you are very observant. the top finial is called ช่อฟ้า representing the garuda,a mythical bird in hindu literature. it is the vehicle of the good vishnu. the lower finials are called หางหงส์ in thai. they represent the heads of the naga, a mythical serpent in hindu literature. and those ridge-like teeth running along the gable edges are the ใบระกา the feathers of the garuda or the scales of the naga.