Human/mammalian/elephant heart is

Human heart is

Human heart is

Mammalian heart is

Human heart has

[A]: in mammalian heart there is a very swift conduction of stimulation all over the walls of the heart [R]: Conduction of stimulation is caused by Purkinje fibres and Bundle of His

Heart of elephant is

What are the similarities and dissimilarities between mammalian and amphibian heart?

Why is a mammalian heart referred to as myogenic ?

Why is a mammalian heart referred to as myogenic?

How do avian and mammalian hearts show convergent evolution ?