Remarkable new Cambrian fossils comparable to those of the Burgess shale

Greetings from Amsterdam!

I want to call your attention to a remarkable new fossil find in southern China; a rich group of soft-bodied animals, the “Qingjiang Fauna”, from about 518 million years ago. It’s comparable in importance to the Burgess Shale fauna popularized by Steve Gould’s book Wonderful Life, and to the Chengjiang fauna China from China. They’re of comparable age, too: The Burgess fauna is 508 million years old, and the new Qingjiang finds are 518 mya, the same age as the Chenjiang fauna. Yet the animals of the two later finds, despite being similar in age and marine habitat, are very different (see below).

You might be able to read this new paper if you have the legal Unpayall application, or you can try getting the pdf here. (I’m in the Netherlands and unable to send pdfs.) There’s also a News and Views piece by Allison Daley, “A treasure trove of Cambrian fossils,” that gives a one-page overview.

The paper:

The fossils are soft-bodied, preserved as exquisitely detailed carbon films on gray “claystone”: sediments interspersed between non-fossil-bearing black claystone. The fossil layers are seen as the light gray bands on the right side of the following picture (site of fossil finds in China are on the left).

From paper: Fig. 1 Locality map and early Cambrian stratigraphy of the study area. (A) Lithofacies map of the Yangtze Platform during Cambrian Stage 3, with type localities of the Qingjiang and Chengjiang biotas. (B) Geological map of the study area, showing the distribution of Cambrian outcrops and the location of studied sections with characteristic couplets of background and event claystone beds within the middle member of the Shuijingtuo Formation. (C) Composite stratigraphic column for the study area. (D) Stratigraphic column at the Jinyangkou type locality.

The fossils were formed in a manner similar to those of the Burgess-Shale fauna. They were one-off gravity flows”, or avalanches, of shallow sea sediments that carried animals and algae to a deeper, oxygen-poor location where they were rapidly covered up and then remained undisturbed by waves above. The animals’ body impressions weren’t replaced by minerals, but were turned into carbonized films that show exquisite detail.

And what detail, and what a variety of animals! Sponges, coelenterates (cnidarians), algae, ctenophores, kinorhynchs (“mud dragons”, found only once before as an early fossil), arthropods, brachiopods, priapulid worms, and even a chordate, a member of our own phylum, resembling the remarkable Pikaia fossil found in the Burgess shale.  There are also a number of tiny larvae, and these aren’t easily placed as to the group because they metamorphose into something that looks very different.

Remarkably, 53% of these fossils belong to previously unknown taxa, making this truly the “treasure trove” described by Daley. Look at these fossils! Note the chordate, possibly along the lineage to our own ancestry, in F.

Fig 2 (from paper). Fig. 2 New soft-bodied taxa from the Qingjiang biota. (A) Medusoid cnidarian, showing radially symmetrical body plan, exumbrellar/subumbrellar surfaces (Eu/Su), manubrium (Ma), and tentacles (Te). (B) Polypoid cnidarian, showing oral disc and mouth (Mo), tentacles, column, and pedal disc (Pd). (C) Ctenophore, showing that comb rows and oral-aboral body axis have a biradial symmetry resulting from sheathed tentacles. (D) Branched alga, showing quadripartite thallus. (E) Sponge Leptomitella sp. (F) New chordate. (G) Yunnanozoon sp.

Look at the remarkable arthropod Leanchoilia in (A) to see the detail of these fossils. Every leg and feeler is preserved.

More details of the above; you can see every bristle on the kinorhynch (right). The cnidarian is on the left and the ctenophore’s in the middle.

Curiously, the fauna isn’t all that similar to that of the Chenjiang fauna that was preserved about the same time. This new fauna, for example, has far more cnidarians (jellyfish, anemones, etc.) and far more kinorhynchs than does the Chengjian samples. As the authors note, “Only a small number of species (n = 8) are shared with Chengjiang (materials and methods), and the most abundant taxa, Kunmingella and Maotianshania, as well as the iconic Fuxianhuia, are absent from the Qingjiang assemblage.”

The authors suggest that these differences represent not different artifacts of preservation but a real difference in the nature of the fauna between the two areas. They could be from different depths in the ocean.

Here’s a reconstruction of the fauna from the original paper:

Fig. 4 from paper. Artist’s rendering of the Qingjiang biota showing characteristic early Cambrian taxa from the Lagerstätte.

The potential of this find is immense, but of course not yet tapped. It could help reconstruct the history of life and the potential of various suggested group—like the ctenophores—to be part of our own ancestry.  And of course there’s the new fishlike chordate above.  Daley sums up this potential in her news and views piece:

One of the most remarkable findings reported by Fu et al. is that 53% of the animals and algae in the Qingjiang biota represent previously unknown taxa. When these taxa are described in detail, the Qingjiang biota will help to illuminate the reasons for faunal variation between localities. The Burgess Shale and the Chengjiang biota, for example, have some similarities in the overall type and abundance of animals found at each site, but only 15% of genera are found at both localities.

. . . Fu et al. convincingly demonstrate that the Qingjiang biota represents an assemblage of organisms that was preserved nearly in place, providing a snapshot of a real animal community 518 million years ago. The treasure trove of the Qingjiang biota provides an exciting opportunity to explore how paleoenvironmental conditions influenced ecological structuring and evolutionary drivers during the Cambrian Explosion.

Now, on to the Poezenboot!

h/t: Barry

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Fu, D., G. Tong, T. Dai, W. Liu, Y. Yang, Y. Zhang, L. Cui, L. Li, H. Yun, Y. Wu, A. Sun, C. Liu, W. Pei, R. R. Gaines, and X. Zhang. 2019. The Qingjiang biota—A Burgess Shale–type fossil Lagerstätte from the early Cambrian of South China. Science 363:1338-1342.