TURNICIDAE

Smith, A, 2015, Sixteen vetted fossil calibrations for divergence dating of Charadriiformes (Aves, Neognathae), Palaeontologia Electronica 18 (1), pp. 1-18 : 8

CLADE TURNICIDAE

Node Calibrated (6): Turnicidae (buttonquail). Divergence of Turnicidae (buttonquails) from Lari (gulls, terns, alcids, and skimmers; Figure 1 ) Fossil Taxon. Turnipax oechslerorum Mayr and Knopf, 2007

Specimen. SMF Av 506a+b (Forschungsinstitut Senckenberg, Frankfurt, Germany) holotype specimen of Turnipax oechslerorum , partial postcranial skeleton .

Phylogenetic Justification. Turnipax represents the stem lineage of Turnicidae (buttonquails) and was originally referred to that clade based on apomorphic characters of the coracoid, scapula, furcula, and humerus ( Mayr, 2000). In addition to characters cited by Mayr (2000), Mayr and Knopf (2007:775) cited the following apomorphies that support referral of species of Turnipax to Turnicidae : (1) impressio musculi sternocoracoidei on extremitas sternalis of coracoid deeply excavated; (2) processus procoracoideus very broad; (3) caudal margin of sternum with single pair of incisions; (4) incisura capitis of humerus with transverse ridge; (5) incisions in caudal margin of sternum proportionally shorter; (6) ulna long and slender; (7) carpometacarpus elongate, with straight os metacarpale minus; (8) presence of a short hallux. Although Turnipax oechslerorum has not been included in a phylogenetic analysis, no alternative hypothesis has been proposed linking this taxon to any clade other than Turnicidae .

Minimum Age. Early Oligocene (Rupelian) 30.0 Ma

Soft Maximum Age. Not specified

Age Justification. Geologic studies of the clay deposits of Frauenweiler, Germany have dated them to the Early Oligocene (MP22) and established an absolute age of 32.0-30.0 Ma for those deposits based on micropaleontological correlations ( Micklich and Hildebrandt, 2005).

Discussion. Although the systematic affinities of buttonquail have long been disputed (i.e., alternatively considered part of Charadriiformes, Gruiformes , or Galliformes; del Hoyo et al., 1996), recent molecular sequence based analyses support Turnicidae as part of Charadriiformes ( Baker et al., 2007; Hackett et al., 2008). Although fossils of Turnicidae (i.e., stem buttonquail) are known from the Early Oligocene (~32 Ma) of France and Germany ( Mayr, 2000; Mayr and Knopf, 2007), the systematic placement of the extant taxon Turnix remains an issue of contention ( Baker et al., 2007; Hackett et al., 2008; Livezey, 2009, 2010). Therefore the node at which Turnipax oechslerorum is applied as a fossil calibration will depend on the topology of the phylogenetic tree being dated. The results of Baker et al. (2007) and Hackett et al. (2008) are congruent in their placement of Turnix as the sister taxon to Lari, and Turnipax oechslerorum is herein suggested as a potential fossil calibration for that node (i.e., the split between Turnix and Lari). Although, a more nested node within Lari can be assigned an older date ( Alcidae divergence from Stercorariidae ; see below), the systematic position of Turnicidae remains an issue of contention. Therefore, as stated above, use of Turnipax oechslerorum as a fossil calibration will depend on the hypothesis of relationships.

Figures

FIGURE 1. Phylogram of charadriiform relationships showing calibrated nodes 1-7 (modified from Baker et al., 2007, figure 1). Numbered nodes in red correspond to the following calibrations: (1) divergence of Charadriiformes from its nearest outgroup; (2) divergence of Charadrii from other Charadriiformes; (3) divergence of Burhinidae from Chionis and Pluvianellus; (4) divergence of Jacanidae from other Scolopaci; (5) basal divergence among Calidridinae; (6) divergence of Turnicidae from Lari; (7) basal divergence of Laromorphae; (8) divergence of Alcidae from Stercorariidae.