Atoposauridae is a family of crocodile-line archosaurs belonging to Neosuchia.[1] The majority of the family are known from Late Jurassic to Early Cretaceous marine deposits in France, Portugal, and Bavaria in southern Germany.[2][3][4] The discovery of the genus Aprosuchus, however, extends the duration of the lineage to the end of the Cretaceous in Romania.[5]

Temporal range: Late Jurassic–Late Cretaceous
Atoposaurus oberndorfi Teylers
Only known specimen of Atoposaurus oberndorfi
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Eusuchia
Family: Atoposauridae
Gervais, 1871
  • Alligatorellidae Tornier, 1933



Cladogram modified from Buscalioni and Sanz (1988)[1] and Buscalioni and Sanz (1990):[6]








  1. ^ a b Buscalioni, Angela D; José Luis Sanz (1988). "Phylogenetic relationships of the Atoposauridae (Archosauria, Crocodylomorpha)". Historical Biology. 1 (3): 233–250. doi:10.1080/08912968809386477.
  2. ^ Tennant, Jonathan P.; Mannion, Philip D.; Upchurch, Paul (2016). "Evolutionary relationships and systematics of Atoposauridae (Crocodylomorpha: Neosuchia): implications for the rise of Eusuchia". Zoological Journal of the Linnean Society. 177 (4): 854–936. doi:10.1111/zoj.12400.
  3. ^ Schwarz, Daniela; Raddatz, Maik; Wings, Oliver (2017-02-15). "Knoetschkesuchus langenbergensis gen. nov. sp. nov., a new atoposaurid crocodyliform from the Upper Jurassic Langenberg Quarry (Lower Saxony, northwestern Germany), and its relationships to Theriosuchus". PLOS ONE. 12 (2): e0160617. doi:10.1371/journal.pone.0160617. ISSN 1932-6203. PMC 5310792. PMID 28199316.
  4. ^ Tennant, Jonathan P.; Mannion, Philip D. (2014-09-25). "Revision of the Late Jurassic crocodyliform Alligatorellus, and evidence for allopatric speciation driving high diversity in western European atoposaurids". PeerJ. 2: e599. doi:10.7717/peerj.599. ISSN 2167-8359. PMC 4179893. PMID 25279270.
  5. ^ Márton Venczel; Vlad A. Codrea (2019). "A new Theriosuchus-like crocodyliform from the Maastrichtian of Romania". Cretaceous Research. 100: 24–38. doi:10.1016/j.cretres.2019.03.018.
  6. ^ Buscalioni, A. D.; Sanz, J. L. (1990). "Montsecosuchus depereti (Crocodylomorpha, Atoposauridae), new denomination for Alligatorium depereti Vidal, 1915 (Early Cretaceous, Spain): Redescription and phylogenetic relationships". Journal of Vertebrate Paleontology. 10 (2): 244–254. doi:10.1080/02724634.1990.10011810.

Alligatorellus is a genus of atoposaurid crocodyliform found in France that was related to Atoposaurus.A skeleton of Alligatorellus has also been found in the Solnhofen Limestone of Kelheim, Germany. The limestone was deposited in a marine environment and the individual may have washed into a lagoon where it was fossilized. Remains of four crinoids that lived in the lagoon are found in the same block as the skeleton. The skeleton includes osteoderms and limb bones, which are three-dimensionally preserved. The German skeleton shows more details of atoposaurid anatomy than most fossils, as other atoposaurid remains are compressed flat.


Alligatorium is an extinct genus of atoposaurid crocodylomorph from Late Jurassic marine deposits in France.


Anteophthalmosuchus (meaning "forward-pointing eye crocodile") is an extinct genus of goniopholidid mesoeucrocodylian from the Early Cretaceous of southern England, eastern Spain, and western Belgium.


Atoposaurus is an extinct genus of crocodylomorph. It is the type genus of the family Atoposauridae. Fossils have been found that were Late Jurassic in age from two distinct species in France and Germany.

One interesting feature of Atoposaurus is that it lacked dorsal scutes, a common characteristic of atoposaurids as well as most crurotarsans. The absence of scutes, along with its relatively small size (specimens reach lengths of up to 17 cm), narrow supratemporal fossae, wide occipital region, thin postorbital bar, and smooth ornamentation, has led some paleontologists to believe that it is perhaps a juvenile form of another genus within Atoposauridae, most likely Alligatorellus.


Brillanceausuchus is an extinct genus of atoposaurid crocodylomorph. Fossils have been found in Early Cretaceous–age rocks of Cameroon. The genus is notable for the position of the secondary choana within its palate. Parts of the pterygoid bones make up the rostral margin of the choana and thus separate it from the palatines, a feature also seen in the more advanced neosuchian suborder Eusuchia. This characteristic was once thought to be characteristic of Eusuchia, but its presence in Brillanceausuchus suggests that the trait is homoplasic, thus making the evolution of the position of the choana within crocodilians more complex than previously thought.


