Paleontologists have uncovered a remarkable new genus and species of early extinct plesioaurooid plesiosaurs from a nearly complete skeleton discovered in the Jurassic Posidonian shale of Holzmaden, Germany.
The newly identified species, Plesionectes longicollum, thrived in the early Jurassic seas approximately 183 million years ago.
This marine reptile reached lengths of about 3.2 m, with a body length of 1.25 m and a tail measuring 81 cm.
The skeleton, complete with fossilized soft tissue remnants, was excavated in 1978 from a Posidonia Shale quarry in Holzmaden, Germany, and its distinct anatomical features are now fully recognized through thorough scientific examination.
“The specimen has been part of our collection for decades, yet prior studies never fully explored its unique anatomy,” remarked Dr. Sven Sachs, paleontologist at Naturkunde-Museum Bielefeld.
“Our in-depth analysis uncovered a rare combination of skeletal traits that distinctly separate them from all previously recognized plesiosaurs.”
Skeleton of Plesionectes longicollum. Scale bar – 30 cm. Image credit: S. Sachs & D. Madzia, doi: 10.7717/Peerj.19665.
Plesionectes longicollum is particularly significant as it represents the oldest known plesiosaur from the Holzmadden area.
“This discovery contributes another piece to the evolutionary puzzle of marine ecosystems during a pivotal period in Earth’s history,” stated Dr. Daniel Magia, a paleontologist at the Polish Academy of Sciences.
“The early Toarcian epoch, when this creature existed, was marked by substantial environmental changes, including major marine anoxic events that impacted life in oceans globally.”
This finding illustrates that the Posidonian shales, well-known for their remarkably preserved fossils, harbor an even greater diversity of marine reptiles than previously acknowledged.
“The Posidonian Shale of Holzmaden has already yielded five other plesiosaur species, encompassing representatives from three major plesiosaur lineages,” the authors noted.
“This new addition provides one of the most vital insights into Jurassic marine life, enhancing our understanding of this era.”
Survey results will be available online in the journal Peerj.
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S. Sachs & D. Madzia. 2025. An unusual early fledgling plesiosauroid from the Lower Jurassic Posidonian Shale in Holzmaden, Germany. Peerj 13:E19665; doi:10.7717/peerj.19665
Source: www.sci.news
