Pakucaris

{{Short description|Extinct genus of bivalved arthropod}}

{{Speciesbox

| fossil_range = {{fossilrange|Miaolingian}}

| image = Pakucaris.png

| image_caption = Life restoration

| genus = Pakucaris

| parent_authority = Izquierdo-López & Caron, 2021

| species = apatis

| authority = Izquierdo-López & Caron, 2021

}}

Pakucaris is an extinct genus of bivalved arthropod known from a single species, Pakucaris apatis, found in the Marble Canyon locality of the Burgess Shale in British Columbia, Canada. It is thought to be a member of Hymenocarina. Unlike other members of that group, the posterior segments are covered with a separate pygidium shield, covergent on other arthropods like artiopods. Specimens range in length from {{Convert|11.65 to 26.6|mm|in}}. The main bivalved carapace covers around 80% of the body, with the pygidium covering the remaining 20%. The head has a forward and downward facing pair of moderately sized eyes on short stalks, along with three pairs of cephalic appendages. The thorax has either 30-35 or 70-80 segments, depending on the specimen, while the pygidium has either 11-13 or 20 segments. The segments of the thorax and pygidium have pairs of thin filamentous limbs divided into 20/21 podomeres, with paddle-like exopods. It was probably nektobenthic (actively swimming close to the seafloor), and its ecology was likely that of a selective suspension feeder, using its limbs to scrape and/or suspend food particles from the sea floor, before using its limbs to capture and transfer them to the mouth.{{Cite journal |last1=Izquierdo-López |first1=Alejandro |last2=Caron |first2=Jean-Bernard |date=November 2021 |editor-last=Zhang |editor-first=Xi-Guang |title=A Burgess Shale mandibulate arthropod with a pygidium: a case of convergent evolution |url=https://onlinelibrary.wiley.com/doi/10.1002/spp2.1366 |journal=Papers in Palaeontology |language=en |volume=7 |issue=4 |pages=1877–1894 |doi=10.1002/spp2.1366 |bibcode=2021PPal....7.1877I |s2cid=236284813 |issn=2056-2799|url-access=subscription }}