Ancient plesiosaur unearthed after decades in museum vault

A fossil stored for decades in a German museum has been reexamined and reclassified as a new genus and species, offering new insight into early plesiosaurs.

Ancient plesiosaur unearthed after decades inside a museum vault

Researchers Sven Sachs and Daniel Madzia reexamined SMNS 51945, a nearly complete plesiosaur skeleton found in 1978 near Holzmaden in the Posidonia Shale. They conclude it represents a new genus and species, Plesionectes longicollum. The neck is extraordinarily long, with at least 43 cervical vertebrae, making up about 1.25 meters of the animal's total length of roughly 3.2 meters. Despite a damaged skull, diagnostic bones such as the paraoccipital process and squamosal helped establish its distinct identity. The find adds a rare, comprehensive view of Early Jurassic marine life.

It is the oldest plesiosaur from Holzmaden and comes from early deposits of the Posidonia Shale, a site known for well preserved fossils. The skeleton preserves rare soft tissue traces and suggests an unusual swimming style that may reflect ecological adaptation during the Toarcian Oceanic Anoxic Event, a time of climate stress that reduced oxygen in oceans. The discovery highlights the value of museum collections and shows how decades-old specimens can still transform our understanding of prehistoric life.

The finding underscores a simple truth about science: patience and new methods can turn a quiet archive into a headline. Reexamining old specimens with modern techniques can rewrite parts of the story of life on Earth. In this case the long neck and other features push us to rethink plesiosaur diversity in the Early Jurassic and how these animals navigated a warming, low oxygen ocean.

More broadly, the result boosts the case for keeping museum collections intact and accessible. Holzmaden's Posidonia Shale remains a gold mine for marine reptiles, as this and other discoveries show. If researchers keep revisiting stored fossils, the archive may reveal more surprises about evolution and the climate history of ancient seas.

Highlights

Science keeps listening to old shelves.