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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 [...]

A rich elasmobranch assemblage was recovered from the early Eocene (Ypresian) Fishburne Formation in a limestone quarry at Jamestown, Berkeley County, South Carolina, USA. Reported herein are 22 species belonging to 8 orders, at least 15 families, and 21 genera. It includes the first occurrence of Protoginglymostoma from North America. Many of the reported species have large palaeobiogeographical ranges and inhabited waters on both sides of the Atlantic, whereas others were endemic to the east coast of North America. The paucity of sizeable dentition from several of the larger species in this assemblage, and the apparent absence of relatively large macrophagous species found in contemporaneous deposits elsewhere, suggests the Jamestown site may represent a nursery ground and refuge for young and smaller individuals. Un riche assemblage d'elasmobranches a ete recupere de la Formation de Fishburne de l'Eocene precoce (Ypresien), dans une carriere de calcaire a Jamestown (comte de Berkeley, Caroline du Sud, Etats-Unis). Nous faisons etat de 22 especes appartenant a 8 ordres, au moins 15 familles et 21 genres. Elles comprennent le premier signalement de Protoginglymostoma en Amerique du Nord. Bon nombre des especes signalees sont caracterisees par une vaste aire de repartition paleobiogeographique et habitaient dans les eaux de part et d'autre de l'Atlantique, alors que d'autres etaient endemiques a la cote est de l'Amerique du Nord. La rarete de dentitions de grande taille pour plusieurs des plus grandes especes de l'assemblage et l'absence apparente d'especes macrophages relativement grandes observees dans des depots contemporains en d'autres endroits donnent a penser que le site de Jamestown pourrait representer une aire de croissance et de refuge pour de jeunes individus de petite taille. [Traduit par la Redaction], Introduction Late Cretaceous and Paleogene elasmobranch (shark and ray) assemblages have been recovered from numerous marine deposits along the Atlantic and Gulf coastal plains of the USA. Herein, we describe [...]

The Fayum Depression of Egypt has produced a great diversity of fossil material, including marine and freshwater fishes. In contrast to the Eocene formations of the Fayum, the Oligocene Jbel Qatrani Formation has been more or less consistently considered to be deposited in a freshwater environment; however, the ichthyofauna indicates a more complex picture. Cenozoic fishes have been convincingly used to interpret the palaeoenvironment in which sediments were deposited. Based on the elasmobranch and osteichthyan faunas of the Jbel Qatrani Formation, we interpret that this formation was not deposited entirely in fresh waters, but had some marine influence, particularly in the lower part of the formation. The mixture of freshwater elements, such as polypterids and alestids, with brackish and marine elements, including myliobatid stingrays, in the Quarry E site suggests a local palaeoenvironment that was very close to the shoreline, in a less protected area, or under more seasonal influence than the rest of the sites in the formation. Additionally, the early Oligocene elasmobranch fishes from Quarry E have a strong biogeographic relationship with sites in Oman and Pakistan, in the eastern Tethys, representing a restricted fauna possibly limited in distribution by cooling global temperatures. La depression du Fayoum en Egypte a produit une grande variete de materiel fossile, dont des poissons marins et d'eau douce. Contrairement aux formations eocenes de la depression, la Formation oligocene de Jbel Qatrani est plus ou moins uniformement consideree comme ayant ete deposee dans un milieu dulcicole. Son ichtyofaune reflete toutefois un portrait plus complexe. Des poissons cenozoiques ont ete utilises de maniere convaincante pour interpreter le paleomilieu dans lequel les sediments ont ete deposes. A la lumiere des faunes d'elasmobranches et d'osteichtyens de la Formation de Jbel Qatrani, nous proposons que cette formation n'a pas ete deposee exclusivement en eau douce, mais qu'elle a egalement subi des influences marines, particulierement en ce qui concerne sa partie inferieure. Le melange, dans le site de la carriere E, d'elements d'eau douce, comme des polypterides et des alestides, et d'elements de milieu saumatre et marin, comme des myliobatides, donne a penser que le paleomilieu local etait tres proche du rivage, dans une zone moins protegee ou sous influence plus saisonniere que les autres sites de la formation. En outre, les elasmobranches de l'Oligocene precoce de la carriere E presentent un fort lien biogeographique avec des sites a Oman et au Pakistan, dans la Tethys orientale, representant une faune restreinte dont le refroidissement des temperatures planetaires a possiblement limite la repartition. [Traduit par le Redaction], Introduction The late Eocene to early Oligocene marked a period of transition from the warmer climates of the early Eocene to cooler global temperatures associated with the onset of glaciation [...]

