A cartilaginous structure, fish-like body and one of the first three-part brains. Chinese Cambrian fossil Myllokunmingia Fengjiaoa was not only a chordate but shows evidence of transitioning into vertebrates.
But what was Myllokunmingia exactly? When and where did it live? How was it different from Haikouichthys, and what does it teach us about the earliest stem vertebrate?
About Myllokunmingia
Myllokunmingia Class & Scientific Classification
Domain: Eukaryota
Kingdom: Animalia (Metazoa)
Subkingdom: Eumetazoa
Infrakingdom: Bilateria
Superphylum: Deuterostomia
Phylum: Chordata
Paleo Classification: Stem Vertebrate
Order: †Myllokunmingiida
Family: †Myllokunmingiidae
Genus: †Myllokunmingia
Species: †Myllokunmingia Fengjiaoa (M. fengjiaoa)
Myllokunmingia Fengjiaoa is part of the Myllokunmingiidae family, a group that diverged from chordates right before the emergence of crown-group vertebrates.
A Phylogeny of Early Chordate-Vertebrate Divergence
Myllokunmingia Time-Frame: When it Appears on Earth
The stem vertebrate Myllokunmingia Fengjiaoa appears in the fossil record during the Middle Cambrian at 518 million years ago. It was found in Yunnan, China and first described by Shu et al. in 1999.
Myllokunmingia Size Comparison with a Human Diver
Myllokunmingia Characteristics (Synapomorphies)
Much like its cousin, Haikouichthys, Myllokunmingia was found and almost immediately known to be a chordate. But closer analysis shows it has more transitional vertebrate characteristics, including:
- Vertebral elements hint at the possible evolution of cartilaginous structures around the notochord. (Note: Myllokunmingia shows no evidence of biomineralisation, so it’s definitely cartilage, not bone.)
- 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.
- Like all members of the Myllokunmingiidae family, Myllokunmingia has a clearly defined skull, albeit cartilaginous.
Notably, those are all vertebrate characteristics, placing Myllokunmingia and all of the Myllokunmingiidae family as transitional forms between chordates and vertebrates. Considered stem vertebrates, they fall just outside of the crown group of Vertebrata.
What is Myllokunmingia?
Myllokunmingia Fengjiaoa is a species of extinct stem vertebrates, a classification it shares with all members of the Myllokunmingiidae family, from the Middle Cambrian period, around 517 million years ago. It was found in the Chengjiang assemblages of Yunnan, China in 1999.
Its fossils average only 2.8cm in size and it shows no evidence of biomineralisation, so it had no actual bones, yet its cartilaginous structures show that it is a transitional form between early chordates, such as Pikaia, to true vertebrates.
How Old is Myllokunmingia?
Myllokunmingia is a fossil from the Cambrian era. It was found in rock layers from China, dating back 518 million years, meaning it is over half a billion years old.
No one would have believed there were chordates let alone vertebrates living that long ago. But now we have the fossil evidence.
Why is Myllokunmingia So Special?
Myllokunmingia teaches us about how chordates evolved into vertebrates – the lineage that would lead from awesome fish like Dunkleoseus to dinosaurs like Spinosaurus and Velociraptor all the way to mammals like us.
Before any of the Myllokunmingiidae family were found, the only fossil evidence we had of vertebrate evolution was the worm/eel-like early chordate Pikaia and then suddenly highly derived but also worm/eel-like cyclostome vertebrates like Conodonts (albeit just their teeth) and then suddenly jawless fish like Anaspida, tens of millions of years later in the Ordovician.
Finding Myllokunmingia allowed us to way more accurately trace the chordate-vertebrate transition in the much earlier Cambrian time, and clearly differentiate between the cyclostomes (our distant vertebrate relatives) and gnathostomes (jawed fishes, our early relatives),
Who are Myllokunmingia’s Closest Relatives?
Myllokunmingia is a genus within the Myllokunmingiidae family. A distinction it shares with the famous Haikouichthys and Zhongjianichthys – all of whom are shown to be stem vertebrates who diverged from the chordate-vertebrate line, just before the crown-group vertebrate appearance that led to the evolution of all backboned animals.
Also discover the unrelated and slightly larger stem vertebrate, Metaspriggina.
How is Myllokunmingia Different from Haikouichthys?
While Myllokunmingia shares many features with its cousin Haikouichthys, there are subtle differences in their anatomy. Myllokunmingia, for example, appears to have a more streamlined body and possibly fewer and more defined myomeres (muscle segments) compared to Haikouichthys, along with a slightly longer tail.
This suggests they might have had a slightly different way of swimming/moving.
Another close stem-vertebrate family relative is Zhongjianichthys.
When and Where Were Myllokunmingia Fossils Found?
Myllokunmingia fossils were discovered in the Maotianshan Shales of Yunnan Province, China and described in 1999 at virtually the same time and place as Haikouichthys.
Is Myllokunmingia The Ancestor of All Vertebrates?
Not quite. It’s more accurately described as a close relative of the lineage that would lead to all later vertebrates, including humans. Its place in the tree of life helps to fill in the evolutionary gaps, illustrating the incremental steps towards the complexity of vertebrate life.
Fossil Locations: Where Are Cambrian Fossils Like Myllokunmingia Found?
- Myllokunmingia itself is only known from the Chengjiang fossil site in Yunnan Province, China
- Yet other Cambrian sites include the Burgess Shale in British Columbia, Canada
- 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. 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.
2. 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.
3. 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
4. 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.
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 & Vertebrates
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. Mankind Rising
2012
This one’s an absolute must for Myllokunmingia fans because it starts off, right after the anchornworm-like ancestor, with a fish-like creature called “Milo” or “Myllo”, which stands for Myllokunmingiidae or possibly Myllokunmingia itself.
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!
2. Walking with Monsters
BBC, 2005
This chapter in the “Walking With” series is an absolute must for Haikouichthys fans, because it’s the main character in the Cambrian segments, facing off against the mighty Anomalocaris. It’s also available via Amazon.
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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