Jules D. Walter and others just dropped a cool new study in Communications Biology. They expanded the phylogenetic analysis of Crocodylia and their closest living relatives. Using this calibrated strict consensus tree of the parsimononious analysis, they found that the Upper Cretaceous Leidyosaurus and Deinosuchus, and the Paleogene-early Neogene Diplocynodon were in fact stem-crocodylians (not to be confused with the broader crocodilian group).
[Illustration of Deinosuchus sp. by Fred the Dinosaurman]
[Reduced time calibration tree achieved with maximum-parsimony analysis, an updated phylogeny of Crocodylia and their stem relatives]
Alligatoroidea were phyletic dwarves early in their evolution, with species like Albertochampsa langstoni and Stangerochampsa mccabei possessing small sized and short snouts. Animals like Purussaurus (my favorite?) achieved enormous sizes in the Neogene.
The authors also find that previous estimates for Deinosuchus's total length, of between 8 and 12 meters, to be inaccurate (especially for the skull, TMM 43620-1, used in such studies), as they used unique extant proxies like estuarine crocodiles (Crocodylus porosus) and American alligators (Alligator mississippiensis), or basing measurements on snout length. The 97.5 percentile estimate of 7.66 meters for Deinosuchus riograndensis of Laramidia and 6.37 meters for D. schwimmeri of Appalachia is considered the most realistic total length.
Some Deinosuchus specimens are larger the studied one.
[Saltie at Crocodylus Park, Barrimah. Crocodylus porosus is capable of making journeys into saltwater to hunt, thanks to osmoregulatory adaptations]
Longirostres, the clade uniting crocodiles, gavials, and false gavials, was recovered in their tree. Thank goodness
With Deinosuchus, it had been previously assumed that vicariance - being geographically separated by a physical barrier - caused their divergence into two species, one on either side of the Western Interior Seaway. This was because, due to percieved alligatoroid affinities, it was thought that they packed lingual salt glands (like modern gators). Given that Deinosuchus was a stem-croc, osmoragulatory properties may be a better explanation.
Lingual salt glands allow modern crocodiles to be in salt water for extended time periods, via osmoragulation - balancing the salt:water ratio in body fluids.
Here is graph in the study that I thought was interesting. It illustrated the distribution of body sizes across stem- and crown-crocodylians through the Cretaceous and Cenozoic.
The study link = https://www.nature.com/articles/s42003-025-07653-4
