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An early C ambrian chelicerate from the E mu B ay S hale, S outh A ustralia
Author(s) -
Jago James B.,
GarcíaBellido Diego C.,
Gehling James G.
Publication year - 2016
Publication title -
palaeontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.69
H-Index - 63
eISSN - 1475-4983
pISSN - 0031-0239
DOI - 10.1111/pala.12243
Subject(s) - telson , appendage , trilobite , anatomy , biology , leech , crustacean , paleontology , zoology , carapace , ordovician , world wide web , computer science
The E mu B ay S hale L agerstätte ( C ambrian Series 2, Stage 4) occurs on the north coast of K angaroo I sland, S outh A ustralia. Over 50 species are known from here, including trilobites and non‐biomineralized arthropods, palaeoscolecids, a lobopodian, a polychaete, vetulicolians, nectocaridids, hyoliths, brachiopods, sponges and chancelloriids. A new chelicerate, W isangocaris barbarahardyae gen. et sp. nov., is described herein, based on a collection of some 270 specimens. It is up to 60 mm long, with the length of the cephalic shield comprising about 30% that of the exoskeleton. The cephalic margin has three pairs of bilaterally‐symmetrical small triangular spines. A pair of small eyes is placed well forwards on the ventral margin of the cephalic shield. The trunk comprises 11 segments that increase in length while narrowing posteriorly, each possibly bearing a pair of biramous appendages; the most posterior segment is almost square whereas the others are transversely elongated. The spatulate telson is proportionately longer than in taxa such as S anctacaris , U tahcaris and L eanchoilia . Up to eight (?four pairs) of 3 mm‐long elements bearing alternating inward‐curving short and long spines beneath the cephalic shield are interpreted as basipodal gnathobases, part of a complex feeding apparatus. A well‐developed gut includes a stomach within the cephalic shield; it extends to the base of the telson. In a few specimens there are shell fragments within the gut, including those of the trilobite E staingia bilobata (the most common species in the biota); these fragments have sharp margins and extend across the gut lumen. The species may have been a predator or a scavenger, ingesting material already broken up by a larger predator/scavenger. The morphology of this taxon shares many overall body features with S anctacaris , and some with S idneyia, particularly its gnathobasic complex. These chelicerate affinities are corroborated by phylogenetic analyses.