Elrhaz Formation

Elrhaz Formation
Stratigraphic range: Early Cretaceous (Barremian to Albian), 125–112  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Outcrops of the formation near Gadoufaoua
Type	Geological formation
Unit of	Tegama Group
Underlies	Echkar Formation
Overlies	Tazolé Formation
Lithology
Primary	Sandstone
Location
Coordinates	16°48′N9°30′E / 16.8°N 9.5°E / 16.8; 9.5
Approximate paleocoordinates	3°06′N4°54′E / 3.1°N 4.9°E / 3.1; 4.9
Region	Africa
Country	Niger
Extent	Tenere desert
Elrhaz Formation (Niger)

The Elrhaz Formation is a geological formation in Niger, West Africa.

Its strata date back to the Early Cretaceous, about 125 to 112 million years ago. Dinosaur remains are among the fossils that have been recovered from the formation, alongside those of multiple species of crocodyliformes.

Gadoufaoua

Reconstructed skeleton of an anhanguerid from the formation

Gadoufaoua (Tuareg for "the place where camels fear to go") is a site within the Elrhaz Formation (located at 16°50′N9°25′E / 16.833°N 9.417°E / 16.833; 9.417 ) in the Tenere desert of Niger known for its extensive fossil graveyard. It is where remains of Sarcosuchus imperator , popularly known as SuperCroc, were found (by Paul Sereno in 1997, for example), including vertebrae, limb bones, armor plates, jaws, and a nearly complete 6 feet (1.8 m) skull.

Dinosaurs of Elrhaz formation

A spinosaurid claw from the Elrhaz formation

Gadoufaoua is very hot and dry. Based on the sedimentary and fossil record, Gadoufaoua had trees, plants, and wide rivers 112 million years ago. The river covered the remains of dead animals, the fossilized remains of which were protected by the drying rivers over millions of years. ^[1]

Vertebrate paleofauna

Chondrichthyes

Chondrichthyes
Genus	Species	Material	Notes	Images
Hybodus [2]	H. sp.	Dorsal spines [2]

Sarcopterygii

Sarcopterygii
Genus	Species	Material	Notes	Images
Asiatoceratodus [2]	A. tiguidiensis [2]		Dipnomorph fish. Originally described as Ceratodus tiguidiensis, [3] assigned to Arganodus by M. Martin (1984) [4] and reassigned by Kemp (1998) to the genus Asiatoceratodus. [5]
Mawsonia [6]	M. tegamensis [6]		A small species. [7]
Neoceratodus [2]	N. africanus [2]	Tooth plates. [8]	Dipnomorph fish. Originally described as Ceratodus africanus, assigned to Neoceratodus by M. Martin, 1982. [9]	Neoceratodus forsteri , a modern species

Actinopterygii

Actinopterygii
Genus	Species	Material	Notes	Images
Pliodetes [10]	P. nigeriensis [10]	Skull and postcranial material including body scales. [11]	Originally thought to be a semionotid, later assigned to Lepisosteoidei. [11]
Pycnodontidae indet. [2]	Indeterminate

Testudines

Testudines
Genus	Species	Material	Notes	Images
Francemys [12]	F. gadoufaouaensis [12]	"Shell of a juvenile individual and several articulated and disarticulated plates." [12]	Pelomedusoid turtle. Named in honour of France de Lapparent de Broin. [12]
Taquetochelys [13]	T. decorata [13]	A few disarticulated plates and nearly complete skeleton. [14]	Araripemydid turtle, similar in shell size to South American Araripemys (20–30 cm). Laganemys tenerensis was synonymysed with Taquetochelys by Pérez-García, 2018. [14]
Teneremys [13]	T. lapparenti [13]	"Several relatively complete skeletons." [12]

Crocodyliformes

Crocodyliformes
Genus	Species	Material	Notes	Images
Anatosuchus [15]	A. minor [15]	"Nearly complete skull"
Araripesuchus [15]	A. wegeneri [15]	"Nearly complete skull"
Sarcosuchus [16]	S. imperator	"Partial skeletons, numerous skulls"
Stolokrosuchus	S. lapparenti

Dinosaurs

Ornithischians

Ornithischians
Genus	Species	Material	Notes	Images
Elrhazosaurus [15]	E. nigeriensis [15]	"Femora." [17]	A dryosaurid
Lurdusaurus [15]	L. arenatus [15]	"Partial skull, fragmentary postcranial skeleton." [18]
Ouranosaurus [15]	O. nigeriensis [15]	"Skull and poscrania, second skeleton." [19]

