 Numerous dinosaur species, for example "Maiasaura", have been found in herds mixing both very young and adult individuals, suggesting rich interactions between them.A dinosaur embryo was found without teeth, which suggests some parental care was required to feed the young dinosaur, possibly the adult dinosaur regurgitated food into the young dinosaur's mouth ("see" altricial).This behaviour is seen in numerous bird species; parent birds regurgitate food into the hatchling's mouth.