The Late Jurassic-Early Cretaceous (164–100 Ma) represents one of the main transitional periods in life history. Recent studies unveiled a complex scenario in which abiotic and biotic factors and drivers on regional and global scales due to the fragmentation of Pangaea resulted in dramatic faunal and ecological turnovers in terrestrial and marine environments. However, chondrichthyan faunas from this interval have received surprisingly little recognition. The presence of numerous entire skeletons of chondrichthyans preserved in several localities in southern Germany, often referred to as Konservat-Lagerstätten (e.g., Nusplingen and the Solnhofen Archipelago), provides a unique opportunity of to study the taxonomic composition of these assemblages, their ecological distributions and adaptations, and evolutionary histories in detail. However, even after 160 years of study, the current knowledge of southern Germany’s Late Jurassic chondrichthyan diversity remains incomplete. Over the last 20 years, the systematic study and bulk sampling of southern Germany’s Late Jurassic deposits significantly increased the number of known fossil chondrichthyan genera from the region (32 in the present study). In the present work, the fossil record, and the taxonomic composition of Late Jurassic chondrichthyans from southern Germany are reviewed and compared with several contemporaneous assemblages from other sites in Europe. Our results suggest, inter alia, that the Late Jurassic chondrichthyans displayed extended distributions within Europe. However, it nevertheless also is evident that the taxonomy of Late Jurassic chondrichthyans is in urgent need of revision.

The Late Jurassic elasmobranch Protospinax annectans is often regarded as a key species to our understanding of crown group elasmobranch interrelationships and the evolutionary history of this group. However, since its first description more than 100 years ago, its phylogenetic position within the Elasmobranchii (sharks and rays) has proven controversial, and a closer relationship between Protospinax and each of the posited superorders (Batomorphii, Squalomorphii, and Galeomorphii) has been proposed over the time. Here we revise this controversial taxon based on new holomorphic specimens from the Late Jurassic Konservat-Lagerstätte of the Solnhofen Archipelago in Bavaria (Germany) and review its skeletal morphology, systematics, and phylogenetic interrelationships. A data matrix with 224 morphological characters was compiled and analyzed under a molecular backbone constraint. Our results indicate a close relationship between Protospinax, angel sharks (Squatiniformes), and saw sharks (Pristiophoriformes). However, the revision of our morphological data matrix within a molecular framework highlights the lack of morphological characters defining certain groups, especially sharks of the order Squaliformes, hampering the phylogenetic resolution of Protospinax annectans with certainty. Furthermore, the monophyly of modern sharks retrieved by molecular studies is only weakly supported by morphological data, stressing the need for more characters to align morphological and molecular studies in the future.

The fossil record of sharks and rays (Elasmobranchii) consists predominantly of isolated teeth, complicating their taxonomic and phylogenetic inferences. Consequently, the study of holomorphic specimens provides crucial information to reassess existing phylogenetic and taxonomic interpretations. The extinct Mesozoic shark genus †Sphenodus exemplifies these challenges. Initially classified based on dental traits, the genus has undergone multiple revisions, reflecting its taxonomic instability. However, the presence of skeletal remains assigned to †'Sphenodus' macer and †'S.' nitidus provides an opportunity to re-evaluate the phylogenetic and taxonomic relations of this genus. In this study, we critically reviewed the systematics and taxonomic relationships of †Sphenodus, through an exhaustive literature review and comparison with previous phylogenetic hypotheses. Our analysis of skeletal characters suggests the synonymy of †S. macer and †S. nitidus and supports previous Hexanchiformes classifications for the genus, placing it in a close relation to †Notidanoides forming a clade in sister relation to Hexanchidae. However, the teeth originally used to define †Sphenodus lack diagnostic traits for taxonomic identification, rendering†'Sphenodus' a nomen dubium. Consequently, we introduce a new name, †Archaeogracilidens, to include the species based on skeletal material and that present teeth with a well-preserved root and a crown, establishing a more stable systematic framework for this group.

