Revised August 09, 2019
with the addition of the Dyoplax skull (Fig. 7b) recently downloaded from Maisch et al. 2013.
Dr. Andrea Cau 2019
recently revised the affinities of the extinct marine crocs (Figs. 1,2). Here (Fig. 3), with more outgroup taxa, the affinities of the outgroups are more refined by adding taxa omitted by Cau. The in-group marine croc clade of Cau 2019 continue as is untested.
As we learned earlier
choosing outgroup taxa is not as scientific as letting a wide gamut phylogenetic analysis, like the large reptile tree (LRT, 1549 taxa, subset Fig. 3), choose outgroup taxa for you.
the proximal outgroup taxon for marine crocs recovered by Dr. Cau (Fig. 2) was tiny Fruitachampsa (Figs. 3, 4), a small, gracile Late Jurassic biped sprinter that nests with Protosuchus in LRT and Cau’s cladogram. Fruitachampsa would seem to have few traits in common with river and marine crocs. Dyoplax has more.
Cau did not include Dyoplax
in his cladogram.
While we’re on the subject of Fruitachampsa,
it had an enormous notch for a mandibular fang, much larger than necessary. The medial choana is similar to sister taxa.
Dyoplax (Fig. 7) is not considered a crocodylomorph, let alone an outgroup to marine crocs, as we learned earlier here.
In the LRT
(subset Fig. 3) Dyopolax (Figs. 7, 7b) is the outgroup taxon to marine crocs while Dibrothosuchus (Fig. 8) is basal to this clade + river crocs.
a wide gamut phylogenetic analysis is key to recovering interrelationships.
Cau A 2019. A revision of the diagnosis and affinities of the metriorhynchoids (Crocodylomorpha, Thalattosuchia) from the Rosso Ammonitico Veronese Formation (Jurassic of Italy) using specimen-level analyses. PeerJ, DOI 10.7717/peerj.7364
Clark JM 2011. A new shartegosuchid crocodyliform from the Upper Jurassic Morrison Formation of western Colorado. Zoological Journal of the Linnean Society, 2011, 163, S152–S172. doi: 10.1111/j.1096-3642.2011.00719.x