Theropods

Theropods
Genus	Species	Material	Notes	Images
Afromimus	A. tenerensis	"caudal vertebrae, chevrons and portions of the right hind limb" [20]	A putative noasaurid [21]
Cristatusaurus [22]	C. lapparenti [22]	Jaw bones and vertebral fragments. [22]	A spinosaurid potentially synonymous with Suchomimus [23]
Eocarcharia [15]	E. dinops [24]	"Partial skull and postcranial remains." [25]	Known from chimaeric remains; the holotype and skull roof material likely derive from a baryonychine spinosaurid, while the referred maxilla is from a carcharodontosaurid. [26]
Kryptops [15]	K. palaios [15]	Postcranial skeleton and partial skull. [27]	An abelisaurid
Suchomimus [15]	S. tenerensis [15]	Partial skull and associated skeleton. [28]	A baryonychine spinosaurid

Sauropods

Sauropods
Genus	Species	Material	Notes	Images
Nigersaurus	N. taqueti	Skull and skeletal remains	A rebbachisaurid.

Flora

Plants
Genus	Species	Material	Notes	Images
Paradoxopteris [29]	P. stromeri		A tree fern and member of Matoniaceae.
Protophyllocladoxylon	P.chudeaui		A conifer [29]

See also

• List of dinosaur-bearing rock formations
• Crato Formation
• Romualdo Formation

References

1. SCIENCE IN THE NEWS - Nov. 13: Digest - 12 November 2001 Voice of America
2. "On the dinosaurian and crocodilian locality of Gadoufaoua (Republic of Niger)" (PDF). From Mr. Philippe Taquet (1970), presented by Mr. Jean Piveteau.
3. N. Tabaste. 1963. Étude derestes de poissons du Crétacé saharien [Study of fish remains from the Saharan Cretaceous]. Mélanges Ichthyologiques Dédiés à la Mémoire d’Achille Valenciennes (1794–1865). Mémoires de l’Institute Français d’Afrique Noire 68:437-485
4. Martin, M., 1984. Révision des Arganodontidés et des Néocératodontidés (Dipnoi, Ceratodontiformes) du Crétacé africain. Neues Jb. Geol. Paläontol. Abh. 169, 225–260.
5. Kemp, A. 1998. Skull structure in post-paleozoic lungfish. Journal of Vertebrate Paleontology, 18(1): 43-63.
6. "Fossilworks: Gateway to the Paleobiology Database". Paleobiology Database . Retrieved 2022-05-16.
7. Taquet, Philippe (1998). Dinosaur impressions : postcards from a paleontologist. Internet Archive. Cambridge; New York : Cambridge University Press. ISBN   978-0-521-58372-5.
8. Federico Fanti, Gabriele Larocca Conte, Luana Angelicola, Andrea Cau, 2016. "Why so many dipnoans? A multidisciplinary approach on the Lower Cretaceous lungfish record from Tunisia." Palaeogeography, Palaeoclimatology, Palaeoecology. 449: 255-265. DOI:10.1016/j.palaeo.2016.02.024
9. M. Martin. 1982. Nouvelles données sur la phylogénie et la systématique des dipneustes postpaléozoïques [New data on the phylogeny and systematics of post-Paleozoic dipnoans]. Comptes Rendus de l'Académie des Sciences, Paris, Série II 294:611-614
10. S. Wenz. 1999. Pliodetes nigeriensis, gen. nov. et. sp. nov., a new semionotid fish from the Lower Cretaceous of Gadoufaoua (Niger Republic): phylogenetic comments. In G. Arratia & H.-P. Schultz (ed.), Mesozoic Fishes 2—Systematics and Fossil Record 107-120
11. A. López-Arbarello. 2012. Phylogenetic interrelationships of ginglymodian fishes (Actinopterygii: Neopterygii). PLoS ONE
12. Pérez-García, Adán (1 October 2019). "The African Aptian Francemys gadoufaouaensis gen. et sp. nov.: New data on the early diversification of Pelomedusoides (Testudines, Pleurodira) in northern Gondwana". Cretaceous Research. 102: 112–126. Bibcode:2019CrRes.102..112P. doi: 10.1016/j.cretres.2019.06.003 . ISSN   0195-6671.
13. F. de Broin. 1980. Les tortues de Gadoufaoua (Aptien du Niger); aperçu sur la Paléobiogéographie des Pelomedusidae (Pleurodira). Mémoires de la Société Géologique de France
14. Pérez-García, Adán (2018). "Identification of the Lower Cretaceous pleurodiran turtle Taquetochelys decorata as the only African araripemydid species". Comptes Rendus Palevol. 18: 24–32. doi: 10.1016/j.crpv.2018.04.004 . ISSN   1631-0683.
15. "68.1 Departement D'Agedez, Niger; 1. Elrhaz Formation," in Weishampel, et al. (2004). Page 572
16. Sereno et al., 2011
17. "Table 19.1," in Weishampel, et al. (2004). Page 415.
18. "Table 19.1," in Weishampel, et al. (2004). Page 416.
19. "Table 19.1," in Weishampel, et al. (2004). Page 417.
20. Sereno, P. (2017). "Early Cretaceous ornithomimosaurs (Dinosauria: Coelurosauria) from Africa". Ameghiniana. 54 (5): 576–616. doi:10.5710/AMGH.23.10.2017.3155.
21. Cerroni, M.A.; Agnolin, F.L.; Brissón Egli, F.; Novas, F.E. (2019). "The phylogenetic position of Afromimus tenerensis Sereno, 2017 and its paleobiogeographical implications". Journal of African Earth Sciences. 159: 103572. Bibcode:2019JAfES.15903572C. doi:10.1016/j.jafrearsci.2019.103572. S2CID   201352476.
22. Taquet, Philippe; Russell, Dale A (1998). "New data on spinosaurid dinosaurs from the early cretaceous of the Sahara". Comptes Rendus de l'Académie des Sciences, Série IIA. 327 (5): 347–353. Bibcode:1998CRASE.327..347T. doi:10.1016/S1251-8050(98)80054-2. ISSN   1251-8050.
23. Rauhut, O.W.M. (2003). "The interrelationships and evolution of basal theropod dinosaurs". Special Papers in Palaeontology 69: 1-213.
24. Sereno & Brusatte, 2008
25. "Table 4.1," in Weishampel, et al. (2004). Page 73.
26. Cau, Andrea; Paterna, Alessandro (May 2025). "Beyond the Stromer's Riddle: the impact of lumping and splitting hypotheses on the systematics of the giant predatory dinosaurs from northern Africa" . Italian Journal of Geosciences. 144 (2): 1–24. doi:10.3301/IJG.2025.10.
27. "Table 4.1," in Weishampel, et al. (2008). Page 72.
28. "Table 4.1," in Weishampel, et al. (2004). Page 72.
29. "Niveau des Innocents, Gadoufaoua (Cretaceous of Niger)". paleobiodb.org. Retrieved 2025-05-29.

