It was André Hubert Dumont (1809–1857) (Fig. 1) who, while mapping at the St Pietersberg south of Maastricht in the summer of 1849, noted that the higher portion of the yellowish-white friable limestones exposed there represented something unique. So unique that he coined a name for it (Dumont, 1849), his ‘système maestrichtien’, with a fossil hash level at its base, replete with faecal pellets. These pellets have since been described and formally named by Van Amerom (1971) as Coprulus maastrichtensis, and Dumont’s ‘système’ has been shown to correspond in part with our current concept of the Maastrichtian Stage, the youngest slice of Cretaceous time.

The inner Atlantic Coastal Plain of New Jersey reveals exposures of fossiliferous Maastrichtian and Danian deposits. Recent fossil discoveries in this interval are here reported, and placed in the context of Cretaceous/Tertiary (K/T) faunal changes. The exposure at the Inversand Pit at Sewell (New Jersey) is the last active marl mine in the region, and stands as an important reference section for the many significant discoveries of vertebrate fossils produced by the marl mining industry at its zenith. Changes in planktonic populations across the K/T boundary are related to Maastrichtian/Danian marine ecosystem community reorganisation, by demonstrating changes in abundance of dominant marine invertebrates in successive fossil assemblages. Marine invertebrates with non-planktotrophic larval stages were briefly the commonest fossils preserved in the Danian sediments of this region. Late surviving examples of Cretaceous fauna now restricted to the Indo-Pacific region may imply biogeographic changes linked to the K/T mass extinction event.

Onshore Maastrichtian strata in the United Kingdom are limited to a few small, isolated blocks of chalk floating within glacial sediments on the Norfolk coast. Isolated outcrops of Campanian and Maastrichtian chalks used to be available around Norwich but the majority of these exposures are now badly degraded. Offshore, in the North Sea Basin, there are complete chalk successions that range throughout the Upper Cretaceous and Lower Cenozoic. There is a limited succession of Maastrichtian chalks exposed on the north coast of Northern Ireland below the Cenozoic flood basalts. In the Western Approaches Basin, Maastrichtian and Danian chalks are known from exploration wells and core samples. West of the United Kingdom a number of DSDP/ODP boreholes have penetrated the Upper Cretaceous succession.

Beginning in the Cenomanian, in southeast England, the whole of the Upper Cretaceous is within the chalk facies, possibly one of the longest intervals of relatively stable environment in the geological record. The Foraminiferida of the chalk have been studied for more than a hundred years and therefore the fauna is exceptionally well known and fully documented. Fifty years ago, the benthonic Foraminiferida were identified as having the potential to provide a viable zonation of the chalk facies and we now have precise, cross-basinal correlation using these taxa.

The planktonic fauna is restricted by both palaeolatitude and water depth. The latter appears to be the most influential as the faunas from onshore are more limited than those recorded from the deeper waters of the North Sea Basin and the Atlantic Margin. Even with this restricted fauna, however, it is still possible to develop a general correlation with the standard Tethyan zonation based on planktonic taxa.

The Late Cretaceous echinoid genus Echinogalerus König, 1825 is remarkably diverse in the Maastrichtian type area (SE Netherlands and adjacent parts of NE Belgium and western Germany). So far, five species have been recognised, namely E. belgicus (Lambert, 1898), E. minutus (Smiser, 1935), E. muelleri (Schlüter, 1902), E. pusillus Lambert, 1911 and E. vetschauensis (Schlüter, 1902), which occur from the base of the Lower Maastrichtian (E. belgicus, E. pusillus, E. muelleri) up to the K/T boundary (E. minutus). Echinogalerus muelleri, which has the longest stratigraphical range, is the most diverse, while E. pusillus is the smallest echinoid in the area, reaching maximum lengths of 4.5 mm. Comparisons with other species of Echinogalerus described in the literature have now led to the recognition of three tentative infrageneric alliances. It is argued that the ordinal position of Echinogalerus (Holectypoida or Cassiduloida) cannot be evaluated as long as many species are still insufficiently known and two genera, from the Maastrichtian of northern Germany and Denmark, intermediate between the two orders, remain undescribed.

In the extended type area of the Maastrichtian Stage (southern Limburg, the Netherlands; provinces of Limburg and Liège, Belgium; Aachen area, Germany), the pachydiscid Pachydiscus (P.) neubergicus (von Hauer, 1858) ranks amongst the rarer species of Campanian-Maastrichtian ammonites. To date, just four specimens are known, which show P. (P.) neubergicus in this area to have been confined to the Vijlen Member (Intervals 0–6, Gulpen Formation). This would correspond to the basal sumensis Zone to the lower cimbrica Zone, or tegulatus/junior Zone, depending on placement of the Lower/Upper Maastrichtian boundary. Material available has been collected in recent years at the CBR-Lixhe (Liège, Belgium) and ENCI-Maastricht bv (Maastricht) quarries as well as from outcrop 62D-26 at Vijlenerbosch (Vijlen, the Netherlands). Records of P. (P.) neubergicus, the proposed index for the base of the Maastrichtian Stage, from elsewhere in Europe (northern Spain, SW France, Austria, Denmark, Bulgaria), suggest it to have been fairly long-ranging and show local first occurrences to have been diachronous.

