User blog comment:Kogath/Monster Hunter: World Discussion/@comment-6050823-20170922122302/@comment-3298463-20170922132734

That's not an official description though, just something someone in this Wiki wrote based on the information we had for a long time: that the only Fanged Wyvern (excluding subspecies) had mammalian traits. It doesn't mean that all Fanged Wyverns must be mammalian-like.