Deinosuchus

[Paleontology • 2025] Expanded Phylogeny elucidates <i>Deinosuchus</i> relationships, Crocodylian Osmoregulation and Body-size Evolutionnovataxa.blogspot.com

Expanded phylogeny elucidates Deinosuchus relationships, crocodylian osmoregulation and body-size evolution - Communications BiologyNature

Expanded phylogeny elucidates Deinosuchus relationships, crocodylian osmoregulation and body-size evolutionPubMed Central (PMC)

[] In a 2025 study, Jules D. Walter and colleagues argue that many character states previously thought to be diagnostic for alligatoroids were Actually much more widespread. In their analysis several genera traditionally viewed as basal alligatoroids,

Among them Deinosuchus, were found to not only fall outside of Alligatoroidea but to not even be '' true crocodilians '' ~~ Instead representing highly derived non-crocodilian eusuchians. { They are still within The neosuchian crocodylomorphs }

Deinosuchus was recovered as having split from the lineage leading up to Crocodilia after Leidyosuchus but before the terrestrial Planocraniidae. []

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

Expanded phylogeny elucidates Deinosuchus relationships, crocodylian osmoregulation and body-size evolution - Communications BiologyNature

However, it's explanation for the Rex's sensory pits while interesting seems to be a big misunderstanding. Here is the article:

No, Tyrannosaurus Rex Was NOT a Sensitive LoverMax Hawthorne

To sum it up: The first part of the explanation makes sense, saying that like big cats, mating would be very awkward for two 10 ton creatures and that like big cats. Trex would have restrained it's mate by the neck to prevent moving for copulation. That makes sense, I guess, doesn't really debunk the idea that they could have just nuzzled after or before to lower aggression and their probably emotionally intelligent, but I digress.

The weird part of the explanation is that it says that in reality it would be an evolutionary adaptation to prevent trex from being killed by crocodiles like deinosuchus.

I'm sorry, but how did bro forget basic research?

Deinosuchus never lived with trex, and the biggest crocodile that lived in the hell creek formation was the one ton, 8 metre thoracosaurus. And that's a big croc don't get me wrong. But that's never killing a TREX, if it tried, it would be trampled or bitten in half. It's suicide. The explanation is interesting but doesn't really make much sense.

That's what part of me thinks, however Albertosaurus lived with Deinosuchus and was probably eaten by the killer croc. And since tyrannosaurs were smaller in the past, this could be an evolutionary left over. Something that might have served the purpose of avoiding predation from water predators that now isn't all too relevant. I'm not entirely sure about that, but what do you guys think?