The Earliest Known Metazoans


In 1964 S.B. Mirsa, a graduate student at Memorial University in Newfoundland, discovered a group of well-preserved fossilized soft-body animals. Subsequent research revealed the fauna were from the Ediacaran Period 635-542 million years ago.

Ediacaran was not officially recognized as a geological period until 2004, the first new period in over 120 years. The period is named after the Ediacaran Hills in Southern Australia, which take their name from aborigine Idiyakra, “water is present”, the type locality for the fauna. Over the globe 25 localities have been discovered that possess fossils from this period. The localities are typically grouped into three types based assemblage of organisms they possess. These organisms represent the oldest known complex multicellular organisms predating the Cambrian Explosion by several million years.

The site that Mirsa discovered and described is Mistaken Point on the southern tip of Avalon Peninsula in Newfoundland. The deposit dates to 550-560 mya and of all the localities has the largest quantity of fossils. Organisms preserved here inhabited a muddy seafloor and were covered by a fine-grain volcanic ash that preserved the fossils in exquisite detail.

I mention Mistaken Point for two reasons. First the biota were deep-dwelling and well below the photosynthetic zone. Perhaps not as deep as the typical organisms we discuss here, they likely represented organisms on a continental shelf fauna. The second reason I mention this is that the recent American Society for Limnology and Oceanography meeting in St. Johns Newfoundland allowed me the oppurtunity to visit this Mecca of Science and see the fossils first hand.

20080614_0219.jpgRiver be damned! The Ediacaran awaits!

The trip require a a quarter day drive down the Newfoundland coast on the Irish Loop. A turn off the highway had colleagues and I driving down a 9 mile unpaved road in a rental hybrid poorly equipped for such an adventure. At the parking lot a 4-6 mile round trip hike is awaited us. The hike over rolling hills right on the beautiful Avalon coast while not strenuous did require wading across a sizable stream (small river?) with Newfoundland’s finest and potentially coldest waters. A hiker and son returning the opposite direction did much to curtail our enthusiasm for the site. Both expressed disappointment, claiming to see only a few small and poorly preserved things.

Thankfully the hiker and son were wrong. The Mistaken point fauna is nothing short of spectacular! The fossils are large, dense, interesting, and well-preserved. I stood in total awe realizing I was viewing a organisms that inhabited the deep 560 million years ago. These animals were the among the first complex organisms and standing there I was viewing a pivotal moment in the history of life.

Now for the best part! Below the fold are pictures of these organisms.

Spindle-Shaped Form

Spindle/Stalk Form with potential holdfast like structure

Another holdfast like structure


The best preserved Spindle-Shaped Form observed

Dr. M (1729 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, a National Science Foundation supported initiative. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (, a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web. His forthcoming book, Science of the South (, connects cultural icons of South such as pecan pie with the science behind them.

7 comments on “The Earliest Known Metazoans
  1. Way cool! I agree, they look a little like sea pens or some relative of a cnidarian.

    I can’t wait to go into the field with my kid and show him fossils. I did it all the time growing up in Iowa. Found fossil shark teeth and shells all over the place at Wildcat Dens at Maquokata Caves. Probably the best hidden wonder in the state!

  2. I had read about the Mistaken Point site in the Snowball Earth and the Eternity of Time. It is fascinating to view the amazing photographs.

  3. I couldn’t expect any lineages from 590 mya to look even remotely the same today. But ever since the April publication of a paper in Nature that identified ctenophores as the oldest multicellular lineage that we have identified, I wonder if they were around in the Ediacaran too.

  4. The discovery was made in the month of June, 1967 on one afternoon when I was hungry,tired and feeling lonely after a day’s field work and was having snacks sitting on the slab containing the imprints. More in my upcoming book “The Story of an Ordinary Indian”

  5. Nice to see that you had a chance to visit my home! I hope St. John’s was kind to you :)

  6. Yes, St. John’s was very kind to me. I had stayed in Portugal Cove South for my field work in 1967. wonderful people. I cherish my memories of those days.I am happy that you are pursuing research on the fauna so vigorously. Please change the year of discovery if possible. Best Wishes.

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