When thinking of human evolution, an image of apes and monkeys most often springs to one’s mind. These primates, however, are not our only transformative link. According to paleontologists, humans have connections to other, less binary (and perhaps, in some opinions, slightly less attractive) ancestors: Saccorhytus coronaries.
Most commonly, scientists who have observed the images of S. coronaries described it as a “small, bag-like marine creature.” Though nearly microscopic (scientists have described the fossils of these creatures to resemble small black dots, not unlike poppy seeds), when put under an electron microscope and using a CT scan, the Saccorhytus coronaries microfossils proved to be vastly detailed in their individual makeup. The body of the organism was, like humans, the same on both sides (bilateral symmetry) and has thin, rather fragile thin skin that has a bit of elasticity to it. The maximum length of the Saccorhytus coronaries is 1,300 μm, width 800 μm and height 900 μm. The mouth the animal was rather large compared to the rest of its body and tiny conical structures circumforaneous it. Scientists conclude that this system allowed water to escape after it had been swallowed, similarly to modern-day gills. Interestingly however, those studying the creature were unable to detect any waste material outlet, namely an anus. This means that excrement was likely eliminated through the mouth.
The “wrinkled sack,” the translation for Saccorhytus coronaries (“Saccus” means “sac” in Latin, and “rhytis” means “wrinkle” in Greek) whose fossil was found in central China, was a product of the Cambrian period (Fortunian stage), a time when there was of mass surge in the diversity of organisms. There were numerous living things that originated during this time, and the food chain was beginning to emerge as well. The world, as we know it now, was materializing.
Deuterostomes is an animal group that includes numerous vertebrates, such as reptiles, birds, fish, amphibians, and mammals, in addition to invertebrates such as starfish. The sea organism S. coronaries, as well as humans, belong to this grouping. Because the 540-million-year-old creature is a part of the deuterostomes group, it is the thought that it is the most early descendent of human beings. Though as tiny as a piece of grain to the naked eye, the extremely detailed fossils of the Saccorhytus coronaries allow for extraordinary breakthroughs in the study of human origin.
Collecting the Microfossils
Through sifting through three tons of limestone in order to find the fossils from the Kuanchuanpu Formation, Hexi, Xixiang County, Shaanxi Province, central China was no simple task, the results were worth the struggle, as many questions were answered by analyzing the tiny critters. As per study co-researcher Jian Han, a paleontologist at Northwest University in China, it is most likely that the S. coronaries is very primitive, more so than a very early echinoderm. Further research was published in the journal Nature on January 30, 2017.