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.
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.
Harpacochampsa is a poorly known Early Miocene crocodilian from the Bullock Creek lagerstätte of the Northern Territory, Australia. The current specimen consists of a partial skull and fragments of a long, slender snout reminiscent of that of a false gharial, demonstrating that it was a piscivore in life.
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.
Xixiasaurus is a genus of troodontid dinosaur that lived during the Late Cretaceous Period in what is now China. The only known specimen was discovered in Xixia County, Henan Province, in central China, and became the holotype of the new genus and species Xixiasaurus henanensis in 2010. The names refer to the areas of discovery, and can be translated as "Henan Xixia lizard". The specimen consists of an almost complete skull, part of the lower jaw, and teeth, as well as a partial right forelimb.
Krabisuchus is an extinct genus of alligatoroid crocodylian that existed in what is now Thailand during the Late Eocene. It was first named by paleontologists Jeremy A. Martin and Komsorn Lauprasert in 2010, and the type species is K. siamogallicus. Fossils have been found from the Krabi Basin of southern Thailand and include mostly cranial and mandibular elements as well as some postcranial remains. Krabisuchus is currently the most well known primitive alligatoroid from Asia; previously, these animals were only represented in Asia by a few fragmentary remains from China. The fossil record of alligatoroids is much more extensive in Europe and North America, where most taxa have been described.
Duerosuchus is an extinct genus of crocodilian. Remains have been found from Corrales del Vino in Zamora, Spain, and are middle Eocene in age. Duerosuchus is known from a single skull that is incomplete but otherwise well preserved, as well as a lower jaw, some osteoderms, and possibly some vertebrae.
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.
Protoalligator is an extinct genus of alligatoroid from the Paleocene Wanghudun Formation of China. It was first described as a species of Eoalligator in 1982 before being placed in its own genus in 2016. The name, which translates to "first alligator", was meant to carry on the same meaning as that of Eoalligator as the latter was thought to be synonymous with another crocodilian by the team describing it. Recent studies have suggested that Protoalligator was part of an early radiation of alligatoroids endemic to Asia known as orientalosuchins, though not all studies agree with it being placed within this group nor with orientalosuchins being alligatoroids in the first place. Protoalligator is a monotypic genus, containing only the type species: Protoalligator huiningensis.
Wahasuchus is an extinct genus of engimatic mesoeucrocodylian, likely a neosuchian, of the Middle Campanian age found in the Quseir Formation, Egypt. First described in 2018, Wahasuchus is known mostly from fragmentary remains representing multiple individuals. Given its incomplete nature, it is not entirely clear what its closest relatives are, though features of the skull including its generally flattened morphology akin to that of modern crocodiles suggests it was part of the clade Neosuchia. However it bears no close resemblance to any of the early Cretaceous forms known from northern Africa nor the contemporary taxa of Europe, suggesting that it might have been part of a unique radiation endemic to Africa. The genus currently only contains a single species, Wahasuchus egyptensis.
Orientalosuchina is an extinct clade of alligatoroid crocodylians from Southeast and East Asia that lived between Maastrichtian and Eocene.
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.
Dentaneosuchus is a genus of large bodied sebecid crocodylomorph from the Middle Eocene of Issel and Réalmont (France). Originally described as Atacisaurus crassiproratus, the discovery of additional remains led to it being placed in a separate genus in 2023. It was tentatively recovered as the basalmost member of the family Sebecidae. Because of this Dentaneosuchus could play an important part in deciphering the origins and dispersal of European sebecids, as their presence on the continent, far away from their primary range in South America, is still not entirely resolved. It reached a similar size to the enormous Barinasuchus, making it not only one of the biggest sebecids but also the biggest terrestrial carnivore of Cenozoic Europe. Dentaneosuchus would have been an apex predator of its environment, capable of taking large prey such as Lophiodon. However, for as of yet unknown reasons crocodylomorphs would lose their spot as top predator in this part of the world by the end of the Eocene, with Dentaneosuchus representing one of the last members of its group in Europe.
Sutekhsuchus is a species of gavialine crocodilian from the Miocene of Libya and Egypt. While this species was originally described as a species of the genus Tomistoma, which includes the modern false gharial, later studies have shown that it was actually a much more derived gavialoid closely related to the Kenyan Eogavialis andrewsi. Since it initially "deceived" paleontologists, it was named for the Egyptian god of deception Sutekh. It once inhabited the slow-moving rivers, estuaries and lagoons of what is now Gebel Zelten and Wadi Moghra, environments it shared with a variety of other crocodilians including the narrow-snouted Euthecodon and the robust Rimasuchus. Depressions on the inner side of the skull might also correlate with the presence of salt glands, which would have allowed it to more easily ventured out into marine environments. Only a single species is currently assigned to Sutekhsuchus, the type species S. dowsoni.
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.
