''Apatosuchus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of non-

crocodylomorph Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. During Mesozoic and early Cenozoic times, cro ...

loricata Loricata is a clade of archosaur reptiles that includes crocodilians and some of their Triassic relatives, such as '' Postosuchus'' and ''Prestosuchus''. More specifically, Loricata includes Crocodylomorpha (the persistent archosaur subset which ...

n pseudosuchian known from the

Late Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. It is known from a partial

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

skull from the middle Stubensandstein (a deposit that dates back to the Norian stage and is part of the

Löwenstein Formation The Löwenstein Formation (Stubensandstein in Baden-Württemberg, Burgsandstein in Bavaria) is a lithostratigraphic formation of the Keuper in Germany. It is underlain by the Mainhardt Formation and overlain by the Trossingen Formation. It dates ...

) in

Baden-Württemberg Baden-Württemberg (; ), commonly shortened to BW or BaWü, is a German state () in Southwest Germany, east of the Rhine, which forms the southern part of Germany's western border with France. With more than 11.07 million inhabitants across a ...

. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

is ''Halticosaurus orbitoangulatus.'' ''A. orbitoangulatus'' was first described by German paleontologist Friedrich von Huene in 1932,Huene, F. von. (1932). ''Die fossile Reptil-Ordnung Saurischia, ihre Entwicklung und Geschichte. Monogr. Geol. Pal.'' 4 (1) pts. 1 and 2, viii + 361 pp. who considered it a species of the

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

dinosaur '' Halticosaurus''. Some later studies proposed that it was an early

or "

sphenosuchia Sphenosuchia is a suborder of basal crocodylomorphs that first appeared in the Triassic and occurred into the Middle Jurassic. Most were small, gracile animals with an erect limb posture. They are now thought to be ancestral to crocodyliforms, ...

n" like ''

Saltoposuchus ''Saltoposuchus'' is an extinct genus of small (1-1.5 m and 10-15 kg), long-tailed crocodylomorph reptile (Sphenosuchia), from the Norian (Late Triassic) of Europe. The name translated means "leaping foot crocodile". It has been proposed th ...

'', another pseudosuchian from the middle Stubensandstein of Baden-Württemberg. The name ''Apatosuchus'', "deceptive crocodile", was erected for ''H. orbitoangulatus'' by Hans-Dieter Sues and Rainer R. Schoch in

2013 File:2013 Events Collage V2.png, From left, clockwise: Edward Snowden becomes internationally famous for leaking classified NSA wiretapping information; Typhoon Haiyan kills over 6,000 in the Philippines and Southeast Asia; The Dhaka garment fa ...

when it was realized that the known material represented a pseudosuchian archosaur rather than a dinosaur, as a result of further preparation of the specimen, coining the '' combinatio nova'' ''Apatosuchus orbitoangulatus''. ''Apatosuchus'' is now thought to be a basal member of the clade Loricata. ''Apatosuchus'' is much smaller in size than other basal loricatans such as '' Teratosaurus '' and ''

Batrachotomus ''Batrachotomus'' is a genus of prehistoric archosaur. Fossils of this animal have been found in southern Germany and dated from the Ladinian stage of the Middle Triassic period, around 242 to 237 million years ago. ''Batrachotomus'' was descr ...

''.

Phylogeny

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis performed by Sues & Schoch (2013) found ''Apatosuchus'' to be the sister taxon of the clade formed by ''Batrachotomus'' and more derived

ns. This position was supported by two unambiguous synapomorphies: the presence of a ridge on the dorsal surface of

squamosal The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral co ...

along the edge of supratemporal fossa, and concaved rear portion of the nasals at the midline. The data matrix of Sues & Schoch (2013), a list of characteristics that was used in the analysis, was based on that of Nesbitt (2011), one of the most extensive on archosaurs. Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

from the analysis.

References

Late Triassic reptiles of Europe Norian life Triassic Germany Fossils of Germany Fossil taxa described in 2013 Prehistoric pseudosuchian genera {{paleo-archosaur-stub