Go back in time to a land shrouded in mist and jungles and swamps. A time hundreds of millions of years before T-Rexes stalked the Earth, growling and rumbling and crashing through thick forests. A time before Pterodactyls soared through the skies, shrieking and diving through clouds to capture unsuspecting prey. It is a land rich with possibilities and emerging life forms. Water covers large portions of the Earth’s surface and in its depths are fish and sea life of an amazing array, all teeming and eating and reproducing. Everywhere growth and change are happening in open seas, pristine lakes, and murky swamps across the continents. Some amphibians – or fish – are growing larger, some are growing fangs, and some are growing legs and becoming tetrapods!
Tetrapods are four-legged creatures with vertebras – or spines. And one of these tetrapods is a murky swamp creature called Crassigyrinus Scoticus – or C. Scoticus – meaning “thick Scottish tadpole.” But don’t let this cute name and fanciful image fool you. This is no wiggly little tadpole that we think of today – something that we capture in shallow ponds and gurgling streams, giggling with delight as they scamper across our wet palms or shimmy up our sun-drenched arms. Oh, no, this is a gigantic tadpole – a fierce water hunter measuring anywhere from 6.5 – 10 feet long (or 2-3 meters) with razor-sharp teeth! Think of an alligator or a crocodile and you get the picture of this amazing tetrapod. He is the T-Rex of tadpoles!
So, let’s go back in time and learn more about him.
THE T-REX OF TADPOLES
The time is 300 million years ago and C. Scoticus, the mighty tadpole, swims through the murky swamp waters of Scotland and West Virginia in North America. He is a fearsome hunter with a narrow skull, large eyes, two rows of sharp teeth, a slim flexible body, and a long tail. He swims slowly and stealthily below the muddy water, searching for tasty fish among the swaying reeds. His powerful body sends out ripples behind him as he swishes his tail to and fro, four little legs floating below him, sometimes treading the water as he slows and eventually stops. Suddenly, he senses prey – possibly through eyesight, vibrations, or electrical signals – and his powerful body lunges forward. He spots the fish. It is bigger than he expected but he knows he can catch it in his strong jaws. With another thrust of his tail, he opens his massive jaws and snaps! The fish is caught! With a few more mighty chomps, his meal is devoured.
His jaws are his most powerful weapon – without them, he would not survive. He can open them 60 degrees, much larger than human jaws at a measly 26 degrees. C. Scoticus’ powerful jaws and sharp teeth give him the ability to capture large amphibians with a single bite. And this is very handy seeing as everything is large in these prehistoric times.
Also, his big eyes help him see prey in the murky waters, plus his skull has a ridge of lines running from top to bottom, allowing him to feel vibrations in the water. Sometimes all he has to do is float silently in the shallows waiting for a wiggly fish to swim by. The moving water ripples over his snout and he knows that dinner is close at hand – and soon in his belly!
C. Scoticus also sports a gap at the front of his snout. Maybe he needs other organs besides his eyes and teeth to help him hunt. Possibly this gap contains a rostral organ – a jelly-filled sack with canals leading outside – to help him detect electrical fields underwater. Or maybe he has a Jacobson’s organ – a smell organ above the roof of his mouth like those in snakes and lizards – to smell chemicals released by his prey. If he has all these attributes – strong jaws, sharp teeth, fine smell, a rostral organ, and vibration-sensitive ridges – then he is a mighty predator indeed and has no need to go onto land.
Therefore, his little legs are a mystery. We know that other tetrapods started moving onto land using newly-sprouted legs around 400 million years ago. C. Scoticus evolved 70 million years later. So, during this evolutionary leap did he make it onto land but then return to water full-time – or did he never go onto land at all? We may never know.
One thing I DO know for certain: if I lived in Scotland or West Virginia – and maybe other places – during that evolutionary time in history, I would not swim in murky waters and I wouldn’t spend my time searching for tadpoles!
THE SABER-TOOTHED ANCHOVY
Now, let’s jump ahead to 45 million years ago, long after C-Scoticus started to sprout legs and swim through the swamps. There is another crazy creature – actually two of them – swimming below the ocean’s surface – and they each have a long, menacing fang or saber-tooth! Don’t believe me? Well, I can understand that because there has never been a creature before – or since – that looks like these two. And what are they? Well, they are actually super large anchovies! Yes, those things come in little cans that you put on pizzas or crackers. But these anchovies are huge – one is almost a foot long (about 29 centimeters) and the other is 3 feet long (or 3 meters)!
So, let’s head back 65 million years in time to learn about the start of the saber-toothed anchovy.
It is a day like any other day – may be sunny, cool, or rainy in various parts of the world. Dinosaurs roam the land and vast forests carpet the Earth. The sea brims with all kinds of prehistoric life. Suddenly, a huge sonic boom shatters the atmosphere and a giant asteroid hurtles towards Earth with a blazing tail of fire and gas. It smashes into Earth with supersonic speed, causing a massive explosion and spewing fire and ash high into the air. Raging wildfires erupt, their towering flames filling the sky. Soon the Earth is on fire and all sunlight is obscured by thick grey clouds of smoke and ash. Rivers, ponds, and lakes dry up. Sea life is decimated. All vegetation burns to the ground. Many dinosaurs are killed and the rest soon perish due to fire, heat, smoke, and lack of food and water. All seems lost. Will Earth become a barren planet devoid of all life? No!
The days tick by, then weeks, then years, then thousands and millions of years. During this time, tiny organisms in the sea begin to form again, then grow, change, and evolve. It is now 15 million years later and the seas are once more home to incredible forms of life. Fish dart here and there and are food for larger fish, sharks, and whales. And one of these fish is an 11-inch anchovy with a lower jaw filled with razor-sharp teeth and an upper jaw with one long saber tooth! He is called Clupeopsis straeleni and he lives in the waters near Belgium. He evolves in the sea as if through a ripple in time. He exists for a period of time and then vanishes – never to be seen again. Why did evolution make this unique sea creature with a saber tooth? Did he need a large tooth to spear larger fish that he could then bite into smaller bits? It’s hard to say.
But C. Straeleni is not alone. He has a larger cousin in Southeast Asia measuring 3 feet (1 meter) long and with the same fierce saber tooth. This larger anchovy cousin is called Monosmilus chureloides or “single-knife Churel.” And what is a Churel? It is a scary fairy tale creature, a shape-shifting demon or vampire with fangs.
M. Chureloides is no fairytale demon, though. He is an actual fish and he swims in the shallows of the sea searching for prey. Just like his smaller cousin, he uses his 16 sharp bottom teeth and one long saber tooth to spear and eat his prey. Periodically, he sheds his teeth as he grows and as they fall out during attacks, but he is constantly growing new ones. And although he is long by modern-day anchovy standards, he is a small fry on the prehistoric scale. He must be wary of larger predators like sharks and the four-legged whale known as Dalanistes. But, like his smaller cousin, the mystery remains. Why did he evolve and why did he disappear? We may never know.
Both of these fish have been called a “bizarre, evolutionary experiment,” one that has never occurred before or since in all the seas throughout time. For some reason, evolution decided that a smaller cousin would thrive – and without the fang!
As for me, I am grateful that my anchovies are now petite and bite-sized – otherwise, they could certainly take a bite out of me!
So, what do you think of these wacky wonders of the swamps and seas? Have you ever heard of them before? I know I haven’t. Isn’t evolution strange and amazing and unpredictable? I wonder what life forms will be on Earth millions of years from now. We’d would love to hear from you and learn what is your favorite dinosaur or prehistoric sea creature.