Mekosuchus is a genus of extinct Australasian mekosuchine crocodilian. Species of Mekosuchus were generally small-sized, terrestrial animals with short, blunt-snouted heads and strong limbs. Four species are currently recognized, M. inexpectatus, M. whitehunterensis, M. sanderi and M. kalpokasi, all known primarily from fragmentary remains.
Australosuchus is an extinct monospecific genus of crocodylian belonging to the subfamily Mekosuchinae. The type and only known species Australosuchus clarkae lived during the Late Oligocene and the Early Miocene in the Lake Eyre Basin of South Australia. It was described in 1991 by Paul Willis and Ralph Molnar from fossil material discovered at Lake Palankarinna.
Kambara is an extinct genus of mekosuchine crocodylian that lived during the Eocene epoch in Australia. It is generally thought to have been a semi-aquatic generalist, living a lifestyle similar to many of today's crocodiles. Four species are currently recognised, the sympatric Kambara murgonensis and Kambara implexidens from sediments near Murgon, the poorly preserved Kambara molnari from the Rundle Formation and the youngest of the four, Kambara taraina, also from the Rundle Formation. Kambara were medium-sized crocodilians, with mature specimens generally reaching lengths from 3–4 m (9.8–13.1 ft).
Ceratosuchus is an extinct genus of alligatorine crocodylian from latest Paleocene rocks of Colorado's Piceance Basin and earliest Eocene rocks of Wyoming's Bighorn Basin in North America, a slice of time known as the Clarkforkian North American Land Mammal Age. Like its modern relatives, Ceratosuchus was a swamp-dwelling predator. It is named for the pair of flattened, triangular bony plates that extend from the back of its head.
Eoalligator is an extinct genus of alligatoroid crocodilian from Paleocene deposits in China.
Necrosuchus is an extinct genus of caiman from modern day Argentina that lived during the Paleocene epoch. It inhabited the marine or fluvio-lacustrine environment of the Patagonian Salamanca Formation.
Asiatosuchus is an extinct genus of crocodyloid crocodilians that lived in Eurasia during the Paleogene. Many Paleogene crocodilians from Europe and Asia have been attributed to Asiatosuchus since the genus was named in 1940. These species have a generalized crocodilian morphology typified by flat, triangular skulls. The feature that traditionally united these species under the genus Asiatosuchus is a broad connection or symphysis between the two halves of the lower jaw. Recent studies of the evolutionary relationships of early crocodilians along with closer examinations of the morphology of fossil specimens suggest that only the first named species of Asiatosuchus, A. grangeri from the Eocene of Mongolia, belongs in the genus. Most species are now regarded as nomina dubia or "dubious names", meaning that their type specimens lack the unique anatomical features necessary to justify their classification as distinct species. Other species such as "A." germanicus and "A." depressifrons are still considered valid species, but they do not form an evolutionary grouping with A. grangeri that would warrant them being placed together in the genus Asiatosuchus.
Chrysochampsa is an extinct monospecific genus of caiman of the clade Brachychampsini. Fossils have been found from the Golden Valley Formation of North Dakota and date back to the Wasatchian regional North American faunal stage of the early Eocene. During this time North Dakota experienced the Early Eocene Climatic Optimum, creating lush forests, swamps and meandering rivers that were the home to at least four distinct crocodilians. Unlike the contemporary Ahdeskatanka, which was a small animal with crushing teeth, Chrysochampsa would have been a generalist and due to its size and lack of significant mammalian carnivores the apex predator of the region. The genus had been proposed to be synonymous with Allognathosuchus in 2004s, but this claim has since then been repeatedly refuted. A 2024 study has recovered it as an early branching member of the Caimaninae, forming a clade with Cretaceous forms such as Brachychampsa. Chrysochampsa is a monotypic genus, containing only the type species, Chrysochampsa mlynarskii.
Sebecus is an extinct genus of sebecid crocodylomorph from Eocene of South America. Like other sebecosuchians, it was entirely terrestrial and carnivorous. The genus is currently represented by two species, the type S. icaeorhinus and S. ayrampu. Several other species have been referred to Sebecus, but were later reclassified as their own genera.
Prodiplocynodon is an extinct genus of basal crocodyloid crocodylian. It is one of the only crocodyloids known from the Cretaceous and existed during the Maastrichtian stage. The only species of Prodiplocynodon is the type species P. langi from the Lance Formation of Wyoming, known only from a single holotype skull lacking the lower jaw.
"Crocodylus" megarhinus is an extinct species of crocodile from the Eocene of Egypt. A partial skull was found by British paleontologist Charles William Andrews in the Fayum Depression. Andrews named Crocodylus megarhinus in 1905 on the basis of the holotype skull. A complete skull was also uncovered from Egypt in 1907 but was not recognized as "C." megarhinus until 1927.
Astorgosuchus is an extinct monospecific genus of crocodilian, closely related to true crocodiles, that lived in Pakistan during the late Oligocene period. This crocodile may have reached lengths of up to 7–8 m (23–26 ft) and is known to have preyed on many of the large mammals found in its environment. Bite marks of a large crocodile have been found on the bones of juvenile Paraceratherium, however if these were left by Astorgosuchus cannot be said with certainty. The genus contains a single species, Astorgosuchus bugtiensis, which was originally named as a species of Crocodylus in 1908 and was moved to its own genus in 2019.
