(Top 5) Diania cactiformis

The walking cactus

We continue to the Top and again worth talking about another Cambrian creature. This creature with plant form, it is known like a “Walking cactus”. His body is formed for 20 spiny legs (10 pairs). A naked eye this “cactus” not looking has a great importance; however, his taxonomy location is very important to understand the arthropoda origin, even not is so clear if it was a brother taxon or a primitive form. In any case, he is an interesting creature.
From another point of view, it is logic to ask: What’s so scary about a walking cactus? The answer is later, I invite you to continue reading…


Domain: Eucariota
Kingdom: Animalia
Phylum: Lobopodia
Class: Xenusia
Order: ¿?
Family: ¿?
Genus: Diania
Species: cactiformis

Picture 1. Diania cactiformis reconstruction, created by Xiaoya Ma. Taken from the ResearchGate page web: https://www.researchgate.net/figure/Reconstruction-of-Diania-cactiformis_fig4_247777382

What is?

In simple words: “Is a cactus with legs”. In not simple words: It is believed could be a primitive taxon associated with the Arthropoda origin. In the picture 1 can be observed his characteristics: ramified body with thorns on their legs, is divided for ten serially segments that joins for “rings”, bilateral symmetry, etc. Also has any characteristics that are not noticeable, for example: only has 6 centimeters of size. The genus name (Diania) is in reference to Yunna, place where it was found, about the abbreviated in Chinese language, is pronounced “Diān or Yún”. While the species name (cactiformis) is for cactus shape.

History of discovery

Diania was discovered in China for Jianni Liu, Ou Qiang and another collaborator in the Chengjiang deposit. It is found in Cambrian rocks from 520 million years ago.

Picture 2. Chengjiang location in the Yunnan province, created by Croquant, taken from Wikipedia page web: https://commons.wikimedia.org/wiki/File:Location_of_Chengjiang_within_Yunnan_(China).png

Own characteristics

Diania is an interesting animal with just long 6 centimeters. His body has spines, hence the nickname “Walking cactus”. Had a proboscis, although not as long as Opabinia, could use to feed himself. Another characteristic of Diania was are invertebrate animal (had no skeleton). Anyone smart person is wonder:

How do we know its shape if not had skeleton?

First, It’s worth to say that exist fossils from 2 types: The first is to Body Fossils, these are organisms (can be just parts) that were preserved for carbonization or permineralization, also can be to fossilize through plaster or molds. The other fossils type are the Trace fossil, as footprint, in any case, the worm tunnels or mammals tunnels. We are interested in the first, because as you can read, it is not necessarily an animal skeleton, in the case of invertebrate animals, these can fossilize through of carbonization process.

Picture 3. Amber fossilization, taken from Miguel Verde blog of the page web Paperblog: https://es.paperblog.com/fosiles-ambar-1-3217812/

Habitat and competition

Diania lived in the water of the Cambrian period, so similar to Opabinia, lived under the shadow of the great animals, for example: Anomalocaris, also is probably that lived with creatures almost as strange as him (Hallucigenia for example) without ruling out any trilobites like Redlichia takooensis.

Picture 4. Redlichia takooensis fossil. Taken from the page web: http://www.fossilmuseum.net/Fossil_Sites/Emu-Bay/Redlichia-takooensis/Trilobites-60.htm


In the beginning it’s found the unanswered question about what is the strange and scary of Diania; is a clear example of the unknown limits by the nature (not only of earth). Here on another reason of why the paleontology is so important, because Diania (same that all creatures of this top) it’s an example of that both inside and outside the planet, exist amazing and almost impossible to imagine.


— Carlto, R. L. (2018). A Concise Dictionary of Paleontology. Springer International Publishing.

— Gould, S. J., & Shale, B. (1994). La vida maravillosa. RBA.

— Liu, J., Steiner, M., Dunlop, J. A., Keupp, H., Shu, D., Ou, Q., … & Zhang, X. (2011). An armoured Cambrian lobopodian from China with arthropod-like appendages. Nature, 470(7335), 526–530.



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