Meet the Saccorhytus, your oldest ancestor and your newest nightmare.
This week a team of paleontologists described a new link in the chain of human evolution — and it isn’t pretty. With its “bag-like body,” “prominent mouth” and no anus (it likely excreted waste from openings by its mouth, almost like primitive gills), the Saccorhytus looks like it crawled off the set of “Alien,” but researchers say the millimeter-long organism is a key early branch off our tree of life.
A 540-million-year-old fossil of the Saccorhytus was discovered in sedimentary rock in central China, according to a paper published in Nature magazine. The creatures are a primitive example of a deuterostome, a common ancestor to a wide range of animals from starfish to humans.
“We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves,” University of Cambridge professor Simon Conway Morrisone, who helped author the paper, told the BBC. “All deuterostomes had a common ancestor, and we think that is what we are looking at here.”
The news sent waves of excitement through the field of paleontology.
“Finding and describing fossils is a critical way that we understand the history of life, and this is an important find,” Matthew I. Palmer, professor of ecology, evolution and biology at Columbia University, told The Post. “The evolutionary tree is long with lots of branches. This fossil illuminates the base of a branch (on which we happen to sit), but there are lots of branches both below and above it.”
This begs the question: How did we get from that to where we are today?
Here, we trace our evolutionary journey from Saccorhytus to Homo sapiens with a few twists in between…
Saccorhytus
540 million years ago
This millimeter-long animal — a primitive example of a deuterostome, a common ancestor of humans and many other animals — was all mouth. It likely lived among grains of sand at the bottom of the sea and inhaled particles into its giant orifice, expelling waste and water through lateral slits in its side (which researchers say may be early gills). The recent fossil discovery, researchers say, illuminates the story of our earliest evolution. They suggest that Saccorhytus had a symmetrical body — a trait inherited by many of its descendants, including humans. They also claim the animal had a thin, somewhat flexible skin and muscles, which helped it to wriggle to move around.
Placodermi
480 million years ago
These prehistoric “plate-skinned” fish (their heads and thoraxes were covered with natural armor) are the earliest known species with a modern jaw — a huge step forward, because this made them into predators. Placodermi lived in fresh and marine water in all continents except South America. Though most were small, some placoderms reached 13-feet long. They are also the first fish to develop pelvic fins, a precursor to legs.
Ichthyostega
362 million years ago
The 5-foot-long Ichthyostega was one of the first terrestrial tetrapods, or four-limbed vertebrae that amphibians, birds and mammals descend from. It had lungs, gills and digits on each limb that allowed the animal to easily navigate outside the water — a place that at the time was safer than the sea because there were fewer predators. It is seen as a transitional fossil that connects fish and other land-bound animals.
Cynodont
220 million years ago
The Cynodonts — described by some researchers as shrew-like, warm-blooded and covered in fur — are the closest relatives of mammals. They had larger brains, a lower jaw and teeth. The Cynodonts survived the greatest mass extinction of all time (which wiped out 70 percent of all marine organisms and 90 percent of all terrestrial animals), and thrived in the aftermath.
Plesiadapis
58 million years ago
The best way to describe these first primates is: squirrel/cat. These long-snouted, rodent-like animals lived in Northern America and likely colonized Europe through a land bridge via Greenland. The Plesiadapis had mobile limbs, strong and curved claws, and a long, bushy tail — well adapted for climbing trees.
Pierolapithecus catalaunicus
13 million years ago
These are the first hominids, or the common ancestor of humans and other great apes. These apes had special adaptations for climbing trees including a stiff lower spine, a wide, flat rib cage, and flexible wrists. Fossils were only recently discovered in Spain in 2004 and the great ape got its name from the village where the remains were found.
Australopithecus
4 million years ago
The Australopithecus afarensis is one of the most well-studied early humans — more than 300 remains have been uncovered, including the famous Lucy skeleton. These humans were spread out in Eastern Africa and survived nearly a million years. Physically they resemble a mix of ape and human — with a protruding lower jaw and a small brain, and with long curved fingers perfect for climbing.
Homo erectus
1.8 million years ago
Known as the “upright man,” this modern human spread out widely across the globe — including in South Africa, Kenya, Spain and China — and lived from about 2 million years ago to 100,000 years ago (overlapping with Homo sapiens). They were about as big as us and had similar limb and torso proportions as well as opposable thumbs. Researchers believe that they walked on two feet and had much bigger brains than predecessors (though only about 60 percent the size of our brains).
Homo sapiens
Our fellow man showed up around 200,000 years ago in Africa. Like other humans, we gathered and hunted, but unlike other humans, we had lighter skeletal structures, smaller teeth and much bigger brains. To accommodate such bigger brains our faces changed — foreheads flattened and we lost the heavy brow ridges of our forebears. But we’re not done adapting just yet! Time will tell how our dependency on technology will change us even further, as many researchers believe it will.
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