#alligatoridae

Yacaré Caiman (Caiman yacare), EAT A TASTY CATFISH!!!, family Alligatoridae, Pantanal, Brazil

A young American alligator (Alligator mississippiensis) rides on the back of its mother in Brazos Bend State Park, Texas, USA

It just goes to show, size is always relative! The dwarf caiman is the smallest crocodilian species, but adults can still reach a length of 1.4 m (4.6 ft) and weigh up to 7 kg (15 lbs)! Since they run on the runty side, dwarf caimans also have much thicker dermal plating than other crocodilians to deter predators.

Black-necked Stilt (Himantopus mexicanus). Family Recurvirostridae, order Charadriiformes.

American Alligator (Alligator mississippiensis). Family Alligatoridae, order Crocodylia.

It always interests me when other animals are soooo close to predators like this.

It's been a busy two-ish weeks for me once again with two "new" crocodilians dropping not even a week apart. These two newcommers couldn't be any more different, as you'll see soon enough.

The first of the two is not exactly a stranger, in more than one way. Sutekhsuchus dowsoni in truth has been known since 1920, when it was described as Tomistoma dowsoni based on fossils from Wadi Moghra in Egypt. Tomistoma being one of those genera that was a popular wastebasket for crocs. Broad snout and overbite? Alligator. Narrow snout? Tomistoma. Everything else? Crocodylus.

Tomistoma is still heavily affected by that, with the paper still referencing about half a dozen species of Tomistoma that are almost definitely not Tomistoma. In that regard, tho its not super new its fantastic to see that one of these Miocene circum-mediterranean forms finally gets its due (especially after having been unceremoniously been lumped into T. lusitanica for a while). Additional fun fact, the original "missinterpretation" as a species of Tomistoma is used as the basis for the new name, basically meaning "Set's crocodile" in reference to Sutekh/Set being god of deception.

Left: Sutekhsuchus by @paleomiguel Right: Sutekhsuchus by @manusuchus Go give them a follow

Another way in which Sutekhsuchus is not "new new" is that, intentional or not, the name was actually dropped a month ago without many people noticing. As has been pointed out to me by @paleomiguel, a recent paper on Eogavialis featured a phylogeny that contained Sutekhsuchus, a name I was not familiar with. However, the species name did ring a bell and after a brief search on google scholar I did find a reference to the then unpublished redescription.

Anyways, background aside Sutekhsuchus has some cool stuff going for it. Its anatomy is in some regards intermediate between the modern false gharial (which the paper regards as one of the basalmost gavialoids) and the Indian gharial (a highly derived weirdo). Ultimately, its just one of several species that lived around the broader Tethys Sea during the Miocene as part of a flourishing croc ecosystem. Given the warmer temperatures, it was in pretty good company. We know it from Gebel Zelten and Wadi Moghra, both of which preserve the bones of the robust Rimasuchus and the bizarre Euthecodon, both members of the Osteolaemines ("dwarf crocodiles", a name that makes more sense when you ignore these fossil forms). Both localities are interpreted as being somewhat coastal, consisting of lagoons, estuaries, slow moving rivers and surrounding forests.

Left: Rimasuchus attacking Zygolophodon by Michael Tripoli Right: Euthecodon arambourgi by yours truly

The other new crocodilian was much more of a surprise to me personally. Ahdeskatanka russlanddeutsche is a species of basal alligatorine from the Eocene of North Dakota. The genus name derives from the Dakota word for alligator, the species name references ethnic Germans that settled the region after emmigrating from the Russian Empire.

Ahdeskatanka via Cossette & Tarailo

It lived during the early Eocene in the Golden Valley Formation of North Dakota and in many regards resembles many early alligators of the time, having been small with a short and blunt snout and globular teeth well suited for crushing hard shelled prey.

During this time period North Dakota experienced the Early Eocene Climatic Optimum, an exceptional warm period that saw lush subtropical to tropical forests grow along the banks of meandering rivers and extensive swamps. Not great for mammalian carnivores but fantastic for crocodilians, of which there were plenty. The Golden Valley was home to at least 4. In addition to Ahdeskatanka there was a similar, possibly closely related unnamed form, a large crocodyloid similar to the ubiquitous Borealosuchus and the large caiman Chrysochampsa, a relic of a Cretaceous offshoot of the family.

Left: Borealosuchus by Wayne Hsieh Right: Chrysochampsa via Cossette & Tarailo

As always, here the respective Wikipedia pages and relevant publications

Sutekhsuchus: https://en.m.wikipedia.org/wiki/Sutekhsuchus https://www.tandfonline.com/doi/full/10.1080/14772019.2024.2384548