A bit of info on the Wyverns
The Heirs are egg tames that spawn at the max level of taming effectiveness possible, so so 225 would be max for them. They also have a passive tame version of them, that remains passive unless you hit them.
They are breed-able and have different mostly different attacks, Ember Crystal Wyvern's are somewhat like Fire Wyverns.
Ember Crystal Wyverns fire a longer-ranged but narrower fiery breath which does more overall damage which increases the more the fire breath is used consecutively.
Blood Crystal Wyverns fire a mid-range blood stream which deals decent damage and siphons health over time to all targets hit (inflicting "Blood Cursed!" effect at target whilst adding "Blood Curse Recovery!" to itself), healing the Blood Crystal Wyvern, it is also capable healing itself by eating corpse (80 health each bite), similar to Argentavis.
Tropical Crystal Wyverns fire a long range jet of water with high knockback and mediocre damage with "Scolded!" effect which reduces both HP and Stamina. They are additionally buffed by water similarly to Spinos.
Crystal Wyverns are faster and have a tighter turning radius (faster turning) than their normal Wyvern counterparts. However, their bite attack does less damage and their attack speed is slower. The are also 25% smaller then normal Wyverns.
They glow in the dark, which makes them easily seen at night.
It's easier to get the primal crystal's needed to feed the babies as higher levels give more crystals.
Ohh and for some weird reason Sweet Vegetable cakes heal them.