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Table 1 Comparison of frontal appendage characters in select hurdiid and tamisiocaridid genera

From: First report of paired ventral endites in a hurdiid radiodont

  Shaft endite(s) Endite morphology and orientation (Fig. 1d, e or Fig. 6b) Auxiliary spines/ setae #pd with elongate endites in d.a.r. Shape of arthrodial membrane Refs
Aegirocassis Elongate, bears proximally facing auxiliary spines 1e Dist 5 Straight [10]
Hurdia Reduced, distally pointing 1e Dist 5 Straight [18, 24, 29]
Pahvantia Two, recurved, with auxiliary spines on distal margin 1e Dist 5 Straight [16]
Peytoia Absent 1e Dist 5 Straight [29]
Peytoia? (?Laggania of Daley & Budd 2010) Elongate, with no auxiliary spines 1e Dist 5 Straight [22]
Stanleycaris Very reduced, distally pointing 1e Dist 5 Straight [30, 37]
Ursulinacaris Elongate, with no auxiliary spines, distally pointing 6b Dist 5 Straight this study
Tamisiocaris Elongate spine with no auxiliary spines 1d Dist and proxa 17 Triangular [11, 23]
Anomalocaris briggsi Wide and short, bearing auxiliary spines on distal and proximal margins 1d Dist and prox 12 Triangular [7]
  1. aNo auxiliary spines are known in Tamisiocaris from the Kinzers Formation, however this could be the result of taphonomic removal [28]. Abbreviations: d.a.r distal articulated region, dist distal margin of endite, prox proximal margin of endite, Refs references