Monsters Of The Sea - Meet The Monsters

Science Centre
Jurong East
January 2016


Period of existence: Late Cretaceous era (99.6 to 65.5 million years ago)
Places of discovery: Worldwide
Size: Up to 2 metres
Meaning "Staff of Stone", Baculite was an ammonite, related to the modern squid and octopus. It had tentacles that grew out of its head. Beginning life with the typical curled shell in its early life, when it grew older, the shell straightened out.

A standalone adult Baculite...

A Baculite in an epic standoff against a Pliosaurus -
which gives a good gauge of the gigantic size of this Cephalopod


Period of existence: Late Eocene era (45 to 36 million years ago)
Places of Discovery: North America, Egypt, Jordan and Pakistan
Size: 18 metres long

Basilosaurus (meaning "King Lizard") was one of the earliest whales although it was initially identified as a marine reptile due to its odd shape. It had massive jaws with strong teeth that could bite with a force of 1,600kg, allowing it to crush the skulls of large prey like small whales or large fish. With a vertebrae that was hollow and filled with fluid, which helped with its buoyancy,  but would collapse from from intense water pressure in deeper waters, the Basilosaurus spent most of its life near the water surface.

The Basilosaurus definitely did not look much like a whale with its elongated snout and huge paddles...

Coelacanth (Latimeria chalumnae)

Period of existence: Modern
Places of discovery: South Africa off the coast from Madagascar southwards

The most famous example of a Lazarus taxon, the Coelacanth was though to have been extinct together with the dinosaurs 64 million years ago. In 1938, it was discovered by a museum curator in a fishing boat. Since the, these fish have been well-documented in the wild.


Period of existence: Late Devonian era (372 to 359 million years ago)
Places of discovery: USA, Canada, Europe, Morocco
Size: Up to 10 metres long
Max weight: 2,000kg

Dunklesteous (meaning "Dunkle’s Bones") belonged to a class of armoured fish called Placoderms. Its head and thorax were covered by armour plates, while the rest of the body had small or no scales.
The piscivorous sea creature was an apex predator capable of killing almost anything it could clasp its jaws on. While it lacked true teeth, razor-like and self-sharpening bony plates in this sea monster’s jaws could snap and crush anything.
The ferocious Dunklesteous was one monster that you would not want to meet while swimming...

Period of existence: Late Cretaceous era (83 to 72 million years ago)
Place of discovery: Pierre Shale in Kansas, USA
Size: 14 metres long

This "Ribbon Lizard" had a particularly long neck comprising 72 of cervical vertebrae (Humans have only 7!), which allowed for greater flexibility and for better control of the head. A massive fish eater, its long and thin teeth intermeshed when clamped together, allowing it to grip fish which are then swallowed whole.

The Elasmosaurus was so long that it could not fit inside a single photo!
For comparison, see the human at its base...

Giant Ammonite

Period of existence: Cretaceous era (100 to 70 million years ago)
Place of discovery: Europe
Size: 2 metres

Giant Ammonites typically featured a ribbed spiral-form shell and possessed a strong protective outer shell to shield their soft interior from damage. Ammonites began life as tiny planktonic creatures less than 1mm in diameter. In their infancy they would have been vulnerable to attack from other predators, including fish; however, they quickly assumed a strong protective outer shell that shielded their soft interior from damage.

Ammonites are excellent index fossils, and it is often possible to link the rock layer in which a particular species or genus is found to specific geological time periods. They are also prized for their iridescence. The spectacular coloration is the result of millions of years of high temperatures and pressures acting on the animal's shell to create a gemstone known as an ammolite.

Great White Shark

Period of existence: Modern
Places of habitation: Worldwide, temperate and tropical coastal areas
Size: Up to 6m (average: 4.5m)
Max weight: 3,000kg

With a name meaning "Sharp Teeth", the Great White has no natural predators in the marine ecosystem. Young sharks make a meal out of squids, stingrays, and smaller sharks, while adults feast on sea lions, seals, dolphins, sea turtles, sea birds, and whale carcasses. Built with a streamlined and torpedo-shaped body, its powerful tail helps to propel it through water and to swim fast with minimal resistance.

As the shark moves, water flows through its two forward-facing nostrils, positioned along the white underside of the snout. The water enters the nasal passage and moves past folds of skin covered with sensory cells. This enables it to detect a single drop of blood in an Olympic-sized pool...

Approaching prey from below...

The Great White Shark "benchmarked" against humans and its prehistoric cousin...


Period of existence: Early Jurassic (201-191 million years ago)
Places of discovery: Europe, including Belgium, England, Germany, Switzerland
Size: 2 metres

Resembling a prehistoric dolphin, Ichthyosaurus was actually a piscivorous reptile, with a diet comprising of fish and occasionally squids. Relying on both sight and hearing for hunting, its streamlined body allowed for efficient movement in water.

Resembling prehistoric dolphins, Ichthyosaurus are actually marine reptiles which adopted a streamlined body for efficient locomotion in water...

Most reptiles on record lay eggs. Yet, fossils have revealed smaller Ichthyosaurus inside larger ones, indicating a possibility of live births...

