Ancient sea monster found: Marine reptile with long neck discovered frozen in Germany's Jurassic fossil beds

New Jurassic Marine Reptile Found in Germany’s Fossil Beds (Image: Peerj)

A newly found sea reptile is making waves. This ancient creature, with a long neck and rare traits, has just joined the Jurassic fossil family.

What is Plesionectes longicollum?
Palaeontologists have named the species Plesionectes longicollum. It means “long-necked near-swimmer” in Latin. This marine reptile swam the seas around 183 million years ago. The fossil adds to the known group of plesiosauroids. These were long-necked reptiles living during the age of dinosaurs.

The specimen came from Germany’s Posidonia Shale, a fossil-rich site. It was first uncovered in 1978 near Holzmaden, Southwest Germany. The bones were well preserved and stored safely for years. Scientists only recently studied them in detail.

Where was the fossil found and what’s special?
The fossil belongs to Stuttgart’s State Museum of Natural History. It holds signs of fossilised soft tissue, which is very rare. Dr Sven Sachs, who led the study, said the skeleton was long overlooked. But new research shows its bones are unlike any known plesiosaurs.

Co-author Dr Daniel Madzia said the fossil is the oldest known plesiosaur from Holzmaden. The animal hadn't grown to full size when it passed away. Nevertheless, its characteristics were defined enough to be able to identify a new species and genus.

Why the find matters for science
The finding enables scientists to better understand the sea creatures of the Jurassic period. It indicates how sea reptiles developed during extreme climate changes.

The fossil dates back to the early Toarcian period. That era had major ocean changes and low oxygen levels, which affected marine life across the globe.

The Posidonia Shale has already given the world five other plesiosaur species. These belong to all three plesiosaur lineages. This new find adds more depth to the fossil record. It also proves how rich the Posidonia site is for studying prehistoric oceans.

The fossil is listed as SMNS 51945 and will remain on display in Stuttgart.