Ophthalmosaurus

Ophthalmosaurus Icenicus, commonly known as Ophthalmosaurus, had a long dolphin-shaped body that was active during the Jurassic period between 165-150 million years ago.

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. Its fossil remains offer a glimpse into a long-lost world, revealing adaptations for life at sea and a fascinating evolutionary journey.

Appearance

With a 13-foot length and 2,000-pound weight, this marine reptile 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. 

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.

Habitat

The majority of the fossils 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.

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.

Diet

They possessed long, narrow jaws that was perfect for grabbing swift, agile prey, like huge fish and squids, which made up the majority of their nutrition. They fed on small fish and squid that are abundant on the reef.

Although nocturnal behavior and deep-water hunting are the two main hypotheses, the current fossil data strongly favors the other. The huge eyes were designed to give them sight acuity in darkness. 

Reproduction

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. Their puppies were prey from the minute they were birthed.

Since they were oxygen breathers, the pups were required to be delivered tail first 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.

Threats

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

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.

5 More Facts about the Ophthalmosaurus

1. Ophthalmosaurus possessed a ring of bony plates within its eye, known as sclerotic rings, which provided structural support.
2. Sub-triangular structures anterior to the orbits in an ichthyosaur skull suggest the presence of paired salt glands, similar to those found in plesiosaurs and marine crocodiles.
3. Their average speed was 4.5 mph.
4. They could dive for 20 minutes at a time on a single breath.
5. Its extinction may be linked to environmental changes or competition with other marine predators during the Jurassic period.

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