Ichthyosaur Pictures and Profiles

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Meet the Ichthyosaurs of the Mesozoic Era

shonisaurus
Shonisaurus (Nobu Tamura).

 Ichthyosaurs--"fish lizards"--were some of the largest marine reptiles of the Triassic and Jurassic periods. On the following slides, you'll find pictures and detailed profiles of 20 different ichthyosaurs, ranging from Acamptonectes to Utatsusaurus.

02
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Acamptonectes

acamptonectes
Acamptonectes (Nobu Tamura).

Name

Acamptonectes (Greek for "rigid swimmer"); pronounced ay-CAMP-toe-NECK-tease

Habitat

Shores of western Europe

Historical Period

Middle Cretaceous (100 million years ago)

Size and Weight

About 10 feet long and a few hundred pounds

Diet

Fish and squids

Distinguishing Characteristics

Large eyes; dolphin-like snout

 

When the "type fossil" of Acamptonectes was discovered, in 1958 in England, this marine reptile was classified as a species of Platypterygius. That all changed in 2003, when another specimen (this time unearthed in Germany) prompted paleontologists to erect the new genus Acamptonectes (a name that wasn't officially confirmed until 2012). Now considered to be a close relative of Ophthalmosaurus, Acamptonectes was one of the few ichthyosaurs to survive the Jurassic/Cretaceous boundary, and in fact managed to prosper for tens of millions of years afterward. One possible reason for Acamptonectes' success may have been its larger-than-average eyes, which allowed it to gather in scarce undersea light and home in more efficiently on fish and squids.

03
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Brachypterygius

brachypterygius
Brachypterygius. Dmitri Bogdanov

Name:

Brachypterygius (Greek for "broad wing"); pronounced BRACK-ee-teh-RIDGE-ee-us

Habitat:

Oceans of western Europe

Size and Weight:

About 15 feet long and one ton

Diet:

Fish and squids

Distinguishing Characteristics:

Large eyes; short front and rear flippers

Historical Period:

Late Jurassic (150 million years ago)

 

It may seem odd to name a marine reptile Brachypterygius--Greek for "broad wing"--but this actually refers to this ichthyosaur's unusually short and round front and rear paddles, which presumably did not make it the most accomplished swimmer of the late Jurassic period. With its unusually large eyes, surrounded by "sclerotic rings" meant to resist intense water pressure, Brachypterygius was reminiscent of the closely related Ophthalmosaurus--and as with its more famous cousin, this adaptation allowed it to dive deep in search of its accustomed prey of fish and squids.

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Californosaurus

californosaurus
Californosaurus (Nobu Tamura).

Name:

Californosaurus (Greek for "California lizard"); pronounced CAL-ih-FOR-no-SORE-us

Habitat:

Shores of western North America

Historical Period:

Late Triassic-Early Jurassic (210-200 million years ago)

Size and Weight:

About nine feet long and 500 pounds

Diet:

Fish and marine organisms

Distinguishing Characteristics:

Short head with long snout; rounded trunk

 

As you may already have guessed, the bones of Californosaurus were unearthed in a fossil bed in the Eureka State. This is one of the most primitive ichthyosaurs ("fish lizards") yet discovered, as evidenced by its relatively unhydrodynamic shape (a short head perched on a bulbous body) as well as its short flippers; still, Californosaurus wasn't quite as old (or as unevolved) as the even earlier Utatsusaurus from the Far East. Confusingly, this ichthyosaur is often referred to as Shastasaurus or Delphinosaurus, but paleontologists now lean toward Californosaurus, perhaps because it's more fun.

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Cymbospondylus

cymbospondylus
Cymbospondylus (Wikimedia Commons).

Name:

Cymbospondylus (Greek for "boat-shaped vertebrae"); pronounced SIM-bow-SPON-dill-us

Habitat:

Shore of North America and Western Europe

Historical Period:

Middle Triassic (220 million years ago)

Size and Weight:

About 25 feet long and 2-3 tons

Diet:

Fish and marine organisms

Distinguishing Characteristics:

Large size; long snout; lack of dorsal fin

 

There's a bit of a disagreement among paleontologists about where Cymbospondylus is located on the ichthyosaur ("fish lizard") family tree: some maintain that this huge swimmer was a genuine ichthyosaur, while others speculate that it was an earlier, less specialized marine reptile from which later ichthyosaurs evolved (which would make it a close relative of Californosaurus). Supporting the second camp is Cymbospondylus’ lack of two distinctive ichthyosaur traits, a dorsal (back) fin and a flexible, fish-like tail.

