# 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, 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.

## 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. 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.
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 | Material | Notes |
| Asteriornis | A. maastrichtensis | | Limb bones and a mostly complete skull | A stem-Galloanserae |
| Betasuchus | B. bredai | Geographically present in the Dutch province of Limburg. | "Femur." | An abelisauroid. |
| Janavis | J. finalidens | | | An ichthyornithine |
| Megalosaurus | M. bredai | Geographically present in the Dutch province of Limburg. | | Reclassified as Betasuchus bredai. |
| Orthomerus | O. dolloi | Geographically present in the Dutch and Belgian provinces of Limburg. | | A dubious hadrosaurid. |
| Indeterminate euhadrosaurian remains | | Geographically present in the Dutch province of Limburg. | | A hadrosauroid. |
| "Unnamed ornithurine" | Unnamed | | | An ornithurine. |
| "Unnamed enantiornithine" | Unnamed | | | An enantiornithine. |

### 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. | |

### 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 | Notes |
| Carinodens | C. belgicus | |
| Carinodens | C. fraasi | Junior synonym of C. belgicus. |
| Globidens | G. fraasi | Reclassified as Carinodens fraasi |
| Mosasaurus | M. hoffmannii | Holotype |
| Mosasaurus | M. lemonnieri | |
| Plioplatecarpus | P. marshi | |
| Prognathodon | P.? saturator | |
| Prognathodon | 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 :
| Genus | Species | Material | Notes |
| Alaconger | A. triquetrus | Otoliths | A conger eel. |
| Ampheristus | A. sp. | Otolith | A cusk-eel. |
| Anomoeodus | A. foriri | Teeth, tooth plates | A pycnodont. |
| Anomoeodus | A. fraiponti | Teeth, tooth plates | A pycnodont. |
| Anomoeodus | A. subclavatus | Teeth, tooth plates | A pycnodont. |
| 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. |
| 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 | M. rostratus | | Middle Meerssen Member | Carapace | A cyclidan crustcean, youngest member of the group, has also alternatively been suggested to be a crab. | |