| Culebrasuchus | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Crocodilia |
| Family: | Alligatoridae |
| Subfamily: | Caimaninae |
| Genus: | † Culebrasuchus Hastings et al., 2013 |
| Type species | |
| †Culebrasuchus mesoamericanus Hastings et al., 2013 | |
Culebrasuchus is an extinct, monotypic genus of caiman alligatorid known from the Early to Middle Miocene (Hemingfordian) of the Panama Canal Zone of Panama. It contains a single species, Culebrasuchus mesoamericanus. [1]
Culebrasuchus was first described and named by Alexander K. Hastings, Jonathan I. Bloch, Carlos A. Jaramillo, Aldo F. Rincona and Bruce J. Macfadden in 2013 based on a single holotype skull and three neck vertebrae from the Culebra Formation. Culebrasuchus is thought to be the most basal member of Caimaninae, meaning that it represents the earliest radiation of caimans in the Americas. The ancestor of Culebrasuchus likely lived farther north, perhaps in what is now southern Mexico, because before the Miocene most of Panama was underwater. The movement of Culebrasuchus into the Panama Canal Zone was an early part of the Great American Interchange in which animals dispersed between North and South America across the newly formed Isthmus of Panama (although during the Early Miocene it had not yet formed, with 20 km of ocean still separating the continents). However, Culebrasuchus was not the earliest caimanine; Orthogenysuchus and Tsoabichi are known from the Eocene of North America and Eocaiman is known from the Eocene of South America, indicating that caimanines were dispersing between the continents across large expanses of ocean long before the isthmus formed. [1]
Like many living caimans, Culebrasuchus was small in size. Other caimans that lived during the same time in South America (including those in the genera Mourasuchus and Purussaurus ) were much larger than Culebrasuchus. Features that Culebrasuchus shares in common with other caimanines include nostrils that open upward (rather than slightly forward, as in alligatorines), and bones that do not overlap the edges of two openings in the skull table called supratemporal fenestrae. Like living caimanines, Culebrasuchus has blunter teeth at the back of the jaw, and the teeth in the upper jaw completely overly the teeth in the lower jaw when the mouth is closed. Features in Culebrasuchus that are not found in other caimanines include the lack of ridges above the eye sockets and the large size of a hole in the lower jaw called the external mandibular fenestra. These features may be plesiomorphic ("primitive") for alligatorids. Culebrasuchus also has a straighter lower jaw than most other alligatorids, it lacks the ridges on the frontal bone between the eye sockets that are common among crocodylians, and the fourth tooth of the maxilla (rather than third, as in almost all other alligatorids) is the largest in the upper jaw. [1]
The 2013 study describing and naming Culebrasuchus placed it as the most basal member of the Alligatoridae subfamily Caimanine, [1] and was confirmed by later studies. [2] [3]
The below cladogram is from the initial 2013 study: [1]
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Alternatively, a 2018 study by Bona et al. noted that Culebrasuchus was enigmatic and difficult to interpret, and instead proposed it to be a member of Alligatorinae, closely related to the living American Alligator and Chinese Alligator, as shown in the cladogram below: [4]
| Alligatoridae |
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The family Alligatoridae of crocodylians includes alligators and caimans.
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.
Diplocynodon is an extinct genus of alligatoroid that lived during the Paleocene to Middle Miocene in Europe. It looked very similar to the modern caiman in that it was small and had bony armour scutes covering its neck, back, belly, and tail. The longest Diplocynodon recovered was 4 feet in length and probably fed on small fish, frogs, and took insects when young.
Wannaganosuchus is an extinct genus of small alligatorid crocodylian. It was found in Late Paleocene-age rocks of Billings County, North Dakota, United States.
Procaimanoidea is an extinct genus of alligatorid from the Eocene of North America. It was named posthumously in 1946 by Charles W. Gilmore; the type species is P. utahensis, from the Uintan of Utah. It is based on USNM 15996, a nearly complete skull and partial left hind leg. A second species, P. kayi, was named in 1941 by C.C. Mook as a species of Hassiacosuchus, for remains from the Bridgerian of Wyoming. It was reassigned to Procaimanoidea in 1967 by Wassersug and Hecht. Procaimanoidea was a small alligatorid, and slightly heterodont, the last four teeth on each side of the jaws having blunt tips.
Hassiacosuchus is an extinct genus of small alligatorid from the early Eocene of Germany, found at the Messel pit. It was named in 1935 by K. Weitzel, and the type species is H. haupti. A second species, H. kayi, was named in 1941 by C.C. Mook for material from the Bridgerian of Wyoming, but was reassigned to Procaimanoidea in 1967 by Wassersug and Hecht. Hassiacosuchus may be the same as Allognathosuchus; Christopher Brochu has recommended continuing to use Hassiacosuchus.
A caiman is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within Alligatoridae, the other being alligators.
Alligatorinae is a subfamily within the family Alligatoridae that contains the alligators, and is the sister taxon to Caimaninae. Many genera in Alligatorinae are described, but only the genus Alligator is still living, with the remaining genera extinct.
Allognathosuchus is an extinct genus of alligatorine crocodylian with a complicated taxonomic history. It was named as a separate species in 1921.