Whatever the case, Cymbospondylus was certainly a giant of the Triassic seas, attaining lengths of 25 feet or more and weights approaching two or three tons. It probably fed on fish, mollusks, and any smaller aquatic reptiles dumb enough to swim across its path, and the adult females of the species may have flocked to shallow waters (or even dry land) to lay their eggs.

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Dearcmhara

dearcmhara
Dearcmhara (University of Edinburgh).

Name

Dearcmhara (Gaelic for "marine lizard"); pronounced DAY-ark-MAH-rah

Habitat

Shallow seas of western Europe

Historical Period

Middle Jurassic (170 million years ago)

Size and Weight

About 14 feet long and 1,000 pounds

Diet

Fish and marine animals

Distinguishing Characteristics

Narrow snout; dolphin-like body

 

It took a long time for Dearcmhara to emerge from the watery depths: over 50 years, ever since its "type fossil" was discovered in 1959 and promptly relegated to obscurity. Then, in 2014, an analysis of its extremely sparse remains (only four bones) allowed researchers to identify it as an ichthyosaur, the family of dolphin-shaped marine reptiles that dominated the Jurassic seas. While it's not quite as popular as its mythological Scottish stablemate, the Loch Ness Monster, Dearcmhara has the honor of being one of the few prehistoric creatures to bear a Gaelic genus name, rather than the standard Greek.

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Eurhinosaurus

eurhinosaurus
Eurhinosaurus (Wikimedia Commons).

Name:

Eurhinosaurus (Greek for "original nose lizard"); pronounced YOU-rye-no-SORE-us

Habitat:

Shores of Western Europe

Historical Period:

Early Jurassic (200-190 million years ago)

Size and Weight:

About 20 feet long and 1,000-2,000 pounds

Diet:

Fish and marine organisms

Distinguishing Characteristics:

Long upper jaw with outward-pointing teeth

 

The very rare ichthyosaur ("fish lizard") Eurhinosaurus stood out thanks to a single odd characteristic: unlike other marine reptiles of its kind, its upper jaw was twice as long as its lower jaw and studded with sideways-pointing teeth. We may never know why Eurhinosaurus evolved this strange feature, but one theory is that it raked its extended upper jaw along the ocean bottom to stir up hidden food. Some paleontologists even believe Eurhinosaurus may have speared fish (or rival ichthyosaurs) with its long snout, though direct evidence for this is lacking.

08
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Excalibosaurus

excalibosaurus
Excalibosaurus (Nobu Tamura).

Unlike most other ichthyosaurs, Excalibosaurus had an asymmetrical jaw: the upper part projected about a foot beyond the lower part, and was studded with outward-pointing teeth, giving it the vague shape of a sword. See an in-depth profile of Excalibosaurus

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Grippia

grippia
Grippia. Dimitry Bogdanov

Name:

Grippia (Greek for "anchor"); pronounced GRIP-ee-ah

Habitat:

Shores of Asia and North America

Historical Period:

Early-middle Triassic (250-235 million years ago)

Size and Weight:

About three feet long and 10-20 pounds

Diet:

Fish and marine organisms

Distinguishing Characteristics:

Small size; bulky tail

 

The relatively obscure Grippia--a small ichthyosaur ("fish lizard") of the early to middle Triassic period--was rendered even moreso when the most complete fossil was destroyed in a bombing raid on Germany during World War II. What we know for sure about this marine reptile is that it was fairly puny as ichthyosaurs go (only about three feet long and 10 or 20 pounds), and that it probably pursued an omnivorous diet (it was once believed that Grippia's jaws were specialized for crushing mollusks, but some paleontologists disagree).

