Biology:Fuxianhuiida

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Fuxianhuiida is an extinct clade of arthropods from the Cambrian of China. All currently known species are from Cambrian Series 2 aged deposits in Yunnan Province, including the Chengjiang biota.[1] They are known from several specimens with exceptional soft-tissue preservation, including remnants of nerve and brain tissue.[2]

Description

Diagrammatic reconstruction of Alacaris, with the underside of the head of Chengjiangocaris bottom right.
Fossil of Fuxianhuia

Fuxianhuiids reached a size of up to 15 centimetres (5.9 in). The fuxianhuiid exoskeleton was unmineralised, and the number of tergites (plates on the back associated with body segments) ranged from 15 to over 40. The cephalon (head section) was covered by a heart-shaped head shield, and contained stalked eyes connected by the anterior sclerite (a plate-like structure attached to the head), a pair of antennae, and a butterfly shaped hypostome (a plate-like structure), which covered the posterior-facing mouth. Fuxianhuiids possessed specialized appendages near the front of the body posterior to the antennae with serrated edges used for food processing, with chengjiangocardids having gnathobases (basal segments of the limbs close to where they connect with the body with sturdy, thick spines), used for processing food. To the underside of the body were attached numerous pairs of two-branched (biramous) limbs, with the lower branches (the endopods), which served as walking legs, having at least 10 segments (podomeres) and were generally short and similar in appearance to each other along the length of the body, with the frontmost legs of chenjiangocaridids ending in pronounced claws, while the upper branches (the exopods) of fuxianhuiids were flap-shaped.[2] In most fuxianhuiids, the thorax tergites narrowed posteriorly, terminating in either a swimming paddle or paired flukes with a tail spine. In members of Fuxianhuiidae the thorax was divided into two sections, the front wide opisthothorax and the posterior narrow limbless tail-like abdomen.[2]

Labelled diagram of Fuxianhuia

A number of specimens are known with exceptional soft tissue preservation, including preserved guts and neural tissue including brain anatomy, which given their historically assumed basal phylogenetic position has made them a considerable focus of paleoneuranatomy research.[3][4] Fuxianhuiids had a straight gut tract that ran along the length of the body, with the sides of the gut tract of Fuxianhuia having pairs of lobe-shaped pockets (diverticulae) associated with each body segment.[5] The ventral nerve cord, which in arthropods functions analogously to the vertebrate spinal cord, has reported to have been found preserved in a specimen of Chengjiangocaris,[3] though the degree of certainty of this identification was later questioned.[4] The brains of fuxianhuiids, based on an exceptionally preserved specimen of Fuxianhuia are suggested to have been composed of three parts (tri-partite) and to have been relatively complex.[2][4]

Paleobiology

Life restoration of Fuxianhuia, engaging in parental care of offspring, as inferred from the fossil record

Fuxianhuiids are interpreted as benthic (seafloor dwelling) animals.[2] Although initially interpreted as passive animals that ingested mud to feed on seafloor detritus,[5][2] they are now considered to have probably been scavengers and possibly predators of slow moving prey such as worms.[2] The presence of gnathobases in members of Chengjiangocardidae suggests that they were capable of durophagy (crushing hard prey).[1] A specimen of Fuxianhuia was found with the remains of the trilobite Pagetia in its gut tract, indicating that it took relatively hard prey at least on occasion.[6][1] The diverticulae in the gut tract of Fuxianhuia may indicate that it only intermittently fed.[2] As fuxianhuiids grew, new segments were added to the posterior of the body. The findings of somewhat advanced juvenile individuals of Fuxianhuia associated with adults suggests that in this taxon the juveniles were subject to extended post-hatching parental care.[7]

Taxonomy

Internal taxonomy of Fuxianhuiida per Liu et al., 2020:[8]

 
Fuxianhuiida
 
 

Shankouia

 
 

Liangwangshania

 
 
 
Chengjiangocarididae
 

Alacaris 100px

 
 

Chengjiangocaris 100px

 
 
Fuxianhuiidae
 

Fuxianhuia 100px

 
 
 

Guangweicaris 100px

 
 

Xiaocaris

 
 
 
 
 
 

It has been suggested that Shankouia zhenghei is synonymous with Liangwangshania biloba, with sexual dimorphism accounting for variation between specimens.[9]

