Ichthyosaurus was an extinct marine reptile from the Lower Jurassic. It was the first member of the order Ichthyosauria to be discovered. The first complete skeleton was discovered in the early 19th century (1810/11) by Mary Anning in the Dorset Jurassic Coast. Many more specimens were found in Europe, especially from the limestone quarries in Holzmaden, southern Germany.
Ichthyosaurus lived from about 199 to 189 million years ago (mya).
This sleek animal could perhaps swim at speeds up to 25 mph (40 kph).
"Ichthyosaurus" bore live young. This we know from fossil evidence. It was thought at first that "Ichthyosaurus" laid eggs on land, but fossil evidence shows that the females gave birth to live young. Because they did, their life habit could be entirely aquatic. They were well-adapted to life as fully pelagic organisms because they never needed to come onto land. The babies were born tail first to prevent them from drowning in the water.
Hundreds of well-preserved, fossilised skeletons have been found in Jurassic rock at Holzmaden. Some of the bones were still articulated. Some fossils still had baby specimens inside them, indicating that "Ichthyosaurus" was viviparous. Similar finds in the related "Stenopterygius" also show this.
The German fossils also featured the outline of "Ichthyosaurus" skin, showing it had a fleshy dorsal fin on its back and a large caudal fin. Other ichthyosaur fossils proved this feature was not limited to "Ichthyosaurus".
"Ichthyosaurus" ear bones were solid, probably transferring water vibrations to the inner ear. Still, hunting by sight was the creature's main feeding activity; it had huge, sensitive eyes, protected by bony shields.
Coprolites (fosillized excreta) of "Ichthyosaurus" show its diet consisted of fish and squid.
Stenopterygius
Stenopterygius was a typical, dolphin-shaped ichthyosaur of the Lower Jurassic. It is like the poster reptile of the ichthyosaur family, "Ichthyosaurus", but with slightly narrower flippers and a smaller head. Its name means "narrow wing".
"Stenopterygius" was more streamlined than the earlier ichthyosaurs of the Triassic period, and likely swam faster in pursuit of prey.
Some "Stenopterygius" fossils have been found with the remains of juveniles inside--clearly instances of mothers dying before they could give birth. As with other ichthyosaurs, "Stenopterygius" females gave birth to live young. Their eggs developed internally before birth.
Temnodontosaurus
Temnodontosaurus was an ichthyosaur from the early Jurassic, some 196 to 190 million years ago. It was found in England by Mary Anning, and later in Germany. It was, in fact, her first ichthyosaur. Her brother found the skull, and she found the rest of the skeleton, in about 1810. It was described in 1814. There are four or five species of "Temnodontosaurus". They grew to killer whale size, about 30 to 40 feet.
This huge ichthyosaur cruised the shallow seas hunting. But hunting what? A discussion by Christopher McGowan suggests that other reptiles might have been on the menu. McGowan also mentions that in the museum collections are some teeth and bones which suggest even larger ichthyosaurs existed.
Ichthyosaurs hold the record for eye size: the largest was 264mm in diameter (~10.4 inches), from the species "Temnodontosaurus platyodon". This is the largest eye ever recorded for any vertebrate; the colossal squid eye is larger still. The eyes are surrounded by sclerotic rings, a kind of bony support.
Californosaurus
Californosaurus was an ichthyosaur, an extinct marine reptile. It was 10 feet (3 m) long. It had four paddle-shaped flippers and sharp teeth in long, pointed jaws (looking a bit like a dolphin).
"Californosaurus" lived during the late Triassic period in seas that covered what is now California. It fed on fish and other small marine creatures. Like other ichthyosaurs it probably never came onto dry land, and gave birth in the water.
It is the most basal known true ichthyosaur, shaped more or less like a dolphin. The long-snouted head is small in comparison with the rest of the body, as in basal ichthyosaurs such as "Mixosaurus" and "Cymbospondylus". The tail is sharply turned downwards, in common with more advanced ichthyosaurs, with a small vertical fluke. It may have had a small dorsal fin.
Cymbospondylus
Cymbospondylus was a large but primitive Triassic ichthyosaur of the Middle and Upper Triassic. It had a long eel-like body up to 10 meters or more in length.
"Cymbospondylus" is known from both Germany and Nevada. No doubt, like other large marine reptiles and present-day aquatic mammals, it had a wide oceanic distribution.
"Cymbospondylus" was one of the largest ichthyosaurs. Fossils ranging from long. It was also one of the least fish-like of the ichthyosaurs, lacking a dorsal fin and fluked tail. It did, however, have an elongated snout like other ichthyosaurs.
The one metre long head of "Cymbospondylus", with large jaws, contained rows of teeth adapted for catching and holding on to fish, belemnites, and cephalopods such as ammonites. The long tail would have been excellent for swimming, and allowed "Cymbospondylus" to move at fast speeds and efficiently hunt down shoals of swimming fish.
Adult "Cymbospondylus" probably spent much of their time hunting in deep offshore water, only coming into shallow water to breed or to catch seasonally available prey. Like other ichthyosaurs, "Cymbospondylus" probably gave birth to live young, as it had no way to lay eggs. These, on reaching adult size, probably had few, if any, predators that could harm them.
The eel-like tail of "Cymbospondylus" made up almost half the total body length, and it is possible that the tail was used as a primary swimming mechanism. Like present day sea snakes, "Cymbospondylus" probably swam by wriggling its body from side to side.
Mixosaurus
Mixosaurus was a small, common and cosmopolitan Triassic ichthyosaur. It was only about a meter in length. Fossils are known from Alaska, Canada, China, Timor, Indonesia, Italy, Nevada, New Zealand, Spitsbergen, and Svalbard. Thus it lived in the Tethys Sea but also ventured further afield.
"Mixosaurus" seems to have been a transitional form between the more primitive eel-shaped icthyosaurs such as "Cymbospondylus" and the more advanced Shatsasaurs and Euichthyosaurs (the latter including the familiar dolphin- or porpoise-shaped icthyosaurs).
Ophthalmosaurus
Ophthalmosaurus was an ichthyosaur of the Upper Jurassic (165 to 150 million years ago), named after its large eyes. Well-preserved skeletons, ranging in age from juveniles to adults, have been found in Europe, North America and Argentina.
"Ophthalmosaurus" had the largest eyes of any vertebrate "relative to its body size". Its eyes, 4 inches in diameter, occupied most of the space in the skull. They were protected by bony plates (sclerotic rings), which most likely assisted to maintain the shape of the eyeballs against water pressure at depth.
The size of the eyes and the sclerotic rings suggests that "Ophthalmosaurus" hunted at a depth where there is not much light or that it may have hunted at night when a prey species was more active. Its snout was long and thin, perfect for snapping at fast, maneuverable, prey.
Calculations suggest that a typical "Ophthalmosaurus" could stay submerged for approximately 20 minutes or more. The swimming speed of "Ophthalmosaurus" has been estimated at 2.5 metres per second or greater. Even assuming a conservative speed of 1 m/s, an "Ophthalmosaurus" would be able to dive to 600 meters and return to the surface within 20 minutes.
The family Ophthalmosauridae continued into the Upper Cretaceous, but this genus became extinct at the end of the Jurassic period.
Valve
A valve is a device that it is used to decrease or stop the flow of a fluid (like gases, liquids, fluidized solids, or slurries). It can be installed for example in a pipe or a vessel.
There are many types of valves. Some examples are: