Meet the 505-million-year-old Pikaia gracilens. Everything we know of this prehistoric “fish-like worm” is discerned from its fossils, but a close investigation reveals that these wiggly little guys might be your oldest ancestors.
The first Pikaia fossils were discovered all the way back in 1911, but scientists almost immediately thought the beastie it was an ancestor of the lowly earthworm. Over the years, though, many scientists weren’t happy with the classification, citing evidence that the Pikaia seems to have traces of a backbone and as such, may actually be the earliest known member of Phylum Chordata — primitive vertebrates. The issue now appears to have been settled by a group of English palaeontologists lead by Jean-Bernard Caron and Simon Conway Morris. The team subjected the fossils to a fresh examination using the latest technology and found what they were looking for. The Vancouver Sun reports the findings from the journal Biological Reviews:
In the ’90s, Caron said more Pikaia specimens were collected and, more recently, were subject to the exacting eye of an electron microscope. Using the latest technology, the researchers were able to identify myomeres, which are bands of muscles that are the precursors to skeletal spines. They also found blood vessels and a vascular system.
That puts Pikaia on humanity’s family tree, along with every other animal with a spine.
Now that you’ve discovered your long-lost ancestor, don’t you want to know what it was like?
In its heyday, the average Pikaia would have grown to the length of a human thumb. It was a flat creature, with a head the size of a period. Two tentacles sprung from the front.
But before you get all freaked out and start ridding your brain of that description, remember, this was millions of years ago. The Pikaia wasn’t your only ancestor, and just because fragments of its DNA are in your own, doesn’t mean you can’t be more than just a worm. [Vancouver Sun via Fark]
Image: The Smithsonian