Tiktaalik is a strange fish. So strange that it’s not easy to recognize the fish in it. Every time I look at this animal, I wonder: is this my ancestor?
Scientists say: possible, but not true. Tiktaalik could be our ancestors or second cousins. This is certainly confusing because Tiktaalik appeared 385 million years ago. And although we can’t trace a clear origin, we understand exactly why they look like the result of an amphibian love affair with a fish.
Scientists continue to interrogate the Tiktaalik people about our family relationships, but they are as silent as fish.
Our heroes were discovered in Northern Canada. During the Devonian period, it was located almost at the equator. In those days, the local plain was located between river valleys, swamps and dense tropical forests. Rotting leaves absorb oxygen from the water, and fragments of dead ferns and moss form ponds and dams. The abundance of free organic matter attracts a wide variety of animals of all structural types.
Organisms that decompose organic matter consume a lot of oxygen. And the lower the oxygen content in water, the lower the rate of decomposition and the more organic matter accumulates in it. Vicious circle!
To survive here, Tiktaalik has changed a lot. They solved the problem of lack of oxygen in an ingenious way: they got lungs. That’s right, to breathe deeply, the fish must give up light, exposed ribs for stronger bones, on which there is a place for the intercostal muscles to attach. After all, neither Tiktaalik nor you nor I could breathe without them.
They solved the problem of movement in difficult terrain in an equally radical way: they turned their fins into limbs! The pectoral fins were further reinforced with strong bones and acquired wrist joints. In modern quadrupeds, they are responsible for the movements of the hands. The hind legs also changed: they became longer and attached to a solid pelvis, which is absent in normal fish.
That’s right, their pectoral and pelvic fins have become stronger. But the back was lost. There may not be a tail yet, but we’re not sure yet.
Such modifications to the fins gave them strong muscles and many degrees of freedom. Tiktaalik can push seaweed aside and escape from a sinking tree trunk! And modern mathematical models show that he can even crawl from one body of water to another.
But he certainly couldn’t lift himself up with his fins like that. They are still too thin and weak.
But fish rarely leave shallow water. Often she lies on the muddy river bottom and slowly shakes her triangular head on her short neck, like some kind of crocodile. Ancient amphibians wait for careless prey and hide from the eyes of dangerous predators. However, she has few enemies. A giant animal 2.7 meters long cannot be swallowed so easily.
It is very likely that the main enemies of Tiktaaliks are the larger Tiktaaliks.
Tiktaalik disappeared from the fossil record about 370 million years ago. But is he extinct? Maybe his descendants fly in the sky, jump through fields and watch stupid shows on TV?
