#crocodilia

[saritawolf]

American Alligator (Alligator mississippiensis) (c) SaritaWolf - please do not repost

[galionne-vibin]

Beloved :) (Inspired by this post)

[incognitomoustache]

[saritawolf]

Malagasy Nile Crocodile (Crocodylus niloticus) - (c) SaritaWolf - please do not repost

[arminreindl]

Fossil Crocs of 2025

Well, well well, look who comes crawling out of the woodwork again after having failed to live up to any promise I made earlier last year.

In my defense, tho my love for crocs continue, I suffered several hits to my motivation not to mention plenty of work both at my job and private life including a complete revision of the clade Itasuchidae on Wikipedia (currently 8 out of 13 pages in).

But I'm taking a brief moment to try and bring back at least a summary of all the new taxa we got last year.

Taihangosuchus Our chronologically oldest animal on this little list is Taihangosuchus from the Anisian (Middle Triassic ) Ermaying Formation. Fittingly this little is also part of one of the most ancient pseudosuchian linages, the gracilisuchids, small, erect-limbed quadrupeds, which it feels have been getting a lot more attention as of late. Two specimens are known, one smaller preserving the head and neck, one larger that exclusively preserves postcrania. The larger furthermore shows at least parts of the animals last meal in the form of several osteoderms in the gut, indicating that this animal was not just predatory but seemingly fed on other archosaurs. Which one is unclear. Shansisuchus had no osteoderms, Halazhaisuchus is from the lower parts of the formation, Fenhosuchus is a candidate, as most osteoderms from Ermaying have historically been referred to it but its just as possible that the victim was a smaller individual of Taihangosuchus.

Tainrakuasuchus Poposauroids keep on winning as of late, at least as far as basal forms are concerned. Tainrakuasuchus bellator (roughly meaning "pointed tooth warrior crocodile") may be one of the most basal poposauroids, having been recovered as a close relative of Mandasuchus and more derived than either Benggwigwishingasuchus or Mambawakale. At a size of roughly 2.4 meters (give or take) and specimens estimated at 3 meters it would have been a sizable predator of the Dinodontosaurus AZ, which is well known for an already diverse croc fauna. Size alone demands it to fill a different nische from behemoths like Prestosuchus, but also as a poposauroid the neck vertebrae weren't built to deal with the same immense stresses anyways, so one way or another different prey was required.

Telkaralura From a poposauroid back to another gracilisuchid, this time from the Carnian of South America. Telkaralura is one of those taxa that have a surprisingly long history for something only really described recently. It was first discovered by famed paleontologist José F. Bonaparte in 1980 in the same rock layers as Gracilisuchus and both were for a time regarded to be early dinosaurs. It was briefly regarded as a juvenile Luperosuchus in 2009, split off in 2017 and finally given a name in 2025.

Telkaralura is notable for being the largest gracilisuchid known today, some 20 to 25% larger than the next largest members of the group including the recently named Parvosuchus, twice the size of Gracilisuchus and five times the size of Maehary (previously thought to be basal to pterosaurs, fun fact). But even that wasn't enough to make it top predator, which is an honor that goes to the proterochampsid Gualosuchus.

Olkasuchus AN AETOSAUR KNOWN FROM MORE THAN JUST A HANDFULL OF ISOLATED OSTEODERMS?! Yes, Olkasuchus was a pleasent surprise, which makes me all the more disappointed in myself that I have yet to find the time to write about it on wikipedia. So this will need to suffice for the time being (I mean sooner or later I gotta give that whole clade an overhaul anyways, no?) Olkasuchus is known from the Late Triassic (Norian) Los Colorados Formation, famous for its enormous "prosauropods" and titanic rauisuchian Fasolasuchus. This basal desmatosuchine is however not nearly as big, for reference the scalebar in the image below is 20 centimeters.

Pattisaura Early pseudosuchians sure loved the small and gracile morphotype, but we're not dealing with a gracilisuchid this time. Pattisaura is an early crocodylomorph, part of the grade frequently referred to as "sphenosuchians".

As an inhabitant of the Cooper Canyon Formation Pattisaura lived around many other famous stem-crocs including Postosuchus, Shuvosaurus and Desmatosuchus. And with a fauna like that you can nicely see just how diverse early pseudosuchians were, covering large predators, gracile bipeds, armored quadrupeds and of course smaller, almost dog-like forms like Pattisaura.