Myledaphus bipartitus is a Late Cretaceous (75 Ma) freshwater guitarfish, commonly represented by teeth and vertebral centra. The species was first described in 1876, but until now, very little has been known about its ecology and life history. We analyzed the age and growth using 117 fossilized centra (74 hemisectioned) from the Oldman and Dinosaur Park formations of southern Alberta. The resulting estimated maximum age was 16 years. Radial distance (RD) at the estimated asymptotic growth was calculated, and average RD at birth and 3 years were compared with two extant marine species of Rhinobatos (R. productus and R. rhinobatos). Birth ring size ranged from 0.9 to 1.8 mm RD. At age three, centrum RD was between 2.8 and 4.6 mm RD for M. bipartitus and significantly less than R. productus and R. rhinobatos (5.0-6.6 mm RD). Myledaphus approached 'asymptotic' growth at 7.8 mm RD in the growth equation. The growth trajectory of Myledaphus had a similar slope to the Rhinobatos species, but with significantly smaller centrum RD. Rhinobatos rhinobatos also outlived Myledaphus by 8 years. Myledaphus bipartitus est un poisson-guitare d'eau douce du Cretace tardif (75 Ma) communement represente par des dents et des centres vertebraux. L'espece a ete decrite pour la premiere fois en 1876, mais jusqu'a present, les connaissances sur son ecologie et son cycle de vie etaient tres limitees. Nous en avons analyse l'age et la croissance a la lumiere de 117 centres fossilises (74 hemisectionnes) des Formations d'Oldman et de Dinosaur Park du sud de l'Alberta. L'age maximum ainsi estime etait de 16 ans. La distance radiale (RD) au taux de croissance asymptotique estime a ete calculee, et les RD moyennes a la naissance et a trois ans ont ete comparees a celles de deux especes marines actuelles de Rhinobatos (R. productus et R. rhinobatos). La taille des anneaux a la naissance, en termes de RD, va de 0,9 mm a 1,8 mm. A 3 ans, la RD des centres va de 2,8 mm a 4,6 mm pour M. bipartitus et est significativement plus faible que celles de R. productus et R. rhinobatos (RD de 5,0-6,6 mm). Myledaphus s'approche de la croissance << asymptotique >> a une RD de 7,8 mm dans l'equation de croissance. La trajectoire de croissance de Myledaphus presente une pente semblable a celle des especes de Rhinobatos, bien qu'avec des RD des centres significativement plus faibles. La duree de vie de Rhinobatos rhinobatos surpasse egalement de 8 ans celle de Myledaphus. [Traduit par la Redaction], Introduction Myledaphus bipartitus, Cope, 1876, is a Late Cretaceous enigmatic freshwater batoid represented predominantly by isolated teeth (Cappetta 2012). It is known from various Campanian formations such as the Oldman [...]

A euselachian assemblage was recovered from the middle Cenomanian Dunvegan Formation situated in northwestern Alberta. This assemblage is the most northern described within the Western Interior Seaway and provides an important insight into the euselachian faunal diversity of this little-known region of the seaway. Despite its high paleolatitude, the assemblage contains a number of elasmobranch taxa, including Hybodus, Squalicorax, Archaeolamna, Cretodus, Dallasiella, and Cretoxyrhina. The Dunvegan assemblage also contains the first known reports from Canada of the odontaspid shark Johnlongia parvidens, the cretoxyrhinid shark Protolamna carteri, and the ray Pseudohypolophus mcnultyi. This assemblage extends the northern geographical range of all taxa. Preliminary comparisons with other middle Cenomanian Western Interior Seaway assemblages show that the core composition of the Dunvegan assemblage is remarkably similar to that of other time-equivalent assemblages; however, conspicuously absent are species that are exceedingly common in other localities situated farther south. We suggest that absence of these taxa from the Dunvegan localities may be caused by a temperature intolerance associated with latitude and sea-water circulation patterns, or by an inability to inhabit environments that exhibit salinity variation. Resume : Un assemblage euselachien a ete recupere dans la Formation de Dunvegan du Cenomanien moyen du nord-ouest de l'Alberta. Cet assemblage est le plus septentrionaux decrits a ce jour provenant des depots de la mer interieure de l'Ouest et il jette un important eclairage sur la diversite faunique euselachienne dans cette region meconnue du bassin. Malgre sa haute paleolatitude, l'assemblage contient divers taxons d'elasmobranches, dont Hybodus, Squalicorax, Archaeolamna, Cretodus, Dallasiella et Cretoxyrhina. L'assemblage de Dunvegan contient egalement les premiers specimens signales au Canada du requin odontaspide Johnlongia parvidens, du requin cretoxyrhinide Protolamna carteri et de la raie Pseudohypolophus mcnultyi. L'assemblage repousse les limites septentrionales de la distribution geographique de tous ces taxons. Des comparaisons provisoires avec d'autres assemblages du Cenomanien moyen de la mer interieure de l'Ouest demontrent que la composition de base de l'assemblage de Dunvegan et celles d'autres assemblages contemporains presentent une remarquable similitude; certaines especes par ailleurs tres repandues en d'autres lieux plus meridionaux brillent toutefois par leur absence. Il est postule que l'absence de ces taxons dans l'assemblage de Dunvegan pourrait etre le resultat d'une intolerance a la temperature associee a la latitude et aux courants marins, ou encore de l'incapacite de ces taxons a s'implanter dans des milieux presentant des variations de salinite. [Traduit par la Redaction], Introduction An assemblage of euselachian remains of Cenomanian (early Late Cretaceous) age was recovered from the Dunvegan Formation of northwestern Alberta (Fig. 1). The assemblage not only provides records of [...]

