Article Spotlight: The dinosaurs that weren’t: osteohistology supports giant ichthyosaur affinity of enigmatic large bone segments from the European Rhaetian

by | Apr 12, 2024 | Article Spotlight

"Do some mysterious bones belong to gigantic ichthyosaurs?"

Several similar large, fossilized bone fragments have been discovered in various regions across Western and Central Europe since the 19th century. The animal group to which they belonged is still the subject of much debate to this day. A study could now settle this dispute once and for all: The microstructure of the fossils indicates that they come from the lower jaw of a gigantic ichthyosaur. These animals could reach 25 to 30 meters in length, a similar size to the modern blue whale.


Read the research 

In the Press

Mysterious 150-year-old bones identified as ichthyosaur jaws

Read more here 




Mysterious Bones May Belong to Giant Ichthyosaur

Science Daily

Read more here


Paleontologists May Have Solved 150-Year-Old Bone Mystery


Read more here 




Huge Fossilized Bones Found Throughout Europe are from a Gigantic Ichthyosaur Hitherto Unknown

La Brújula Verde

Read more here 

“We compared specimens from South West England, France and Bonenburg. They all displayed a very specific combination of properties. This discovery indicated that they might come from the same animal group.”

Marcello Perillo

Rheinische Friedrich-Wilhelms Universität Bonn

For All Readers - AI Explainer


What is the research about?

This research investigates the origin of large, unidentified fossil bone segments found in European Rhaetian (Late Triassic) deposits, which have puzzled scientists since the 19th century.

What were the proposed explanations for these fossils?

Various hypotheses were suggested, including giant amphibian bones, dinosaur long bone shafts, and giant ichthyosaur jaw bone segments.

What is the ‘Giant Ichthyosaur Hypothesis’?

It proposes that the large bone segments are actually jaw bone fragments from giant ichthyosaurs.

How did the researchers test this hypothesis?

They used bone histology, studying the microscopic structure of the bone tissue, to compare the European specimens with known ichthyosaur specimens.

What did they find in their analysis?

The histological features of the European specimens, such as a unique bone matrix type, vascular architecture, growth marks, and abundance of secondary osteons, were consistent with those of giant ichthyosaurs.

What does this mean for our understanding of these fossils?

It rules out previous theories suggesting the bones belonged to dinosaurs or other ancient reptiles, supporting the idea that they are indeed remnants of giant ichthyosaurs.

Why is this significant?

This research showcases the power of paleohistology in identifying the taxonomic affinity of fragmentary bone specimens and adds to our knowledge of the diversity of ancient marine reptiles during the Late Triassic period.



The dinosaurs that weren’t: osteohistology supports giant ichthyosaur affinity of enigmatic large bone segments from the European Rhaetian

Very large unidentified elongate and rounded fossil bone segments of uncertain origin recovered from different Rhaetian (Late Triassic) fossil localities across Europe have been puzzling the paleontological community since the second half of the 19th century. Different hypotheses have been proposed regarding the nature of these fossils: (1) giant amphibian bones, (2) dinosaurian or other archosaurian long bone shafts, and (3) giant ichthyosaurian jaw bone segments. We call the latter proposal the ‘Giant Ichthyosaur Hypothesis’ and test it using bone histology.

What are Article Spotlights?

PeerJ Article Spotlights feature research published in PeerJ journals that is of interest  to non-specialists and the general public.

Spotlighted articles are press released, and feature author interviews, AI explainers and more.

If you have published in Peer J and would like to be featured in an Article Spotlight please contact PeerJ.




Get PeerJ Article Alerts