Myllokunmingia, Zhongjianichthys and the world-famous Haikouichthys. The tiniest and most insignificant-seeming Cambrian creatures had a world-changing impact on animal evolution on prehistoric Earth.
Meet the members of the Myllokunmingiidae family, the ones who teach us more about the deep-time origins of some of the most awesome vertebrate prehistoric creatures we know, from Dunkleosteos to T Rex to Smilodon, to the Blue Whale, all the way to us humans.
This is where vertebrates come from…
About Myllokunmingiidae
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
The Myllokunmingiidae family is a group of early transitionary stem vertebrates that diverged from chordates right before the emergence of crown-group vertebrates.
A Phylogeny of Early Chordate-Vertebrate Divergence
Myllokunmingiidae Time-Frame: When it Appears on Earth
All members of the stem-vertebrate Myllokunmingiidae family appear in the fossil record during the Middle Cambrian at 518 million years ago. They were found in Yunnan, China and first described by Shu et al. in 1999.
Myllokunmingia Size Comparison with a Human Diver
Myllokunmingiidae Characteristics (Synapomorphies)
The members of the Myllokunmingiidae family all share the ancestral chordate characteristics of a notochord, dorsal nerve chord and post-anal tail. But, in addition, most exhibit specific (or at least seem to show transitional evidence of) vertebrate characteristics, such as:
- 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 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 the Myllokunmingiidae Family Exactly?
The Myllokunmingiidae family represents a crucial phase in the evolutionary history of life on Earth, comprised of stem-vertebrates that lived during the Middle Cambrian period (518 million years ago).
These creatures were among the earliest to display vertebrate-like features, such as a notochord and dorsal nerve, along with a potential skull, brain and the beginning of vertebrae, suggesting they were on the cusp of evolving into true vertebrates.
Found primarily in China, their fossil records are pivotal for understanding the transition from simple chordates to complex vertebrate life forms.
3 Members of the Myllokunmingiidae Family
1. Myllokunmingia
Described as a small, fish-like creature, Myllokunmingia showcases primitive features that hint at the beginnings of vertebrate evolution. Its anatomical structures suggest the presence of a notochord, segmented muscles, and a simple circulatory system, marking it as a significant transitional form. Discover the age, size and characteristics of Myllokunmingia.
2. Haikouichthys
Known for its more defined vertebrate characteristics, thanks to the discovery of over 500 specimens, Haikouichthys provides evidence of early vertebral elements and a more complex organization of sensory organs.
This indicates a significant advancement in the evolutionary narrative towards more sophisticated vertebrate organisms. See the fascinating story of Haikouichthys.
3. Zhongjianichthys
Possibly the most enigmatic member of the family, Zhongjianichthys is characterized by its distinctive features, such as thicker skin and lobe-like head extensions, adding another layer to our understanding of vertebrate evolution.
Despite its small size, it plays a big role in piecing together the evolutionary puzzle of early vertebrates. Help unlock the mysteries of Zhongjianichthys.
Where was Myllokunmingia Found?
The fossils of Myllokunmingia were uncovered in the late 1990s in Yunnan Province, China. The handful of specimens indicate it lived 518 million years ago.
This discovery has provided invaluable insights into the early stages of vertebrate evolution.
When did Haikouichthys exist?
Haikouichthys, similarly, has been traced back to the same geographical region and time frame, dating back to the Middle Cambrian period, around 518 million years ago.
Who and What Lived Alongside the Myllokunmingiidae Family?
The Myllokunmingiidae family shared their habitats with a diverse array of Cambrian fauna, from various invertebrates to the earliest known echinoderms and arthropods, from Anamlocaris to Opabinia, Wiwaxia to Hallucigenia.
This period was marked by rapid diversification of life forms, with the Cambrian explosion laying the groundwork for the complex ecosystems that would follow.
What Did Myllokunmingiidae Evolve Into?
While the Myllokunmingiidae family does not have direct modern descendants, true vertebrates emerged shortly after them.
Their existence and the evolutionary traits they exhibit are crucial for understanding the lineage of vertebrates.
They represent a formative stage in the evolutionary narrative, bridging the gap between simple chordates like Pikaia and the diverse range of vertebrates present today.
When Did Myllokunmingiidae Go Extinct?
Their extinction, part of the broader Cambrian extinction events, reflects the dynamic and often volatile nature of life’s history on Earth.
Science does not have much evidence of any specific catastrophes that might have caused Cambrian mass extinctions. Life likely evolved at such apace back in those ancient seas that species turnover had to be very high to make place for what was to follow in the Ordovician.
Despite their disappearance, the legacy of the Myllokunmingiidae family continues to illuminate the path of vertebrate evolution, offering a glimpse into the intricate processes that shape the natural world.
Also discover the unrelated and slightly larger stem vertebrate, Metaspriggina.
Fossil Locations: Where Are Cambrian Fossils Like the Myllokunmingiidae Found?
- All the Myllokunmingiidae members are 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. David Attenborough’s Rise of Animals: Triumph of the Vertebrates
BBC, 2013
Although it doesn’t specifically feature any of the Myllokunmingiidae family, it is focused on the evolution of vertebrates, it’s still an awesome documentary to watch. It’s available to purchase from Amazon.
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.
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