Livyatan Melvillei

Time Period: Miocene era (12-13 million years ago)
Place of discovery: South America, Peru
Size: 13.5-17.5m (skull was around 3m long)
Max weight: 50,000kg

The Livyatan was armed with massive teeth in both its upper and lower jaws, and a huge skull that supported its jaw muscles. The species name,‭ ‬L.‭ ‬melvillei is in honour of the author Herman Melville,‭ ‬the man who wrote the world famous novel‭ "Moby Dick"‬.

This sea monster hunted baleen whales, using its teeth to inflict deep wounds and to tear off their flesh. At 35cm long, it had the longest teeth (excluding tusks) amongst all living and dead animals.


Period of existence: Miocene to Pliocene era (15-2.6 million years ago)
Places of discovery: Worldwide
Size: 15 to 17 metres

Megalodon (meaning “Big Tooth”) had large teeth that grew up to 18cm. Its serrated and multiple rows of teeth allowed the sea monster to latch onto its prey tightly and thereafter tear it apart before consumption. This prehistoric shark fed on aquatic marine mammals, especially small- to medium-sized whales, and also ate large sea turtles.

Megalodon was the biggest shark ever lived. A study published in 2013 suggests a maximum length of 59 feet, or roughly three times as long as the longest Great White Shark! Are they related?

Megalodon had a very robust dentition with a total of about 276 teeth in its jaws, spanning 5 rows. Paleontologists suggest that a very large megalodon had jaws over 2 metres (6.6 ft) across...

Visible differences between the teeth of the Megalodon & Great White Shark...

Slight differences can be spotted between the Megalodon's and Great White's snouts...


Period of existence: Late Cretaceous period (72 to 66 million years ago)
Places of discovery: Western Europe, North America
Size: 15 to 18 metres in length
Weight: 5,000kg

A predator of the upper oceans, Mosasaurus (meaning "Meuse River Lizard") tended to wait for other marine reptiles to surface for air, before using its tail to provide a quick burst of speed to launch its attack.

This 5-ton sea monster ate marine reptiles, fish (including sharks), birds, land dinosaurs and Pterosaurs. Used its fearsome array of teeth, it ensures that any prey sliding down through its throat could not escape.


Period of existence: Middle to late Jurassic, 168 to 145 million years ago
Places of discovery: Europe, North America)
Size: Up to 6m
Max weight: 3,000kg
Among sea creatures of the late Jurassic seas, Ophthalmosaurus ("Eye Lizard") possibly had the largest eyes (22cm diameter; 10cm aperture) in proportion to its body length. These traits helped to provide better vision under low light conditions for deep water hunting and nocturnal activity.


Period of existence: Late triassic to early Jurassic period (209 to 191 million years ago)
Place of discovery: Lias Group in England, United Kingdom
Size: 3.5 metres in length, 1 metre in height
Weight: 450kg
Plesiosaurus ("Almost Lizard") with simple needle-like teeth which formed a perfect fish traps it approached prey from the side or bottom. With 40 vertebrae, its neck was surprisingly inflexible and was most stable when projected horizontally, serving the strongest evidence it had an entirely aquatic lifestyle.


Period of existence: Late Jurassic, 157 to 145 million years ago
Place of Discovery: Europe
Size: Up to 13m long (skull approximately 2m long)

Pliosaurus (meaning “More Lizard”) was a massive marine reptile with a short neck and a large head. Despite it streamlined shape, it hunted mainly in the shallow seas and was known to consume their long-necked cousins - the Plesiosaurs. Built for speed, this massive sea monster had limbs that were paddle-shaped to help them move swiftly through the water.

Humans are really small, beside the Pliosaurus... 


Period of existence: Miocene era (13 to 8 million years ago)
Places of discovery: Brazil, Colombia, Peruvian Amazonia, N. Venezuela
Size: 11-13 metres long (skull could grow up to 1.4 metres)
Max weight: 8,400kg

Known to have the strongest jaw bite among four-footed animals, Purussaurus was an apex predator capable of attacking very large vertebrates.

Its conical teeth curved backwards and slightly inwards, making it ideal for the smashing and piercing to maintain its daily food intake of 40kg...


Period of existence: Late Cretaceous era (88 to 78 million years ago)
Places of discovery: Canada, central states of USA
Size: Up to 15 metres  

Tylosaurus (meaning "Knob Lizard") was dubbed the “Predator of the late Cretaceous Seas”. It was an apex predator that ate fish, sharks, flightless birds, and large marine reptiles like Plesiosaurs and other Mosasaurs.  It relied on its hydrodynamic body and its muscular, long and vertically flattened tail to propel itself through water at great speeds.

Holding its own against other predators with its elongated sharp teeth...

Whale Shark

Period of existence: Modern
Places of habitation: Worldwide; both shallow and deep, tropical and subtropical coastal waters
Size: Up to 20m (average: 7m)
Max weight: 31,000kg

Akin to some bony fish and baleen whales, the whale shark is a filter feeder and eats by straining tiny food particles from the water. A whale shark’s favourite meal is plankton. It uses its colossal gaping mouth (with a 1.5m cross section) to scoop these tiny animals up, along with any small fish that happen to be around. Its diet also includes jellyfish, squids, and fish eggs. The whale shark’s best defensive adaptation is its skin which is covered in tough dermal denticles (small teeth-like skin), instead of scales. In some parts on the body, particularly the upper back, the skin can be around 10 cm thick.