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Table 2 Selected skeletal and dental characters in selected pelagic durophagous stingray genera

From: Mosaic of plesiomorphic and derived characters in an Eocene myliobatiform batomorph (Chondrichthyes, Elasmobranchii) from Italy defines a new, basal body plan in pelagic stingrays

   Promyliobatis Weissobatis Myliobatis Aetomylaeus Aetobatus
Skeletal characters
 Rostral radials   12–15 ? 7–17 7–10 10–16
 Propterygial radials (excl. rostral)   35 25 19–23 13–16 11–15
 Mesopterygial radials   10–12 ? 16–23 24–28 30–37
 Metapterygial radials   40 ? 41–52 41–53 55–66
 Total pectoral radials (excl. rostral)   87 ? 79–92 79–92 89–116
 Pelvic radials   22–23 ? 17–25 14–19 14–19
 Monospondylous trunk vertebrae (excl. synarcual)   20–22 ? 24–32 31–42 31–41
 Diplospondylous vertebrae (anterior to sting)   148 ? 34–48 5–20 13–31
 Diplospondylous vertebrae (posterior to sting)   50 ? 36–47 34–36 25–33
 Total vertebrae   218 85 +? 108–117 80–86 80–97
 Number of stings   1 1 1–3 0–2 1–2
 Compagibus laminam   absent present? absent/present present present
 Continuity pectoral - rostral radials   continuous ? continuous interrupted interrupted
 Rostral radials less developed than pectoral radials   yes ? no yes yes
 Mesopterygium   single fragmented? fragmented absent/fused absent/fused
 Puboischiadic bar   slightly arched ? slightly arched slightly arched greatly arched
Tooth characters
 Medial teeth width/length ratio Upper 3.6–4.1 6.0 3.0–7.0 4.0–18.0 10.0–13.0
Lower 3.8–4.5 6.0 3.0–5.0 4.0–18.0 6.0–11.0
 Medial teeth shape Upper slightly bent moderately bent straight to moderately bent straight to bent to M-shaped (adult) straight to M-shaped
Lower straight to slightly bent almost straight straight to moderately bent straight to strongly bent V-shaped
 Lateral tooth row number Upper 2 1 2–3 0–2 0
Lower 2 1 2–4 0–2 0
 Posterior tooth row number   1 1 1 0–1 0
 Lateral teeth shape   hexagonal/rhomboidal hexagonal/square hexagonal/square/lozenge square/lozenge –
  1. Data from Nishida [1], Hovestadt and Hovestadt-Euler [21], White et al. [61, 62, 82, 83], White [16], Hall et al. [59]. Although the mesopterygium is absent (fused to scapulocoracoid) in Aetomylaeus and Aetobatus, Hall et al. [59] considered radials not distinctly articulated with the propterygium or metapterygium as ‘mesopterygial radials’
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Zoological Letters

ISSN: 2056-306X

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