Museum grade specimen. It is one of the few complete skulls of Halisaurus that exist. In fact, we have all of its postcranial skeleton, which we are preparing right now.
This specimen has been stabilized on its surface by Paraloid B-72 to ensure its stability and consistency. This process does not affect neither the color nor any of the characteristics. It simply makes the specimen better preserved in the long term. The base of this specimen has been cast in a process of "mummification" similar to that carried out in paleontological excavations to recover large specimens on matrix with the least possible damage.
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
MOSASAURIDAE GERVAIS, 1853
HALISAURINAE BARDET & PEREDA SUBERBIOLA, 2004
NEW TAXON HALISAURUS MARSH, 1869
Type species: Halisaurus platyspondylus Marsh, 1869, Maastrichtian of New Jersey, USA (Holmes & Sues, 2000).
Referred species: Halisaurus ortliebi (Dollo, 1889), Maastrichtian of Belgium (Lingham-Soliar,1996).
HALISAURUS ARAMBOURGI BARDET & PEREDA SUBERBIOLA, SP. NOV. 2004
Sources: The Fossil Forum - Moroccan Mosasaurs - General Fossil Discussion
Etymology: In honour of the late Prof. Camille Arambourg, for his pioneering work on fossil vertebrates from the phosphates of North Africa and the Middle East.
Type locality and horizon: Grand Daoui area, near Khouribga, central Morocco; phosphates of the Oulad Abdoun Basin, upper Couche III, Late Cretaceous, Late Maastrichtian (Cappetta, 1987).
Diagnosis: Small mosasaurid (adult total length 3,4 m). External nares extend from 6th to 12th maxillary teeth, V -shaped anteriorly and U-shaped posteriorly; prefrontal contributes moderately to margin of naris and possesses small anterior supraorbital ridge; frontal with median dorsal ridge extending on two-thirds of the bone length, and two anterior oblique ridges; parietal with triangular table ornamented by transverse undulated ridges and a lenticular foramen, the anterior end of which is located half its length from the frontal suture; quadrate with a vertical oval stapedial notch; pterygoid with short palatine process at about 45° relative to the ectopterygoid process; dental formula: 2 premaxillary, at least 16 maxillary and 12 pterygoid teeth,19 dentary teeth; teeth very fine and sharp, abruptly posteriorly recurved, with a circular basal cross-section, two carinae and enamel ornamented by minute ridges.
The informations cited here come from the publication :
A new species of Halisaurus from the Late Cretaceous phosphates of Morocco, and the phylogenetical relationships of the Halisaurinae (Squamata: Mosasauridae) 2004 NATHALIE BARDET`, XABIER PEREDA SUBERBIOLA, MOHAMED IAROCHENE, BAADI BOUYA and MBAREK AMAGHZAZ.
1996. The first description of Halisaurus (Reptilia Mosasauridae) from Europe, from the Upper Cretaceous of Belgium. Theagarten LINGHAM-SOLIAR.
BAIRD, D. 1986a. Halisaurus and prognatodon. two uncommon mosasaurs from the Upper Cretaceous of New Jersey. The Mosasaur, 3 : 37-45.
HALISAURUS (SQUAMATA: MOSASAURIDAE) FROM THE
MAASTRICHTIAN OF ANGOLA
Le mosasauride basal Halisaurus sternbergii du Cretace superieur du Kansas (Amerique du Nord): une revision du specimen type d'Uppsala
Polcyn, M., Jacobs L., Schulp A., & Mateus O. (2007). Halisaurus (Squamata: Mosasauridae) from the Maastrichtian of Angola. Journal of Vertebrate Paleontology. 27(Suppl. to 3), 130A., Jan: Museu Lourinha, So Methodist Univ, Nat Hist Museum Maastricht