John W.M. Jagt

A large new mosasaur from the Upper Cretaceous of The Netherlands

We report the discovery of a new species of marine reptile, a mosasaur, from the Upper Cretaceous (Maastrichtian) of The Netherlands. Prognathodon saturator sp. nov. is represented by an almost complete skull and much of the postcranial skeleton, and is one of the largest mosasaurs discovered to date. The stout skull and extremely massive jaws are more powerfully built than in any other known mosasaur. Bite marks, the partial disarticulation and scattering of the skeleton, and the presence of associated teeth of Squalicorax and Plicatoscyllium suggest extensive scavenging by sharks.

Parasites in the Fossil Record: A Cretaceous Fauna with Isopod-Infested Decapod Crustaceans, Infestation Patterns through Time, and a New Ichnotaxon

Parasites are common in modern ecosystems and are also known from the fossil record. One of the best preserved and easily recognisable examples of parasitism in the fossil record concerns isopod-induced swellings in the branchial chamber of marine decapod crustaceans. However, very limited quantitative data on the variability of infestation percentages at the species, genus, and family levels are available. Here we provide this type of data for a mid-Cretaceous (upper Lower Cretaceous, upper Albian) reef setting at Koskobilo, northern Spain, on the basis of 874 specimens of anomurans and brachyurans. Thirty-seven specimens (4.2%), arranged in ten species, are infested. Anomurans are more heavily infested than brachyurans, variability can be high within genera, and a relationship may exist between the number of specimens and infestation percentage per taxon, possibly suggesting host-specificity. We have also investigated quantitative patterns of infestation through geological time based on 88 infested species (25 anomurans, 55 brachyurans, seven lobsters, and one shrimp), to show that the highest number of infested species can be found in the Late Jurassic, also when corrected for the unequal duration of epochs. The same Late Jurassic peak is observed for the percentage of infested decapod species per epoch. This acme is caused entirely by infested anomurans and brachyurans. Biases (taphonomic and otherwise) and causes of variability with regard to the Koskobilo assemblage and infestation patterns through time are discussed. Finally, a new ichnogenus and -species, Kanthyloma crusta, are erected to accommodate such swellings or embedment structures (bioclaustrations).

Ammonite extinction and nautilid survival at the end of the Cretaceous

One of the puzzles about the end-Cretaceous extinctions is why some organisms disappeared and others survived. A notable example is the differential extinction of ammonites and survival of nautilids, the two groups of co-occurring, externally shelled cephalopods at the end of the Cretaceous. To investigate the role of geographic distribution in explaining this outcome, we compiled a database of all the occurrences of ammonites and the nautilid genus Eutrephoceras in the last 0.5 m.y. of the Maastrichtian. We also included recently published data on ammonite genera that appear to have briefly survived into the Paleocene. Using two metrics to evaluate the geographic range of each genus (first, a convex hull encompassing all of the occurrences of each genus, and second, the maximum distance between occurrences for each genus), we documented that most ammonite genera at the end of the Maastrichtian were restricted in their geographic distribution, possibly making them more vulnerable to extinction. The geographic distribution of those genera that may have briefly survived into the Paleocene is significantly greater than that of non-surviving genera, implying that more broadly distributed genera were more resistant to extinction. This pattern is further emphasized by the broad distribution of Eutrephoceras , which matches that of the most widely distributed ammonites at the end of the Maastrichtian. However, even the most widely distributed ammonites eventually succumbed to extinction, whereas Eutrephoceras survived. Evidently, a broad geographic distribution may have initially protected some ammonites against extinction, but it did not guarantee their survival.

NEW MATERIAL OF THE MOSASAUR CARINODENS BELGICUS FROM THE UPPER CRETACEOUS OF THE NETHERLANDS

Current knowledge of the durophagous mosasaur genus Carinodens Thurmond, 1969 (Squamata, Mosasauridae) is scant. In addition to the holotype, an incomplete right dentary, only isolated teeth (mostly crowns) are known. In the holotype, only the posteriormost teeth are preserved, so that until recently no data concerning the remainder of the dentition of this species were available. We here record a fragment of a left dentary assignable to Carinodens from the Maastrichtian type area (Late Cretaceous, Fig. 1) of The Netherlands, which furthers our understanding of the morphology of the species and its dietary habits. Institutional Abbreviations—FHSM, Fort Hays State University’s Sternberg Museum of Natural History, Hays, Kansas, USA; IRScNB, Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium; NHMM, Natuurhistorisch Museum Maastricht, Maastricht, The Netherlands; PR, Field Museum of Natural History, Chicago, Illinois, USA; USNM, United States National Museum, Washington D.C., USA.

