Phosphatosaurus

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Phosphatosaurus
Temporal range: Early Eocene, 48.6  Ma (ghost lineage extends from Maastrichtian) [1]
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Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Pseudosuchia
Superorder: Crocodylomorpha
Family: Dyrosauridae
Genus: Phosphatosaurus
Bergounioux, 1955
Species
  • P. gavialoidesBergounioux, 1955 (type)

Phosphatosaurus is an extinct genus of dyrosaurid crocodylomorph. It existed during the early Eocene, with fossils having been found from North Africa in Tunisia and Mali. Named in 1955, Phosphatosaurus is a monotypic genus; the type species is P. gavialoides. [2] A specimen has been discovered from Niger, but it cannot be classified at the species level. [3]

Contents

Phosphatosaurus is closely related to the Cretaceous genus Sokotosuchus , which is known from Niger and Mali. Because Phosphatosaurus is only known from Paleogene localities, the close relationship with Sokotosuchus implies that there is a long ghost lineage extending back into the Maastrichtian that is not known in the fossil record. [1]

Description

Phosphatosaurus is a large-bodied dyrosaurid with blunt teeth. [1] [2] [4] The tip of the snout is spoon-shaped from a lateral expansion of the rostral portion of the mandible. The dentition is nonhomodont. Alveolar "couplets" are present in the lower jaw of Phosphatosaurus in which paired tooth sockets, or alveoli, are closer to one another than to the alveoli next to them. This is not seen in any other dyrosaurid but is seen in some other longirostrine (long snouted) crocodylomorphs such as the gavialoid Eosuchus . [5] It is possible that the diastemata between the couplets served to receive larger maxillary teeth. [1]

Classification

Phosphatosaurus was assigned in 1979 to the newly named subfamily Phosphatosaurinae by Eric Buffetaut, who considered the subfamily to be the clade formed by Phosphatosaurus and the closely related Sokotosaurus. [6] However, other authors of more recent studies have been tentative in considering the taxon valid because there is currently little knowledge of the anatomy of either genus. [4]

Phylogenetics

Phylogenetic position of Phosphatosaurus
Buffetaut 1978 [7]
Dyrosauridae  

Phosphatosaurus

Rhabdognathus

Hyposaurus

Dyrosaurus

Jouve 2005 [8]
Dyrosauridae  

Sokotosuchus

Phosphatosaurus

Dyrosaurus

Hyposaurus

Rhabdognathus

Jouve et al. 2005 [4]
Dyrosauridae  

Chenanisuchus

Sokotosuchus

Phosphatosaurus

Dyrosaurus

Arambourgisuchus

Congosaurus

Hyposaurus

Rhabdognathus

Phosphatosaurus is considered to be a basal dyrosaurid, and is often positioned near the base of phylogenetic trees of dyrosaurids. An early phylogenetic analysis by Buffetaut (1978), not based on a cladistic data matrix, puts Phosphatosaurus at the base of the tree due to the presence of many primitive characters in the genus. [7] Later phylogenetic analyses, such as the one by Jouve (2005), have also shown Phosphatosaurus to be a basal member of the family. [8] In most analyses, Phosphatosaurus and Sokotosuchus form a clade. These two genera are more closely related to one another than to any other genus of dyrosaurid. More recent phylogenetic studies have considered Chenanisuchus , a short-snouted dyrosairid named in 2005, to be even more basal than the clade containing Phosphatosaurus and Sokotosuchus. [9]

Related Research Articles

<i>Chenanisuchus</i> Extinct genus of reptiles

Chenanisuchus is a genus of dyrosaurid crocodyliform from the Late Cretaceous of Mali and the Late Palaeocene of Sidi Chenane in Morocco. It was described in 2005, after expeditions uncovered it in 2000.

Dyrosauridae Extinct family of reptiles

Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Late Cretaceous (Maastrichtian) to the Eocene. Dyrosaurid fossils are globally distributed, having been found in Africa, Asia, Europe, North America and South America. Over a dozen species are currently known, varying greatly in overall size and cranial shape. A majority were aquatic, some terrestrial and others fully marine, with species inhabiting both freshwater and marine environments. Ocean-dwelling dyrosaurids were among the few marine reptiles to survive the Cretaceous–Paleogene extinction event.

<i>Arambourgisuchus</i> Extinct genus of reptiles

Arambourgisuchus is an extinct genus of dyrosaurid crocodylomorph from the late Palaeocene of Morocco, found in the region of Sidi Chenane in 2000, following collaboration by French and Moroccan institutions, and described in 2005 by a team led by palaeontologist Stéphane Jouve. Arambourgisuchus was a large animal with an elongated skull 1 meter in length.

Elosuchus is an extinct genus of neosuchian crocodyliform that lived during the Middle Cretaceous of what is now Africa.

<i>Dyrosaurus</i> Extinct genus of reptiles

Dyrosaurus is a genus of extinct crocodylomorph that lived during the early Eocene. The name Dyrosaurus comes from sauros (σαῦρος) the Greek for lizard or reptile, and Dyr for Djebel Dyr (mountain) close to where the type species was discovered.

