that is because he lost health and damage percentage after taming, because they power and specs was improved to match to they're size and to not be so easy victims for the other predators. Basicly they become like the original Giganotosaurus - lost health and damage after taming, because are not fighters and are already pretty strong. But taming low level sauropod is not a good idea - will happen this - negative health.
with next update they're basic level will be increased to prevent situations like yours - sorry, they still are on process of development

thanks aprecciate your work

cant download the mod