In the international market is very common to find Mosasaurus rests coming from the phosphate quarries of the Upper Cretaceous of the Ouled Abdoun Basin (Morocco).
This quarries have been exploited since the beginning of the past century. Many sellers that sell this fossils do not make a good precise taxonomic identification work.
In these sites there are numerous different species of Mosasaurus described in the enormous assemblage of giant marine reptiles that reigned the seas during the Cretaceous.
The main rich levels in these paleontological taxons are in the deeper stratigraphic levels of the sedimentarian filling of the Ouled Abdoun Basin. The age of these correspond to the Maastrichtian stage, 66 million years ago.
Most of the research carried out on these marine reptiles from Morocco have been performed by French researchers.
Next we list the different Mosasaur species which have been recognised in the phosphate rocks in North Africa:
-Halisaurus aramborgi (Bardet et al., 2005)
-Halisaurus walkeri (Lingham-Solier, 1998)
-Prognathodon sp (Dollo, 1889)
-Prognathodon anceps (Leiodon anceps)
-Prognathodon solvay (Dollo, 1889)
-Prognathodon currii (Christiansen & Bonde, 2002)
-Eremiasaurus heterodontus (LeBlanc et al., 2012)
-Mosasaurus beaugei (Arambourg, 1952)
-Mosasaurus hoffmanni (Mantell, 1829)
-Tylosaurus (Marsh, 1872)
-Platecarpus ptychodon (Arambourg, 1954)
-Globidens phosphaticus (Bardet et al., 2005)
-Carinodens belgicus (Bardet et al., 2005)
The Ouled Abdoun Basin (or Khouribga Basin), located in the central sector of Morocco, is an enormous sedimentarian basin represented mostly by a vast filling of phosphate sediments. Apart from having a relevant raw material to be extracted, it has a series of very important paleontological sites in which amazing assemblages from big and small marine vertebrates are present. The basin has a so great continuity in its stratigraphic record that both the Upper Cretaceous as well as the two first epochs of the Paleogene (Paleocene and Eocene) can be studied.
The main assemblage of vertebrate fossils of the Paleogene sector present there is composed by sharks, fish, turtles, marine snakes, rays, crocodiles, other types of reptiles and even marine birds. In the Cretaceous part we can add Mosasaurs, Pterosaurs and Plesiosaurs.
Next you can visit a link with very interesting information about this sedimentarian basin rich in fossil vertebrates: Ouled Abdoun Basin
Halisaurus walkeri
SYSTEMATIC
PALAEONTOLOGY
SQUAMATA, OPPEL, 1811
MOSASAURIDAE , GERVAIS, 1853
HALISAURINAE
BARDET & PEREDA SUBERBIOLA ,2004
NEW TAXON
HALISAURUS MARSH,1869
Type species:
Pluridens walkeri , ( Lingham-Soliar , 1998 )
Maastrichtian of illulemedden bassin , NIGER
Sources: The Fossil Forum - Moroccan Mosasaurs - General Fossil Discussion
Rare species, not even published yet from moroccan phosphates. Even I used the name of Halisaurus walkeri, this specie must be studied and will have probably a new name.
All specimens have the same size, that make me thinking they are jung adult migrants, with the other species you found the complete ontogeny from babies to old.
Locality:
Sidi Chenan, Morocco
Upper Maestrichian level 3
Etymology: after cyril A. Walker to mark is contributions as a vertebrate paleontologist at the natural history museum of London (BMNH) and is generosity to uninitiated student and to the famous alike.
PUBLICATIONS
A new species of Pluridens (Mosasauridae: Halisaurinae) from the upper Campanian of Southern Nigeria
Konishi, Takuya; Caldwell, Michael W.; Nishimura, Tomohiro; Sakurai, Kazuhiko; Tanoue, Kyo (2015). "A new halisaurine mosasaur (Squamata: Halisaurinae) from Japan: the first record in the western Pacific realm and the first documented insights into binocular vision in mosasaurs". Journal of Systematic Palaeontology.
Holmes, Robert B.; Sues, Hans-Dieter (2000). "A partial skeleton of the basal mosasaur Halisaurus platyspondylus from the Severn Formation (Upper Cretaceous: Maastrichtian) of Maryland" (PDF). Journal of Paleontology 74 (2): 309–16.
University of Cincinnati (8 December 2015). "Unique Mosasaur fossil discovered in Japan". ScienceDaily. Retrieved 12 December 2015
DIAGNOSIS: moderatly large mosasaur very long. Slender dentary, anterior half cross section almost circular extending to tip. 28 -plus teeth
in dentary, close set. Tooth crown short. The teeth looking like Halisaurus arambourgi but bigger and serrated on cutting edge. 21 teeth on a maxillary 28 teeth on a dentary.
This very rare mosasaur is not described in a moroccan phosphates all the skull mesured the same size: 32 inches. They probably are migrants because of lack of young or senile form.