Hyposaurus is a genus of extinct marine dyrosaurid crocodyliform. Fossils have been found in Paleocene aged rocks of the Iullemmeden Basin in West Africa, Campanian–Maastrichtian Shendi Formation of Sudan and Maastrichtian through Danian strata in New Jersey, Alabama and South Carolina. Isolated teeth comparable to Hyposaurus have also been found in Thanetian strata of Virginia. It was related to Dyrosaurus. The priority of the species H. rogersii has been debated, however there is no sound basis for the recognition of more than one species from North America. The other North American species are therefore considered nomina vanum.

Argochampsa is an extinct genus of eusuchian crocodylomorph, usually regarded as a gavialoid crocodilian, related to modern gharials. It lived in the Paleocene of Morocco. Described by Hua and Jouve in 2004, the type species is A. krebsi, with the species named for Bernard Krebs. Argochampsa had a long narrow snout, and appears to have been marine in habits.

Pholidosauridae Extinct family of reptiles

Pholidosauridae is an extinct family of aquatic neosuchian mesoeucrocodylian crocodylomorphs. Fossils have been found in Europe, Africa, North America and South America. The pholidosaurids first appeared in the fossil record during the Bathonian stage of the Middle Jurassic. Jouve & Jalil (2020) described postcranial material of a pholidosaurid from the Paleocene (Danian) of Ouled Abdoun Basin (Morocco), representing the most recent record of the family. The authors also reinterpreted putative Maastrichtian dyrosaurid Sabinosuchus as a pholidosaurid, and argued that at least two independent pholidosaurid lineages reached the Maastrichtian, among which one survived the Cretaceous–Paleogene extinction event. Before the publication of this study it was thought that the family became extinct during the Late Turonian stage of the Late Cretaceous.

Atlantosuchus is an extinct genus of dyrosaurid crocodylomorph from Morocco. One defining characteristic that distinguishes it from other long-snouted dyrosaurids was its proportionally elongate snout, the longest in proportion to body size of any dyrosaurid. Rhabdognathus, a hyposaurine dyrosaurid, is believed to have been the closest relative of the genus.

Congosaurus is an extinct genus of dyrosaurid mesoeucrocodylian. Fossils have been found from Lândana, in Angola and date back to the Paleocene epoch. In 1952 and 1964 Congosaurus was proposed to be synonymous with Dyrosaurus. The genus was later thought synonymous with Hyposaurus in 1976 and 1980. It has since been proven a distinct genus of dyrosaurid separate from both Dyrosaurus and Hyposaurus.

<i>Pholidosaurus</i> Extinct genus of reptiles

Pholidosaurus is an extinct genus of neosuchian crocodylomorph. It is the type genus of the family Pholidosauridae. Fossils have been found in northwestern Germany. The genus is known to have existed during the Berriasian-Albian stages of the Early Cretaceous. Fossil material found from the Annero and Jydegård Formations in Skåne, Sweden and on the island of Bornholm, Denmark, have been referred to as a mesoeucrocodylian, and possibly represent the genus Pholidosaurus.

Cerrejonisuchus is an extinct genus of dyrosaurid crocodylomorph. It is known from a complete skull and mandible from the Cerrejón Formation in northeastern Colombia, which is Paleocene in age. Specimens belonging to Cerrejonisuchus and to several other dyrosaurids have been found from the Cerrejón open-pit coal mine in La Guajira. The length of the rostrum is only 54-59% of the total length of the skull, making the snout of Cerrejonisuchus the shortest of all dyrosaurids.

Rhabdognathus is an extinct genus of dyrosaurid crocodylomorph. It is known from rocks dating to the Paleocene epoch from western Africa, and specimens dating back to the Maastrichtian era were identified in 2008. It was named by Swinton in 1930 for a lower jaw fragment from Nigeria. The type species is Rhabdognathus rarus. Stéphane Jouve subsequently assessed R. rarus as indeterminate at the species level, but not at the genus level, and thus dubious. Two skulls which were assigned to the genus Rhabdognathus but which could not be shown to be identical to R. rarus were given new species: R. aslerensis and R. keiniensis, both from Mali. The genus formerly contained the species Rhabdognathus compressus, which was reassigned to Congosaurus compressus after analysis of the lower jaw of a specimen found that it was more similar to that of the species Congosaurus bequaerti. Rhabdognathus is believed to be the closest relative to the extinct Atlantosuchus.

Sokotosuchus is an extinct genus of dyrosaurid crocodyliform which existed during the Maastrichtian in western Africa. Fossils of the genus were found in the Dukamaje Formation of Nigeria, and some cranial material has possibly been found in Mali.

Acherontisuchus is an extinct genus of dyrosaurid neosuchian from Middle to Late Paleocene deposits of Colombia. The only known species is A. guajiraensis, whose name means "Acheron crocodile of the Guajira Peninsula".

