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FHSM VP-5515 is a medium-sized russellosaurine mosasaur collected in the 1970s in Logan County, western Kansas, USA. A suite of cranial features are unique to this specimen at the species level. One is a conspicuous lack of a predental rostrum on the premaxilla, whose dentigerous portion is spatula shaped in dorsoventral aspect. Furthermore, the frontal of FHSM VP-5515 exhibits the following unique combination of features: (1) the median dorsal keel absent; (2) straight, long preorbital borders converging anteriorly at 30[degrees] from each other; and (3) supraorbital border thick and extensive, clearly separating the prefrontal and the postorbitofrontal above the orbit. The fifth character pertains to the uniquely square outline of the intramandibular joint surface of the splenial, resulting from a robust dorsomedial flange. Finally, hitherto unreported on any mosasaur jaws, a deep notch excavates the dorsal border of the articular immediately posterior to the glenoid fossa. Examination of preexisting Ectenosaurus specimens suggests that this articular notching diagnoses the genus. Based on the unique suite of characteristics including the articular notch, we consequently hypothesize the following for FHSM VP-5515: (1) it is most comparable with the enigmatic russellosaurine Ectenosaurus clidastoides (Merriam, 1894); and (2) it represents a new species of Ectenosaurus. Key words: Mosasauridae, Plioplatecarpinae, Ectenosaurus, new species, Late Cretaceous, Smoky Hill Chalk Member. FHSM VP-5515 est un mosasaure russellosaurine de taille moyenne preleve dans les annees 1970 dans le comte de Logan (ouest du Kansas, Etats-Unis). Un ensemble d'elements craniens n'est observe quechez cespecimen a l'echelle de l'espece. Parmi ces elements figure l'absence evidente d'un rostre predentaire sur le premaxillaire, dont la portion dentigere est en forme de spatule en vue dorsoventrale. L'os frontal de FHSM VP-5515 presente en outre la combinaison unique suivante d'elements: (1) l'absence d'une quille dorsale mediane, (2) des bordures preorbitales longues et droites conver-geant anterieurement a 30[degrees] l'unedel'autre et (3) une epaisse et vaste bordure supraorbitale separant clairement le prefrontal et le postorbitofrontal au-dessus de l'orbite. Le cinquieme caractere concerne la silhouette singulierement carree de la surface de l'articulation intramandibulaire du splenial, qui produit une collerette dorsomediale robuste. Enfin, une encoche profonde, jusqu'ici jamais documentee sur une machoire de mosasaure, creuse la bordure dorsale de l'articulaire immediatement derriere les fosses glenoides. L'examen de specimens preexistants d'Ectenosaurus donne a penser que cette encoche sur l'articulaire est diagnostique du genre. A la lumiere de l'ensemble singulier de caracteristiques incluant l'encoche de l'articulaire, nous postulons donc ce qui suit en ce qui concerne FHSM VP-5515: (1) il s'apparente le plus au russellosaurine enigmatique Ectenosaurus clidastoides (Merriam, 1894) et (2) il represente une nouvelle espece d'Ectenosaurus. Mots-cles: mosasaurides, plioplatecarpines, Ectenosaurus, nouvelle espece, Cretace tardif, membre crayeux de Smoky Hill., Introduction In 1967, Russell established a new plioplatecarpine genus, Ectenosaurus, to which he reassigned Platecarpus clidastoides Merriam, 1894. After more than 50 years since its establishment, the genus Ectenosaurus continues [...]

Abstract: Herein, we report an euselachian assemblage from the late Campanian Bearpaw Formation recovered from southern Alberta, Canada. This small yet uniquely diverse fauna includes the northernmost occurrences of Paraorthacodus [...]

