Chenanisuchus
Life restoration of Chenanisuchus lateroculi
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Clade: Crocodylomorpha
Family: †Dyrosauridae
Genus: †Chenanisuchus
Jouve et al., 2005
Type species
†Ch. lateroculi
Jouve et al. 2005

Chenanisuchus ("Chenane crocodile") 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. lateroculi ("lateralis", lateral; "oculi", eyes), in reference to the laterally facing eyes.

Currently, Chenanisuchus is the most basal known dyrosaurid.[1]

Material

Two specimens of C. lateroculi – OCP DEK-GE 262 (holotype, nearly complete skull with mandibular fragments) and OCP DEK-GE 61 (nearly complete skull) – come from the Sidi Chenane area in Morocco, which is Late Palaeocene (Thanetian) in age.[2] Fossils of Chenanisuchus were also found in Maastrichtian age strata in Mali, showing that Chenanisuchus survived the Cretaceous–Paleogene extinction event.[3]

Systematics

Chenanisuchus lateroculi is referred to Dyrosauridae by Jouve et al. (2005), based on three morphological characters:

  • Presence of occipital tuberosities
  • Presence of an anterolateral postorbital process
  • Large participation of the quadratojugal and surangular to the jaw joint

Palaeobiology

Chenanisuchus lateroculi has an estimated adult length between 4 and 4.5 meters, based on the 60 centimeter long skull. It has the shortest snout relative to the dorsal skull length among all dyrosaurids, but its snout is thicker and its skull less slender than in dyrosaurids such as Sokotosuchus. There appear to be 4 teeth on each premaxilla, with an estimated 13 on each maxilla. The teeth on the maxillae and dentaries are short and robust, but sharp.[2]

Studies of the inner ear morphology of Malian dyrosaurids suggest that they were adapted for walking on the sea floor as opposed to swimming, a hypothesis supported by the apparent lack of adaptations for swimming seen in other marine crocodyliforms (e.g. Metriorhynchidae) such as paddlelike fins.[4] This mode of subaqueous locomotion is suggested to have contributed to the survival of dyrosaurids such as Chenanisuchus across the K-Pg boundary.[3]

References

  1. ↑ Hastings, A.K.; Bloch, J. & Jaramillo, C.A. (2011). "A new longirostrine dyrosaurid (Crocodylomorpha, Mesoeucrocodylia) from the Paleocene of north-eastern Colombia: biogeographic and behavioural implications for new-world dyrosauridae". Palaeontology. 54 (5): 1095–116. doi:10.1111/j.1475-4983.2011.01092.x.
  2. 1 2 Jouve et al., 2005.
  3. 1 2 Hill, Robert V.; McCartney, Jacob A.; Roberts, Eric; Bouaré, Mohamed; Sissoko, Famory; O'Leary, Maureen A. (2008). "Dyrosaurid (Crocodyliformes: Mesoeucrocodylia) Fossils from the Upper Cretaceous and Paleogene of Mali: Implications for Phylogeny and Survivorship across the K/T Boundary". American Museum Novitates (3631): 1–19. doi:10.1206/598.1. hdl:2246/5940. S2CID 56118152.
  4. ↑ Georgi, J. (2006). "Dyrosaurid inner ear morphology as evidence for locomotor behavior". Journal of Vertebrate Paleontology. 26: 66A.

Bibliography

  • 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


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