The carbon isotope composition of tooth enamel from all five mosasaur taxa known to date from the type Maastrichtian (southeast Netherlands, northeast Belgium) has been analysed. Differences in enamel δ 13 C values between taxa suggest resource partitioning. Body size and δ 13 C value correlate surprisingly well, with larger taxa having δ 13 C values more depleted in the heavier 13 C isotope.

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We describe pathologies and post-mortem damage observed in specimens of the late Maastrichtian marine cheloniid turtle Allopleuron hofmanni. Shallow circular lesions on carapace bones are common and possibly illustrate barnacle attachment/embedment. Deep, pit-like marks are confined to the neural rim and the inner surface of peripheral elements; these may have been caused either by barnacle attachment or disease. A number of linear marks found on outer carapace surfaces are identified as tooth marks of scavengers, others as possible domichnia of boring bivalves. A fragmentary scapula and prescapular process displays radular traces of molluscs (gastropods and/or polyplacophorans; ichnogenus Radulichnus). These diverse types of bone damage suggest both live and dead marine turtles to have been commonly utilised by predators, scavengers and encrusters in the type Maastrichtian marine ecosystem.

Remains of elasmosaurid plesiosaurs are exceedingly rare in the type-Maastrichtian strata (Late Cretaceous, southeast Netherlands and northeast Belgium), in stark contrast to relatively common skeletal remains of mosasaurs. Here, we present an analysis of δ13C stable isotope values for tooth enamel of two elasmosaur teeth from the type Maastrichtian. The δ13C signal is a proxy for foraging area, trophic level and diving behaviour, the net value of which in these rare elasmosaurs turns out to be not noticeably different from that for the much commoner mosasaurs in the type Maastrichtian. Therefore, the rarity of elasmosaurs in the area probably reflects a primary near-absence of such reptiles during the latest Cretaceous, rather than a taphonomic artefact

An exhaustive screening of public collections containing remains of the latest Cretaceous (late Maastrichtian) marine turtle Allopleuron hofmanni (Gray, 1831) from the type area of the Maastrichtian Stage (southeast Netherlands, northeast Belgium) shows the available material to represent almost exclusively adult individuals. The various skeletal elements are not preserved in proportionally equal abundance, with portions of carapace, pectoral girdle, cranium and mandible overrepresented. These observations can be explained by population characteristics and taphonomic factors. During the late Maastrichtian, while hatchlings and juveniles in all likelihood lived and fed elsewhere, extensive seagrass meadows might have supported a population of only adult marine turtles.