reptiledom

It is common enough practice for them to turn cannibals and eat their own offspring — rather despicable business, this eating of one's own children, but possibly considered good form in reptiledom.

1922, Edmund Carroll Jaeger, Denizens of the Desert, page 237

For hibernation means more than taking a long sleep when it is very cold and the metaphorical wolf is at the door; it means a definite imperfection in the warm-bloodedness, and a peculiar lapse towards reptiledom, with very remarkable constitutional changes in heart and blood, in breathing and excretion.

1927, John Arthur Thomson, Ways of Living: Nature and Man, page 34

Leaning against bookcases filled with medical works were huge test tubes of alcohol and formalin preserving the remains of many of the most dangerous characters of reptiledom.

1931, Paul Kane, “Howard Atwood Kelly, In Whom the Naturalist Rivals the Physician”, in Nature Magazine, volumes 17-18, page 104

In the absence of earlier eggs, it is hard for scientists to tell exactly when the amphibians crossed the threshold into reptiledom, for the earliest known reptiles are so amphibianlike that their assignment to one category or the other is largely a matter of opinion.

1964, Ruth Moore, Evolution, page 114