Proherodius oweni Lydekker ( 1891 )

DYKE, GARETH J., 2001, The Fossil Waterfowl (Aves: Anseriformes) from the Eocene of England, American Museum Novitates 3354, pp. 1-16 : 9-10

Proherodius oweni Lydekker ( 1891)

Proherodius oweni Harrison and Walker ( 1977)

Proherodius oweni Harrison and Walker ( 1978)

Owen ( 1846) illustrated and described an incomplete cranial portion of sternum (BMNH PAL 43164; fig. 6 ) as a small wading bird, and he referred to the similarity of the overlapping sulcus carinae seen on the specimen to the condition seen in living herons (family Ardeidae ). Owen ( 1846) did not name this specimen, leaving this to Lydekker ( 1891) who formally referred it to the family as the holotype of the taxon Proherodius oweni . This assignment met with the agreement of Harrison and Walker ( 1977), who described and re­figured the specimen after additional preparation.

TAXONOMIC REMARKS: Harrison and Walk­ er (1978, 1979c) remarked on the possible referral of the holotype of Proherodius oweni to the family Presbyornithidae , and they (1979c) noted that ‘‘the shape and angle of articulation of the surfaces of the coracoid sulci, in differing from those of herons, matched those of the large Headonornis hantoniensis of the Upper Eocene’’. It is unclear what to make of this remark: Harrison and Walker ( 1976) made no mention of the referral of a sternum to H. hantoniensis , and no museum catalog number was given in the later paper either (Harrison and Walker, 1979c).

The possible affinity of this specimen with the family Presbyornithidae was noted by Ericson (1999b), but in this paper the taxon name Proherodius oweni Lydekker was incorrectly attributed to Harrison and Walker ( 1978). Of the features of the sternum listed by Ericson (1999b: 4), only the character ‘‘right sulcus articularis coracoideus crossing below left past midpoint of the rostrum sterni with a ridge present between the two’’ (Howard, 1955; Ericson, 1997) is preserved in Proherodius (Harrison and Walker, 1978, 1979c). This feature was listed by Ericson (1997: 471) as present in the members of the Presbyornithidae , as well as in Phoenicopterus and Threskiornis , but absent in remaining anseriforms. However, although this specimen is of a similar size with respect to the known specimens of Presbyornis pervetus (Howard, 1955; Ericson, 1999b), the presence of crossed coracoidal sulci is widespread among basal Neornithes, seen also in Lithornithidae , for example (Houde, 1988). At present, more anatomical details are required to confirm the placement of Proherodius within Anseriformes and Presbyornithidae (Dyke, 2000) . This situation would be complicated further by the resulting synonymy of the two existing generic names— Proherodius Lydekker (Lydekker, 1891) would clearly have priority over Presbyornis Wetmore , as stated by Harrison and Walker ( 1978). At present, this material is considered to be Aves incertae sedis, because of the lack of diagnostic characters seen in the existing material.

Figures

Fig. 6. The original holotype sternum of Proherodius oweni Lydekker (BMNH PAL 43164) in right lateral view. Scale bar is 10 mm.