Ichthyosaurs inhabited much of the
Earth’s seas and oceans during the
mid-Triassic to late Cretaceous periods.
To date there are more than 80 recorded species of
Ichthyosaur, with more being added regularly.
Although some bared a physical resemblance to
modern day dolphins or sharks, skeletally they
were more closely linked to reptiles – in fact
Ichthyosaur translates as ‘fi sh lizard’.
Ichthyosaurs ranged vastly in size, with the
smallest (the Chaohusaurus) measuring in at
around 70cm and the largest (as yet unnamed)
was found in Canada and is believed to measure
in the region of 23 meters in length. A t ypical
ichthyosaur was the Ichthyosaurus, which
frequented the waters around the British Isles
during the early Jurassic period and measured
two meters in length. Designed for speed with
four fl ippers (in the hands and feet positions), a
paddle-like tail and a dorsal fi n, the
Ichthyosaurus hunted mainly fi sh, its elongated
skull and rows of sharp teeth ideal for catching
slipper y prey. It is thought that the smooth,
Dolphin-like torso of the Ichthyosaurs could see
them swim at speeds of up to 45kph, their
powerful bodies being able to maintain that top
speed for up to half an hour.Mosasaurs lived in the late Cretaceous
period and were the true giants of the
sea. Some mosasaurs, such as the
Hainosaurus, could reach lengths of up to 17
meters, their huge frames t ypically spent
swimming slowly along the sea beds stalking
slow-moving prey such as ammonites and
turtles. However, as mosasaurs could breathe
air, seabirds were also part of their ecosystem.
Possessing two sets of conical teeth, mosasaurs
used rocks and underwater plantation as cover
to close in on their prey and then strike quickly.
Some skeletal remains indicate that they were
susceptible to attacks by shark-like predators.
The fi rst mosasaur remains were uncovered
around the 1770s in an underground mine near
Maastricht, Holland, on the Meuse River. Fossil
skin impressions indicate that they possessed
scaly skin similar to that of a snake.Ichthyosaur
Length: Up to 16m (52ft)
Weight: 930kg (2090lb)
Diet: Carnivore
Discovered: Dorset, UKThe statistics...
DID YOU KNOW? (^) The remains of a Dakosaurus, a marine reptile of the late Jurassic era were discovered high in the Andes mountains
Few marine creatures could outrun these ‘fi sh lizards’
Introducing the T-Rex of the seas...
Ichthyosaurs
Mosasaurs
Teeth
The Ichthyosaur
often had
conical teeth to
assist with
catching
smaller prey
Dorsal fi n
Not all species of
Ichthyosaur had a
dorsal fi n, but it is
believed that
many types did
Flippers
The Ichthyosaur
had fl ippers which
contained a large
number of digits
and phalanges
Jaw
Most mosasaurs had a
double jaw which allowed
them to eat their prey in
one go
Snake-like
In 1869 it was suggested
that mosasaurs shared
common ancestry with
snakes, who coined the
term Pythonomorpha to
unite them
Eating habits
The larger mosasaurs
were the kings of the Late
Cretaceous seas, feeding
on fi sh and ammonites
Mosasaur
Length: Up to 17m (56ft)
Weight: Up to 20 tonnes
Diet: Carnivore
Discovered: Maastricht,
Netherlands
The statistics...