Cardiodictyon

Cardiodictyon is a genus of lobopodian known from 518 millions years old Chengjiang Lagerstätte. 525 millions years old partial fossil is also reported.[1] It has ~25 pairs of legs, each associated with a pair of dorsal plates.

Cardiodictyon
Temporal range: Early Cambrian
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
(unranked): Panarthropoda
Phylum: †"Lobopodia"
Class: †Xenusia
Order: †Archonychophora
Family: †Cardiodictyidae
Genus: †Cardiodictyon
Hou, Ramsköld, and Bergström, 1991
Type species
Cardiodictyon catenulum
Hou, Ramsköld, and Bergström, 1991

Each leg terminates in a pair of claws.[2] It may or may not have a head shield,[3] though it certainly has an expanded head.[4]

In 2022, a 518 million years old specimen of C. catenulum was researched and shown an unsegmented head and a brain composed of three separate cephalic parts.[1] However, although "three parts" in this study means prosocerebrum, protocerebrum and deutocerebrum,[1] it is different from earlier studies that referred protocerebrum, deutocerebrum and tritocerebrum as tripartite brain of arthropod, and treated posocerebrum as part of protocerebrum.[5][6]

References
  1. Strausfield, Nicholas J.; Hou, Xianguang; Sayre, Marcel E.; Hirth, Frank (24 November 2022). "The lower Cambrian lobopodian Cardiodictyon resolves the origin of euarthropod brains". Science. 378 (6622): 905–909. doi:10.1126/science.abn6264. PMID 36423269. S2CID 253839538. Retrieved 2 December 2022.
  2. Ramsköld, L., & Chen, J.-Y. (1998). Cambrian Lobopodians: Morphology and Phylogeny. In Arthropod fossils and phylogeny (pp. 107–150). New York: Columbia University Press. ISBN 978-0231096546
  3. Bergstrom, J.; Hou, X. (2001). "Cambrian Onychophora or Xenusians". Zoologischer Anzeiger. 240 (3–4): 237–245. doi:10.1078/0044-5231-00031.
  4. Jianni Liu; Jason A. Dunlop (15 March 2014). "Cambrian lobopodians: A review of recent progress in our understanding of their morphology and evolution". Palaeogeography, Palaeoclimatology, Palaeoecology. 398: 4–15. doi:10.1016/j.palaeo.2013.06.008.
  5. Lan, Tian; Zhao, Yuanlong; Zhao, Fangchen; He, You; Martinez, Pedro; Strausfeld, Nicholas J. (2021-10-11). "Leanchoiliidae reveals the ancestral organization of the stem euarthropod brain". Current Biology. 31 (19): 4397–4404.e2. doi:10.1016/j.cub.2021.07.048. ISSN 0960-9822. PMID 34416180. S2CID 237235251.
  6. Lev, Oren; Edgecombe, Gregory D; Chipman, Ariel D (2022). "Serial Homology and Segment Identity in the Arthropod Head". Integrative Organismal Biology. 4 (1): obac015. doi:10.1093/iob/obac015. ISSN 2517-4843. PMC 9128542. PMID 35620450.


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