Small devilsaurs yes, small direhorns no (so far).
If you going for the eggs, fastest way to get them by far is to form a group of 3-4 people (tank, healer, then 1-2 dps) and farm the adult devilsaurs. Bone acquisition rate is about the same as soloing small direhorns once you average it out, but the drop chance for eggs is significantly higher. With a 3 man group it usually takes us 30-45 mins to each get an egg.