Panlongia
{{Italic title}}
{{Taxobox
| name = Panlongia
| fossil_range = {{fossilrange|520|521|lowest Botomian}}
| image = Panlongia spinosa CRF.jpeg
| image_caption = Panlongia spinosa
| regnum = Animalia
| phylum = Arthropoda
| classis = Artiopoda
| ordo = Nektaspida
| familia = Incertae sedis
| genus = Panlongia
| genus_authority = Liu et al., 2006
| subdivision_ranks = Species
| subdivision =
}}
Panlongia was a small-sized marine arthropod. Panlongia lived during the late Lower Cambrian (Botomian) in what is today South China. The genus consists of two species, P. spinosa and P. tetranodus.{{cite journal|last1=Liu|first1=Q.|last2=Luo|first2=H.-L.|last3=Chen|first3=L.-Z.|last4=Lu|first4=S.-X.|year=2006|title=Panlongia, a new trilobitomorph genus from the Lower Cambrian, Kunming, Yunnan|journal=Acta Palaeontologica Sinica|volume= 45|pages=384–392}}
Description
Panlongia is a flat, {{cvt|2|cm|1}} long nektaspid, with an oval-shaped non-calcified exoskeleton. Both the head shield (or cephalon) and the tail shield (or pygidium) are semi-circular. In between the cephalon and pygidium are four thoracic body segments (somites). The cephalon occupies approximately ⅓ of the body length, the thorax ¼ and pygidium about 45%.
In Panlongia spinosa, the edge of the exoskeleton carries several small sawtooth-like spines, that are absent in P. tetranodusa.
File:Panlongia_tetranodusa_reconstruction.png|Panlongia tetranodusa reconstruction
Distribution
- Panlongia spinosa is found in the late Lower Cambrian (Botomian) of China (Wulongqing Formation, only at Gaoloufang Kgs-2).
- Panlongia tetranodusa occurs in the late Lower Cambrian (Botomian) of China (Wulongqing Formation, Gaoloufang Kgs-1, and Shijiangjun Wsh-14, Wuding County, Yunnan, "Guanshan fauna").
Taxonomy
The phylogenetic position of Panlongia remained uncertain due to the lack of appendages until 2024, when more well-preserved specimens with appendages narrowed its placement down to as a nektaspid. {{cite journal |last1=Luo |first1=Shengxiang |last2=Liu |first2=Jianni |title=Exceptionally preserved Panlongia tetranodusa from the early Cambrian sheds light on the evolution of arthropods |journal=Science Bulletin |date=February 2024 |volume=69 |issue=3 |pages=308–313 |doi=10.1016/j.scib.2023.11.043|pmid=38057233 |bibcode=2024SciBu..69..308L }}
Ecology
Panlongia tetranodusa occurs with the coeloscleritophoran Allonia sp., the vetulicolian Vetulicola gangtoucunensis, lingulate brachiopods Lingulellotreta malongensis, Diandongia pista, Acrothele rara, and Westonia gubaiensis; radiodonts Houcaris saron and Guanshancaris kunmingensis, hyolith Linevitus malongensis, eocrinoid Wudingeocrinus rarus, Trilobites Redlichia yunnanensis, R. mansuyi, R. noetlingi, R. conica, R. shijiangjunensis, Palaeolenus douvillei, and P. lantenoisi; crustaceans: Tuzoia sinensis, T. tylodesa, Branchiocaris sp., Liangshanella liangshanensis, and Neokunmingella sp., and several other arthropods like Longquania bispinosa, Guangweicaris spinatus; Leanchoilia illecebrosa, Isoxys minor and I. wudingensis.