Navajosuchus is an extinct genus of alligatorine crocodylian. Its fossils have been found in the Paleocene-age Nacimiento Formation of the San Juan Basin, New Mexico. It was named in 1942 by Charles C. Mook, and the original type species was N. novomexicanus. N. novomexicanus was based on AMNH 5186, a partial skull collected in 1913. Later research showed that Navajosuchus novomexicanus was the same as the earlier-named Allognathosuchus mooki. However, A. mooki may or may not belong to the genus Allognathosuchus, and if it does not, the name of the crocodilian would become Navajosuchus mooki. Under whichever name is used, this animal would have been a generalized predator of the Nacimiento floodplains. It was the most common Nacimiento Formation crocodilian, found in both the Puercan and Torrejonian faunal assemblages.
Arambourgia is an extinct monotypic genus of alligatorine crocodylian from Europe. It was named in 1905 and synonymized with Allognathosuchus haupti in 1990, but later reassigned as its own genus once again in 2004. Arambourgia was likely to have been part of an early dispersal event of alligatorines from North America to Europe during the Eocene epoch. Arambourgia had non-serrated teeth and a deep orienirostral snout, unlike the flatter snouts of most other alligatorids.
Bottosaurus is an extinct genus of alligatorid from the Late Cretaceous-Early Paleocene of New Jersey, Texas, and possibly North Carolina and South Carolina. Two species are currently accepted, with a third requiring re-evaluation.
Brachychampsa is an extinct genus of alligatoroid. Specimens have been found from New Mexico, Colorado, Wyoming, Montana, North and South Dakota, New Jersey, and Saskatchewan. One specimen has been found from the Darbasa Formation of Kazakhstan, although the species status is indeterminant for the fossil. The genus first appeared during the late Campanian stage of the Late Cretaceous and became extinct during the early Danian stage of the Paleocene, a few million years after the Cretaceous–Paleogene extinction event. Brachychampsa is distinguished by an enlarged fourth maxillary tooth in the upper jaw.
Prodiplocynodon is an extinct genus of basal crocodyloid crocodylian. It is the only crocodyloid 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.
Stangerochampsa is an extinct genus of globidontan alligatoroid, possibly an alligatorine or a stem-caiman, from the Late Cretaceous of Alberta. It is based on RTMP.86.61.1, a skull, partial lower jaws, and partial postcranial skeleton discovered in the late Campanian–early Maastrichtian-age Horseshoe Canyon Formation. Stangerochampsa was described in 1996 by Wu and colleagues. The type species is S. mccabei. The generic name honors the Stanger family, the owners of the ranch where the specimen was found, and the species name honors James Ross McCabe, who discovered, collected, and prepared it. Stangerochampsa is described as "small to medium–sized"; the type skull is 20.03 centimetres (7.89 in) long from the tip of the snout to the occipital condyle, and is 13.0 centimetres (5.1 in) wide at its greatest, while the thigh bone is 14.2 centimetres (5.6 in) long. It had heterodont dentition, with large crushing teeth at the rear of the jaws.
Tsoabichi is an extinct genus of caimanine crocodylian. Fossils are known from the Green River Formation in Wyoming, and date back to the Wasatchian stage of the Eocene. The genus was named and described in 2010 by paleontologist Christopher A. Brochu, with the type species being Tsoabichi greenriverensis. According to the current understanding of caiman evolutionary relationships, Tsoabichi is a basal member of Caimaninae and may have evolved after caimans dispersed into North America from northern and central South America, their main center of diversity in the Cenozoic.
Globidonta is a clade of alligatoroids that includes alligators, caimans, and closely related extinct forms. It is defined as a stem-based clade including Alligator mississippiensis and all forms more closely related to it than to Diplocynodon. The group's fossil range extends back into the Late Cretaceous with early alligatoroids such as Albertochampsa and Brachychampsa. Extinct globidontans were particularly common in North America and Eurasia, and their modern range also includes South America.
Centenariosuchus is an extinct genus of caimanine crocodylian known from the Miocene of the Panama Canal Zone of Panama. It contains a single species, Centenariosuchus gilmorei, that was named in 2013 in honor of the upcoming centennial anniversary of the digging of the Panama Canal. Two fossil specimens consisting of skull fragments were found in the Early to Middle Miocene Cucaracha Formation in 2009 and 2011, and may belong to a single individual. The species is diagnosed by a combination of skull features that it shares with basal caimans like Tsoabichi, Eocaiman, Culebrasuchus, and the living genus Paleosuchus, as well as more derived caimans such as those in the genus Caiman. One feature that distinguishes Centenariosuchus from all other caimans is the straight outer margin of a hole on the underside of the skull called the suborbital fenestra. According to one phylogenetic analysis of caimanine relationships, Centenariosuchus falls within a clade or evolutionary grouping of caimans that includes the very large and highly specialized forms Purussaurus and Mourasuchus, known from the Miocene of South America.
The Culebra Formation (Tcb) is a geologic formation in Panama. It preserves fossils dating back to the Miocene period; Early Miocene epoch, Aquitanian to Burdigalian stages. Fossils of Culebrasuchus have been found in and named after the formation. The thickness of the formation is at least 250 metres (820 ft) thick, and the age has been estimated as from 23 to 19 Ma.
Acresuchus is an extinct genus of large caiman from the Late Miocene of western Brazil and of Venezuela. The genus contains a single species, A. pachytemporalis. Acresuchus is a close relative of the giant caiman Purussaurus.
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