Eosuchia is generally seen as comprising two families,
Tangasauridae and
Younginidae. The
monophyly of the group—whether tangasaurids and younginids form a clade rather than distinct branches—is disputed. A 2009 study found them to be an unresolved
polytomy at the base of Neodiapsida. In their 2011 description of
Orovenator,
Reisz et al. recovered the group as
paraphyletic. These results are displayed in
Topology A below. A 2022 study by Simões et al. recovered the Younginiformes as a
monophyletic group of basal neodiapsid reptiles, also including
Claudiosaurus and
Saurosternon as part of the group. These results are displayed in
Topology B below.
Topology B: Results of Reisz et al. (2011) In their description of the EAZ taxon in 2026, Jenkins et al. used an updated version of this matrix for their phylogenetic analyses. They recovered conflicting results regarding the relationships of tangasaurids to younginids; an
implied weighting parsimony analysis placed them as successive lineages (rendering paraphyletic), while a time-calibrated
Bayesian analysis recovered a monophyletic Younginiformes, with Tangasauridae as the sister group to Younginidae (including
Saurosternon). Abbreviated versions of these analyses are displayed below. As explained by Buffa et al. (2025),
Topology C: Implied weighting analysis
Topology D: Bayesian analysis ==References==