Ichthyosaurs were aquatic reptiles that resembled dolphins that lived 160 million years ago in the Mesozoic era. Their name Ichthyosaur is derived from 2 ancient Greek words, “ichthys” meaning fish, and “sauros” meaning lizard, combined together to form “fish lizard.” For most prehistoric vertebrates, petrified teeth, and bones are the main sources of information on these well-known creatures.
Their history reveals a fast-evolving collection of creatures capable of reaching vast sizes and sharing a body form with whales and dolphins due to their adaptation to pelagic settings.
Appearance
Ichthyosaurus was around 6-10 feet long and could possibly move at great speeds across the water. It was most likely dark brown with countershading properties, a typical tactic used by pelagic animals to conceal themselves in open waters by lowering the geometrical contour of their bodies.
The head merged seamlessly into the torso, and the body would extend seamlessly with no obvious neck. Their limbs were transformed into paddle-like appendages for superior mobility underwater. Alongside a well-developed fish-like tail and body, undulations served as propulsion.
Ichthyosaurus had huge jaws and a long, long head that was packed with rows of sharp teeth. Their large eyes, often protected by bony rings, suggest excellent vision, adapted for hunting in various light conditions.
Habitat
Ichthyosaurs thrived in the world’s oceans during the Mesozoic Era, from the early Triassic to the late Cretaceous periods. They occupied a variety of marine habitats, from shallow coastal waters to the open ocean. Their fossils have been found worldwide, indicating a global distribution. They were particularly abundant in the warm, shallow seas that covered much of Europe during the Jurassic period.
Its presence in polar regions can be attributed to the fact that it was a warm-blooded animal with excess fat that would keep it warm during greater-depth swims into extremely cold mesopelagic zones in search of prey as well as help them tolerate journeys into chilly waters at northern latitudes.
Diet
They were carnivorous, and given their vast variation in size and extended lifespan, it is likely that they consumed a variety of animals. The ability to snag smaller creatures was developed in species with pointy mouthparts, which is their notable feature.
Skeletal remains in fossilized stomachs point to larger prey species, such as sea turtles and birds, as well as fragments of prey that range from cephalopods, and all kinds of fish.
Reproduction
Ichthyosaurs were viviparous, which means they gave birth to live children rather than eggs. Even though they were reptiles and evolved from external fertilization forebears, viviparity is not as unusual at first glance.
Air-breathing marine animals must either give birth to live offspring in open seas, such as dolphins and whales, or hit the coast to produce eggs, as tortoises as well as some sea serpents.
It would have been difficult, if not impossible, for them to get far enough on land to lay eggs considering their sleek and diagonally flat bodies, which were extensively specialized for quick swimming. If compared to placental mammals, ichthyosaur fetuses are frequently quite small and numerous in each batch.
Threats
Natural predators were other members of its species and sharks; however, this wasn’t the reason for their extinction. Recent research in palaeontology suggests that the Ichthyosaurs’ extinction happened in 2 stages. Feeding groups were exterminated by the first extinction event at the start of the Cenomanian ages. During the Cenomanian-Turonian border event, the second major Ichthyosaur extinction occurred, and just one species remained.
Thus, rather than a gradual decrease, their extinction unfolded in a couple of rapid occurrences. These events were likely triggered by the climatic and environmental shifts that occurred in the Cenomanian and Turonian ages.
5 More Facts about the Ichthyosaur
- They had about 150 teeth.
- They had a vertically oriented tail fin, similar to sharks.
- They weren’t technically dinosaurs but marine vertebrates.
- They lived anywhere between 90-250 million years ago.
- These reptiles had the biggest eyes of any animal spanning 10 inches across.
FAQs
How fast could an Ichthyosaur swim?
According to estimates, ichthyosaurs could swim up to 25 mph. They were air-breathing and viviparous, just as contemporary cetaceans like dolphins and whales are, as some adult fossils have even been found with fetuses inside.
Why are Ichthyosaurs, not dinosaurs?
Ichthyosaurs are a different phylum of aquatic vertebrates that were not dinosaurs. Researchers really do not know which species of vertebrates were comparable to ichthyosaurs because they were so evolved and altered for the oceanic environment.
Why did Ichthyosaurs have big eyes?
Compared to extant marine mammals and reptiles, many species of prehistoric aquatic Ichthyosaurs possessed eyes that were considerably larger, given their body proportions. Recently, it has been proposed that the cause for these species’ big eyes is their responsiveness to low light at extreme depths in the deep-diving genus Ophthalmosaurus.
Was an Ichthyosaur bigger than a blue whale?
According to researchers, the ichthyosaur, which lived 200 million years ago, was bigger than a blue whale. At a staggering elevation in the mountains of Switzerland, they were excavated from rocks. The Shastasaurus sikanniensis, a whale-like dinosaur that may have reached a length of 70 ft, is the longest one known to science.
How many eggs did Ichthyosaurs lay at a time?
Although one specimen reveals 11 embryos maintained within the body cavity, majority of them would give birth to 1 or 2 single newborns, commonly known as pups.