Kuttysuchus Now that's more like what I'm used to with aetosaurs: OSTEODERMS AND NOTHING ELSE. Perhaps the most shocking developement of having had to deal with these over the past few years is that I'm getting scarily comfortable with how these isolated bony plates are described, but I won't make you suffer through that.

So I'll keep this one at the key points. Kuttysuchus is a new typothoracine from the Norian to Rhaetian of India. It coexisted with mystriosuchine phytosaurs, early sauropodomorphs and two other aetosaurs, an as of yet unnamed desmatosuchine and Venkatasuchus, which you might remember (or not, I won't blame you). Excuse me for being a little glib, but with so many crocs its hard to really sell something thats known from a handfull of bony plates without giving info thats super generalized to the group as a whole.

And with that we finish the Triassic and actually jump straight to the Cretaceous. Yup, no Jurassic taxa for you.

Paarthurnax Yes, like the dragon from Skyrim. While this 4 meter animal from the middle Cretaceous appears similar to modern crocodiles, its actually part of the older family Goniopholididae, and one that actually proves to be quite informative at that.

The thing with Goniopholidids is that they were most successfull during the Late Jurassic and Early Cretaceous, filling the crocodilian nische throughout North America, Europe and Asia prior to Eusuchians making it big. But we knew even before 2025 that goniopholidids didn't go out without a fight and in fact made it until the Maastrichtian in the form of Denazinosuchus. This of course left a massive gap in time we didn't quite know how to fill. But the discovery of Paarthurnax allowed Platt and co to create a neat line from early Cretaceous European goniopholidids like Anteophthalmosuchus all the way to Denazinosuchus in America, briding the gap with Paarthurnax, Paluxysuchus and Deltasuchus. Will this hypothesis hold? Only time will tell.

Sissokosuchus Remember me mentioning itasuchids at the beginning? Well in 2025 we got two of those. The first I want to talk about is the one that I am still relatively satisfied with as far as the Wikipedia page goes.

Sissokosuchus maliensis (Famory Sissoko's crocodile from Mali) is known from multiple specimens, none of which especially complete sadly, found within the poorly defined Continental intercalaire of Mali, which date to the Aptian and Albian. At that point in time Mali cotained part of what was once an enormous ancient river system, the  Paleo-Tegama, perfect for anything that loved freshwater.

This included Sissokosuchus, which, despite looking suspiciously like a normal crocodile, was actually part of an off-shoot of the otherwise famously terrestrial notosuchians. Itasuchids in general are quite a fascinating group in that regard, ranging from more robust types like Barreirosuchus to slender-snouted animals such as Stolokrosuchus. But more on that some other time.

Thikarisuchus Now for something entirely different, Thikarisuchus xenodens (strange-toothed sheath crocodile). Small, terrestrial, long and slender limbs and actually closer to modern crocodiles than either of our previous two newcommers.

This adorable little guy from the Cenomanian Blackleaf Formation is a wannchampsid, close kin to the similarily gracile and terrestrial atoposaurids. What makes Thikarisuchus interesting is the fact that it had three different tooth types (hence the name), ranging from pointed and conical to mediolaterally flat and very low-crowned. This likely reflects a broad diet that could have included insects, small animals and even plants. The front teeth would be used to grab food items, the cheek teeth served to slice.

Thilastikosuchus Staying with the nimble, terrestrial genre of crocodylomorphs for a bit takes us across the sea into South America to meet Thilastikosuchus scutorectangularis (Mammal crocodile with rectangular osteoderms), a notosuchian of the family Candidodontidae.

Candidodontids are perhaps the most obscure family of notosuchian to an outsider, perhaps even more obscure than itasuchids, and similarily its partially because we're still only just beginning to understand them (fun fact, Malawisuchus, another candidodontid, was actually among the first two taxa assigned to Itasuchidae alongside Itasuchus itself, tho the family has changed drastically since then).

Like Thikarisuchus, Thilastikosuchus is noted for its teeth. Two types of teeth are known from this animal, subconical incisors in the front of the jaw and molariform teeth in the back, but no canines, despite the fact that they are present in other notosuchians incleading some fellow candidodontids. But while the posterior teeth of Thikarisuchus are also different, Thilastikosuchus goes a step beyond, its teeth being and well mammal-like.

