Pygmaclypeatus

{{Speciesbox

| fossil_range = {{Fossil range|Chengjiang}}

| image = Pygmaclypeatus.tif

| image_caption = Fossils

| image2 = Pygmaclypeatus.png

| image2_caption = Life restoration

| genus = Pygmaclypeatus

| species = daziensis

| authority = Zhang et al., 2000

| parent_authority = Zhang et al., 2000

| display_parents = 3

}}

Pygmaclypeatus is a genus of trilobite-like arthropod from the Cambrian aged Chengjiang biota of southern China.{{Cite journal | last1 = Zhang | first1 = X. | last2 = Han | first2 = J. | last3 = Shu | first3 = D. | title = A New Arthropodpygmaclypeatus Daziensisfrom the Early Cambrian Chengjiang Lagerstätte, South China | journal = Journal of Paleontology | volume = 74 | issue = 5 | pages = 979 | year = 2000 | doi = 10.1666/0022-3360(2000)074<0979:ANAPDF>2.0.CO;2 | s2cid = 131279534 }} The carapace is flat and broad, and slightly shorter than it is wide, reaching a maximum width of {{Convert|17.5|mm|in}} and length of {{Convert|14|mm|in}}. The headshield makes up about 25% of the total length, and has attached a pair of antennae, as well as a pair of unstalked eyes on the top of the headshield and pair of stalked eyes attached to the underside.{{Cite journal |last=Schmidt |first=Michel |last2=Schoenemann |first2=Brigitte |last3=Hou |first3=Xianguang |last4=Melzer |first4=Roland R. |last5=Liu |first5=Yu |date=2025-02-26 |title=Pygmaclypeatus daziensis, a unique lower Cambrian arthropod with two different compound eye systems |url=https://www.nature.com/articles/s42003-025-07664-1 |journal=Communications Biology |language=en |volume=8 |issue=1 |pages=1–12 |doi=10.1038/s42003-025-07664-1 |issn=2399-3642|pmc=11865447 }} The headshield also has four pairs of biramous (two branched) limbs. The trunk has 6 tergites (segments), each associated with a pair of biramous limbs along with a terminal pygidium associated with four pairs of biramous appendages and a segmented short tailspine. The well developed paddle-like exopodites (upper branch) on the trunk and pygidium limbs along with its small size suggests that it was an effective swimmer with a strong power stroke, and that it probably had a nektobenthic mode of life, swimming close to the ocean floor. Given its delicate spinose endites ( structures projecting from the underside of the limbs) it likely only consumed soft food and organic particles. It is considered to be closely related to Retifacies from the same deposit with shared characters including a segmented tailspine. It has been placed as a member of Artiopoda, possibly along with Retifacies the earliest diverging lineage of the Trilobitomorpha.{{Cite journal |last1=Schmidt |first1=Michel |last2=Hou |first2=Xianguang |last3=Zhai |first3=Dayou |last4=Mai |first4=Huijuan |last5=Belojević |first5=Jelena |last6=Chen |first6=Xiaohan |last7=Melzer |first7=Roland R. |last8=Ortega-Hernández |first8=Javier |last9=Liu |first9=Yu |date=2021-08-19 |title=Before trilobite legs: Pygmaclypeatus daziensis reconsidered and the ancestral appendicular organization of Cambrian artiopods |url=http://biorxiv.org/lookup/doi/10.1101/2021.08.18.456779 |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |language=en |doi=10.1101/2021.08.18.456779 |s2cid=237261790|doi-access=free }}

Implied weights parsimony phylogeny after Berks et al. 2023.{{Cite journal |last1=Berks |first1=H. O. |last2=Nielsen |first2=M. L. |last3=Flannery-Sutherland |first3=J. |last4=Nielsen |first4=A. T. |last5=Park |first5=T.-Y. S. |last6=Vinther |first6=J. |year=2023 |title=A possibly deep branching artiopodan arthropod from the lower Cambrian Sirius Passet Lagerstätte (North Greenland) |journal=Papers in Palaeontology |volume=9 |issue=3 |at=e1495 |doi=10.1002/spp2.1495 |s2cid=259253098 |doi-access=free}}{{clade|{{clade

|1={{clade

|1=Thulaspis 100px

|2=Squamacula 80px

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|2={{clade

|label1=Protosutura

|1={{clade

|1=Zhiwenia 50px

|2=Australimicola

|3=Acanthomeridion 100px

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|2={{clade