What do you imagine when you think of the ancestors of humans? Most people think of chimpanzees, gorillas, or another animal from the ape family.
But new research is leading scientists to think further in the past than the apes. Imagine this: one of your ancestors from 540 million years ago, a mere four millimeter (.16 inches) bag-like creature with a prominent mouth, named Saccorhytus coronarius!
You might be asking yourself, “Is this really true?” That’s exactly what a team of experts from University of Cambridge in the UK, the University of Kassel in Germany, Northwest University, China University of Geosciences and Xi’an Shiyou University in China investigated.
Late last year, a team of expert scientists worked hard excavating 3 tons of limestone to get to the fossils, in central China's Shaanxi Province.
To most average people, the specimens just seemed like black sand-like specks in a slab of stone. But the scientists knew better. Using an electron microscope and CT scan, they were able to clearly observe the characteristics of Saccorhytus coronarius. These microscopic sac-like creatures perhaps lived on the sea bed between grains of sand.
A thin skin covering suggests S. coronarius had muscles to wriggle around. And they had only one opening which would have been used to ingest food and excrete waste (quite unappealing when you think about it!). Scientists also found small conical structures on either side of the mouth which may have allowed for swallowed water to escape -- these may have later evolved into gills.
From Sea To Land
How did this microscopic, fish-like creature become some of the most advanced species on the planet? It all happened because of evolution.
The first living creatures were water-dwellers, and if these creatures were alive today, we would classify them as fish. Then, between 360-390 million years ago, the descendants of these creatures slowly began moving to shallower waters. Eventually, the gills evolved into lungs, and they became land animals. Through natural selection (the process through which different species develop certain characteristics that help them survive), these creatures split into different land species, including our ancestors-- the apes.
S. coronarius has a symmetric body, which is characteristic of deuterostomes -- the ancestor to all the creatures in the animal kingdom’s major group. Deuterostomes includes echinoderms (sea urchins and starfish) and chordates (creatures with a backbone). Some of the earliest known deuterostomes are from 510-520 million years ago. S. coronarius appears to be the missing link that goes back to 540 million years!