Maastricht Formation

The Maastricht Formation (Dutch: Formatie van Maastricht; abbreviation: MMa), named after the city of Maastricht in the Netherlands, is a geological formation in the Netherlands and Belgium whose strata date back to the Late Cretaceous, within 500,000 years of the Cretaceous–Paleogene boundary,^[1] now dated at 66 million years ago. The formation is part of the Chalk Group and is between 30 and 90 metres (98 and 295 ft) thick. It crops out in southern parts of Dutch and Belgian Limburg and adjacent areas in Germany. It can be found in the subsurface of northern Belgium and southeastern Netherlands, especially in the Campine Basin and Roer Valley Graben. Dinosaur remains are among the fossils that have been recovered from the formation.^[2]

Maastricht Formation
Stratigraphic range: Maastrichtian–Danian PreꞒ Ꞓ O S D C P T J K Pg N
Old stone quarry at Kunrade, where the Kunrade Member of the Maastricht Formation outcrops
Type	Geological formation
Sub-units	Meerssen Member, Nekum Member, Emael Member, Schiepersberg Member, Gronsveld Member, Valkenburg Member and Kunrade Member
Underlies	Houthem Formation
Overlies	Gulpen Formation
Thickness	30–90 m (98–295 ft)
Lithology
Primary	Chalk
Other	Marl, flint
Location
Region	Europe
Country	Netherlands Belgium
Type section
Named for	Maastricht
Named by	Dumont
Year defined	1849

Lithology

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.

Stratigraphy

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.^[5]

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

Vertebrate paleofauna

Dinosaurs

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Dinosaurs reported from the Maastricht Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Asteriornis	A. maastrichtensis[6]			Limb bones and a mostly complete skull	A stem-Galloanserae
Betasuchus	B. bredai	Geographically present in the Dutch province of Limburg.		"Femur."[7]	An abelisauroid.[2]
Janavis	J. finalidens[8]				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][9]
"Unnamed enantiornithine"	Unnamed				An enantiornithine.[1][9]

Mammals

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

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 marsupial.[10]

Mosasaurs

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

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

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

• Glyptochelone suyckerbuyki
• Allopleuron hoffmani

Bony fish

Bony fish reported from the Maastricht Formation[11][12][13]
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.
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.
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.
Pelargorhynchus	P. grandis			Skull bones, scutes, scales	A dercetid aulopiform.[14]
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.

Invertebrate paleofauna

Invertebrates reported from the Maastricht Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Maastrichtiocaris[15]	M. rostratus		Middle Meerssen Member	Carapace	A cyclidan crustcean, youngest member of the group, has also alternatively been suggested to be a crab.

See also

• List of dinosaur-bearing rock formations
• The dictionary definition of maastricht formation at Wiktionary