Maastricht Formation

The Maastricht Formation consists of soft, sandy shallow marine limestone (in Limburg locally called "mergel"), in fact chalk and calcareous arenite. These lithologies locally alternate with thin bands of marl or clay. The lower parts of the formation contain flint concretions. The upper parts can have shellrich layers. Its age is between about 70 and 66 million years, which puts it in the Maastrichtian, a stage that was named after the formation. The top of the formation has been identified as Danian (early Paleocene) in age.^[3][4] The type locality is at the ruins of Lichtenberg castle on Mount Saint Peter, Maastricht.

Two primary environment-types have been described in the Maastricht Formation. The lower Kunrade Chalk representing a shallow, semi-lagoonal area near land of low relief which supplied terrigenous material. The Biofacies of the Kunrade Chalk are dominated by burrowing bivalves and abundant seagrass. In contrast, the upper Maastricht Chalk was deposited further offshore in clean carbonate sands. Periods of non deposition resulted in the lithification of sands forming hardgrounds that supported a diversity of echinoids and corals.^[5]

The Maastricht Formation was first described by Belgian geologist André Dumont in 1849. The formation is subdivided in seven members, from top to bottom these are the Meerssen Member, Nekum Member, Emael Member, Schiepersberg Member, Gronsveld Member, Valkenburg Member and Kunrade Member. The members are often hard to distinguish.^[6]

The Maastricht Formation is overlain by the Paleocene Houthem Formation and was deposited on top of the older Gulpen Formation.

Dinosaurs reported from the Maastricht Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Asteriornis	A. maastrichtensis[7]			Limb bones and a mostly complete skull	A stem-Galloanserae
Betasuchus	B. bredai	Geographically present in the Dutch province of Limburg.		"Femur."[8]	An abelisauroid.[2]
Janavis	J. finalidens[9]				An ichthyornithine
Megalosaurus	M. bredai	Geographically present in the Dutch province of Limburg.			Reclassified as Betasuchus bredai.[2]
Orthomerus	O. dolloi	Geographically present in the Dutch and Belgian provinces of Limburg.			A dubious hadrosaurid.[2]
Indeterminate euhadrosaurian remains		Geographically present in the Dutch province of Limburg.			A hadrosauroid.[2]
"Unnamed ornithurine"	Unnamed				An ornithurine.[1][10]
"Unnamed enantiornithine"	Unnamed				An enantiornithine.[1][10]

Mammals reported from the Maastricht Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Maastrichtidelphys	M. meurismeti	Geographically present in the Dutch province of Limburg.		"Right upper molar."	A herpetotheriid.[11]

Mosasaurs reported from the Maastricht Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Carinodens	C. belgicus
	C. fraasi				Junior synonym of C. belgicus.
Globidens	G. fraasi				Reclassified as Carinodens fraasi
Mosasaurus	M. hoffmannii				Holotype
	M. lemonnieri
Plioplatecarpus	P. marshi
Prognathodon	P.? saturator
	P.? sectorius

Testudines reported from the Maastricht Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Allopleuron	A. hofmanni
Glyptochelone	G. suyckerbuyki

• Indeterminate elasmosaurids^[12][13]

Bony fish reported from the Maastricht Formation[14][15][16]
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Alaconger	A. triquetrus			Otoliths	A conger eel.
Ampheristus	A. sp.			Otolith	A cusk-eel.
Anomoeodus	A. foriri			Teeth, tooth plates	A pycnodont.
	A. fraiponti
	A. subclavatus
Apateodus	A. corneti			Jaws, teeth, articulated skull	An ichthyotringid aulopiform.
Archaemacruroides	A. vanknippenbergi			Otoliths	A gadiform of uncertain affinities.
Argentina	A. voigti			Otoliths	A herring smelt.
Argyroberyx	A. dentatus			Otoliths	A beryciform of uncertain affinities.
Belonostomus	B. sp.			Teeth, jaws	An aspidorhynchid.
Beukidercetis[17]	B. grandis			Skull bones, scutes, scales	A dercetid aulopiform.[18]
Caudadercetis	C. taverni				A dercetid aulopiform.
Centroberyx	C. fragilis			Otolith	A nannygai.
Cimolichthys	C. sp.			Teeth	A cimolichthyid aulopiform.
Cretaserranus	C. maastrichtiensis			Otoliths	A perciform, possibly a serranid.
Cyranichthys	C. jagti			Articulated specimen, scutes	A dercetid aulopiform.
	C. sideralis
Dercetis	D. triqueter			Articulated specimens	A dercetid aulopiform.
Enchodus	E. faujasi			Jaws with teeth	An enchodontid aulopiform.
Hoplopteryx	H. sp.			Articulated specimens	A trachichthyiform.
?Ichthyotringa	?I. tavernei			Otoliths	An ichthyotringid aulopiform.
Ophidercetis	O. italiensis			Skull bones, scutes	A dercetid aulopiform.
Paraulopus	P. sp.			Otolith	A cucumberfish.
Petrodercetis	P. bidirectus				A dercetid aulopiform.
Pfeilichthys	P. pfeili			Otolith	A holocentriform of uncertain affinities.
Plesiopoma	P. otiosa			Otoliths	A percomorph, possibly a lanternbelly.
Rhinocephalus	R. cretaceus			Otoliths	A hake.
Saurocephalus	S. woodwardii			Teeth, jaws, vertebrae	An ichthyodectiform.
Severnichthys	S. sp.			Otolith	A beardfish.
Sillaginocentrus	S. alienus			Otolith	A holocentriform of uncertain affinities.
?Sparidae indet.				Otoliths	A potential seabream, but may be another non-percomorph teleost instead.
Tetraodontiformes indet.				Scale plates	A tetraodontiform.