PALEONTOLOGY REVELATION: Plesionectes longicollum – The Super Long-Necked “Sea Dragon” Finally Identified from a 47-Year-Old Fossil!

A stunning Early Jurᴀssic plesiosaur, hidden in plain sight for nearly five decades, has been formally named Plesionectes longicollum (“long-necked near-swimmer”). The nearly complete skeleton—excavated in 1978 from the world-famous Posidonia Shale quarry in Holzmaden, southwestern Germany—represents the oldest known plesiosaur from the region and a previously unrecognised lineage of long-necked marine reptiles.

Described in August 2025 in PeerJ by an international team, the osteologically immature specimen measures about 3.2 metres long, with an astonishing neck comprising at least 43 vertebrae that accounts for nearly 40% of its total length. Even soft-tissue remnants are preserved, offering rare glimpses into its anatomy. Living around 183 million years ago during the Toarcian stage, this small plesiosauroid glided through the warm, oxygen-poor seas of what is now Europe.

Its extreme neck elongation and unique vertebral morphology distinguish it from all other Early Jurᴀssic plesiosaurs, suggesting specialised feeding strategies—likely snapping at fish and squid in the mid-water column. As the first new plesiosaur species named from Holzmaden in decades, Plesionectes dramatically expands the known diversity of the Posidonia Shale marine ecosystem, one of the richest fossil Lagerstätten on Earth.

After 47 years in museum collections, modern re-examination with CT scanning and comparative anatomy finally revealed its true idenтιтy. Researchers emphasise that many “known” fossils still hold surprises. Plesionectes longicollum proves that the “sea dragons” of the Jurᴀssic were far more varied—and their stories far from fully told—than previously imagined. The long-necked wonder has finally emerged from the shadows of time.