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Ichthyosaurus

ichthyosaurus
Ichthyosaurus. Nobu Tamura

With its bulbous (yet streamlined) body, flippers and narrow snout, Ichthyosaurus looked startlingly like the Jurassic equivalent of a giant tuna. One odd feature of this marine reptile is that its ear bones were thick and massive, the better to convey subtle vibrations in the surrounding water to Ichthyosaurus' inner ear. See an in-depth profile of Ichthyosaurus

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Malawania

malawania
Malawania. Robert Nicholls

Unusually, Malawania plied the oceans of central Asia during the early Cretaceous period, and its dolphin-like build was a throwback to its ancestors of the late Triassic and early Jurassic periods. See an in-depth profile of Malawania

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Mixosaurus

mixosaurus
Mixosaurus. Nobu Tamura

Name:

Mixosaurus (Greek for "mixed lizard"); pronounced MIX-oh-SORE-us

Habitat:

Oceans worldwide

Historical Period:

Middle Triassic (230 million years ago)

Size and Weight:

About three feet long and 10-20 pounds

Diet:

Fish and marine organisms

Distinguishing Characteristics:

Small size; long tail with downward-pointing fin

 

The early ichthyosaur ("fish lizard") Mixosaurus is notable for two reasons. First, its fossils have been found pretty much all over the world (including North America, Western Europe, Asia, and even New Zealand), and second, it appears to have been an intermediate form between early, ungainly ichthyosaurs like Cymbospondylus and later, streamlined genera like Ichthyosaurus. Judging by the shape of its tail, paleontologists believe Mixosaurus wasn't the fastest swimmer around, but then again, its widespread remains point to its having been an unusually effective predator.

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Nannopterygius

nannopterygius
Nannopterygius. Nobu Tamura

Name:

Nannopterygius (Greek for "little wing"); pronounced NAN-oh-teh-RIDGE-ee-us

Habitat:

Oceans of western Europe

Historical Period:

Late Jurassic (150 million years ago)

Size and Weight:

About six feet long and a few hundred pounds

Diet:

Fish

Distinguishing Characteristics:

Large eyes; long snout; relatively small flippers

 

Nannopterygius--the "little wing"--was named in reference to its close cousin Brachypterygius ("broad wing"). This ichthyosaur was characterized by its unusually short and narrow paddles--the smallest, compared to total body size, of any identified member of its breed--as well as its long, narrow snout and large eyes, which call to mind the closely related Ophthalmosaurus. Most important, the remains of Nannopterygius have been discovered all over western Europe, making this one of the best-understood of all the "fish lizards." Unusually, one Nannopterygius specimen was found to contain gastroliths in its stomach, which weighted this mid-sized marine reptile down as it searched the depths of the ocean for its accustomed prey.

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Omphalosaurus

omphalosaurus
Omphalosaurus. Dmitry Bogdanov

Name:

Omphalosaurus (Greek for "button lizard"); pronounced OM-fal-oh-SORE-us

Habitat:

Shores of North America and Western Europe

Historical Period:

Middle Triassic (235-225 million years ago)

Size and Weight:

About six feet long and 100-200 pounds

Diet:

Fish and marine organisms

Distinguishing Characteristics:

Long snout with button-shaped teeth

 

Thanks to its limited fossil remains, paleontologists have had a hard time deciding whether or not the marine reptile Omphalosaurus was a genuine ichthyosaur ("fish lizard"). This creature's ribs and vertebrae had much in common with those of other ichthyosaurs (such as the poster genus for the group, Ichthyosaurus), but that's not quite enough evidence for a definitive classification, and in any case, the flat, button-shaped teeth of Omphalosaurus set it apart from its presumed relatives. If it turns out not to have been an ichthyosaur, Omphalosaurus may wind up being classified as a placodont, and thus closely related to the enigmatic Placodus.

