An evolutionary giant you could hold in your hand. Although not a direct ancestor, the fossils of Pikaia Gracilens that lived in the Cambrian seas over 500 million years ago, give us insights into the early chordates that would give rise to the largest and most spectacular animals ever to walk the Earth – the vertebrates.
But how big was Pikaia itself?
We discover: Pikaia size, weight and evolutionary impact…
What was Pikaia Size and Weight?
Pikaia gracilens was a relatively small creature. The handful of Cambrian fossils we have of this early chordate measure on average around 4cm. With the largest specimens at 5cm (about 2 inches) in size.
That is Pikaia size. As for its weight, precise measurements are challenging, because it was so small and soft-bodied.
However, when comparing Pikaia’s size with similar modern organisms, it would have been very lightweight, likely only a few grams.
What Time Period Did It Live?
Pikaia lived during the Cambrian period, approximately 505/508 million years ago. This era, known as the Cambrian Explosion, saw the rapid emergence and diversification of complex multicellular life.
Is Pikaia a Fish?
While it shares some characteristics with fish, such as a notochord (a primitive backbone), it lacks definitive fish features like fins, gills, and a complex organ system, placing it among early non-vertebrate chordates.
Get more insights as we explore: Is Pikaia a fish?
What Was Pikaia’s Diet?
Pikaia likely fed on small particles or microorganisms in the water. Its body plan suggests it was a filter feeder or maybe a scavenger, ingesting organic matter suspended in the water or settled on the ocean floor.
Discover all about Pikaia’s diet.
Is Pikaia a Vertebrate?
No, Pikaia is not considered a vertebrate. It might have had a notochord and dorsal nerve chord (the precursors to our backbones) but it lacked a true backbone or vertebrae.
The presence of a notochord places it within the chordate lineage, though, which includes vertebrates, but Pikaia itself predates the evolution of vertebrate features.
How Do You Describe Pikaia’s Anatomy?
Pikaia‘s anatomy was simple yet significant for its time. It possessed a notochord, a dorsal nerve cord, and myomeres (muscle segments), resembling the basic body plan of chordates.
Its elongated, ribbon-like body was bilaterally symmetrical, making it a bilaterian, of course, with a series of chevron-shaped muscle blocks and a tail fin for movement.
What Is So Special About Pikaia?
Pikaia is special because it represents one of the earliest known chordates, providing key insights into the evolutionary origins of vertebrates, including everything from fish to dinosaurs, mammals and us humans.
Its existence during the Cambrian time makes it a crucial piece in understanding the early development of complex life forms.
Find out more: What is so special about Pikaia?
What Did the Pikaia Look Like?
Pikaia resembled a small, slender aquatic worm/eel with a flattened body. It had a distinct head region, though without eyes, and a tail fin that likely aided in its swimming.
The body featured visible segments, indicative of its muscle structure.
What Is the Closest Living Relative to the Pikaia?
The closest living relatives to Pikaia are cephalochordates, such as lancelets (Amphioxus). These small, fish-like marine animals share several anatomical features with Pikaia, including the notochord and a similar overall body plan.
It’s also about Pikaia size, just 4-5cm at most.
Does Pikaia Have Eyes?
There is no direct evidence to suggest that Pikaia had eyes. Just look at the Pikaia size indicators, it was a mere 5cm in length. The fossil record does not clearly show features such as eyes, which are not typically preserved in soft-bodied creatures like Pikaia.
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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