Ophthalmosaurus Icenicus, commonly known as Ophthalmosaurus, was a dolphin-like ichthyosaur that was active during the Jurassic period between 165-150 million years ago. In addition to showing that Ophthalmosaurus was indeed a prevalent ichthyosaur of the age, the availability of its fossils has served as the foundation for a great deal of data on ichthyosaurs in principle. One of the most notable features of this creature was the large eyes on either side of its head, so much so that the name translates to literally “Large eye lizard” from Latin.


With a 13-foot length and 2,000-pound weight, Ophthalmosaurus was a moderate ichthyosaur. It featured a strong, sleek body that, when viewed from the front, was almost as broad as it was tall. They had a strong tail that ended in a caudal fluke with two distinct lobes; the bottom lobe was developed all around the caudal column, while the uppermost lobe was exclusively constituted of soft tissue. 

Ophthalmosaurus was 13 feet long and weighed 2,000 pounds
Ophthalmosaurus was 13 feet long and weighed 2,000 pounds

Their forelimbs were considerably larger than the rear limbs while being short and rounded. Combining a relatively stiff trunk with a strong caudal fluke and short limbs indicates a tail-propelled form of propulsion with the appendages aiding in navigating. The eyes of the Ophthalmosaurus were 9 inches in diameter, and it had a long, thin, toothed rostrum and an expanded rear section of the skull.


Ophthalmosaurus possessed a long, narrow jaw that was perfect for grabbing swift, agile prey, like huge fish and squids, which made up the majority of its nutrition. In order to satisfy a somewhat specialized aquatic requirement, this elegant ichthyosaur was likely active during the night as species that engaged in deep dives, or sometimes both. Although nocturnal behavior and deep-water hunting are the two main hypotheses, the current fossil data strongly favors the other. The huge eyes were plainly designed to give Ophthalmosaurus sight acuity in darkness. 


The majority of the fossil discoveries from the Ophthalmosaurus genus have been located throughout Europe, while an additional species may have been discovered in North America. In terms of habitat, where they spent most of their time, joint and bone damage can provide answers.

Ophthalmosaurus had the largest eyes (nearly 9 inches in diameter) of any ichthyosaur
Ophthalmosaurus had the largest eyes (nearly 9 inches in diameter) of any ichthyosaur

A prevalent hypothesis suggests that they would stay at a depth of 160 ft and 80-95 miles away from the shoreline. They would also have had to descend extremely low and quickly to be considered capable of taking on this kind of damage, according to an assessment of the joints of the animal. Decompression sickness trauma to the joints could not have occurred without an extremely long descent.


For birthing their young, females migrated from deep oceans into moderate depths. Ophthalmosaurus gave birth to living offspring instead of eggs, unlike most aquatic reptiles that swam onto shore to lay eggs. A single female could give birth to between 2-5 pups. Ophthalmosaurus puppies were prey from the minute they were birthed.

Due to the fact that they were oxygen breathers, the pups were required to be delivered tail first in order to avoid being suffocated in the time required for them to get out of their mother’s womb if they’d been delivered any other way. They were only given a limited time frame to rise to the surface and inhale their initial breath, hence the moderate mating depth.


Large pliosaurs like Liopleurodon and Pliosaurus were the main predators of many other ichthyosaurs in the late Jurassic seas, which include the Ophthalmosaurus. Their aquatic prowess allowed them to simply be faster, go deeper, and further away than most predators. 

Despite its size, Ophthalmosaurus was hunted by other large pliosaurs like Liopleurodon and Pliosaurus
Despite its size, Ophthalmosaurus was hunted by other large pliosaurs like Liopleurodon and Pliosaurus

However, the juveniles of the species were the ones most under threat. Their very birth is an instant race to the surface to initiate the first inhalation on their own, compounded with all possible opportunistic predators looking for an easy kill.

Facts about the Ophthalmosaurus

  1. Ophthalmosaurus was initially discovered by Harry Seeley in 1874.
  2. Ophthalmosaurus’s average speed was 4.5 mph.
  3. Ophthalmosaurus sight acuity allowed for night vision.
  4. Ophthalmosaurus could dive for 20 minutes at a time on a single breath.


How fast could an Ophthalmosaurus swim?

The Ophthalmosaurus needed to be swift to live in the heavy, turbid seas of the primitive oceans. When juxtaposed to other species at the time, this reptile’s approximated velocity was 10 mph, which was considered quite superb for survival.

What caused the extinction of Ophthalmosaurus?

The Ophthalmosaurus is thought to have perished because it was unable to adjust to its surroundings evolving. On a species level, their birthing strategy wouldn’t allow them to thrive as well as other creatures due to the juvenile vulnerability, subsequently, other species that would have better feeding and mating methods would make it impossible to compete.

How did Ophthalmosaurus communicate?

The researchers who examined young Ophthalmosaurus fossils discovered tiny fragments inside the nose cavities and indicated how they communicated. Although immersed beneath a level too deep for visual interaction among specimens, they may have made a sound similar to what modern whales make when interacting across far distances.

How aggressive were Ophthalmosaurus?

The Ichthyosaur genus Ophthalmosaurs was somewhat violent because it frequently engaged in courtship warfare against other males in order to procreate. If a reptile could locate sufficient food or area, they could coexist peacefully.

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