REVISION OF THE GENUS TITANOCARCINUS (DECAPODA: BRACHYURA: XANTHOIDEA) WITH TWO NEW GENERA AND ONE NEW SPECIES

Abstract The brachyuran genus Titanocarcinus A. Milne-Edwards, 1864, is rediagnosed and restricted to six species. It is referred to the Tumidocarcinidae Schweitzer, 2005, based upon characters of the sternum, male pleon, and dorsal carapace, along with the closely related Lobonotus A. Milne-Edwards, 1864. Several species that had been referred to Titanocarcinus are herein referred to other genera, including two new ones, Nitotacarcinus and Lathahypossia, or to other families in indeterminate genera. One new species is described from the lowermost Eocene of Spain, Titanocarcinus decor. Titanocarcinus as currently defined ranged from the Cretaceous to Eocene in northern and central Europe. Lobonotus is known only from the Eocene of North and Central America.

Stratigraphy of the upper Vijlen Member (Gulpen Formation; Maastrichtian) in northeast Belgium, the southeast Netherlands and the Aachen area (Germany), with special reference to belemnitellid cephalopods

Recent studies have demonstrated the complex depositional history of the Vijlen Member (Gulpen Formation) in the Maastricht-Aachen-Liege area, on which synsedimentary tectonics had a profound impact, in conjunction with regressive and transgressive episodes, the oldest portion of this member being preserved only locally, within channel-like structures. Our reinterpretation of the Vijlen Member, here presented, is at variance with current belemnite stratigraphy. To account for incongruities, reworking of belemnites is here proposed as a typical feature during Vijlen Member deposition. A renewed study of belemnites on the basis of these new data suggests that intervals 4–6 of the Vijlen Member are of late Maastrichtian age. With respect to the mean values of populations of Belemnitella junior Nowak and Belemnitella Iwowensis Naidin, Vijlen Member intervals 4–5 are coeval with the Spyridoceramus tegulatus/Belemnitella junior Zone (sensu germanico), whereas at least the upper portion of interval 6 is correlatable with the basal Tenuipteria argentea/Belemnitella junior Zone (sensu germanico). Although reworking of belemnites appears to have been a common feature, this cannot be properly substantiated without additional geochemical analyses of individual guards. For this reason, we refrain from proposing a biostratigraphic zonation of the Vijlen Member based on belemnites. Alternatively, scaphitid ammonites might be used to subdivide this member, because species such as Acanthoscaphites ( Acanthoscaphites ) tridens (Kner), A. ( Euroscaphites ) varians blaszkiewiczi Jagt, Kennedy & Machalski, Hoploscaphites constrictus (J. Sowerby), H. tenuistriatus (Kner) and Hoploscaphites sp. have been recorded. The last-named taxon represents an interspecies hybrid between the North American Jeletzkytes dorfi Landman & Waage and an unidentified subspecies of the endemic European lineage of H. constrictus , allowing correlation of the lower portion of Vijlen Member interval 6 with the Hoploscaphites birkelundae Zone of the United States Western Interior.

Revision of the Family Gastrodoridae (Crustacea, Decapoda), with Description of the First Species from the Cretaceous

Abstract Representatives of the family Gastrodoridae were exclusively known from Jurassic deposits in central Europe. Here, the first Cretaceous species, Gastrodorus cretahispanicus n. sp., is recorded from reefal strata of the Eguino Formation (Albeniz Unit) of Albian-Cenomanian age, in western Navarra (northern Spain). Not only does the occurrence of the new species extend the stratigraphic range of the family upward for approximately 45 million years into the mid-Cretaceous, it also constitutes the first record of gastrodorids from southern Europe. For over a century, the taxonomic position of the genus Gastrodorus has been debated. It is revised here and the family Gastrodoridae is given a full superfamily status within the Anomura. The genus Eogastrodorus is also redefined. Gastrodorids underwent a remarkable size reduction from the Middle to Upper Jurassic, which may be explained by their migration into reef environments.

