Dyrosauridae

Taxobox

---

image_caption = "Dyrosaurus"
image_width = 270px
name = Dyrosauridae
fossil_range = Fossil range|70|35 Maastrichtian - Eocene
regnum = Animalia
phylum = Chordata
classis = Sauropsida
subclassis = Diapsida
superordo = Crocodylomorpha
unranked_familia = Neosuchia
familia = Dyrosauridae
familia_authority = de Stefano, 1903
subdivision_ranks = Genera
subdivision = "Arambourgisuchus" "Atlantosuchus" "Chenanisuchus" "Congosaurus" "Dyrosaurus" "Guarinisuchus" "Hyposaurus" "Phosphatosaurus" "Rhabdognathus" "Sokotosuchus" "Tilemsisuchus"

Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Late Cretaceous (Maastrichtian) to the Eocene. Fossils of this group have been found in almost every continent, specifically Africa, Asia, Europe, North America and South America.

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

History of the group

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, 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

Composite cladogram for Dyrosauridae (from Jouve "et al". 2008 and Barbosa "et al". 2008):

Dyrosauridae
--"Chenanisuchus" `--+--Phosphatosaurinae
|--"Sokotosuchus"
`--"Phosphatosaurus" `--Dyrosaurinae
--"Dyrosaurus" `--+--"Arambourgisuchus"
--"Guarinisuchus" `--+--"Hyposaurus" `--+--"Congosaurus" `--+--"Atlantosuchus" `--"Rhabdognathus" ´ Dyrosauridae "incertae sedis": "Tilemsisuchus"

Analysis suggest that the closest relatives of dyrosaurids are "Sarcosuchus" and "Terminonaris".

Palaeobiology

Dyrosaurids were a group of marine crocodiles.

References

*Babosa, J.A., Kellner, A.W.A. and Viana, M.S.S. (2008). New dyrosaurid crocodylomorph and evidences for faunal turnover at the K–P transition in Brazil. "Proceedings of the Royal Sociey B: Biological Sciences": Firstcite
*Buffetaut, E. (1985). L'evolution des crocodiliens. Les animaux disparus-Pour la science, Paris 109.
*Jouve, S., Bouya, B. and Amaghzaz, M. (2008). A long-snouted dyrosaurid (Crocodyliformes, Mesoeucrocodylia) from the Paleocene of Morocco: phylogenetic and palaeogeographic implications. "Palaeontology" 51 (2): 281-294
*Jouve, S., Iarochène, M., Bouya, B. & Amaghzaz, M., (2005) A new dyrosaurid crocodyliform from the Palaeocene of Morocco and a phylogenetic analysis of Dyrosauridae. "Acta Palaeontologica Polonica" 50 (3): 581-594

External links

* [http://www.app.pan.pl/acta50/app50-581.pdf Jouve et al. (2005)]
* [http://www.fmnh.helsinki.fi/users/haaramo/metazoa/deuterostoma/Chordata/Archosauria/Crocodylia/Dyrosauridae.htm Mikko's Phylogeny Archive Dyrosauridae page]
* [http://paleopedia.free.fr/croco_neosuchia.html#Dyrosauridae Paleopedia page on Dyrosauridae]