Crocodyloidea may also include the extinct Mekosuchinae,[1][2] native to Australasia from the Eocene to the Holocene, although this is disputed.

Traditionally, crocodiles and alligators were considered more closely related and grouped together in the clade Brevirostres, to the exclusion of the gharials.

This classification was based on morphological studies primarily focused on analyzing skeletal traits of living and extinct fossil species.

[6] However, recent molecular studies using DNA sequencing have rejected Brevirostres upon finding the crocodiles and gavialids to be more closely related than the alligators.

[7] A 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data established the inter-relationships within Crocodilia,[3] which was expanded upon in 2021 by Hekkala et al. using paleogenomics by extracting DNA from the extinct Voay.