UALVP 40, an articulated and reasonably complete skull of a small chasmosaurine dinosaur collected in 1920 by George F. Sternberg from the lower unit of the Dinosaur Park Formation, Dinosaur Provincial Park, Alberta, Canada, is here redescribed. The focus of the study is on the newly prepared right side of the skull and the hitherto undescribed mandible. There are substantial differences between the right and the left side of the skull, most notably the right postorbital horncore exhibits a greater angle of inclination at 60° from horizontal, which is approximately 15° greater than that of the left. The right side of the skull also shows many unfused cranial sutures that are obliterated on the left side. These unfused sutures and the short predentary lacking an anterior elongation, indicate that UALVP 40 likely represents a subadult individual. UALVP 40 is diagnosed to the genus Chasmosaurus by its possession of the following: (i) premaxillary flange along entire anterior margin of external naris; (ii) supraorbital horns curving posteriorly along their length; and (iii) squamosal dorsal border laterally adjacent to supratemporal fenestra straight in profile, sloping posteroventrally at a shallow angle before ascending farther posteriorly to form lateral border of parietal fenestra. The last character is newly proposed. A bivariate correlation in UALVP 40 and other Canadian specimens of Chasmosaurus bearing long postorbital horncores (>150 mm long) reveals a near isometric relationship between interorbital width and horn length. This may indicate those specimens represent an ontogenetic series of a single species diagnosed by long postorbital horncores. UALVP 40, le crane articule et raisonnablement complet d'un petit dinosaure chasmosaurine preleve en 1920 par George F. Sternberg de l'unite inferieure de la Formation de Dinosaur Park, dans le Dinosaur Provincial Park (Alberta, Canada), est decrit a nouveau. L'etude se concentre sur le cote droit nouvellement prepare du crane et sur la mandibule, qui n'avait pas encore ete decrite. Les cotes droit et gauche du crane presentent d'importantes differences, la plus remarquable etant le fait que le cornillon postorbital droit est plus incline par rapport a l'horizontale, a 60°, soit environ 15° de plus que le cornillon du cote gauche. Le cote droit du crane presente egalement de nombreuses sutures craniennes non soudees qui sont obliterees sur le cote gauche. Ces sutures non soudees et le court predentaire depourvu d'elongation anterieure indiquent qu'UALVP 40 represente vraisemblablement un individu subadulte. UALVP 40 est diagnostique comme appartenant au genre Chasmosaurus en raison des caracteres suivants: (i) une collerette premaxillaire sur toute la bordure anterieure du naris externe, (ii) des cornes supraorbitales courbees posterieurement sur leur longueur et (iii) une bordure dorsale du squamosal lateralement adjacente a la fenetre supratemporale en profil, faiblement inclinee posteroventralement avant de monter plus posterieurement pour former une bordure laterale de la fenetre parietale. Ce dernier caractere est nouvellement propose. Une correlation bivariee chez UALVP 40 et d'autres specimens de chasmosaurines canadiens presentant de longs (>150 mm) cornillons postorbitaux revele une relation presque isometrique entre la largeur interorbitale et la longueur des cornes. Cela pourrait indiquer que ces specimens representent une serie ontogenique d'une seule espece dont les longs cornillons postorbitaux constituent un caractere diagnostique. [Traduit par la Redaction], Introduction In 1920, George F. Sternberg collected a small-sized ceratopsian skull from the present-day Dinosaur Provincial Park, Alberta, Canada (Fig. 1). The specimen, when subsequently brought back to the University [...]

The marine reptile Prognathodon (Squamata: Mosasauridae), a mosasaurine mosasaur exhibiting a characteristically robust skull and dentition, lived during the last two ages of the Late Cretaceous. Fossilized remains of animals assigned to this genus are so far known from North America, Europe, Africa, and New Zealand, indicating their wide geographic ranges and presumed ecological and evolutionary success. Assignable to Prognathodon, a newly discovered partial marginal tooth from Dorothy, Alberta, Canada (51°15'48'N), extends the geographic range of the genus by 190 km northward in the Northern Hemisphere. Coupled with the New Zealand record of this mosasaur, the new discovery indicates that Prognathodon likely ranged anywhere from 60°N to 60°S paleolatitude, and these reptiles may even have been occasional inhabitants of the polar regions. Le reptile marin Prognathodon (Squamata : Mosasauridae), un mosasaure mosasaurien presentant un crane et une dentition particulierement robustes, vivait durant les deux derniers ages du Cretace tardif. Les restes fossilises d'animaux assignes a ce genre sont actuellement connus en Amerique du Nord, en Europe, en Afrique et en Nouvelle-Zelande, indiquant leur vaste distribution geographique et leur presume succes ecologique et evolutionnaire. Assignable a Prognathodon, une dent partielle marginale recemment decouverte provenant de Dorothy, Alberta, Canada (51°15'48'N), etend, de 190 km vers le nord dans l'hemisphere Nord, la portee geographique du genre. Jumelee avec les donnees de ce mosasaure en NouvelleZelande, la nouvelle decouverte indique que Prognathodon pouvait se retrouver n'importe ou a des paleolatitudes entre 60°N et 60°S, voire meme occasionnellement dans les regions polaires. [Traduit par la Redaction], Introduction Mosasaurs (Squamata: Mosasauridae) were large carnivorous marine lizards of the Late Cretaceous. Among them, the mosasaurine Prognathodon exhibited a particularly heavy set of jaws that typically bore conical, blunt-ended [...]