Calsoyasuchus (meaning "[Dr. Kyril] Calsoyas' crocodile") is a genus of goniopholidid mesoeucrocodylian that lived in the Early Jurassic. Its fossilized remains were found in the Sinemurian-Pliensbachian-age Kayenta Formation on Navajo Nation land in Coconino County, Arizona, United States. Formally described as C. valliceps, it is known from a single incomplete skull which is unusually derived for such an early crocodile relative. This genus was described in 2002 by Ronald Tykoski and colleagues; the species name means "valley head" and refers to a deep groove along the midline of the nasal bones and frontal bones.


The Eusuchia ("true crocodiles") are a clade of crocodylomorphs that first appears in the Early Cretaceous with Hylaeochampsa. Along with Dyrosauridae and Sebecosuchia, they were the only crocodyliformes who survived the K-T extinction. Since the other two clades died out 35 and 11 million years ago, all living crocodilian species are eusuchians, as are many extinct forms.


Goniopholididae is an extinct family of moderate-sized semi-aquatic crocodyliforms superficially similar to living crocodiles (but see below). They lived between the Early Jurassic and the Late Cretaceous.


Hulkepholis is an extinct genus of goniopholidid mesoeucrocodylian from the Early Cretaceous of southern England and eastern Spain. It contains two species, the type species, Hulkepholis willetti, and also H. plotos. Hulkepholis is most closely related to both species of Anteophthalmosuchus (including "Dollo's goniopholidid").


Karatausuchus is an extinct genus of atoposaurid crocodylomorph. It is known from a single specimen discovered in the Late Jurassic (Oxfordian - Kimmeridgian) Karabastau Svita from the vicinity of Mikhailovka in the Karatau Mountains of southern Kazakhstan. The type specimen is PIN 25858/1, a complete but poorly preserved juvenile skeleton with some possible soft tissue preservation. It is notable for having over 90 teeth, but its other anatomical details are difficult to discern. The length of this individual is estimated at 160 millimetres (6.3 in). Karatausuchus was described in 1976 by Mikhail Efimov, and the type species is K. sharovi.


Knoetschkesuchus is a genus of small atoposaurid crocodylomorph from the Late Jurassic of Germany and Portugal. Two species are known: the German species K. langenbergensis, described by Schwarz and colleagues in 2017 based on two partial skeletons and various isolated bones; and the Portuguese species K. guimarotae, named from over 400 specimens including several partial skeletons. Knoetschkesuchus was a small and short-snouted crocodilian, measuring about 55 centimetres (22 in) in length, that primarily fed on small prey, including invertebrates, amphibians, and mammals. This specialization towards small prey ecologically separated Knoetschkesuchus from most of the other diverse crocodilians that it lived with in the island ecosystem of Jurassic Europe.

Both species were formerly recognized as belonging to Theriosuchus; K. guimarotae was initially named as T. guimarotae, and specimens of K. langenbergensis were initially referred to T. pusillus upon their discovery. Schwarz and colleagues recognized a number of characteristics that united these two taxa to the exclusion of other species of Theriosuchus; in particular, Knoetschkesuchus only has two distinct types of teeth, lacking the leaf-shaped teeth seen in other atoposaurids. Other distinguishing traits include the relatively wide skull, and the presence of the antorbital and mandibular fenestrae in all life stages.


"Mesosuchia" is an obsolete name for a group of terrestrial, semi-aquatic, or fully aquatic crocodylomorph reptiles. The marine crocodile Metriorhynchus had paddle-like forelimbs, Dakosaurus andiniensis had a skull that was adapted to eat large sea reptiles, and Shamosuchus was adapted for eating molluscs and gastropods. Shamosuchus also looked like modern crocodiles and was very closely related to their direct ancestor.

The "Mesosuchia" were formerly placed at Suborder rank as within Crocodylia. The "first" crocodiles were placed within their own suborder, Protosuchia; whilst extant species where placed within Suborder Eusuchia (meaning 'true crocodiles'). Mesosuchia were the crocodylians "in between". As it is a paraphyletic group however, it is not considered valid anymore. It is replaced by its phylogenetic equivalent Mesoeucrocodylia, which contains the taxa herein, the Crocodylia, and some allied forms more recently discovered.

