The north-central Texas Cretaceous section and its contained fossils, as compared to sections at ‘Ein Yabrud in the eastern Mediterranean region, demonstrate that dolichosaurs and primitive mosasaurs inhabited marine environments at least from the intertidal zone to <100 m in depth. The small body size of dolichosaurs and primitive mosasaurs, and the association of Haasiasaurus with marine snakes at ‘Ein Yabrud, suggest similar temperature requirements to modern sea snakes and marine iguanas (Amblyrhynchus cristatus), specifically sea-surface temperatures between approximately 20° and 30° С The Cenomanian and Turonian stages are characterised by widespread shallow seas with relatively high sea-surface temperatures extending to at least 45° N and 65° S latitude. The distribution of dolichosaurs, mosasaurs and snakes during this interval contradicts palaeoclimate models that predict high (>30° C) equatorial sea-surface temperatures and a steep latitudinal temperature gradient in the Northern Hemisphere.

Mosasaur taxa currently known from Campanian-Maastrichtian strata in the Liège-Limburg (SE Netherlands, NE Belgium) and Mons (southern Belgium) basins are listed and briefly discussed and their stratigraphic ranges indicated. Recently published and/or ongoing work on coleoid and ammonoid cephalopods in these areas allows tie points between NW Europe and the United States (Western Interior, Gulf Coast, Atlantic Seaboard) to be established. Future studies need to refine the resultant, rather crude, scheme. The ultimate aim is a more robust picture of mosasaur taxonomy, biostratigraphy and palaeobiogeography, and a detailed evaluation of migratory patterns across the Atlantic.

Two isolated mosasaur teeth, one from the upper Campanian of Piotrawin, the other from the upper Maastrichtian at Nasilów (Wisla River valley, central Poland), recently described as Plioplatecarpinae sp. A and Plioplatecarpinae sp. B, respectively, are reassigned to the tylosaurine genus Hainosaurus Dollo, 1885. The present record thus adds to the list of Hainosaurus species known to date from elsewhere in Europe (Sweden, Belgium and England).

Mosasaurs are rare in Australia with fragmentary specimens known only from the Cenomanian-lower Turonian Molecap Greensand (Perth Basin), Campanian - lower Maastrichtian Korojon Calcarenite (Carnarvon Basin), and upper Maastrichtian Miria Formation (Carnarvon Basin), Western Australia. These units were laid down during a near-continuous marine inundation of the western margin of the Australian landmass (which followed separation from India in the Valanginian and genesis of the Indian Ocean) in the Early-Late Cretaceous. The Australian mosasaur record incorporates evidence of derived mosasaurids (mainly plioplatecarpines); however, as yet no specimen can be conclusively diagnosed to genus or species level. The fragmentary nature of the remains provides little basis for direct palaeobiogeographic comparisons. However, correlation with existing data on associated vertebrates, macroinvertebrates and microfossils suggests that the Western Australian mosasaur fauna might have been transitional in nature (particularly following palaeobiogeographic separation of the northern and southern Indian Oceans during the mid-Campanian), potentially sharing elements with both northern Tethyan and austral high-latitude regions.

Presented are the first formal descriptions of mosasaur remains of Maastrichtian age from the Danish mainland (Jylland, Sjælland); just two taxa are recognised, viz. Mosasaurus cf. hoffmanni and Plioplatecarpus sp. Recent finds include an association of skeletal fragments, inclusive of a single marginal tooth crown, from within 10 metres or so of the K/T boundary near Holtug, Stevns Klint (Sjælland, eastern Denmark), here assigned to Plioplatecarpus sp. A brief review of previous records of Danish mosasaurs is added.

A new mosasaur, Russellosaurus coheni, is described from the Collignoniceras woollgari Zone (lower Middle Turonian) at Cedar Hill, Dallas County, Texas. At approximately 92 Ma, it is the oldest well-preserved mosasaur skull from North America. It possesses characters diagnostic of Plioplatecarpinae but retains numerous plesiomorphies as well. Phylogenetic analysis indicates a close relationship with Yaguarasaurus columbianus, and these two, together with Tethysaurus nopcsai, form a clade that occupies a position basal to the divergence of the subfamilies Tylosaurinae and Plioplatecarpinae. Russellosaurus coheni is proposed as the nominal taxon of a new mosasaur clade, parafamily taxon novum Russellosaurina, which includes Plioplatecarpinae, Tylosaurinae, their common ancestor and all descendants. Tethysaurus retains a plesiopedal limb and girdle morphology, and along with Russellosaurus and Yaguarasaurus, cranial plesiomorphies. Dallasaurus turneri, a temporally and geographically sympatric plesiopedal mosasaur, occupies a basal position within Mosasaurinae. This phyletic arrangement confirms that marine adaptations, such as development of paddle-like limbs, occurred independently in at least two lineages of mosasaurs, once within Mosasaurinae and once within Russellosaurina.