Cardabiodon ricki and Cardabiodon venator were large lamniform sharks with a patchy but global distribution in the Cenomanian and Turonian. Their teeth are generally rare and skeletal elements are less common. The centra of Cardabiodon ricki can be distinguished from those of other lamniforms by their unique combination of characteristics: medium length, round articulating outline with a very thick corpus calcareum, a corpus calcareum with a laterally flat rim, robust radial lamellae, thick radial lamellae that occur in low density, concentric lamellae absent, small circular or subovate pores concentrated next to each corpus calcareum, and papillose circular ridges on the surface of the corpus calcareum. The large diameter and robustness of the centra of two examined specimens suggest that Cardabiodon was large, had a rigid vertebral column, and was a fast swimmer. The sectioned corpora calcarea show both individuals deposited 13 bands (assumed to represent annual increments) after the birth ring. The identification of the birth ring is supported in the holotype of Cardabiodon ricki as the back-calculated tooth size at age 0 is nearly equal to the size of the smallest known isolated tooth of this species. The birth ring size (5-6.6 mm radial distance [RD]) overlaps with that of Archaeolamna kopingensis (5.4 mm RD) and the range of variation of Cretoxyrhina mantelli (6-11.6 mm RD) from the Smoky Hill Chalk, Niobrara Formation. The revised, reconstructed lower jaw dentition of the holotype of Cardabiodon ricki contains four anterior and 12 lateroposterior files. Total body length is estimated at 5.5 m based on 746 mm lower jaw bite circumference reconstructed from associated teeth of the holotype. [ABSTRACT FROM AUTHOR]

The type species of the extinct lamniform genus Cretalamna, C. appendiculata, has been assigned a 50 Ma range (Albian--Ypresian) by a majority of previous authors. Analysis of a partly articulated dentition of a Cretalamna from the Smoky Hill Chalk, Kansas, USA (LACM 128126) and isolated teeth of the genus from Cenomanian to Campanian strata of Western Australia, France, Sweden, and the Western Interior of North America, indicates that the name of the type species, as applied to fossil material over the last 50 years, represents a large species complex. The middle Cenomanian part of the Gearle Siltstone, Western Australia, yielded C. catoxodon sp. nov. and "Cretalamna" gunsoni. The latter, reassigned to the new genus Kenolamna, shares several dental features with the Paleocene Palaeocarcharodon. Early Turonian strata in France produced the type species C. appendiculata, C. deschutteri sp. nov., and C. gertericorum sp. nov. Cretalamna teeth from the late Coniacian part of the Smoky Hill Chalk in Kansas are assigned to C. ewelli sp. nov., whereas LACM 128126, of latest Santonian or earliest Campanian age, is designated as holotype of C. hattini sp. nov. Early Campanian deposits in Sweden yielded C. borealis and C. sarcoportheta sp. nov. A previous reconstruction of the dentition of LACM 128126 includes a posteriorly situated upper lateroposterior tooth, with a distally curved cusp, demonstrably misplaced as a reduced upper "intermediate" tooth. As originally reconstructed, the dentition resembled that of cretoxyrhinids (sensu stricto) and lamnids. Tooth morphology, however, indicates an otodontid affinity for Cretalamna. The root is typically the most diagnostic feature on an isolated Cretalamna tooth. This porous structure is commonly abraded and/or corroded and, consequently, many collected Cretalamna teeth are indeterminable at species level. [ABSTRACT FROM AUTHOR]

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