The "Mesosuchia" was composed as:

Family Hsisosuchidae

Family Gobiosuchidae

Infraorder Notosuchia

Family Notosuchidae

Family Sebecidae

Family Baurusuchidae

Infraorder Neosuchia

Family Trematochampsidae

Family Peirosauridae

Genus Lomasuchus

Genus Montealtosuchus

Family Elosuchidae

Family Atoposauridae

Family Dyrosauridae

Family Pholidosauridae

Genus Sarcosuchus

Infraorder Thalattosuchia - Sea "Crocodiles"

Family Teleosauridae

Family Metriorhynchidae

Genus Dakosaurus

Family Goniopholididae

Family Paralligatoridae

Genus Shamosuchus


Montsecosuchus is an extinct genus of atoposaurid crocodylomorphs. It is the replacement generic name for Alligatorium depereti, which was described in 1915 from the Montsec Lithographic Limestone quarry of Spain. Fossils found from this locality are from the Early Cretaceous, being Upper Berriasian-Lower Valanginian in age. While many publications concerning atoposaurids after 1915 have included mentions of A. depereti, none has offered a redescription or revision of the species, though some recognized that great differences existed between it and other members of the genus. In these publications, the skull of A. depereti was shorter in relation to body length than any other species of Alligatorium (being less than half of the presacral length), and this may have been evidence for the genetic distinction of the species, although no replacement name was proposed. However, better preparation of the holotype specimen MGB 512, a nearly complete articulated skeleton embedded in a limestone matrix now housed in the Museu de Ciències Naturals de Barcelona, allowed for a revision of the species in 1990 in which the name Montsecosuchus was first used.

Montsecosuchus differs in several ways from other atoposaurids such as Alligatorium, Alligatorellus, and Theriosuchus. Several characteristics of the skull including the presence of an ungrooved parietal-squamosal suture and a caudally projecting retroarticular process distinguish Montsecosuchus from these genera. Both Montsecosuchus and Alligatorellus possess three sacral vertebrae; this may be a shared synapomorphy of the two genera. The shortness of the radius is an autapomorphy of the genus that is not seen in any other atoposaurid, although it is common in more derived crocodylomorphs.


Neosuchia is a clade within Mesoeucrocodylia that includes all modern extant crocodilians and their closest fossil relatives. It is defined as the most inclusive clade containing all crocodylomorphs more closely related to Crocodylus niloticus (the Nile Crocodile) than to Notosuchus terrestris. Neosuchia is very diverse and may be polyphyletic, as the clade has undergone many revisions since it was first named in 1988. Neosuchians first appear in the Early Jurassic with the earliest known goniopholid Calsoyasuchus, which lived during the Sinemurian and Pliensbachian stages.


Pholidosauridae is an extinct family of aquatic neosuchian mesoeucrocodylian crocodylomorphs. Fossils have been found in Europe (Denmark, England, France, Germany, Spain and Sweden), Africa (Algeria, Niger, Mali, Morocco and Tunisia), North America (Canada and the United States) and South America (Brazil and Uruguay). The pholidosaurids first appeared in the fossil record during the Bathonian stage of the Middle Jurassic and became extinct during the Late Turonian stage of the Late Cretaceous.Sarcosuchus is one of the best known pholidosaurs. It is believed to have attained lengths of up to 12 metres (39 ft 4 in) and weighed up to 8 tonnes (7.9 long tons; 8.8 short tons). One genus, Suchosaurus, once thought to be a pholidosaur, has since been shown to be a spinosaurid theropod dinosaur.


Sabresuchus is an extinct genus of neosuchian crocodyliform from the Cretaceous of Europe. The name is derived from 'Sabre' in reference to the enlarged and curved fifth maxillary tooth, and 'suchus' from the Ancient Greek for crocodile.


Shantungosuchus is an extinct genus of Early Cretaceous crocodyliform found in China. It includes three species: Shantungosuchus chuhsienensis and S. brachycephalus, which were both described by Yang Zhongjian – usually referred to as "Young" – in 1961 and 1982, and S. hangjinensis, which was described by Xiao-Chun Wu et al in 1994. S. chuhsienensis is the type for this genus.


Tethysuchia is an extinct clade of neosuchian mesoeucrocodylian crocodylomorphs from the late Middle Jurassic (Bathonian stage) to the Early Eocene (Ypresian stage) of Asia, Europe, North America and South America. It was named by the French paleontologist Eric Buffetaut in 1982 as a suborder. Tethysuchia was considered to be a synonym of Dyrosauridae or Pholidosauridae for many years. In most phylogenetic analyses the node Dyrosauridae+Pholidosauridae was strongly supported. De Andrade et al. (2011) suggested that Tethysuchia be resurrected for that node. They defined it as a node-based taxon "composed of Pholidosaurus purbeckensis (Mansel-Pleydell, 1888) and Dyrosaurus phosphaticus (Thomas, 1893), their common ancestor and all its descendants". In their analysis they found that the support for Tethysuchia is actually stronger than the support for Thalattosuchia. The following cladogram shows the position of Tethysuchia among the Neosuchia sensu this study.


Theriosuchus is an extinct genus of atoposaurid mesoeucrocodylian from Late Jurassic to Early Cretaceous of Europe (southern England), Southeast Asia (Thailand) and western North America (Wyoming), with fragmentary records from Middle Jurassic and Early Cretaceous sites in China, Morocco, and Scotland.


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