Ibirasuchus Oh boy....well, this is our second itasuchid of 2025 and its beyond the shadow of a doubt worse than Sissokosuchus. I'll be honest I'm not gonna spend a lot of time on it. It was named in a broader paper describing various fossils and the only things known of Ibirasuchus are admittedly most of a parietal and supraoccipital and a tiny corner of a squamosal... yeah its not even half a skull table. The paper does propose a possible length of four meters, but problematically itasuchid postcrania are barely described and my current plans are to start reconstructing them once I've got the writing down. Will this animals Wikipedia page get another overhaul beyond my initial script, yes, will it be significantly better, well, theres only so much I can work with.

Wadisuchus Moving on to something a lot more pleasent, we have Wadisuchus kassabi (Kassab's Valley Crocodile), known from two fairly complete skulls that were found in the sediments of the Campanian Quseir Formation.

The animal, which may have grown as long as 4 meters, is among the oldest known dyrosaurids, a group closely related to pholidosaurids like Sarcosuchus and that held out until the Eocene. Given its basal position its unsurprising that Wadisuchus displays a mix of derived dyrosaurid and more basal pholidosaurid features. For example pholidosaurids have a famously hooked snout tip, which is absent in dyrosaurids. Well in Wadisuchus we see a mix, with the first teeth strongly downturned and the rest positioned normally, which may be related to the way the lower jaw grew longer throughout this groups evolutionary history.

Kostensuchus A Kostensuchus, how excited I was when you dropped. And rightfully so, its not every day you get a 3 meter terrestrial behemoth of a notosuchian known from a complete skull and almost the entire vertebral collumn up to the hip. What makes this animal even more fascinating is the fact that tho superficially similar to baurusuchids, its actually a peirosaur.

The fact that there is a whole distinct clade of robust peirosaurids actually lead to an interesting hypothesis. Novas and colleagues speculate that South America may have been split into two distinct predator faunal zones. In the northern parts, i.e. Brazil's Bauru Group, the top predators were abelisaurs and baurusuchids, while the south their rolle may have been filled by megaraptorans and peirosaurids. Here's hoping we find more to support this idea because I for one love it.

Animation by PALEOGDY

Tewkensuchus Tewkensuchus in some aspects is not all that different from Kostensuchus. The "forehead crocodile", tho known from rather limited material, was likely a robust, terrestrial animal that stalked what is now Argentina during the earliest days of the Paleogene.

And that's where things get interesting. With an estimated weight of 300 kg this sebecoid is exceptionally large for its time, which has prompted researchers to question how that came to be. The two main explanations are as follows. 1. Sebecoids have been as large as this since before the meteor whiped out the dinosaurs and underwent a brief aquatic phase that allowed them to stay in this range without being annihilated as the purely terrestrial fauna was (a method employed by the ancestors of our modern crocs) 2. These guys were small prior to the impact and, somehow, got absolutely fucking jacked the second theropods were out of the picture.

A final note, despite being from almost southernmost South America, Tewkensuchus appears to have actually been more closely related to Eocene European sebecoids like Bergisuchus and Dentaneosuchus rather than the geographically closer proper sebecids. This whole paleogeography continues to be a headache let me tell you that.

Paleoart by Michael Tripoli

Pseudogavialis Pseudogavialis is a classic case of authors trying to make sense of something thats been an issue we've had for hundreds of years. In this case the fact that Oligocene to Miocene Pakistani gavialoids are a mess. Several species were coined in the 1800s and have repeatedly been lumped, split, lumped again. Courville and colleagues published an extensive paper on some of them, including "Gavialis" curvirostris. Their conclusion: the animal is clearly distinct and it was given the new name Pseudogavialis. It was probably close to todays Indian gharial, may have featured a similar soft tissue bulb on its snout and grew to a length of 6 to 7 meters.

Rhamphosuchus brevirostris Ok one could argue this ones a bit of a cheat because obviously Rhamphosuchus has been well established for over a hundred years and the species is similarily old. However, given that we weren't even sure brevirostris was legit and its now been redescribed and pretty firmly placed in the genus Rhamphosuchus I'll include it here.