A new extinct sclerorhynchoid sawfish, Ptychotrygon ameghinorum sp. nov., is presented here based on abundant isolated teeth and some dermal denticles, which were recovered from the Mata Amarilla Formation, belonging to the lower Upper Cretaceous of the Santa Cruz Province in the Austral Basin of Patagonia, Argentina. This new species is the first Ptychotrygon occurrence in the southern hemisphere, which so far only has been reported from northern hemisphere deposits (Europe, North Africa, and North America). The presence of P. ameghinorum sp. nov. in these southern high-latitude deposits of Patagonia, Argentina, extends the geographic range of Ptychotrygon considerably southwards. This distribution pattern in the “middle” Cretaceous seems to correlate with the South Atlantic opening at the end of the Albian. The presence of lateral cephalic dermal denticles and the simultaneous absence of rostral denticles in the abundant fossil material support the view that Ptychotrygon did not develop such rostral structures. A reinvestigation of all known species assigned to Ptychotrygon reveals that P. ellae is a junior synonym of P. boothi, P. benningensis belongs to Texatrygon, P. rugosum belongs to Asflapristis, and P. clementsi represents an unidentifiable species (Ptychotrygon? sp.). The stratigraphic distribution demonstrates that Ptychotrygon might have originated in the Albian in south-western Europe and subsequently dispersed to obtain its widest distribution during the Cenomanian. In the Coniacian, a steep diversity decline is recognizable with a subsequent distribution shift from Europe to North America.

Two new vertebrate assemblages rich in elasmobranch isolated teeth and dermal denticles from the lower Cenomanian (Upper Cretaceous) of Patagonia in southern Argentina comprise ten identified taxa († Protosqualus sp., † Heterodontus sp., † Orectoloboides sp., † Carcharias sp., † Scapanorhynchus patagonensis sp. nov., † Squalicorax sp., † Paraorthacodus sp., † Rhinobatos aff. † R. incertus , † Ptychotrygon ameghinorum , † Ptychotrygon sp.) and five unidentified lamniforms. The material comes from two closely positioned sites representing proximal palaeoenvironments (delta and lagoonal foot barrier, respectively). The new elasmobranch sites are the most diverse known from the Upper Cretaceous of Patagonia until today and indicate a remarkable elasmobranch diversity in high latitudes of the Southern Hemisphere. They are dominated by warm-water taxa demonstrating a strong Tethyan influence into the southern part of the Austral Basin, contrasting with the later Weddellian influence as indicated by the presence of cold-water taxa in that area during the Campanian and the Maastrichtian.

The majority of the fossil records of elasmobranch fishes (sharks, rays, skates) consists of isolated teeth and dermal denticles. Over their long and complex evolutionary history, dental remains are particularly indicative of the group’s plasticity and adaptability, which has hampered the classification of fossil species with highly specialised dental morphologies that deviate from those of extant species. One of such cases is † Synechodus prorogatus recovered from Middle and Late Jurassic deposits in Poland and Germany. Its original description and diagnosis were based on a single complete and two very incomplete teeth, which showed a very peculiar morphology with some features resembling several groups. These similarities resulted in its placement within synechodontiforms. However, subsequent findings showing numerous differences with the type species of the genus, † Synechodus dubrisiensis , cast doubt on its assignment within this group and this genus. Here, we describe new material from Upper Jurassic offshore deposits in SW Germany, which provides additional information about this species. We conducted a comprehensive morphological comparison between † S. prorogatus , various Jurassic selachian taxa and the type species of † Synechodus , † S. dubrisiensis (Late Cretaceous, England), confirming the taxonomic distinctiveness of this Jurassic species, which requires the establishment of a new genus, † Curvorudentis , with † C. prorogatus gen. et comb. nov . being type species. The discovery of this taxon in Late Jurassic deposits of Germany represents its stratigraphically youngest occurrence, extending its chronostratigraphic range and geographical distribution. † Curvorudentis prorogatus is considered here a galeomorph shark, rather than being a member of the stem clade †Synechodontiformes, although its precise systematic position within this group remains ambiguous.