikefoot: father, Odon's older brother
Lightningtail: Guan's friend, same size and age, but lighter in color
Thundertail: Lightningtail's father, slightly larger than Spikefoot
Again, I'll try to keep them minor.