In the annals of prehistoric life, few mysteries captivate like that of Pikaia, an enigmatic bilaterian metazoan creature from the Cambrian period.
This ancient organism offers invaluable insights into the early evolution of chordates, the broad animal group that would lead to vertebrates – and all the way down to us humans.
But is Pikaia our direct ancestor? What is its early evolutionary journey, and when did Pikaia go extinct?
When did Pikaia go extinct?
The precise timing of Pikaia’s extinction is hard to pinpoint. We only have a few fossils of Pikaia, and all of them are from the same rocks and the same slice of time.
Its fossils are all from Canada’s famous Cambrian Burgess Shale. And it is specifically from rocks dating back to 505/508 million years ago.
It might well have lived before and after that. But going by the fossils we have, we have to assume Pikaia went extinct in the Cambrian, at least by the end of it around 488 million years ago. This was a time of severe environmental changes and great evolutionary pressures, so it was a likely time for extinction.
But it was also a time when new and more complex life forms appeared.
Pikaia’s extinction marks the end of an era for one of the earliest chordates we know. But it also opens a new chapter on the story of vertebrates (backboned animals like dinosaurs, reptiles and mammals like us), which evolved from those early chordates.
What is so Special About Pikaia?
Pikaia gracilens, a slender, ribbon-like creature, holds a special place in the study of life’s history because it’s one of the earliest known chordates.
Discovered in the Burgess Shale of British Columbia, Canada, its significance stems from the notochord, a flexible rod-like structure along its back, marking a primitive backbone.
This feature links it directly to the lineage leading to vertebrates, including all backboned animals, from fish to dinosaurs and humans, highlighting an early step in the evolutionary ladder leading to complex life forms.
Discover more fascinating insights into: what is so special about Pikaia.
When did Pikaia First Evolve?
We can only assume that Pikaia first emerged during the “Cambrian Explosion”, a period of rapid evolutionary diversification approximately 541 million years ago since we don’t have any fossil evidence of it living before that.
The Cambrian era saw the appearance of most major animal groups and set the stage for the evolution of complex ecosystems.
Pikaia thrived around 508 million years ago, during the middle Cambrian time, indicating the early origins of chordate features.
Then, it abruptly disappears from the fossil record.
Is Pikaia a Fish?
A notochord, streamlined body, gill slits and fin-like structures on the tail. When Charles Doolittle Walcott first discovered the fossils of Pikaia Gracilens in Canada’s Burgess Shale in 1911, he thought it was an annelid (worm).
When it was reclassified in the 1970s as a primitive chordate, the evolutionary precursor to vertebrates, scientists looked to see if it was linked to vertebrates like fish.
But no, Pikaia is not classified as a fish. While it shares some characteristics with modern fish, such as a notochord, it lacks other definitive fish features, like jaws, fins, and a complex brain.
Discover the full story as we explore: is Pikaia a fish?
Do Pikaia Still Exist?
Pikaia as a species, has long been extinct. There are no direct descendants of Pikaia alive today, though its closest living relatives, the cephalochordates (lancelets) give us some insights into what Pikaia must have been like in life.
Discover: Did Pikaia have bones?
What is the Closest Living Relative to the Pikaia?
The closest living relatives to Pikaia are not specific modern animals but rather the broader group of cephalochordates, which include lancelets (also known as amphioxus).
These small, fish-like marine animals share several key characteristics with Pikaia, such as a notochord and a similar body plan, providing insights into the structure and lifestyle of early chordates.
Also discover: Pikaia size.
What did Pikaia Evolve Into?
While Pikaia itself did not directly evolve into any specific modern animal, it represents an early branch of the chordate lineage that would eventually lead to vertebrates, including fish, amphibians, reptiles, birds, and mammals.
Its existence underscores the shared ancestry and evolutionary pathways that connect a wide array of life forms across the aeons.
Discover: Did humans evolve from Pikaia?
Where did the Pikaia live?
Pikaia inhabited the ancient seas of the Cambrian period, specifically in the area now known as the Burgess Shale in modern-day British Columbia, Canada. Around 508 million years ago.
This region was a deep marine environment, where Pikaia likely swam near the sea floor, feeding on microscopic particles in a world teeming with newly diversified life forms.
Fossil Locations: Where Are Cambrian Fossils Like Pikaia Found?
- Pikaia itself is only known from the Burgess Shale in British Columbia, Canada
- Yet other Cambrian sites include the Chengjiang fossil site in Yunnan Province, China
- The Wheeler Shale in the House Range of western Utah, USA
- The Sirius Passet site in North Greenland is another critical location for understanding Cambrian life.
Museum Fossils: Where can you Go to See Early Chordate and other Cambrian Fossils?
If you live nearby or can make the trip, there are a few great places to go and see some of the first animals and eumetazoans, including bilaterians, protostomes, deuterostomes and chordates, for yourself…
1. The Burgess Shale
Did you know you can actually go to the Burgess Shale fossil sites in the Canadian Rockies yourself? You can book a guided hike with The Burgess Shale Geoscience Foundation and visit the Walcott quarry, Mt. Stephen – the works.
Phone 1 (250) 343-6006, email info@burgess-shale.bc.ca or visit their website
2. Royal Ontario Museum
The Royal Ontario Museum in Toronto, Canada is famous for its connection to the world-famous Cambrian site, the Burgess Shale. They have both an amazing fossil collection if you visit in-person or even here online and a cool virtual sea odyssey you can experience online right now.
Phone: 416 586 8000 (Canada) | or visit their website
3. Smithsonian National Museum of Natural History
The Smithsonian has quite a large Cambrian fossil collection. And it’s completely free! So, if you’re ever in Washington DC, it’s one of the coolest places to go check out Cambrian fossils.
4. Chengjiang Fossil Site Natural History Museum
Being in China, it’s a bit hard to track down English info. But the Chinese government says there is a Chengjiang Fossil Site Natural History Museum. With over 60’000 fossil specimens at its location in Xincun Road, Chengjiang county, Yuxi City in Yunnan province.
5. The Natural History Museum, London, UK
With a rich collection of fossils and exhibitions that trace the history of life on Earth, the London Natural History Museum’s displays on Cambrian and Precambrian life provide context for the evolution of complex organisms.
Phone +44 (0)20 7942 5000 or visit their website.
6. Field Museum of Natural History, Chicago, USA
Boasting a broad collection of fossils and active in paleontological research, its Evolving Planet exhibition takes visitors through the history of life on Earth, including the Cambrian time.
Phone +1 312 922 9410 or visit their website.
Documentaries Featuring some of the First Chordates
They’re not always 100% accurate because we make new scientific discoveries all the time. But documentaries at least deliver the gist of the information in a fun and engaging way. Just click play, hit full screen and enjoy hours’ worth of awesome documentaries on first animals, right here…
1. Walking with Monsters
BBC, 2005
A bit older now and flashing past early animals a bit too quickly, this one in the “Walking With” series is still pretty cool for its Cambrian bits. It’s also available via Amazon.
2. Mankind Rising
2012
The 2012 TV movie production of Mankind Rising is a single animated journey from the earliest vertebrate ancestors right through to present-day humans. It’s pretty cool, maybe a bit dated, but still a lot of fun!
3. David Attenborough’s Rise of Animals: Triumph of the Vertebrates
BBC, 2013
Although more focused on the evolution of vertebrates, it’s still an awesome documentary to watch. It’s available to purchase from Amazon.
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