Dyrosauridae is a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of extinct neosuchia

Neosuchia

Neosuchia is an unranked 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 than to Notosuchus terrestris...

n crocodyliforms

Crocodyliformes

Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians."In 1988, Michael J. Benton and James M. Clark argued that all traditional names for well-known groups of animals should be restricted to their crown clades, that is, used only for...

 that lived from the Late Cretaceous

Late Cretaceous

The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

 (Maastrichtian

Maastrichtian

The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...

) to the Eocene

Eocene

The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

. Fossils of this group have been found in almost every continent, specifically Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

, Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

, Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 and South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

.

Dyrousaurids were one of the few groups of marine reptiles to survive the End Cretaceous mass extinction. Several distinct genera have been documented, varying in overal size and cranial shape. Genera such as Dyrosaurus

Dyrosaurus

Dyrosaurus was an extinct genus of dyrosaurid crocodyliform from the Eocene of North Africa. The type species D. phosphaticus possessed slender jaws with numerous recurved teeth, indicative of a primarily fish diet...

possessed long, slender jaws with numerous teeth (indicative of a primarily fish diet much like the extant gharial

Gharial

The gharial , , also called Indian gavial or gavial, is the only surviving member of the once well-represented family Gavialidae, a long-established group of crocodilians with long, slender snouts...

). It was a large animal, growing up to 6 meters (20 feet) in length. Even bigger, possibly up to 9 meters (30 feet), was Phosphatosaurus

Phosphatosaurus

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...

. More robust in its morphology, its jaws were relatively shorter, wider and much stronger, with large, partly rounded teeth. This jaw morphology would have been unsuitable for grasping slippery prey; instead a diet involving catching and crushing larger marine animals (such as sea turtles) is more likely.

Paleobiogeography

Dyrosaurids were once considered an African group, but more recent discoveries indicate they inhabited the majority of the continents. In fact, basal forms suggest that their cradle may have been North America.

Systematics

This group is poorly known, due to poor preservation of remains despite being relatively abundant. Despite this, Jouve et al. (2005) found Dyrosauridae to be a clade

Clade

A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

, based on seven synapomorphies:

• Posteromedial wing of the retroarticular process dorsally situated ventrally on the retroarticular process
• Occipital tuberosities small
• Exoccipital participates largely to the occipital condyle
• Supratemporal fenestra anteroposteriorly strongly elongated
• Symphysis about as wide as high
• Quadratojugal participates largely to the cranial condyle for articulation with the jaw
• 4 premaxillary teeth

Cladogram after Jouve et al. (2005) showing phylogenetic relationships of Dyrosauridae and other closely related neosuchia

Neosuchia

Neosuchia is an unranked 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 than to Notosuchus terrestris...

ns:
Composite cladogram for Dyrosauridae (from Jouve et al. 2008 and Barbosa et al. 2008):
Cladogram after Hastings et al. (2011) showing geographic occurrences of taxa:
Analysis suggest that the closest relatives of dyrosaurids are Sarcosuchus

Sarcosuchus

Sarcosuchus is an extinct genus of crocodyliform and distant relative of the crocodile that lived 112 million years ago. It dates from the early Cretaceous Period of what is now Africa and is one of the largest giant crocodile-like reptiles that ever lived...

and Terminonaris

Terminonaris

Terminonaris is a genus of extinct crocodilian reptiles that lived in the Late Cretaceous . Its remains are known from North America...

.