Shark bite marks on mosasaur bones abound in the fossil record. Here we review examples from Kansas (USA) and the Maastrichtian type area (SE Netherlands, NE Belgium), and discuss whether they represent scavenging and/or predation. Some bite marks are most likely the result of scavenging. On the other hand, evidence of healing and the presence of a shark tooth in an infected abscess confirm that sharks also actively hunted living mosasaurs.

Recognition of decompression syndrome-related pathology (in the form of avascular necrosis) reveals diving behaviour in mosasaurs. Macroscopic and radiologic examination was performed to identify linear bone death characteristic of avascular necrosis in vertebrae from the major North American and European collections. This survey of mosasaurs extends throughout most of their geographic and stratigraphic range and includes examples across their diversity.

Avascular necrosis was invariably present in Platecarpus coryphaeus and P. ictericus, Tylosaurus proriger, Mosasaurus lemonnieri and M. conodon, Plioplatecarpus houzeaui and Pl. primaevus, Prognathodon giganteus, Hainosaurus bernardi and an as yet unnamed Antarctic mosasaur. The frequency of occurrence in a given genus was independent of geography, present equally in European and North American and in the Niobara and Selma chalks. It was invariably absent from Clidastes propython and C. liodontus, Ectenosaurus, Halisaurus and Kolposaurus.

The bone pathology, avascular necrosis, has a characteristic distribution in seven genera and thirteen species of mosasaurs and is absent in five genera and seven species. It segregated according to diving habits, uniformly present in supposed deep divers and uniformly absent in the shallow-habitat group.

Carinodens is among the smallest known mosasaurs, and one of the most elusive at that. This enigmatic taxon is known from only two dentary fragments and just over a dozen of isolated teeth. Based on this material, an attempt is made to improve our understanding of the dietary habits of this mosasaur, by comparing tooth and jaw morphology to extant analogues, and by testing a biomechanical model with ‘feeding’ experiments using an artificial mosasaur jaw equipped with a force gauge. Carinodens appears to have been a durophagous mosasaur, capable of crushing small molluscs and arthropods, although its dietary habits may not necessarily have been limited to hard-shelled food.

Ever since the first mosasaur restorations were published, these extinct marine reptiles have been pictured with either notched, forked or undivided tongues. Here, we present an overview of existing iconography, a review of the previous literature, and we discuss how best to reconstruct tongue form in mosasaurs. Despite disagreement about their precise phylogenetic position, most authors consider mosasaurs members of the Varanoidea, derived anguimorphans including Helodermatidae, Varanidae, Lanthanotus and probably snakes. All anguimorphans share a diploglossan (two-part) tongue, in which the foretongue is derived and modified into a highly protrusible chemosensor, while the hindtongue is plesiomorphic, retaining well-developed papillae, mucocytes and robust posterior lobes. We suggest that mosasaurs had a diploglossan tongue that remained in a relatively underived state. The form of the tongue would probably have been most like modern Heloderma or Lanthanotus with a protrusible chemosensory foretongue and a plesiomorphic, papillose hindtongue. Such a tongue is consistent with well-developed vomeronasal chemoreception through tongue-flicking, with the retention of the ancestral function of hyolingual food transport and swallowing following jaw-prehension of prey. The presence of paired fenestrae in the palate associated with the vomers, as well as the presence of pterygoid teeth are in accordance with such a tongue form in mosasaurs.

Until recently, mosasaur remains from the Izumi Group (Upper Cretaceous) in southwest Japan comprised only scattered finds; now a richer material is available. From the upper Campanian Hiketa Formation in Kagawa Prefecture, Kourisodon sp. has just been recorded, on the basis of portions of skull and mandible which has small and laterally compressed teeth. A few teeth of the same or similar type have previously been described from the Maastrichtian Mutsuo Formation in Osaka Prefecture. A report of Mosasaurus sp. A, which resembles M. missouriensis and M. dekayi, is based on some cranial and mandible remains, inclusive of numerous teeth and a few well-preserved cervical and two incomplete dorsal vertebrae, from the Maastrichtian Mutsuo Formation in Osaka Prefecture. A slender tooth of Mosasaurus sp. from the Mutsuo Formation has since been reassigned to Platecarpus (Plioplatecarpinae); yet, this may indeed by a species of Mosasaurus, here listed as Mosasaurus sp. B. To date, smaller specimens of mosasaurids have been shown to be abundant in the Izumi Group, which suggests two possible explanations. Either most of these represent juveniles, or smaller-sized, Kourisodon-like animals flourished here. Finds of Kourisodon sp. from the upper Campanian Hiketa Formation and the Maastrichtian Mutsuo Formation suggests the second explanation is the more likely one.