The same paper I just mentioned in regards to Pseudogavialis also touched on "Gavialis" pachyrhynchus. Unlike Pseudogavialis it was not separated on a genus level, but instead sunk into Rhamphosuchus as you already know.

Now Rhamphosuchus pachyrhynchus is notably more robust than Pseudogavialis, but not quite as much as the still poorly known Rhamphosuchus crassidens. It had more of an overbite rather than the interlocking teeth seen in modern gharials and crocs, may have grown to 8 meters in length and we still don't really know how these guys related to other gavialoids really.

This whole paper did inspire me to give the Wikipedia page for Rhamphosuchus a complete overhaul tho and despite the scarcity of proper descriptions I'm actually still quite happy with it.

Piscogavialis laberintoensis Our third and final gavialoid for 2025 is yet another species of an established genus, this time all the way over in Peru. Piscogavialis laberintoensis is known from the Miocene Laberinto area of the Pisco Formation (keep an eye open for the upcoming formation piece by Joschua Knüppe). As in the type species, the snout of Piscogavialis laberintoensis is very long and narrow, but the transition between the snout and orbital region is a lot more abrupt and not as fluid. And of course as its relative, this species was a marine animal. Body length has been estimated to range from 5.4 to 6.2 meters.

Crocodylus sudani The geologically youngest new fossil crocodile of last year takes us to Sudan, hence its name, specifically to the 60.000 year old rocks found near the Atbara River, one of the tributaries of the Nile. Theres several fascinating things to mention for this species. Morphologically for example it combines both the presence of a pronounced boss before the eyes with upturned squamosal horns. Evolutionarily, despite being as young as it is, Crocodylus sudani is not closely related to todays Nile or Sacred crocodiles but may actually be part of the Paleoafrican Crocodylus species, which includes the enormous Crocodylus thorbjarnarsoni. Perhaps one of the more out there claims by the authors is the idea that maybe, just maybe, this species is still out there.... Now granted, modern crocs are more diverse than we give them credit for and many a crypic species is still likely hidden out there, only distinguished by subtle features, differences in the genome and hidden by harsh and inaccessible environments. However as Salih and co. themselves admitt, its gonna require some substantial research into modern Sudanese crocodile populations to proof that this is more than just wishfull thinking.

Artwork again by Michael Tripoli

And thats the fossil crocs that were described last year. Lesson learned, I gotta stop making promises that I can't keep, but hopefully next years batch will be less work intensive and not be posted 4 months into 2027.

[oaresearchpaper]

Crocodilians are a diverse group of reptiles that have been extensively studied for their morphology, behaviour, and ecology. However, the communication and signalling mechanisms in crocodilian species, especially for the critically endangered gharial, remain poorly understood. Acoustic communication in crocodilians is relatively well-documented, but the production and reception of acoustic signals remain understudied. The application of new technological advancements, such as the acoustic camera used in frogs, could greatly advance acoustic research in various species of crocodilians. In contrast, chemical communication research is comparatively more limited for all species of crocodilians, and has been limited to sampling captive animals, primarily in zoos. Studying both acoustic and chemical signalling in gharials could significantly contribute to the understanding of their behavioural ecology and aid conservation aspects. Furthermore, it would considerably enlarge the representation of contemporary crocodilians since gharials in captivity are few and largely unstudied. This review summarizes current understanding of acoustic and chemical communication in crocodilians and highlights the need for future research.

[uncharismatic-fauna]

Stick 'Em Up for the Mugger Crocodile

The mugger crocodile, also known as the marsh crocodile (Crocodylus palustris) is a species of crocodile native to south Asia, including Iran, Pakistan, Nepal, Sri Lanka, and India south of the Himalayan mountain range. They can be found in most freshwater habitats including rivers, lakes, and wetlands; on occasion they may also be sighted in brackish wetlands and estuaries.

Mugger crocodiles average 2 to 3.5 m (6 ft 7 in to 11 ft 6 in) in length and weigh on average 450 kg (990 pounds), with males typically being larger than females. Despite being only medium sized among crocodilians, C. palustris boasts the broadest snout of any crocodile species. Like most crocodiles, they are covered in thick scales which can range from brown to grey to green in color, sometimes with a spotted pattern, which allows them to blend in to the muddy waters in which they hunt.

