CHARADRIIFORMES (Hope, 2002)

Smith, A, 2015, Sixteen vetted fossil calibrations for divergence dating of Charadriiformes (Aves, Neognathae), Palaeontologia Electronica 18 (1), pp. 1-18 : 5-6

CLADE CROWN CHARADRIIFORMES

Node Calibrated (2): crown Charadriiformes . Divergence of Charadrii (plovers and allies) from all other Charadriiformes (i.e., the split between Charadrii and clade including the Lari and Scolopaci; Figure 1 )

Fossil Taxon. Jiliniornis huadianensis Hou and Ericson, 2002 .

Specimen. IVPP V.8323 ( Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China) holotype specimen of Jiliniornis huadianensis , humerus .

Phylogenetic Justification. The systematic position of Jiliniornis huadianensis was evaluated by Smith (2011a) in a combined analysis of morphological and molecular sequence data ( Figure 1 ). Not surprisingly, given that it could only be scored for 26 of 365 characters, Jiliniornis huadianensis was placed in a polytomy near the base of Charadriiformes along with Scolopaci and Charadrii species in the strict consensus cladogram resulting from the analysis of that taxon and extant charadriiform species ( Smith, 2011a, figure 8.7). No alternative hypothesis has been proposed linking this specimen to any clade other than Charadrii.

Minimum Age. Middle Eocene (Lutetian) 41.3 Ma Soft Maximum Age. Not specified

Age Justification. Jiliniornis huadianensis was collected from the Middle Eocene Huadian Formation in the Jilin Province, China. Because the age

of the Middle Eocene Huadian Formation is not precisely known a conservative approach was taken regarding the choice of the age prior on the node representing the split between Charadrii and the rest of the charadriiform crown clade. Although the holotype of Jiliniornis huadianensis may be older than latest Middle Eocene, an age of 41.3 Ma, corresponding to the uppermost Middle Eocene boundary (Lutetian-Bartonian boundary) is suggested as a qualitative prior on the split between Charadrii and the rest of crown Charadriiformes .

Discussion. With the exception of the putative crown charadriiform from the Middle Eocene Messel Shale of Germany (discussed above), the earliest known crown charadriiform fossil is the humerus from the Middle Eocene Huadian Formation of Jilin Province, China. The holotype specimen of Jiliniornis huadianensis (IVPP V.8323) was tentatively referred to Charadrii by Hou and Ericson (2002) and the possibility that Jiliniornis huadianensis represents a stem charadriiform cannot be completely ruled out. However, Jiliniornis huadianensis was recovered nested within Charadriiformes in the analysis of Smith (2011a; i.e., not as sister to extant charadriiforms or stem Charadriiformes ).

Charadrius sheppardianus was used by Baker et al. (2007) to date the split between Charadrius and Elseyornis + Thinornis . Not only was the date assigned to that taxon incorrect, but the affinities of Charadrius sheppardianus have not been confidently established ( Olson, 1985; Smith, 2011a; Parham et al., 2012). The holotype of C. sheppardianus (AMNH 2576) was re-examined by Ksepka and Clarke (2009), who concurred with the designation of that specimen as Aves incertae sedis by Olson (1985). Therefore, Charadrius sheppardianus should not be used as a fossil calibration in future divergence analyses.

Vanellus selysii was used a prior on the divergence between Vanellus and other closely related Charadrii by Baker et al., (2007). However, the taxonomic affinities of Vanellus selysii have not been confidently established ( Olson, 1985; Smith, 2011a).

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.