Bigger and slightly easier to study, Metaspriggina Walcotti is a basal- or stem vertebrate of about 10cm in size from Canada’s famous Cambrian Burgess Shale that shows a clear transition from the basic chordate body plan to that of early vertebrates.
But it’s one of the first Cambrian fossils, so why did we know so little about it until now?
When and where did Metaspriggina live? How does it fit into the story of life on Earth? And how can this early fish-like creature tell us more about where all mammals, reptiles, birds and us humans come from?
About Metaspriggina
Metaspriggina Class & Scientific Classification
Domain: Eukaryota
Kingdom: Animalia (Metazoa)
Subkingdom: Eumetazoa
Infrakingdom: Bilateria
Superphylum: Deuterostomia
Phylum: Chordata
Paleo Classification: Stem Vertebrate (in Biology: Craniate)
Order: ??
Family: Metaspriggiidae
Genus: Metaspriggina
Species: Metaspriggina Walcotti (M. walcotti)
Metaspriggina is a Stem Vertebrate, who, along with the members of the Myllokunmingiidae family, diverged from chordates right before the emergence of crown-group vertebrates.
A Phylogeny of Early Chordate-Vertebrate Divergence
Metaspriggina Time-Frame: When it Appears on Earth
A little younger than its other Cambrian stem-vertebrate counterparts from China, the Myllokunmingiidae family, Metaspriggina Walcotti is from Canada’s famous Burgess Shale, placing its stratigraphic occurrence at 508 million years ago – about the same time as Pikaia, funny enough.
Metaspriggina Size Comparison with a Human Diver
Metaspriggina Characteristics (Synapomorphies)
Metaspriggina shares the ancestral chordate characteristics of a notochord, dorsal nerve chord and post-anal tail. But, in addition, it also has vertebrate characteristics, such as:
- Vertebral elements hint at the possible evolution of cartilaginous structures around the notochord.
- Possible lobe-like extensions in the head, with potential eyes and cavities that could be interpreted as nasal and otic (hearing) function, which is the possible development of a primitive tri-partite brain.
- A clearly defined skull, albeit likely cartilaginous.
Notably, those are all vertebrate characteristics, placing all of the Metaspriggina as a transitional form between chordates and vertebrates. Considered a stem-vertebrate, it falls just outside of the crown group of Vertebrata.
It notably also has gill bars (not just slits), the first two of which don’t seem to support gill openings (Morris et al. 2014), possibly even hinting at gnathostome ancestry.
What is Metaspriggina Exactly?
Metaspriggina Walcotti is a stem vertebrate or basal vertebrate from the Cambrian period, reminiscent of the Myllokunmingiidae family members from 518 million years ago, yet distinct in its younger age of approximately 508 million years and a larger size, reportedly around 10cm.
Unlike crown group vertebrates, Metaspriggina showcases pivotal body features that show it’s a transitionary form between chordates and vertebrates, underlining its significance in the evolutionary narrative.
These features include the chordate notochord (primitive spine), dorsal nerve chord and post-anal tail, along with the beginnings of vertebral elements, possible lobe-like extensions in the head (primitive brain), fish-like myomeres (muscle segments), a primitive braincase, and upward-facing eyes, presenting a clear depiction of its transitional form between earlier chordates and true vertebrates.
The initial discovery of Metaspriggina traces back to Charles Doolittle Walcott, who, despite finding it in his famous Burgess Shale in the early 1900s, did not describe it.
It was later in the 1970s mistakenly categorised as a relative of Spriggina, the mysterious bilaterian-seeming Ediacaran organism, reflecting the challenges in deciphering early life forms.
Only more recently has Metaspriggina been accurately recognised as a basal vertebrate, marking a critical point in understanding vertebrate evolution (Morris et al. 2014).
When did Metaspriggina live?
Metaspriggina thrived during the Cambrian period, with its presence recorded in the fossil-rich beds of the Burgess Shale, originally discovered by Walcott. The precise age of these fossils is estimated at 508 million years, making Metaspriggina a contemporary to primitive chordate Pikaia.
Subsequent findings, including at a location referred to as Marble Canyon in Canada, have enriched our understanding of its ecology.
Metaspriggina has been found in deep-water deposits, mainly in ocean floor settings, which makes sense since it has upward-facing eyes.
Though it’s noted its body plan would have allowed it to swim through the water column.
Furthermore, Metaspriggina Walcotti has only been found in rocks dating back 508 million years ago. As far as we can tell, it left no direct descendants but diverged from the chordate-vertebrate line just before the emergence of crown-group vertebrates (Vertebrata).
What does a Metaspriggina look like?
Metaspriggina’s anatomy is strikingly fish-like, setting it apart from other stem vertebrates of its era in both appearance and size. At 10cm in length, it’s 3 times larger than any of the Myllokunmingiidae family members such as Haikouichthys and Myllokunmingia from 518 million years ago.
Its body, was streamlined, suggesting an adaptation to a more active lifestyle in the Cambrian seas. The myomeres, braincase, and positioning of the eyes are notable evolutionary adaptations that hint at the evolutionary trajectory leading to modern vertebrates.
Metaspriggina Size: How big was it?
Metaspriggina’s size, larger than many of its stem-vertebrate peers, is an essential factor in its study. This larger size might have given it certain ecological advantages or reflects a particular evolutionary development stage.
The generally agreed average length of its fossils is about 10cm, making it a significant specimen for studying early vertebrate life.
Why is Metaspriggina important?
Metaspriggina is a crucial puzzle piece in the evolutionary story, offering insights into the transition from simple chordates to complex vertebrates.
Its well-preserved fossils, particularly the myomeres and braincase, provide invaluable data on the early development of key vertebrate features.
These insights help bridge gaps in our understanding of vertebrate evolution, emphasising Metaspriggina’s role as a transitional form.
When and Where Were The First Metaspriggina Fossils Found?
The first Metaspriggina fossils were unearthed in the Burgess Shale by Walcott over 100 years ago in the early 1900s. However, their significance was not immediately recognised, leading to a prolonged misunderstanding of their place in the evolutionary tree.
It wasn’t until further discoveries and analyses, especially in sites like Canada’s nearby Marble Canyon, that the true value of Metaspriggina was appreciated.
These findings underscore the dynamic nature of paleontological research and the continuous reevaluation of past life forms.
Fossil Locations: Where Are Cambrian Fossils Like Metaspriggina Found?
- Metaspriggina itself is known from the Burgess Shale and Marble Canyon sites 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 Awesome Cambrian Creatures
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. Fossil Wonderlands: Nature’s Hidden Treasures
BBC, 2014
Dr Richard Fortey, a British palaeontologist and trilobite specialist you might recognise from a few David Attenborough documentaries, explores some of the most amazing Lagerstätte fossil sites in the world.
2. 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.
3. Lost Worlds, Vanished Lives, Episode 4
BBC, 1989
Definitely old and dated, film-wise. But, apart from the almost impossible-to-track-down First Life series, this is the only one where David actually goes to Walcott’s original quarry in the Burgess Shale itself. Old as it is, the entire series is still remarkable to watch.
4. Mankind Rising
2012
The 2012 TV movie production of Mankind Rising is a single animated journey from the earliest vertebrates ancestors right through to present-day humans – it’s pretty cool, maybe a bit dated, but still a lot of fun!
5. 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.
About PrehistoricLife.co
I aim to have everything as up-to-date as possible and will continually update this post. Please notify me of any necessary updates, information you think should be included, and references or citations needed.
Enjoy the journey of discovery through Earth’s ancient past, geology, big ideas and, of course, awesome prehistoric life.
