A new genus and species of Plesiosaurus that lived near the beginning of the Early-Middle Jurassic period has been identified from two exquisite three-dimensional skeletons found in Bavaria, Germany. Franconiasaurus brevispinus They lived in the seas of the early Jurassic period, about 175 million years ago. The ancient reptile was a member of the Plesiosauroidea, a group of plesiosaurs known from the Jurassic and Cretaceous periods.

“plesiosaurs “These species are Mesozoic reptiles fully adapted to an aquatic lifestyle,” said Sven Sachs from the Naturkunde Museum in Bielefeld and his colleagues. “During their evolutionary history of over 140 million years, plesiosaurs dispersed across the globe, achieved considerable diversity, occupied a variety of ecological niches, and underwent numerous faunal changes.”

“Of these, the Early/Middle Jurassic transition event (175-171 million years ago) has been of increasing interest recently because it appears to have profoundly affected all three major plesiosaur lineages: Rhomaleosauridae, Pliosauridae, and Plesiosauroidea.”

“This event apparently had a marked impact on several classes of marine tetrapods, including ‘fish-like’ ichthyosaurs, marine relatives of crocodilians (thalatosaurs), and the three major lineages of plesiosaurs.”

“The carnivorous plesiosaurs Rhomaleosauridae, which dominated the early Jurassic seas, began to disappear and eventually became extinct around 161.5 million years ago (end of the Middle Jurassic), while Pliosauridae and Plesiosauroidea diversified.”

“Pliosaurids formed a successful group of macropredators that regulated the upper tier of marine ecosystems from 171 million years ago to 90 million years ago and included some of the largest aquatic predatory tetrapods that ever lived, with forms exceeding 10 meters in length.”

“Plesiosauroids, in turn, transitioned from microclade-rich assemblages typical of the Toarian European Epean seas to cryptoclade faunas representing the globally dominant plesiosauroid component in the Middle and Late Jurassic, until they were replaced by leptoclids and elasmosaurids during the Jurassic-Cretaceous boundary.”

Two petrified skeletons Franconiasaurus brevispinus It was found in a now-abandoned clay pit, part of the Jurensismergel Formation, in Mistelgau, Bavaria, Germany.

“Franconiasaurus brevispinus It was created based on two excellent specimens preserved in three-dimensional space, paleontologists reported.” “The holotype contains an almost complete skeleton, but most of the skull is missing.” “The specimen in question represents a larger individual and includes vertebrae, ribs and some girdle and limb elements. contains.”

Franconiasaurus brevispinus It displays a mixture of traits that combine features that were almost evenly distributed among early plesiosaurs with features typically seen in later members of the lineage.

“Phylogenetic analysis conclusively reveals that: Franconiasaurus brevispinus It is the sister taxon of Cryptoclidia, filling the evolutionary gap between early plesiosauroids. plesiosaur-like forms and microcleidids, and later members of the clade such as cryptocleidids, leptocleids, and elasmosaurids,” the researchers noted.