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Ophthalmosaurus

ophthalmosaurus
Ophthalmosaurus. Sergio Perez

Name:

Ophthalmosaurus (Greek for "eye lizard"); pronounced AHF-thal-mo-SORE-us

Habitat:

Oceans worldwide

Historical Period:

Late Jurassic (165 to 150 million years ago)

Size and Weight:

About 16 feet long and 1-2 tons

Diet:

Fish, squids and mollusks

Distinguishing Features:

Streamlined body; unusually large eyes compared to head size

 

Looking a bit like a foreshortened, bug-eyed dolphin, the marine reptile Ophthalmosaurus wasn't technically a dinosaur, but an ichthyosaur--a populous breed of ocean-dwelling reptiles that dominated a good stretch of the Mesozoic Era until they were rendered defunct by better-adapted plesiosaurs and mosasaurs. Since its discovery in the late 19th century, specimens of this reptile have been assigned to a variety of now-defunct genera, including Baptanodon, Undorosaurus and Yasykovia.

As you may have surmised from its name (Greek for "eye lizard") what set Ophthalmosaurus apart from other ichthyosaurs were its eyes, which were hugely oversized (about four inches in diameter) compared to the rest of its body. As in other marine reptiles, these eyes were encircled by bony structures called "sclerotic rings," which allowed the eyeballs to maintain their spherical shape in conditions of extreme water pressure. Ophthalmosaurus likely used its enormous peepers to locate prey at extreme depths, where a marine creature's eyes have to be as efficient as possible in order to gather in the increasingly scarce light.

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Platypterygius

platypterygius
Platypterygius. Dimitry Bogdanov

Name:

Platypterygius (Greek for "flat wing"); pronounced PLAT-ee-ter-IH-gee-us

Habitat:

Shores of North America, Western Europe and Australia

Historical Period:

Early Cretaceous (145-140 million years ago)

Size and Weight:

About 23 feet long and 1-2 tons

Diet:

Probably omnivorous

Distinguishing Characteristics:

Streamlined body with long, pointed snout

 

By the start of the Cretaceous period, about 145 million years ago, most genera of ichthyosaurs ("fish lizards") had long since died out, replaced by better adapted plesiosaurs and pliosaurs (which were themselves rendered defunct millions of years later by even better-adapted mosasaurs). The fact that Platypterygius survived the Jurassic/Cretaceous boundary, in numerous locations worldwide, has led some paleontologists to speculate that it wasn't a true ichthyosaur at all, meaning that the exact classification of this marine reptile may still be up for grabs; however, most experts still assign it as an ichthyosaur closely related to the big-eyed Ophthalmosaurus.

Interestingly, one preserved Platypterygius specimen contains the fossilized remnants of its last meal--which included baby turtles and birds. This is a hint that maybe--just maybe--this presumed ichthyosaur survived into the Cretaceous period because it had evolved the ability to feed omnivorously, rather than solely on marine organisms. One other interesting fact about Platypterygius is that, like many other marine reptiles of the Mesozoic Era, the females gave birth to live young--an adaptation that obviated the need to return to dry land to lay eggs. (The young emerged from the mother's cloaca tail-first, to avoid drowning before it got used to life underwater.)

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Shastasaurus

shastasaurus
Shastasaurus. Dmitry Bogdanov

Name:

Shastasaurus (Greek for "Mount Shasta lizard"); pronounces SHASS-tah-SORE-us

Habitat:

Shorelines of the Pacific Ocean

Historical Period:

Late Triassic (210 million years ago)

Size and Weight:

Up to 60 feet long and 75 tons

Diet:

Cephalopods

Distinguishing Characteristics:

Streamlined body; blunt, toothless snout

 

Shastasaurus--named after Mount Shasta in California--has an extremely complicated taxonomic history, various species having been assigned (either mistakenly or not) to other giant marine reptiles like Californisaurus and Shonisaurus. What we do know about this ichthyosaur is that it comprised three separate species--ranging in size from unremarkable to truly gigantic--and that it differed anatomically from most others of its breed. Specifically, Shastasaurus possessed a short, blunt, toothless head perched at the end of an unusually slender body.

Recently, a team of scientists analyzing the skull of Shastasaurus came to a startling (though not entirely unexpected) conclusion: this marine reptile subsisted on soft-bodied cephalopods (essentially, mollusks without the shells) and possibly small fish as well.