Like most other crocodiles, marsh crocodiles are ambush predators, lying in wait for prey. However, mugger crocodiles are unique in that they are one of the first recorded reptiles to use tools; in particular, they have been documented using sticks to lure birds into striking distance. They have a wide and varied diet, which can include fish, snakes, turtles, birds, monkeys, otters, and smaller crocodiles; they may also feed opportunistically on carrion. Adults are rarely predated upon, but juveniles and eggs often fall prey to snakes, birds, rodents, and larger crocodiles.

When not hunting, mugger crocodiles spend most of their basking on the shore, as all reptiles do. They will also dug burrows in the mud to hide in when temperatures drop below 5 C (41 F) or exceed 38 C (100 F). Both males and females are territorial, though they may make overland journeys to seek out mates or if their local water body becomes unsuitable.

The mating season begins in November and continues throughout the dry season. Male C. palustris compete for females by slapping their heads against the water and humming. After breeding, the female deposits a clutch of 8-46 eggs in a shallow-dug hole on the bank, and both she and the siring male will protect the nest for the next two months. The ratio of male to female offspring is dependent on the average incubation temperature; cooler temperatures produce more females. After hatching, both parents continue to protect their young, often by carrying them in their mouths, until they reach independence at about 1 year of age. Females reach sexual maturity at 8-10 years old, while males reach maturity at 12-15 years. Adults may live to be well over 30 years old in the wild.

Conservation status: The IUCN has declared the mugger crocodile as Vulnerable. Their primary threat is habitat destruction and conflict with humans. They are also hunted for their skin and meat.

Photos

David Raju

Paul G. Schrijvershof

Yve Morrell

[uncharismatic-fauna]

Salutations to the Saltwater Crocodile

The saltwater crocodile (Crocodylus porosus), also known as the estuarine crocodile, is a species of crocodile found in the coasts and islands of southeast Asia, and the northern coast of Australia. As their name implies, saltwater crocodiles reside in saltwater and brackish environments, including coastal mangroves, river deltas, swamps, and floodplains. Adult C. porosus may also occasionally be seen out at sea, as they are proficient swimmers capable of traversing between islands and coastlines.

Saltwater crocodiles are the largest species of crocodile, and indeed of all reptiles. Males are significantly larger than females; adult males can range anywhere from 3.5 to 5 m (11 ft 6 in – 16 ft 5 in) in length and weighs between 200 to 1,100 kg (440 to 2,430 lb), while females range only a measly 2.7 to 3.4 m (8 ft 10 in to 11 ft 2 in) in total length and weigh 76 to 200 kg (168 to 440 lb). Both sexes are olive, with a lighter underbelly and darker spots along the back.

C. porosus's breeding season occurs in the wet season, beginning in September or October. After a female selects her mate, the pair dig a nest, and the female lays a clutch of 40-60 eggs. The pair then guard the nest together until the eggs hatch about 90 days later. The sex of the hatchlings is dependent on the average temperature at which the egg was incubated; between 28–33° C (82-91° F) the hatchlings are predominantly male, while incubation temperatures on either side of that range produce predominantly female hatchlings. The female continues to care for the hatchlings, guarding them by carrying them in her mouth, until they disperse at about 8 months old. Young reach sexual maturity at 10 years old, and individuals may live for as long as 70 years.

Saltwater crocodiles are active mainly at night, and spend most of the day basking on banks or partially submerged logs. As adults, they are opportunistic predators with a wide variety of prey, including mud crabs, turtles, snakes, juvenile crocodiles, birds, buffalo, kangaroos, tigers, wild boar, monkeys, and humans. As juveniles, they target smaller prey such as insects, amphibians, crustaceans and small fish. They hunt via ambush, dragging their prey back into the water for easier consumption. Adults have no natural predators, but juveniles are frequently predated upon by monitor lizards, larger fish like barramundi, wild boar, storks, eagles, and pythons.

Conservation status: C. porosus is considered Least Concern by the IUCN. They are often hunted for their skin, meat, and eggs, although international trade of saltwater crocodile parts is prohibited. They are also hunted for their perceived threat to nearby human populations. Habitat loss and human encroachment is also a major threat for estuarine crocodiles.

Photos

Fabian Roudra Baroi

Jafet Potenzo Lopes

Shubhra Shu