The presence of Halisaurus (Squamata, Mosasauridae) in the uppermost Cretaceous of the Maastrichtian type area, suggested by Lingham-Soliar (1996) on the strength of two partial vertebrae, is questioned. The anatomy of these elements suggests that they pertain not to Halisaurus, but more probably to Plioplatecarpus marshi Dollo, 1882.

Two sections, just below the Nivelle Horizon in the upper Gulpen Formation (Upper Maastrichtian), and seven kilometres apart (CBR-Lixhe and ENCI-Maastricht bv quarries) have been analysed (samples every 5 cm) for dinocyst, pollen grains and bioclast contents as well as for carbon and oxygen isotopic composition, to obtain better insight into the influence of weathering on these sediments. The CBR section lies above groundwater level, while that at the ENCI quarry is some metres below. At the former quarry we recognised the influences of weathering (karst) nearby.

At ENCI, palynological, bioclast and stable isotope results of the carbonate phase (mainly consisting of coccoliths) co-vary remarkably, displaying two cycles which may be interpreted tentatively as climatic fluctuations. The ∂18O curve varies roughly between −1.6‰ and −1.1‰ (on PDB scale), corresponding to a temperature change of about 2°C. Less negative values (i.e. cooler seawater) coincide with larger amounts of pollen of Normapolles and Triporates type assumed to represent temperate forest elements of a vegetation also containing tropical elements such as palms. Assuming the 5 cm sample intervals at ENCI to correspond to 1 ka, climatic maxima (and minima) may be 20–25 ka apart, obviously recalling Milankovitch precession cycles.

These are independent of a sharp sedimentological change noted in the upper part of the lowest cycle (samples 42 to 24). Upwards of sample 42, bioclast contents increase and dinocysts, Spiniferites in particular, decrease significantly, corresponding to a marked shallowing. This turning point is also recorded in the ∂13C curve at ENCI. Bioclast percentages appear to follow composite trends that are influenced by both climatic and sedimentological conditions.

The first occurrence (FO) of the ammonite Pachydiscus neubergicus (von Hauer, 1858) has been correlated to calcareous nannofossil zonations in several European sections along the northern margin of the Tethyan palaeobiogeographic realm. Both the proposed stratotype section of Tercis (SW France) and complete, ammonite-bearing sections in northern Spain document the FO of P. neubergicus within standard nannofossil zone CC23a (UC16), below the LO of Broinsonia parca constricta. Other sections such as the type locality Neuberg (Austria), Nagoriani (the Ukraine) and Bjala (Bulgaria) indicate considerable diachroneity of local FOs and show P. neubergicus to range up to nannofossil zone CC25b/c (UC20; Late Maastrichtian).

Inoceramid bivalve shells from outcrops of mid-Maastrichtian deep-water carbonate, hemipelagic beds in the Bay of Biscay exhibit post-depositional diagenetic alteration. New data from isotopic analysis (carbon and oxygen), together with observations of the inoceramid shells and carbonate host-rock using cathodoluminescence (CL) and scanning electron microscopy (SEM), confirm a lateral, westerly increase in the degree of diagenesis, without any substantial textural changes in the alternating dark and clear growth lines of the shell microstructure. Under CL, a bright yellowish to red colour is observed in the most diagenetically altered inoceramid samples. Non-luminescent areas are restricted to the central parts of the less altered shells. A detailed geochemical analysis by electron microprobe, along intrashell profiles of the non-luminescent and luminescent zones has revealed that Mg/Ca, Sr/Ca, Na/Ca, Fe/Ca and Mn/Ca ratios show oscillatory curves but behave differently. Fe/Ca, Mn/Ca and Na/Ca ratios are well correlated but usually show an opposite relationship when compared with the Mg/Ca and Sr/Ca ratios of both luminescent and non-luminescent shell areas. Our findings have palaeoenvironmental implications in that the geochemistry of the regular, alternating dark and clear growth lines seems to be related to the input of seasonally controlled phytodetritus to the basin floor.

Two specimens of a pachydiscid ammonite, a fragmentary silicified phragmocone from the Kunrade Limestone facies at Kunrade (Schunck), and a partial external mould preserved in flint from the Nekum Member (both Maastricht Formation, Belemnitella junior Zone of authors) at the former Blom quarry (Berg en Terblijt), are identified as Pachydiscus (P.) noetlingi Kennedy, 1999, a species previously known only from the Upper Maastrichtian of Baluchistan (Pakistan). This new record underscores the proposal of incursions of Tethyan biota into the type area of the Maastrichtian Stage, previously documented for other groups, including echinoderms and bivalves, as well.

This contribution deals with the dual spelling of the terminal Cretaceous Stage, the Maastrichtian or Maestrichtian. From a historical point of view and in agreement with the recommendations of the International Stratigraphic Guide (1st and 2nd editions) only Maestrichtian is justified. Nevertheless, the spelling Maastrichtian is proposed, or equivalents in other languages, because stratigraphic names should employ the spelling of place names in the country of their origin and, to be realistic, because Maastrichtian has been well established by its use in an overwhelming majority of the publications which have appeared during the last decades.