List

Genus	Status	Age	Location	Description	Images
†Acherontisuchus Acherontisuchus 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".-Description:...	Valid.	Paleocene Paleocene The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era... .	South America South America South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east... .	A long-snouted South American dyrosaurid.
†Arambourgisuchus Arambourgisuchus Arambourgisuchus was a 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.Its type and only species is A...	Valid.	Paleocene Paleocene The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era... .	Africa Africa Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area... .	A recently discovered dyrosaurid from Morocco. Its skull was a full meter in length and it appears to have been a marine predator.
†Atlantosuchus Atlantosuchus 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...	Valid.	Paleocene Paleocene The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era... .	Africa Africa Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area... .	A Morrocan dyrosaurid with extremely elongate jaws.
†Cerrejonisuchus Cerrejonisuchus 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...	Valid.	Paleocene Paleocene The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...	South America South America South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...	A small, short-snouted Colombian dyrosaurid.
†Chenanisuchus Chenanisuchus 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.The type species is C...	Valid.	Paleocene Paleocene The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era... .	Africa Africa Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area... .
†Congosaurus Congosaurus Congosaurus is an extinct genus of dyrosaurid mesoeucrocodylian. Fossils have been found from Angola and date back to the Paleocene epoch. In 1952 and 1964 Congosaurus was proposed to be synonymous with Dyrosaurus. The genus was later regarded to be synonymous with Hyposaurus in 1976 and 1980...	Valid.
†Dyrosaurus Dyrosaurus Dyrosaurus was an extinct genus of dyrosaurid crocodyliform from the Eocene of North Africa. The type species D. phosphaticus possessed slender jaws with numerous recurved teeth, indicative of a primarily fish diet...	Valid.	Eocene Eocene The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the... .	North Africa North Africa North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and... .
†Guarinisuchus Guarinisuchus Guarinisuchus is an extinct genus of marine crocodyliform from the Early Paleocene 62 million years ago of Brazil. The type species is G. munizi.- Sources :*http://news.nationalgeographic.com/news/2008/03/photogalleries/crocodile-pictures/index.html...	Valid.	Paleocene Paleocene The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era... .	South America South America South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east... .
†Hyposaurus Hyposaurus Hyposaurus is a genus of extinct dyrosaurid crocodyliform. Fossils have been found in Paleocene aged rocks of the Maria Farinha Formation in Pernambuco, Brazil and Iullemmeden Basin in West Africa and Maastrichtian strata in New Jersey. It was related to Dyrosaurus....	Valid.	Late Cretaceous Late Cretaceous The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series... .
†Phosphatosaurus Phosphatosaurus 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...	Valid.
†Rhabdognathus Rhabdognathus 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...	Valid.
†Sokotosaurus	Junior synonym.			— junior synonym of Hyposaurus Hyposaurus Hyposaurus is a genus of extinct dyrosaurid crocodyliform. Fossils have been found in Paleocene aged rocks of the Maria Farinha Formation in Pernambuco, Brazil and Iullemmeden Basin in West Africa and Maastrichtian strata in New Jersey. It was related to Dyrosaurus....
†Sokotosuchus Sokotosuchus Sokotosuchus is an extinct genus of dyrosaurid crocodyliform which existed in Africa.-External links:* at the Paleobiology Database...	Valid.
†Tilemsisuchus Tilemsisuchus Tilemsisuchus is an extinct genus of dyrosaurid crocodyliform which existed in what is now Mali during the Eocene period. It was first named by Eric Buffetaut in 1979 and contains the species Tilemsisuchus lavocati.-External links:...	Valid.

Habitat

Most dyrosaurids were marine crocodiles. Dyrosaurids found from what is now northern and western Africa are thought to have inhabited the Trans-Saharan Sea, an epicontenental seaway that covered low-lying basins that formed during the late Mesozoic breakup of Africa and South America through crustal attenuation and fault reactivation, during a time of great global sea level elevation.

Dyrosaurids have also been found from nonmarine sediments. In northern Sudan

Sudan

Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...

, dyrosaurids are known from fluvial

Fluvial

Fluvial is used in geography and Earth science to refer to the processes associated with rivers and streams and the deposits and landforms created by them...

 deposits, indicating that they lived in a river setting. Bones from indeterminate dyrosaurids have been found in inland deposits in Pakistan

Pakistan

Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...

 as well. Some dyrosaurids, such as those from the Umm Himar Formation in Saudi Arabia

Saudi Arabia

The Kingdom of Saudi Arabia , commonly known in British English as Saudi Arabia and in Arabic as as-Sa‘ūdiyyah , is the largest state in Western Asia by land area, constituting the bulk of the Arabian Peninsula, and the second-largest in the Arab World...

, inhabited estuarine

Estuary

An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

 environments near the coast. The recently named dyrosaurids Cerrejonisuchus and Acherontisuchus have been recovered from the Cerrejón Formation

Cerrejón Formation

The Cerrejón Formation is a geologic formation in Colombia dating back to the Middle-Late Paleocene. It is found in the El Cerrejón subbasin of the Racheria basin of La Guajira. The formation consists of bituminous coal fields that are an important economic resource. Coal from the Cerrejón...

 in northwestern Colombia

Colombia

Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

, which is thought to represent a transitional marine-freshwater environment surrounded by rainforest more inland than the estuarine environment of the Umm Himar Formation. Cerrejonisuchus and Acherontisuchus lived in a neotropical setting during a time when global temperatures were much warmer than they are today.

Reproduction

In 1978, it was proposed that dyrosaurids lived as adults in the ocean but reproduced in inland freshwater environments. Remains belonging to small-bodied dyrosaurids from Pakistan were interpreted as juveniles. Their presence in inland deposits was viewed as evidence that dyrosaurids hatched far from the ocean. Recently however, the large-bodied and fully mature dyrosaurids of the Cerrejón Formation have shown that some dyrosaurids lived their entire lives in inland environments, never returning to the coast.

External links

• Jouve et al. (2005)
• Mikko's Phylogeny Archive Dyrosauridae page
• Paleopedia page on Dyrosauridae