Orientalosuchina is an extinct clade of alligatoroid crocodylians from Southeast and East Asia that lived between Maastrichtian and Eocene.
Orientalosuchus is an extinct genus of crocodilian from the Late Eocene that was found in the Na Duong Formation in Vietnam. The genus was described in 2019 based on the fossil remains of at least 29 individuals and was key in establishing the clade Orientalosuchina, initially interpreted as a group of early alligatoroids endemic to Asia, although later studies have argued for them actually being crocodyloids instead. Orientalosuchus was a comparably small crocodilian with a blunt and rounded snout and dentition that featured both pointed teeth towards the front of the jaw and blunt, conical teeth in the back. During the Late Eocene it would have inhabited the tropical to warm-subtropical freshwater biomes of the Na Duong Formation, which featured ponds, an annoxic lake and swamp forests as some of the primary habitats. Orientalosuchus would have shared these with the narrow-snouted gavialoid Maomingosuchus and a large taxon similar to Asiatosuchus. Compared to these, interpreted as a piscivore and a generalist respectively, Orientalosuchus would have been better equiped to deal with hard-shelled prey, such as the plethora of turtles found in the region.
Dongnanosuchus is an extinct monotypic genus of orientalosuchin crocodilian known from the middle to late Eocene Youganwo Formation of China. Like other members of Orientalosuchina, Dongnanosuchus was a comparably small-bodied animal with a short, rounded snout that shares characteristics with both early alligatoroids and crocodylids, rendering the precise placement of the clade uncertain. It contains a single species, Dongnanosuchus hsui, which lived during the latter part of the Eocene in what is now the Maoming Basin of China, which at the time featured subtropical forests and a prominent lake that would be the foundation of the local oil shale. This environment was shared by the tomistomine Maomingosuchus and similar cohabitation between Maomingosuchus and orientalosuchins is known from similar sites across East Asia.
Jiangxisuchus is an extinct genus of crocodylian that lived during the Late Cretaceous, likely Maastrichtian, in what is now China. At the time of its description in 2019 it was proposed to be a basal member of Crocodyloidea. However, another concurrent 2019 study recovered Jiangxisuchus instead placed it in the clade Orientalosuchina, which were proposed to be early alligatoroids. The classification of Jiangxisuchus has since then remained in flux. Like other orientalosuchins, Jiangxisuchus was a small to medium-sized animal with a short, blunt snout. The genus is monotypic, containing only the species Jiangxisuchus nankangensis.
Ultrastenos is an extinct genus of Australian mekosuchine crocodilian that lived during the Late Oligocene in northwestern Queensland, Australia. Following its discovery, it was speculated that Ultrastenos was a slender-snouted animal similar to modern gharials or freshwater crocodiles due to the seemingly abruptly narrowing mandible. However, a later study found that this was a missinterpretation of the fossil specimen and that Ultrastenos instead had a more generalized lower jaw. The same publication also provided evidence that the fossils of Ultrastenos belonged to the same animal previously named "Baru" huberi, adding further evidence to the idea that the animal was short snouted, contrary to the initial hypothesis. Given that "Baru" huberi was named first, the type species of Ultrastenos changed from U. willisi to U. huberi in accordance with the rules of the ICZN. Ultrastenos was a small mekosuchine, measuring upwards of 1.5 m long.
Qianshanosuchus is a genus of basal crocodyloid from the Paleocene of the Qianshan Basin, China. The fossil material, which includes an incomplete skull and parts of the lower jaw, show various features usually associated with juvenile crocodiles alongside various unique traits that were used to erect a new genus. It is the first and only basal crocodyloid currently known from the Paleocene of China, which had previously only yielded alligatoroids and planocraniids. Its presence in this part of the world and its basal position to species of the genus Asiatosuchus supports the idea that crocodyloids dispersed from Asia into Europe. Qianshanosuchus only includes a single species, Qianshanosuchus youngi.
Eurycephalosuchus is an extinct genus of orientalosuchine alligatoroid from the Late Cretaceous Jiangxi Province of China. Known from a well preserved skull and mandible alongside various postcranial remains, Eurycephalosuchus possessed a short and broad skull with a very short skulltable. Eurycephalosuchus lived with at least one other crocodilian, an indetermined member of the clade Brevirostres. The genus is monotypic, containing only the species Eurycephalosuchus gannanensis.
Ahdeskatanka is an extinct genus of alligator from the Early Eocene Golden Valley Formation of North Dakota, USA. Ahdeskatanka had a short, rounded snout with globular teeth that are well-suited for crushing hard-shelled prey, though its exact ecology is not known. Ahdeskatanka inhabited the vast wetlands that covered much of western North Dakota during the Early Eocene Climatic Optimum, an environment it shared with at least three other crocodilians. These include the large caiman Chrysochampsa and at least two unnamed forms, one a large crocodyloid and one more similar to Ahdeskatanka. Phylogenetic analysis suggests that it was an early diverging member of the Alligatorinae, possibly related to Allognathosuchus, though its position is not very stable. Only a single species, Ahdeskatanka russlanddeutsche, is placed in this genus.
