JACANIDAE, Chenu & Des Murs, 1854

Smith, A, 2015, Sixteen vetted fossil calibrations for divergence dating of Charadriiformes (Aves, Neognathae), Palaeontologia Electronica 18 (1), pp. 1-18 : 7

CLADE JACANIDAE

Node Calibrated (4): Jacanidae (Jesus birds)

Divergence of Jacanidae (i.e., Jacana and Hydrophasianus , lily trotters) from other Scolopaci (e.g., Bartramia longicauda , Numenius minutus ; Figure 1 )

Fossil Taxon. Nupharanassa bulotorum Rasmussen et al., 1987

Specimen. DPC 3848 ( Duke Lemur Center , Division of Fossil Primates, Durham, North Carolina, USA) holotype specimen of Nupharanassa bulotorum , distal tarsometatarsus .

Phylogenetic Justification. The results of a combined phylogenetic analysis place Nupharanassa bulotorum as the sister taxon to the extant species Hydrophasianus chirurgus ( Smith, 2011a, figure 8.4). Although material referred to three Oligocene species of Jacanidae (including Nupharanassa bulotorum ) consists entirely of distal tarsometatarsi, fossil jacanid species are characterized by the “huge distal foramen, broad tendinal groove, and flattened shaft unique to this family” ( Rasmussen et al., 1987:7). The relatively enlarged distal vascular foramen was optimized as an apomorphy of Jacanidae and the possession of a broad anterior groove that extends proximally form the distal vascular foramen is optimized as an apomorphy of Jacanidae , Glareolidae , and Scolopacidae among charadriiforms sampled by Smith (2011a).

Minimum Age. Early Oligocene (Rupelian) 30.0 Ma

Soft Maximum Age. Not specified

Age Justification. Jacanidae fossils are known from quarries M and E (see Rasmussen et al., 1987) of the Jebel Qatrani Formation in Egypt, which span the period between ~33-30 Ma. That age estimate has been established using biostratigraphic, radiometric, and magnetostratigraphic correlations ( Seiffert, 2006 and references therein). Although remains of the jacanid Nupharanassa tolutaria are definitely older than Nupharanassa bulotorum , that taxon has not been included in a phylogenetic analysis and therefore, a more conservative date of 30.0 Ma is suggested to calibrate the split between Jacanidae and other Scolopaci until the affinities of Nupharanassa tolutaria are better established.

Discussion. The oldest known fossils referable to the Jacanidae , and of the Scolopaci are from the Early Oligocene Jebel Qatrani Formation of Egypt ( Rasmussen et al., 1987). However, because Nupharanassa bulotorum can be referred to a more nested position within Scolopaci, this fossil should not be used as a calibration for the split between Scolopaci and Lari. The enigmatic taxon Halcyornis topiapicus (sic, Halcyornis toliapicus ) was used by Pereira and Baker (2008) to date the minimum age of divergence between the Lari and Scolopaci. The systematic position of H. toliapicus has not been previously evaluated in a phylogenetic analysis and H. toliapicus has been previously allied with charadriiforms, coraciiforms, and stem psittaciforms (reviewed by Smith and Clarke, 2012). The isolated holotype specimen of H. toliapicus consists of an incomplete cranium, and although current evidence supports placement of this taxon in Charadriiformes , endocranial characteristics may be too ecologically plastic (i.e., potentially phylogenetically misleading) to facilitate taxonomic referrals ( Smith and Clarke, 2012). Therefore, because the true affinities of H. toliapicus remain uncertain, that specimen should not be used as a fossil calibration. Subsequently, because the taxonomic affinities of H. toliapicus remain uncertain, consideration should be given to resurrecting the taxon name Pseudasturidae Mayr 1998 for the stem Psittaciformes taxa known from Europe and North America (see Mayr, 2009; Ksepka et al., 2011).

Additional scolopacid taxa including Micropalama hesternus , Limosa gypsorum , and Numenius antiquus , have been applied as fossil calibrations within Charadriiformes ( Baker et al., 2007; Cibois et al., 2012). Although those taxa and other fragmentary remains referred to the clade likely represent examples of fossil Scolopaci (reviewed by Mayr, 2009), none of those taxa can be confidently referred to extant genera (i.e., crown Scolopaci), and those fossils should not be used to calibrate node ages until their systematic positions can be more precisely established ( Mayr, 2009; Smith, 2011a; De Pietri and Mayr, 2012).

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.