Theriosuchus

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.[1]

Theriosuchus
Temporal range: Late Jurassic to Early Cretaceous
Theriosuchus
Fossil of T. pusillus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Family: Atoposauridae
Genus: Theriosuchus
Owen, 1879
Species
  • T. pusillus Owen, 1879 (type)
  • T. grandinaris Lauprasert et al., 2011
  • T. morrisonensis Foster, 2018

Taxonomy

Theriosuchus pusillus
Skull elements of T. pusillus

Three valid species are currently recognized: Theriosuchus pusillus from southern England,[2] T. grandinaris from Thailand,[3] and T. morrisonensis from the Morrison Formation of North America.[4] Theriosuchus was previously assigned to Atoposauridae, but a 2016 cladistic analysis recovered it as a neosuchian more closely related to members of the family Paralligatoridae than to atoposaurids.[1]

Two species previously assigned to this genus, Theriosuchus ibericus[5] and T. symplesiodon,[6] have been reassigned to the new genus Sabresuchus.[1] On the other hand, Theriosuchus guimarotae from Portugal[7] has been reassigned to Knoetschkesuchus.[8]

Paleobiology

Fossils belonging to the genus are abundant at several European sites, namely Dorset, southern England.

References

  1. ^ a b c Jonathan P. Tennant; Philip D. Mannion; Paul Upchurch (2016). "Evolutionary relationships and systematics of Atoposauridae (Crocodylomorpha: Neosuchia): implications for the rise of Eusuchia". Zoological Journal of the Linnean Society. in press.
  2. ^ Owen, R. (1879). "Monograph on the fossil Reptilia of the Wealden and Purbeck Formations. Supplement IX, Crocodilia (Goniopholis, Brachydectes, Nannosuchus, Theriosuchus, and Nuthetes)". Palaeontographical Society of London Monograph. 33: 1–19.CS1 maint: Uses authors parameter (link)
  3. ^ Komsorn Lauprasert; Chalida Laojumpon; Wanitchaphat Saenphala; Gilles Cuny; Kumthorn Thirakhupt; Varavudh Suteethorn (2011). "Atoposaurid crocodyliforms from the Khorat Group of Thailand: first record of Theriosuchus from Southeast Asia". Paläontologische Zeitschrift 85 (1): 37–47. doi:10.1007/s12542-010-0071-z.
  4. ^ Foster, J. (2018). "A new atoposaurid crocodylomorph from the Morrison Formation (Upper Jurassic) of Wyoming, USA". Geology of the Intermountain West. 5: 287–295. doi:10.31711/giw.v5i0.32. ISSN 2380-7601.
  5. ^ Brinkmann, W. (1992). "Die Krokodilier-Fauna aus der Unter-Kreide (Ober-Barremium) von Uña (Provinz Cuenca, Spanien)". Berliner Geowissenschaftliche Abhandlungen (E). 5: 1–123.CS1 maint: Uses authors parameter (link)
  6. ^ Jeremy Martin, Márton Rabi and Zoltán Csiki (2010). "Survival of Theriosuchus (Mesoeucrocodylia: Atoposauridae) in a Late Cretaceous archipelago: a new species from the Maastrichtian of Romania". Naturwissenschaften 97 (9): 845–854. doi:10.1007/s00114-010-0702-y. PMID 20711558.
  7. ^ Schwarz, Daniela and Salisbury, Steven W. (2005). "A new species of Theriosuchus (Atoposauridae, Crocodylomorpha) from the Late Jurassic (Kimmeridgian) of Guimarota, Portugal". Geobios. 38 (6): 779–802. doi:10.1016/j.geobios.2004.04.005. ISSN 0016-6995.CS1 maint: Uses authors parameter (link) PDF
  8. ^ Daniela Schwarz; Maik Raddatz; Oliver Wings (2017). "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.
Aegyptosuchidae

Aegyptosuchidae is an extinct family of eusuchian crocodyliforms from the Cretaceous period of Africa. They are characterized by their large size and flat heads. The family includes two genera, Aegyptosuchus and Aegisuchus.

Anteophthalmosuchus

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.

Atoposauridae

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

Calsoyasuchus

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.

Coelosuchus

Coelosuchus is an extinct genus of goniopholidid mesoeucrocodylian. Fossils have been found from the Graneros Shale of the Benton Group in Wyoming, and are of Cenomanian age. It was slightly over 1 meter in length.

Goniopholididae

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.

Goniopholis

Goniopholis is an extinct genus of goniopholidid crocodyliform that lived in Europe and Africa during the Late Jurassic and Early Cretaceous. Being semi-aquatic it is very similar to modern crocodiles. It ranged from 2–4 metres in length, and would have had a very similar lifestyle to the American alligator or Nile crocodile.

Hulkepholis

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").

Knoetschkesuchus

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.

Montsecosuchus

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.

Nannosuchus

Nannosuchus (meaning "dwarf crocodile") is an extinct genus of goniopholidid mesoeucrocodylian from the Berriasian of England.

Neosuchia

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.

Oweniasuchus

Oweniasuchus is an extinct genus of goniopholidid mesoeucrocodylian. Remains have been found from England and Portugal that are Cretaceous in age.

The type species of Oweniasuchus is O. major from the Early Cretaceous Upper Purbeck Group in Beccles, England. It is known from a mandibular ramus that was first described as Brachydectes minor by Richard Owen in 1879. Because the generic name Brachydectes was preoccupied by a beetle, the species was reassigned to the new genus Oweniasuchus by Arthur Smith Woodward in 1885, along with another species, B. minor, also described by Owen from material from Beccles. Recently, O. major has been considered a nomen dubium because the holotype specimen (BMNH 48304) is too fragmentary to provide an adequate diagnosis. O. minor has since been proposed to be a synonym of the atoposaurid Theriosuchus pusillus. Two other species, O. lusitanicus and O. pulchelus, are known from the Late Cretaceous of Portugal.

Paralligatoridae

Paralligatoridae is an extinct family of neosuchian crocodyliforms that existed during the Jurassic and Cretaceous periods. It includes the genera Paralligator, Brillanceausuchus, Kansajsuchus, Shamosuchus, Scolomastax, Sabresuchus, Rugosuchus, Batrachomimus and Wannchampsus, as well as the yet-unnamed "Glen Rose form".

Pholidosauridae

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

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.

Symptosuchus

Symptosuchus is an extinct genus of goniopholidid mesoeucrocodylian. It is known from the Late Cretaceous of Argentina. Argentine paleontologist Florentino Ameghino named the genus in 1899, along with the type species S. contortidens. It was formally described by Carlos Rusconi in 1934.

Tethysuchia

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.

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