Bibliography

• Sereno, P. C.; Larsson, H. C.; Sidor, C. A.; Gado, B. (2001), "The giant crocodyliform Sarcosuchus from the Cretaceous of Africa", Science , 294 (5546): 1516–1519, Bibcode:2001Sci...294.1516S, doi:10.1126/science.1066521, PMID   11679634 ISSN   0036-8075 PMID   11679634
• Sereno, Paul C.; Brusatte, Stephen L. (2008), "Basal abelisaurid and carcharodontosaurid theropods from the Lower Cretaceous Elrhaz Formation of Niger" (PDF), Acta Palaeontologica Polonica , 53: 15–49, doi:10.4202/app.2008.0102 , retrieved 2018-10-06
• Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004), The Dinosauria, 2nd edition, Berkeley: University of California Press, pp. 1–880, ISBN   0-520-24209-2 , retrieved 2019-02-21

Further reading

• P. M. Galton and P. Taquet. 1982. Valdosaurus, a hypsilophodontid dinosaur from the Lower Cretaceous of Europe and Africa. Géobios 15(2):147-159
• H. C. E. Larsson and B. Gado. 2000. A new Early Cretaceous crocodyliform from Niger. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 217(1):131-141
• P. C. Sereno and S. J. ElShafie. 2013. A New Long-Necked Turtle, Laganemys tenerensis (Pleurodira: Araripemydidae), from the Elrhaz Formation (Aptian–Albian) of Niger. In D. B. Brinkman, P. A. Holroyd, J. D. Gardner (eds.), Morphology and Evolution of Turtles 215–250
• P. C. Sereno and H. C. E. Larsson. 2009. Cretaceous crocodyliformes from the Sahara. ZooKeys 28:1-143
• P. C. Sereno, A. L. Beck, D. B. Dutheil, B. Gado, H. C. E. Larsson, G. H. Lyon, J. D. Marcot, O. W. M. Rauhut, R. W. Sadleir, C. A. Sidor, D. D. Varricchio, G. P. Wilson, and J. A. Wilson. 1998. A long-snouted predatory dinosaur from Africa and the evolution of spinosaurids. Science 282:1298-1302