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 11.65 to 26.6 millimetres (0.459 to 1.047 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.[1]
^Izquierdo‐López, Alejandro; Caron, Jean‐Bernard (November 2021). Zhang, Xi‐Guang (ed.). "A Burgess Shale mandibulate arthropod with a pygidium: a case of convergent evolution". Papers in Palaeontology. 7 (4): 1877–1894. doi:10.1002/spp2.1366. ISSN 2056-2799. S2CID 236284813.
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...
multisegmentation with over 100 segments Unlike other hymenocarines, Pakucaris had a separate pygidium carapace covering its posterior Unlike other taxa...
new taxa including other hymenocarines like Tokummia, Fibulacaris and Pakucaris, large hurdiid radiodonts like Cambroraster and Titanokorys, as well as...
vertical – which were used to stabilise the animal as it swam on its back. Pakucaris Arthropoda Order Hymenocarina A hymenocarine that ranged in length from...
Formation Italy A horseshoe crab. Genus includes new species O. latus. Pakucaris Gen. et sp. nov Valid Izquierdo-López & Caron Cambrian (Wuliuan) Burgess...
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