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Mysterious 150-year-old bones identified as ichthyosaur jaws

Picture a time before sharks dominated the seas, when colossal creatures, with bones that hinted at their enormity, made even the largest whales seem insignificant. These were the ichthyosaurs, sleek and powerful marine reptiles that ruled the prehistoric oceans.

For centuries, paleontologists have puzzled over mysterious bone fragments that hint at ichthyosaurs of mind-boggling size. Now, new research sheds light on these enigmatic giants, revealing creatures that could rival even the mighty blue whale.

Mysterious bones in Europe

Since the 1800s, scientists have grappled with the origin of enormous fossilized bones found in various locations across Europe. Found embedded in ancient ocean sediments, these bones have sparked a long-standing debate.

At first, some believed they belonged to an extinct lineage of crocodile-like beasts roaming the prehistoric coasts. Others thought these relics were more likely from long-necked dinosaurs or even a completely unknown group of colossal lizards.

The puzzle deepened as similar fragments were discovered across locations as varied as the cliffs of Southern England and the hills of central France. But a recent study from the University of Bonn may finally put these theories to rest.


The researchers delved into the very structure of these fossilized bones, turning to a field known as osteohistology. This branch of science examines the microscopic details and organization of bone tissue in different species.

Think of it this way: the internal patterns present in bone provide clues to the identity and lifestyle of the creature, much like the microscopic composition of a material can help investigators understand its origins.

Upon analyzing the mysterious samples, the researchers found something extraordinary. Long strands of a protein called collagen woven in a unique pattern, a structure that did not match any known land-dwelling animal.

The team took a systematic approach, carefully comparing bone samples from various sites across Europe. They discovered that the collagen structure and other microscopic details were remarkably similar in these scattered bones.

This similarity strongly suggested that the bones, despite their wide geographic distribution, originated from the same type of creature.

Ichthyosaurs bones of unbelievable size

Armed with this knowledge, the researchers cross-referenced their discoveries with known fossils of giant ichthyosaurs. They concluded that the enigmatic bones likely belonged to massive members of this marine reptile family. Just how massive?

They could possibly have reached a length of 25 to 30 meters – a similar size to the modern blue whale, according to study lead author Marcello Perillo.

It seems the long-standing theories of those championing the ichthyosaur hypothesis may have been correct. These scattered bone fragments might just be the remains of some of the largest creatures ever to grace the Earth’s oceans.

“However, this number is only an estimate and far from certain – until, that is, we find more complete fossil remains,” said Perillo.

Further insights from Ichthyosaurs bones

The bone structure revealed more than just size. These ichthyosaurs had a unique adaptation – protein fibers woven through their bones much like carbon-fiber composites used in modern engineering. This implies immense strength and likely allowed these giants to grow rapidly, reaching their tremendous size.

But what did such massive predators eat? Ancient marine reptiles would have been prime contenders, alongside prehistoric versions of squid and large fish. These colossal ichthyosaurs must have been formidable hunters, their streamlined bodies slicing through the water in pursuit of their unfortunate prey.

“These huge jaws would have been exposed to strong shearing forces even when the animal was eating normally,” said Perillo. Imagine the bone-crushing power as these creatures clamped down on their meals.

Perhaps, like modern-day killer whales, they even rammed their prey to stun or kill before feeding. Those protein-reinforced bones would have been indispensable when taking down large, struggling creatures, or wrestling with rival ichthyosaurs.

Ichthyosaurs bones and glimpse of sea dragons

Ichthyosaurs first appeared over 250 million years ago. Resembling a cross between a dolphin and a shark, these predators dominated the oceans, their sharp teeth and powerful bodies perfectly adapted for their watery domain.

For over 150 million years they flourished in seas across the globe. Yet, for reasons still debated, the ichthyosaurs eventually vanished – a testament to the ever-changing nature of our planet.

The colossal bone fragments tantalize us with a glimpse of these “sea dragons” – of a world where the oceans were a battleground of giants.

They remind us that the Earth holds countless mysteries, and creatures far beyond our wildest imagination once roamed freely.

More about ichthyosaurs

As discussed above, ichthyosaurs roamed the oceans during the Mesozoic era, approximately between 250 million and 90 million years ago.

These creatures, often likened to dolphins in appearance due to their streamlined bodies and elongated snouts, present a remarkable example of convergent evolution, where unrelated species evolve similar traits. Here’s more on these ancient mariners:

Evolution and diversity

  • Ichthyosaurs first appeared in the early Triassic period and quickly diversified into a variety of forms and sizes, some measuring up to 60 feet in length. Their evolution showcases a transition from terrestrial to fully aquatic lifeforms, paralleling the evolutionary path of modern whales.
  • Their body shapes varied significantly, from robust, slow-moving individuals to slender, fast-swimming forms, indicating a wide range of ecological niches.

Anatomy and physiology

  • These reptiles had large eyes, suggesting they were visual predators capable of seeing in dim light, possibly hinting at deep diving capabilities or a partially nocturnal lifestyle.
  • They possessed vertical, fish-like tails and fins, unlike the horizontal tail flukes of modern cetaceans, a feature that likely aided in their propulsion through ancient seas.
  • Some species had very long, toothy snouts, perfect for snapping up small fish and squid, while others had broader, toothless mouths, suggesting a diet possibly consisting of soft-bodied cephalopods.


  • Ichthyosaurs were viviparous, meaning they gave birth to live young rather than laying eggs. This reproductive strategy is advantageous for aquatic life, as it eliminates the need to return to land to lay eggs.
  • Fossil evidence, including rare finds of pregnant females with embryos, indicates that ichthyosaurs likely had a complex reproductive behavior, caring for their young in the early stages of life.


  • The reasons behind the extinction of ichthyosaurs are still a topic of research and debate. It is believed that a combination of factors, including climate change, decreased food availability, and competition with other marine reptiles and emerging fish species, contributed to their decline.
  • Unlike dinosaurs, which perished in the mass extinction event at the end of the Cretaceous period, ichthyosaurs disappeared in the Late Cretaceous, about 90 million years ago, well before the asteroid impact that ended the era of the dinosaurs.

The legacy of Ichthyosaurs beyond fossil bones

  • Ichthyosaurs play a crucial role in understanding the history of marine life on Earth. Their fossils, distributed globally, provide insights into the Mesozoic marine ecosystems and the evolutionary history of reptiles.
  • Studies on ichthyosaurs contribute to our knowledge of adaptation, survival strategies, and the impact of environmental changes on marine species.

Their intriguing evolution from land-dwellers back to the sea, remarkable adaptations for marine life, and the mystery surrounding their extinction continue to captivate scientists and the public alike. Ichthyosaurs remain emblematic of the dynamic, ever-changing nature of life on Earth.

The results are published in the journal PeerJ.

Image Credit: © Marcello Perillo / University of Bonn


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