These Ancient Animals Have Survived Since the Age of Dinosaurs

Nature craves novelty. A look around the wide earth shows her hands engaged in eternal experiments—mixing this with that, urging one mutation over another—until new forms and figures of increasing complexity emerge. Most living systems have profited from this sandbox approach. Humans are the product of these perennial tests. Some creatures, however, have eluded transformation and survived relatively unchanged for hundreds of millions of years.

It seems that nature hit upon gold with some organisms early in the evolutionary process. While one ancient type of mammal has survived into the present day, it is mostly reptiles, fish, and arthropods that have remained largely unchanged. The environments into which they emerged have changed, but their attributes have carried them through countless eras, epochs, and cataclysms. Several species were graced with the Midas touch, outliving dinosaurs and more. Let’s learn about five of them.

Crocodile

No creature on the planet symbolizes creeping ferocity like the crocodile. They stalk the murky depths before striking and dragging prey underwater. However, crocodiles have had plenty of time to refine their vicious techniques, considering they first evolved around 95 million years ago during the Late Cretaceous period.

This was a transitional time for the Earth: Tyrannosauroids lived alongside birds, early mammals, and Deinosuchus—a prehistoric relative of alligators and a member of the archosaur group (ruling reptiles). Crocodiles and alligators that roam the planet’s current waterways are descended from these ancient creatures. Much like their Deinosuchus ancestor, they have long snouts, strong tails, and rows of sharp teeth.

Horseshoe Crab

Don’t be fooled by the name. Horseshoe crabs aren’t true crustaceans. They are more closely related to spiders and scorpions. These ‘crabs’ get their name from their prosoma (fused head and thorax), which houses their internal organs and resembles a horseshoe. They are also the only surviving members of the Xiphosuran order. This has led to horseshoe crabs being called “living fossils.” They first appeared during the Early Triassic era, some 250 million years ago, and have barely changed since. Due to their unique biology, they evolve much more slowly than other creatures. Perhaps this snail’s pace is helpful, as horseshoe crabs have survived at least four of the planet’s extinction events, including the one that killed most of the dinosaurs.

Duck-Billed Platypus

While the duck-billed platypus may seem like the odd one out among modern mammals, this was not always the case. Scientists believe the earliest ancestors of the platypus emerged during the Early Cretaceous period. A true symbol of nature’s countless mixtures, the duck-billed platypus lays eggs, produces venom, and can spot prey in murky waters thanks to a sense of electroporation. The platypus and four species of echidna are the only living, egg-laying mammals (monotremes) that have survived since the dinosaur age. The modern duck-billed platypus is descended from monotreme ancestors that lived around 120 million years ago during the Early Cretaceous period. They may seem unusual today, but their ancient lineage means they have outlasted many other mammal lineages.

Coelacanth

Some creatures, like the coelacanth, survived for so long and so inconspicuously that they were believed to be extinct. An ancient fish in the subclass Actinistia (within the class Sarcopterygii), coelacanths have lobe fins that function like primitive limbs. The oldest fossils of these fish date back more than 410 million years. Scientists thought they went extinct several hundred million years ago, during the Late Cretaceous era. That is, until they were spotted alive and well off the coast of South Africa in 1938. While modern coelacanths have evolved since their ancient relatives, they have done so at a much slower rate than many other animals, making them appear remarkably similar to their prehistoric ancestors. The surviving coelacanths are few in number, but because they are fish-eating fish, they are not considered good to eat.

Tuatara

Don’t be fooled by the tuatara’s appearance. It is not actually a lizard or a dinosaur, but rather the last surviving species of the Sphenodontia order. This order of ancient reptiles first appeared around 240 million years ago during the Triassic era. Back then, tuataras enjoyed widespread distribution. Today, it can only be found in the wild in New Zealand.

While scientists have become increasingly hesitant to use the term “living fossil,” the tuatara makes a good candidate. They retain many unique characteristics of their dinosaur-era ancestors. These include two rows of teeth in the upper jaw, the ability to hear without external ears, and girdle-like structures in their skeletons. Remarkably, tuataras have a genome of about 5 billion base pairs, which is roughly 67% larger than the human genome.