Some had enormous eyes. Others had long, tooth-filled jaws, powerful flippers and streamlined bodies beautifully adapted for life at sea.
Among the most remarkable were the ichthyosaurs, whose name means "fish lizards."
These ancient marine reptiles looked remarkably like modern dolphins, although they were not closely related to them.
Their story is one of evolution's most fascinating experiments.
MEET THE ICHTHYOSAURS
Their ancestors were land-dwelling reptiles that returned to the water, eventually evolving bodies wonderfully suited to an aquatic existence.
Many developed streamlined shapes, powerful tails and paddle-like limbs.
Their resemblance to dolphins is an example of convergent evolution: unrelated animals independently evolving similar features because they face similar challenges in their environments.
A streamlined body is rather useful when your dinner is swimming away from you.
GIANTS OF THE ANCIENT SEAS
Not all ichthyosaurs were small, dolphin-sized hunters.
Some became enormous.
The Late Triassic ichthyosaur Shonisaurus popularis, known from Nevada, reached impressive lengths and inhabited seas that covered parts of western North America.
Even larger ichthyosaurs have been proposed from fragmentary remains, although estimating their full size is difficult when scientists have only a few bones to work with.
These discoveries remind us how much remains hidden in ancient marine sediments.
BABIES BORN AT SEA
One of the most wonderful things we know about ichthyosaurs comes from fossils preserving mothers with developing embryos.
These animals gave birth to live young rather than returning to land to lay eggs.
Some remarkable specimens even preserve evidence of birth.
Imagine the extraordinary circumstances required for such a fleeting moment to become part of the fossil record.
It is a rare window into the lives of animals that disappeared tens of millions of years ago.
WHAT DID THEY EAT?
Many ichthyosaurs hunted fish and squid-like cephalopods, using their sharp teeth to seize slippery prey.
Some species had different tooth shapes and feeding specialisations, suggesting that ichthyosaurs occupied a variety of ecological roles.
Fossilised stomach contents and coprolites — fossilised faeces — can help palaeontologists understand what ancient predators ate.
Even prehistoric poop has a story to tell.
THE OCEANS STILL HOLD THEIR SECRETS
Marine reptile fossils have been discovered across the world, including spectacular specimens from British Columbia.
The Triassic rocks of northeastern British Columbia have yielded important ichthyosaur fossils, including the giant Shastasaurus sikanniensis.
Each new specimen helps scientists reconstruct the ecosystems of ancient oceans, the animals that inhabited them and the remarkable evolutionary changes that unfolded beneath the waves.
FOSSIL HUNTRESS FIELD NOTE
Ichthyosaurs were reptiles, not dinosaurs. Dinosaurs were primarily terrestrial animals, while ichthyosaurs belonged to a separate evolutionary lineage that became highly specialised for life in the sea.
They shared their oceans with ammonoids, fishes and many other marine creatures whose fossils we can still discover today.
Image: Ichthyosaur Fossil Asset ID: 2547389153
