where did they appear? In China. They are fossils that provide the first anatomical evidence of a vertebrate spiracle. What is the spiracle? It is part of the middle ear, and it originated in the gills of fish. Yes, the human ear evolved from gills.
From gills
The findings were published in Frontiers in Ecology and Evolution. Professor Gai Zhikun is first author of the study. He tells that they found a 438-million-year-old cranial box fossil and the first galapspid fossil of 419 million years old. It is completely preserved with gill filaments in the first gill chamber.
“These fossils provided the earliest anatomical and fossil evidence. A vertebrate spiracle originated from fish gills,” Gai said in a statement.
“Many important structures of humans can be traced back to our fish ancestors. The teeth, the jaws, the middle ear, etc. The main task of paleontologists is to find the missing links.”
The blowhole is a small hole behind each eye that opens to the mouth in some fishes. In sharks, it is the entrance of water into the mouth space before it is expelled through the gills. The blowhole is often located towards the top of the animal. It allows it to breathe even when the animal is buried under sediment.
History of evolution
Fish spiracles were eventually replaced in most non-fish species. They evolved to breathe through the nose and mouth. Then evolved to become the ear of modern tetrapods. Eventually it became the auditory canal used to transmit sound to the brain through the tiny bones of the inner ear. This function has been maintained throughout evolution until humans.
It is an extraordinary evolutionary story. The human ear evolved from gills. Think about it the next time you see a fish around: we have more in common than you might imagine.