Relationship with other arthropods

Although historically suggested to be members of the arthropod stem group,[1] studies from the early 2020s onwards have supported their placement as closely related to living mandibulates, which include crustaceans, insects, and Myriapoda (the group which contains centipedes and millipedes, among others), due to the suggestion that their head feeding appendages are homologous to the mandibles of mandibulates.[10][11][12][13][14][15] Cladogram of the position of Fuxianhuiida in relation to living and extinct arthropods after O’Flynn et al, 2023:[11]

Total group Arthropoda
 

"Gilled lobopodians" (Pambdelurion, Kerygmachela)100px

 
 
 

Opabinia 100px

 
 
 

Radiodonta (e.g Anomalocaris) 100 px

 
Deuteropoda
 
 

Kylinxia 100px

 
 

Fengzhengia 100px

 
 
 
 
 

Kiisortoqia 100px

 
 

Bushizheia 100px

 
 
 
 

Megacheira 100 px

 
 
 

Habeliida 100px

 
 
 

Mollisonia 100px

 
 

Chelicerata (horseshoe crabs, sea spiders, arachnids, etc) 100px

 
 
 
 
 
 
 

"Great appendage bivalved forms" (Occacaris, Forfexicaris)

 
 

Isoxyida 100 px

 
 
 
 

Artiopoda (including Trilobita) 100 px

 
Mandibulata
 

Fuxianhuiida 100 px

 
 
 

Myriapoda (millipedes, centipedes, etc) 100px

 
 
 

Hymenocarina 100px

 
 

Pancrustacea (crustaceans, insects, etc)

 
 
 
 
 
 
 
 
 
 
 

