''Dyrosaurus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of extinct

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. Extinct crocodylomorphs were considerably mor ...

that lived during the early

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

. The name ''Dyrosaurus'' comes from () the Greek for lizard or reptile, and Dyr for

Djebel Dyr : ''For mountains or other uses, see: Jabal.'' Djebel (1937–1958) was a French Thoroughbred racehorse, who won 15 of 22 races during 1939–1942 including the Prix d'Essai, 2000 Guineas and Prix de l'Arc de Triomphe. He was later a leading sir ...

(mountain) close to where the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

was discovered. It was a large reptile with an estimated body length of .

Species

Although the family

Dyrosauridae Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Campanian to the Eocene. Dyrosaurid fossils are globally distributed, having been found in Africa, Asia, Europe, North America and South America. Over a dozen sp ...

is quite diverse and contains a variety of

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

, the genus ''Dyrosaurus'' has only two described species: ''D. phosphaticus'' and ''D. maghribensis''. ''D. phosphaticus'' was first discovered in

Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...

and

Tunisia Tunisia, officially the Republic of Tunisia, is a country in the Maghreb region of North Africa. It is bordered by Algeria to the west and southwest, Libya to the southeast, and the Mediterranean Sea to the north and east. Tunisia also shares m ...

whereas ''D. maghribensis'' has only been found in

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

. ''D. maghribensis'' differs from ''D. phosphaticus'' by several

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to ...

, most notably: a smooth dorsal margin of the parietal and widely opened

choanae The choanae (: choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the pharynx, in humans and other mammals (as well as crocodilians and most skinks). They ...

, interfenestral bar wide and strongly T-shaped instead of moderately T-shaped. In ''D. maghribensis'' the lateral and medial dorsal

osteoderm Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amph ...

s 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. ''Dyrosaurus'' have been inferred to have been

ectothermic An ectotherm (), more commonly referred to as a "cold-blooded animal", is an animal in which internal physiological sources of heat, such as blood, are of relatively small or of quite negligible importance in controlling body temperature.Daven ...

on the basis of bone

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...

and stable isotope analysis.

History of discovery

French paleontologist

Auguste Pomel Nicolas Auguste Pomel (20 September 1821 – 2 August 1898) was a French geologist, paleontologist and botanist. He worked as a mines engineer in Algeria and became a specialist in north African vertebrate fossils. He was Senator of Algeria for Or ...

named the genus ''Dyrosaurus'' in 1894 for Djebel Dyr, a mountain near Tebessa in

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.Buffetaut E. 1985. L'évolution des crocodiliens. Les animaux disparus-Pour la science, Paris, p. 109 In 1903, the family Dyrosauridae was named by Giuseppe de Stefano referring to the locality for the holotype was found in Djebel Dyr, Algeria. Thévenin (1911a, 1911b), with some better preserved material, recognized that ''Dyrosaurus phosphaticus'' was a Lower Eocene

crocodyliform Crocodyliformes is a clade of Crurotarsi, crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the ...

. 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.

References

{{Taxonbar, from=Q136439 Dyrosauridae Prehistoric pseudosuchian genera Prehistoric marine crocodylomorphs Eocene crocodylomorphs Eocene animals of Africa Taxa named by Auguste Pomel Fossil taxa described in 1894