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Shonisaurus

shonisaurus
Shonisaurus. Nobu Tamura

How did a gigantic marine reptile like Shonisaurus wind up being the state fossil of parched, landlocked Nevada? Easy: back in the Mesozoic Era, large portions of North America were submerged in shallow seas, which is why so many marine reptiles have been unearthed in the otherwise bone-dry American west. See an in-depth profile of Shonisaurus

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Stenopterygius

stenopterygius
Stenopterygius (Wikimedia Commons).

Name:

Stenopterygius (Greek for "narrow wing"), pronounced STEN-op-ter-IH-jee-us

Habitat:

Shores of Western Europe and South America

Historical Period:

Early Jurassic (190 million years ago)

Size and Weight:

About six feet long and 100-200 pounds

Diet:

Fish, cephalopods, and various marine organisms

Distinguishing Characteristics:

Dolphin-shaped body with narrow snout and flippers; large tail fin

 

Stenopterygius was a typical, dolphin-shaped ichthyosaur ("fish lizard") of the early Jurassic period, similar in build, if not size, to the poster genus of the ichthyosaur family, Ichthyosaurus. With its narrow flippers (hence its name, Greek for "narrow wing") and smaller head, Stenopterygius was more streamlined than the ancestral ichthyosaurs of the Triassic period, and likely swam at tuna-like speeds in pursuit of prey. Tantalizingly, one Stenopterygius fossil has been identified as harboring the remains of an unborn juvenile, clearly an instance of the mother dying before she could give birth; as with most other ichthyosaurs, it's now believed that Stenopterygius females birthed live young out in the sea, rather than crawling onto dry land and their laying eggs, like modern marine turtles.

Stenopterygius is one of the best-attested ichthyosaurs of the Mesozoic Era, known by over 100 fossils and four species: S. quadriscissus and S. triscissus (both previously attributed to Ichthyosaurus), as well as S. uniter and a new species identified in 2012, S. aaleniensis.

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Temnodontosaurus

temnodontosaurus
Temnodontosaurus (Wikimedia Commons).

Name:

Temnodontosaurus (Greek for "cutting-toothed lizard"); pronounced TEM-no-DON-toe-SORE-us

Habitat:

Shores of western Europe

Historical Period:

Early Jurassic (210-195 million years ago)

Size and Weight:

About 30 feet long and five tons

Diet:

Squids and ammonites

Distinguishing Characteristics:

Dolphin-like profile; large eyes; large tail fin

 

If you happened to be out swimming during the early Jurassic period and saw a Temnodontosaurus in the distance, you might be forgiven for mistaking it for a dolphin, thanks to this marine reptile's long, narrow head and streamlined flippers. This ichthyosaur ("fish lizard") wasn't even remotely related to modern dolphins (except to the extent that all mammals are distantly related to all aquatic reptiles), but it just goes to show how evolution tends to adopt the same shapes for similar purposes.

The most remarkable thing about Temnodontosaurus was that (as evidenced by the remains of baby skeletons found fossilized inside adult females) it gave birth to live young, meaning it didn't have to make the arduous journey to lay eggs on dry land. In this regard, Temnodontosaurus (along with most other ichthyosaurs, including the poster genus Ichthyosaurus) appears to have been one of the rare prehistoric reptiles that spent its entire life in the water.

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Utatsusaurus

utatsusaurus
Utatsusaurus (Wikimedia Commons).

Name:

Utatsusaurus (Greek for "Utatsu lizard"); pronounced oo-TAT-soo-SORE-us

Habitat:

Shores of western North America and Asia

Historical Period:

Early Triassic (240-230 million years ago)

Size and Weight:

About 10 feet long and 500 pounds

Diet:

Fish and marine organisms

Distinguishing Characteristics:

Short head with narrow snout; small flippers; no dorsal fin

 

Utatsusaurus is what paleontologists call a "basal" ichthyosaur ("fish lizard"): the earliest of its kind yet discovered, dating to the early Triassic period, it lacked later ichthyosaur features such as long flippers, a flexible tail, and a dorsal (back) fin. This marine reptile also possessed an unusually flat skull with small teeth, which, combined with its small flippers, implies that it didn't pose much of a threat to the larger fish or marine organisms of its day. (By the way, if the name Utatsusaurus sounds strange, that's because this ichthyosaur was named after the region in Japan where one of its fossils was unearthed.)