Dinosaur remains from the type Maastrichtian: an update

Isolated cranial and post-cranial remains of hadrosaurid dinosaurs have been collected from various outcrops in the type area of the Maastrichtian stage during the last few years. In the present contribution, dentary and maxillary teeth are recorded from the area for the first time. Post-cranial elements comprise a newly collected, fragmentary, large right metatarsal III and a broken ?right humerus, recently recognised in the collections of Teylers Museum (Haarlem). Unfortunately, none of these remains can be identified to species level. The available material suggests, however, that more than one taxon of non-lambeosaurine hadrosaurid and a possible euhadrosaurian are represented. Most of the new finds are stratigraphically well documented, which means that they may be linked to the recently published sequence-stratigraphic interpretation of the type Maastrichtian. Dinosaur remains recorded previously from the Maastrichtian type area are tabulated.

New Paleocene Sepiid Coleoids (Cephalopoda) from Egypt: Evolutionary Significance and Origin of the Sepiid ‘Rostrum’

New coleoid cephalopods, assignable to the order Sepiida, are recorded from the Selandian/Thanetian boundary interval (Middle to Upper Paleocene transition, c. 59.2 Ma) along the southeastern margin (Toshka Lakes) of the Western Desert in Egypt. The two genera recognised, Aegyptosaepia n. gen. and ?Anomalosaepia Weaver and Ciampaglio, are placed in the families Belosaepiidae and ?Anomalosaepiidae, respectively. They constitute the oldest record to date of sepiids with a ‘rostrum-like’ prong. In addition, a third, generically and specifically indeterminate coleoid is represented by a single rostrum-like find. The taxonomic assignment of the material is based on apical parts (as preserved), i.e., guard, apical prong (or ‘rostrum-like’ structure), phragmocone and (remains of) protoconch, plus shell mineralogy. We here confirm the shell of early sepiids to have been bimineralic, i.e., composed of both calcite and aragonite. Aegyptosaepia lugeri n. gen., n. sp. reveals some similarities to later species of Belosaepia, in particular the possession of a distinct prong. General features of the phragmocone and protoconch of the new form are similar to both Belocurta (Middle Danian [Lower Paleocene]) and Belosaepia (Eocene). However, breviconic coiling and the presence of a longer ventral conotheca indicate closer ties with late Maastrichtian–Middle Danian Ceratisepia. In this respect, Aegyptosaepia n. gen. constitutes a link between Ceratisepia and the Eocene Belosaepia. The occurrence of the new genus near the Selandian/Thanetian boundary suggests an earlier origin of belosaepiids, during the early to Middle Paleocene. These earliest known belosaepiids may have originated in the Tethyan Realm. From northeast Africa, they subsequently spread to western India, the Arabian Plate and, probably via the Mediterranean region, to Europe and North America.

Dinosaurs from the Maastrichtian-type area (southeastern Netherlands, northeastern Belgium)

Abstract In comparison to pre-1980 records of nonavian dinosaur remains from the Maastrichtian type strata, material collected during the past 20 years is both fairly common and diverse, consisting mostly of isolated cranial and post-cranial remains of hadrosaurids. With the exception of the type specimen of Megalosaurus bredai Seeley, a fragmentary right femur, no theropod material is represented in collections screened by us. In the present contribution, specimens recognised in various collections subsequent to our last tabulation (1999) are illustrated and briefly discussed. Although we are fully aware that the material is too limited to draw meaningful conclusions from, the specimens are here tied-in with a preliminary sequence-stratigraphic interpretation of the type Maastrichtian, which is currently being refined by strontium-isotope studies of coleoid cephalopods. To cite this article: J.W.M. Jagt, E.W.A. Mulder, A.S. Schulp, R.W. Dortangs, R.H.B. Fraaije, C. R. Palevol 2 (2003) 67–76.