| Igdamanosaurus | |
|---|---|
 | |
| Life restoration | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Clade: | †Mosasauria |
| Family: | †Mosasauridae |
| Tribe: | †Globidensini |
| Genus: | †Igdamanosaurus Lingham-Soliar, 1991 |
| Type species | |
| Igdamanosaurus aegyptiacus (Zdansky, 1935) | |
| Synonyms | |
| |
Igdamanosaurus, meaning "lizard from Igdaman", is anextinctgenus ofCretaceous marine lizard belonging to themosasaur family. It is classified as part of theGlobidensini tribe (within theMosasaurinae), and is like the other members of the tribe recognised by its rounded and knob-like teeth. These teeth indicate a highly specialized lifestyle, likely including adurophagous diet.
The genus contains a single species,Igdamanosaurus aegyptiacus, fromMaastrichtian-aged marine environments ofAfrica. Its fragmentary fossil remains have been recovered from theDuwi Formation ofEgypt and theDukamaje Formation ofNiger.[1]
Igdamanosaurus was a small durophagous mosasaur at a size roughly similar to the closely relatedglobidensinCarinodens. Its fossils preserve blunt, rounded teeth similar to those of the other members of theGlobidensini. These teeth were better suited for crushing armored prey likemolluscs andturtles, rather thanfish or other reptiles normally preyed on by other mosasaurs.
The type specimen, BMNH R11898, is fragmentary and consists of three poorly preserved jaw fragments, two almost complete finely striated teeth, three tooth bases and fragments from at least five broken teeth. Though it is difficult to tell, these remains likely come from the same individual.[2]
The dentary is noted as being of massive proportions, similar to the massive and robust dentaries found inGlobidens andPrognathodon. A medially located shallow recess on the dentary indicates the groove for the splenial.[2]
The type specimen preserves seven teeth in various degrees of preservation which increase in size in an anteroposterior direction, except for the last tooth which is slightly smaller than the penultimate of the preserved teeth. The teeth are straight, broad cones with rounded and domed tips. In cross-section the teeth are subcircular. Tooth crowns possess unwaisted bases and are covered in fine parallel ribbing orstriae, numbering at approximately 65 to 70 per tooth. The teeth are more or less uniform across the dentary and the largest one measures approximately 27 mm high and 22 mm wide.[2]
Originally named asGlobidens aegyptiacus byOtto Zdansky (1935),[3] the species was first recognised as sufficiently distinct to be separated into its own genus by Lingham-Soliar (1991), who named itIgdamanosaurus after the village of Igdaman (sometimes called In Dama), which was near to where the type specimen was found.[2]
Though undoubtedly similar toGlobidens in its dental adaptations and similar toG. alabamaensis in possessing unusually small foramina for exits of the mandibular nerve on the lower lateral surface of the dentary, Lingham-Soliar (1991) noted that the vertical striae present inIgdamanosaurus would suggest that it represented a completely new type of durophagous mosasaur that was derived from aPlatecarpus-like ancestor rather than aClidastes-like one and thus classified it as part of thePlioplatecarpinae.[2]
The latest analyses all placeIgdamanosaurus within theMosasaurinae however, within theGlobidensini tribe as a close relative ofCarinodens andGlobidens,[4] or even an indeterminate species ofGlobidens.[5]