References

  1. ↑ 1.0 1.1 1.2 1.3 Yang, Jie; Ortega-Hernández, Javier; Legg, David A.; Lan, Tian; Hou, Jin-bo; Zhang, Xi-guang (2018-02-01). "Early Cambrian fuxianhuiids from China reveal origin of the gnathobasic protopodite in euarthropods". Nature Communications 9 (1): 470. doi:10.1038/s41467-017-02754-z. ISSN 2041-1723. PMID 29391458. Bibcode: 2018NatCo...9..470Y. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Ortega-Hernández, Javier; Yang, Jie; Zhang, Xi-guang (2018-07-01). "Fuxianhuiids" (in en). Current Biology 28 (13): R724–R725. doi:10.1016/j.cub.2018.04.042. PMID 29990450. Bibcode: 2018CBio...28.R724O. 
  3. ↑ 3.0 3.1 Yang, Jie; Ortega-Hernández, Javier; Butterfield, Nicholas J.; Liu, Yu; Boyan, George S.; Hou, Jin-bo; Lan, Tian; Zhang, Xi-guang (2016-03-15). "Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda" (in en). Proceedings of the National Academy of Sciences 113 (11): 2988–2993. doi:10.1073/pnas.1522434113. ISSN 0027-8424. PMID 26933218. Bibcode: 2016PNAS..113.2988Y. 
  4. ↑ 4.0 4.1 4.2 Aria, Cédric; Vannier, Jean; Park, Tae-Yoon S.; Gaines, Robert R. (March 2023). "Interpreting fossilized nervous tissues" (in en). BioEssays 45 (3). doi:10.1002/bies.202200167. ISSN 0265-9247. PMID 36693795. https://onlinelibrary.wiley.com/doi/10.1002/bies.202200167. 
  5. ↑ 5.0 5.1 Ortega-Hernández, Javier; Fu, Dongjing; Zhang, Xingliang; Shu, Degan (2018-02-19). "Gut glands illuminate trunk segmentation in Cambrian fuxianhuiids" (in English). Current Biology 28 (4): R146–R147. doi:10.1016/j.cub.2018.01.040. ISSN 0960-9822. PMID 29462577. Bibcode: 2018CBio...28.R146O. https://www.cell.com/current-biology/abstract/S0960-9822(18)30073-3. 
  6. ↑ Zhu, M.–Y.; Vannier, J.; Iten, H. V.; Zhao, Y.–L. (2004-08-07). "Direct evidence for predation on trilobites in the Cambrian" (in en). Proceedings of the Royal Society of London. Series B: Biological Sciences 271 (suppl_5): S277-80. doi:10.1098/rsbl.2004.0194. ISSN 0962-8452. PMID 15503993. 
  7. ↑ Fu, Dongjing; Ortega-Hernández, Javier; Daley, Allison C; Zhang, Xingliang; Shu, Degan (December 2018). "Anamorphic development and extended parental care in a 520 million-year-old stem-group euarthropod from China" (in en). BMC Evolutionary Biology 18 (1). doi:10.1186/s12862-018-1262-6. ISSN 1471-2148. PMID 30268090. Bibcode: 2018BMCEE..18..147F. 
  8. ↑ Liu, Yu; Ortega-Hernández, Javier; Chen, Hong; Mai, Huijuan; Zhai, Dayou; Hou, Xianguang (1 June 2020). "Computed tomography sheds new light on the affinities of the enigmatic euarthropod Jianshania furcatus from the early Cambrian Chengjiang biota" (in en). BMC Evolutionary Biology 20 (1): 62. doi:10.1186/s12862-020-01625-4. ISSN 1471-2148. PMID 32487135. Bibcode: 2020BMCEE..20...62L. 
  9. ↑ Chen, Ailin; Chen, Hong; Legg, David A.; Liu, Yu; Hou, Xian-guang (September 2018). "A redescription of Liangwangshania biloba Chen, 2005, from the Chengjiang biota (Cambrian, China), with a discussion of possible sexual dimorphism in fuxianhuiid arthropods" (in en). Arthropod Structure & Development 47 (5): 552–561. doi:10.1016/j.asd.2018.08.001. PMID 30125735. Bibcode: 2018ArtSD..47..552C. 
  10. ↑ Aria, C.; Zhao, F.; Zhu, M. (2021). "Fuxianhuiids are mandibulates and share affinities with total-group Myriapoda". Journal of the Geological Society 178 (5). doi:10.1144/jgs2020-246. Bibcode: 2021JGSoc.178..246A. 
  11. ↑ 11.0 11.1 O’Flynn, Robert J.; Liu, Yu; Hou, Xianguang; Mai, Huijuan; Yu, Mengxiao; Zhuang, Songling; Williams, Mark; Guo, Jin et al. (August 2023). "The early Cambrian Kylinxia zhangi and evolution of the arthropod head". Current Biology 33 (18): 4006–4013.e2. doi:10.1016/j.cub.2023.08.022. ISSN 0960-9822. PMID 37643622. Bibcode: 2023CBio...33E4006O. http://dx.doi.org/10.1016/j.cub.2023.08.022. 
  12. ↑ Izquierdo-López, Alejandro; Caron, Jean-Bernard (August 2024). "The Cambrian Odaraia alata and the colonization of nektonic suspension-feeding niches by early mandibulates" (in en). Proceedings of the Royal Society B: Biological Sciences 291 (2027). doi:10.1098/rspb.2024.0622. ISSN 1471-2954. PMID 39043240. 
  13. ↑ Pulsipher, Mikaela A.; Anderson, Evan P.; Wright, Lauren S.; Kluessendorf, Joanne; Mikulic, Donald G.; Schiffbauer, James D. (2022-12-31). "Description of Acheronauta gen. nov., a possible mandibulate from the Silurian Waukesha Lagerstätte, Wisconsin, USA" (in en). Journal of Systematic Palaeontology 20 (1): 1–24. doi:10.1080/14772019.2022.2109216. ISSN 1477-2019. https://www.tandfonline.com/doi/full/10.1080/14772019.2022.2109216. 
  14. ↑ Strausfeld, Nicholas J.; Andrew, David R.; Hou, Xianguang; Hirth, Frank (2025-08-28). "Brain anatomy of the Cambrian fossil Jianfengia multisegmentalis informs euarthropod phylogeny" (in en). Nature Communications 16 (1). doi:10.1038/s41467-025-62849-w. ISSN 2041-1723. PMID 40877252. Bibcode: 2025NatCo..16.7938S. 
  15. ↑ Liu, Yao; Zeng, Han; Zhao, Fangchen; Zhu, Yuyan; Li, Yimeng; Yin, Zongjun; Zhu, Maoyan (2025-05-31). "A tiny Cambrian stem-mandibulate reveals independent evolution of limb tagmatization and specialization in early euarthropods" (in en). Scientific Reports 15 (1). doi:10.1038/s41598-025-03544-0. ISSN 2045-2322. PMID 40450053. Bibcode: 2025NatSR..1519115L. 

Wikidata ☰ Q89800970 entry



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