Tethysuchia Extinct clade of reptiles

Tethysuchia is an extinct clade of neosuchian mesoeucrocodylian crocodylomorphs from the late Middle Jurassic to the Early Eocene 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 and Dyrosaurus phosphaticus, 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.

Ouled Abdoun Basin

The Oulad Abdoun Basin is a phosphate sedimentary basin located in Morocco, near the city of Khouribga. It is the largest in Morocco, comprising 44% of Morocco's phosphate reserves, and at least 26.8 billion tons of phosphate. It is also known as an important site for vertebrate fossils, with deposits ranging from the Late Cretaceous (Cenomanian-Turonian) to the Eocene epoch (Ypresian), a period of about 25 million years.

<i>Anthracosuchus</i> Extinct genus of reptiles

Anthracosuchus is an extinct genus of dyrosaurid crocodyliform from the Paleocene of Colombia. Remains of Anthracosuchus balrogus, the only known species, come from the Cerrejón Formation in the Cerrejón mine, and include four fossil specimens with partial skulls. Anthracosuchus differs from other dyrosaurids in having an extremely short (brevirostrine) snout, widely spaced eye sockets with bony protuberances around them, and osteoderms that are smooth and thick. It is one of the most basal dyrosaurids along with Chenanisuchus and Cerrejonisuchus.

Coelognathosuchia Extinct clade of reptiles

Coelognathosuchia is an extinct clade of neosuchian crocodyliforms that includes all taxa more closely related to the family Pholidosauridae than to Bernissartia fagesii or Eusuchia. Martin et al. (2014) named the clade after finding goniopholidids and pholidosaurids to group together in their phylogenetic analysis of crocodyliform evolutionary relationships. In their analysis, Pholidosauridae was monophyletic and Goniopholididae was paraphyletic, being an assemblage of successively more basal taxa within Coelognathosuchia. Coelognathosuchia itself was positioned near the base of the larger clade Neosuchia as the sister group to a clade containing the Early Cretaceous neosuchian Bernissartia and Eusuchia, the group that includes all modern crocodilians and their closest extinct relatives.

Fortignathus is an extinct genus of dyrosaurid or peirosaurid crocodylomorph known from the Late Cretaceous Echkar Formation in Niger. It contains a single species, Fortignathus felixi.

References

  1. 1 2 3 4 Hill, R. V.; McCartney, J. A.; Roberts, E. M.; Bouaré, M. L.; Sissoko, F.; O'Leary, M. A. (2008). "Dyrosaurid (Crocodyliformes: Mesoeucrocodylia) fossils from the Upper Cretaceous and Paleogene of Mali: implications for phylogeny and survivorship across the K/T Boundary" (PDF). American Museum Novitates (3631): 15–17. doi:10.1206/598.1. S2CID   56118152.
  2. 1 2 Bergounioux, F. M. (1956). "Les reptiles fossiles des dépôts phosphatés sud tunisiens". Annales des Mines et de la Géologie. 15: 105.
  3. Buffetaut, E. (1979). "Présence du Crocodilien Phosphatosaurus (Mesosuchia, Dyrosauridae) dans le Paléocène du Niger et du Mali". Paläontologische Zeitschrift. 53 (3–4): 323–333. doi:10.1007/bf02986594. S2CID   129809504.
  4. 1 2 3 Jouve, S.; Iarochène, M.; Bouya, B.; Amaghzaz, M. (2005). "A new dyrosaurid crocodyliform from the Palaeocene of Morocco and a phylogenetic analysis of Dyrosauridae" (PDF). Acta Palaeontologica Polonica. 50 (3): 581–594.
  5. Brochu, C. A. (2006). "Osteology and phylogenetic significance of Eosuchus minor (Marsh, 1870) new combination, a longirostrine crocodylian from the late Paleocene of North America". Journal of Paleontology. 80: 162–186. doi:10.1666/0022-3360(2006)080[0162:oapsoe]2.0.co;2.
  6. Buffetaut, E. (1979). "Sokotosuchus ianwilsoni and the evolution of the dyrosaurid crocodilians". The Nigerian Field Monograph. 1: 31–41.
  7. 1 2 Buffetaut, E. (1978). "Les Dyrosauridae (Crocodylia, Mesosuchia) des phosphates de l'Eocène inférieur de Tunisie: Dyrosaurus, Rhabdognathus, Phosphatosaurus". Géologie Méditerranéenne. 5 (2): 237–256. doi:10.3406/geolm.1978.1046.
  8. 1 2 Jouve, S. (2005). "A new description of the skull of Dyrosaurus phosphaticus (Thomas, 1893) (Mesoeucrocodylia: Dyrosauridae) from the Lower Eocene of North Africa". Canadian Journal of Earth Sciences. 42 (3): 323–337. Bibcode:2005CaJES..42..323J. doi:10.1139/e05-008.
  9. Jouve, S.; Bouya, B; Amaghzaz, M. (2005). "A short-snouted dyrosaurid (Crocodyliformes, Mesoeucrocodylia) from the Palaeocene of Marocco". Palaeontology. 48 (2): 359–369. doi: 10.1111/j.1475-4983.2005.00442.x .