FHSM VP-5515 is a medium-sized russellosaurine mosasaur collected in the 1970s in Logan County, western Kansas, USA. A suite of cranial features are unique to this specimen at the species level. One is a conspicuous lack of a predental rostrum on the premaxilla, whose dentigerous portion is spatula shaped in dorsoventral aspect. Furthermore, the frontal of FHSM VP-5515 exhibits the following unique combination of features: (1) the median dorsal keel absent; (2) straight, long preorbital borders converging anteriorly at 30° from each other; and (3) supraorbital border thick and extensive, clearly separating the prefrontal and the postorbitofrontal above the orbit. The fifth character pertains to the uniquely square outline of the intramandibular joint surface of the splenial, resulting from a robust dorsomedial flange. Finally, hitherto unreported on any mosasaur jaws, a deep notch excavates the dorsal border of the articular immediately posterior to the glenoid fossa. Examination of preexisting Ectenosaurus specimens suggests that this articular notching diagnoses the genus. Based on the unique suite of characteristics including the articular notch, we consequently hypothesize the following for FHSM VP-5515: (1) it is most comparable with the enigmatic russellosaurine Ectenosaurus clidastoides (Merriam, 1894); and (2) it represents a new species of Ectenosaurus. [ABSTRACT FROM AUTHOR]

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We examined the morphological diversity of the quadrate bone in squamate reptiles (i.e. lizards, snakes, amphisbaenians). The quadrate is the principal splanchnocranial element involved in suspending the lower jaw from the skull, and its shape is of particular interest because it is potentially affected by several factors, such as phylogenetic history, allometry, ecology, skull kinesis and hearing capabilities (e.g. presence or absence of a tympanic ear). Due to its complexity, the quadrate bone is also considered one of the most diagnostic elements in fragmentary fossil taxa. We describe quadrates from 38 species spread across all major squamate clades, using qualitative and quantitative (e.g. geometric morphometrics) methods. We test for possible correlations between shape variation and factors such as phylogeny, size, ecology and presence/absence of a tympanum. Our results show that the shape of the quadrate is highly evolutionarily plastic, with very little of the diversity explained by phylogenetic history. Size variation (allometric scaling) is similarly unable to explain much shape diversity in the squamate quadrate. Ecology (terrestrial/fossorial/aquatic) and presence of a tympanic ear are more significant, but together explain only about 20% of the diversity observed. Other unexplored and more analytically complex factors, such as skull biomechanics, likely play additional major roles in shaping the quadrates of lizards and snakes. [ABSTRACT FROM AUTHOR]

A specimen of a halisaurine mosasaur is reported from Japan for the first time, closing the pre-existing biogeographical gap between the Middle East and the eastern Pacific.Phosphorosaurus ponpeteleganssp. nov., from the lowermost Maastrichtian of Hokkaido, has been assigned to the genusPhosphorosaurusfor sharing the following suite of major cranial characters withP.ortliebi, the type species from Belgium: apex of posterodorsal triangular plateau on frontal reaching level of interorbital constriction; frontal lateral border forming a step-like junction between interorbital and preorbital segments of frontal; preorbital segment of frontal sloping anteroventrally; and stapedial meatus parallel-sided in latero-medial view. Potential autapomorphies that distinguishP.ponpetelegansfrom other members of Halisaurinae include: postorbitofrontal jugal process elongate and stalk-like, projecting laterally; this process distally bearing a ventrally facing depression for jugal articulation; and lateral surangular–articular suture angular rather than round. The long and laterally projecting jugal processes, when combined with a depressed as well as narrow snout, provide compelling evidence for well-developed binocular vision for the new mosasaur, with an estimated binocular field of view (BFoV) of 35°. This value is unusually high for non-ophidian squamates that typically exhibit a BFoV of 10—20°, and is higher than those of other measured mosasaur taxa by at least 5°. Among colubrid snakes, nocturnal species exhibit greater BFoV than diurnal ones in both arboreal and terrestrial taxa. Known also from the Maastrichtian of Hokkaido are fossils of lantern fish (myctophids) and 10-armed cephalopods (coleoids), both of which are typically bioluminescent today. It is hence proposed that the exceptionally large, forward-facing eyes ofP.ponpetelegansmay well have been a special adaptation for a nocturnal lifestyle, where they hunted small, bioluminescent prey at night while avoiding direct competition with larger, more piscine mosasaurine taxa such asMosasaurus hobetsuensisthat co-existed withP.ponpetelegans. http://zoobank.org/urn:lsid:zoobank.org:pub:3EF73BE7-B3FE-4441-BA5E-29C5D5FCCBC9 [ABSTRACT FROM PUBLISHER]