Dyrosaurus

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For the ornithopod dinosaur, see Dryosaurus.

Dyrosaurus
Temporal range: early Eocene (Ypresian), 56–47 Ma
Restored skeleton
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Clade: Crocodylomorpha
Clade: Crocodyliformes
Family: †Dyrosauridae
Genus: †Dyrosaurus
Pomel, 1894
Species
  • †D. phosphaticus (Thomas, 1893) (type)
  • †D. maghribensis Jouve et al., 2006

Dyrosaurus is a genus of extinct crocodylomorph that lived during the early Eocene.[1] 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.[2] It was a large reptile with an estimated body length of 6.5 metres (21 ft).[3]

Species

Although the family Dyrosauridae is quite diverse and contains a variety of species, the genus Dyrosaurus has only two described species: D. phosphaticus and D. maghribensis. D. phosphaticus was first discovered in Algeria and Tunisia whereas D. maghribensis has only been found in Morocco.[2] D. maghribensis differs from D. phosphaticus by several synapomorphies, most notably: a smooth dorsal margin of the parietal and widely opened choanae, interfenestral bar wide and strongly T-shaped instead of moderately T-shaped. In D. maghribensis the lateral and medial dorsal osteoderms are not sutured and have no serrated margin. The anterolateral margin of medial row of the dorsal osteoderms have a rounded lateral lobe and the lateral row of dorsal osteoderms are square in shape with rounded corners. In D. phosphaticus there are four longitudinal rows of square osteoderms that are thin and have shallow and wide pits. The osteoderms are square and the anterolateral margin of the medial dorsal osteoderms have an acute rounded process directed laterally.[2] Dyrosaurus have been inferred to have been ectothermic on the basis of bone histology and stable isotope analysis.[4]

History of discovery

Restoration of the animal
Jaw and other fragments

French paleontologist Auguste Pomel named the genus Dyrosaurus in 1894 for Djebel Dyr, a mountain near Tebessa in Algeria where its fossilized vertebrae were found in a phosphate mine. The holotype named MNHN 1901-11 includes one tooth, one caudal vertebra, one distal extremity of an ulna and one distal extremity of a radius. The first remains of Dyrosaurus were named Crocodilus phosphaticus by Thomas (1893) for Early Eocene crocodyliform remains from Gafsa, Tunisia. Pomel eventually synonymized the type species D. thevestensis with C. phosphaticus to form the new combination D. phosphaticus, making phosphaticus the epithet of the Dyrosaurus type species.[5][6][7] In 1903, the family Dyrosauridae was named by Giuseppe de Stefano referring to the locality for the holotype was found in Djebel Dyr, Algeria.[8] Thévenin (1911a, 1911b), with some better preserved material, recognized that Dyrosaurus phosphaticus was a Lower Eocene crocodyliform. Many dyrosaurid remains are known, but unfortunately they are often poorly preserved which makes it difficult for paleontologists to get a strong understanding of the family.[1]

References

  1. ^ a b Jouve, Stéphane; Iarochène, Mohamed; Bouya, Baâdi & Amaghzaz, Mbarek (2005). "A new dyrosaurid crocodyliform from the Palaeocene of Morocco and a phylogenetic analysis of Dyrosauridae". Acta Palaeontologica Polonica. 50 (3): 581–594.
  2. ^ a b c Jouve, Stéphane; Iarochène, Mohamed; Bouya, Baâdi & Amaghzaz, Mbarek (2006). "A new species of Dyrosaurus (Crocodylomorpha, Dyrosauridae) from the early Eocene of Morocco: phylogenetic implications". Zoological Journal of the Linnean Society. 148 (4): 603–656. doi:10.1111/j.1096-3642.2006.00241.x.
  3. ^ Houssaye, A. (2013). "Bone histology of aquatic reptiles: what does it tell us about secondary adaptation to an aquatic life?". Biological Journal of the Linnean Society. 108 (1): 3–21. doi:10.1111/j.1095-8312.2012.02002.x.
  4. ^ Faure-Brac, M.G.; Amiot, R.; de Muizon, C.; Cubo, J.; Lécuyer, C. (2021). "Combined paleohistological and isotopic inferences of thermometabolism in extinct Neosuchia, using Goniopholis and Dyrosaurus (Pseudosuchia: Crocodylomorpha) as case studies". Paleobiology. Cambridge University Press (for The Paleontological Society): 1–22. doi:10.1017/pab.2021.34.
  5. ^ Jouve, Stéphane (1 March 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.
  6. ^ Pomel, A. (1894). "Découverte de champsosauriens dans les gisements de phosphorite du suessonien de l'Algérie". Comptes rendus de l'Académie des Sciences. 118: 1309–1310.
  7. ^ Buffetaut E. 1985. L'évolution des crocodiliens. Les animaux disparus-Pour la science, Paris, p. 109
  8. ^ Khosla, Ashu; Sertich, Joseph J. W.; Prasad, Guntupalli V. R. & Verma, Omkar (2009). "Dyrosaurid remains from the Intertrappean beds of India and the Late Cretaceous distribution of Dyrosauridae". Journal of Vertebrate Paleontology. 29 (4): 1321–1326. doi:10.1671/039.029.0416. JSTOR 20627142. S2CID 130987967.
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