Ciconia sp. Brisson, 1760

Dyke, Gareth J. & Walker, Cyril A., 2008, New Records of Fossil ‘ Waterbirds’ from the Miocene of Kenya, American Museum Novitates 3610 (1), pp. 1-12 : 8

publication ID	https://doi.org/ 10.1206/0003-0082(2008)3610[1:NROFWF]2.0.CO;2
persistent identifier	https://treatment.plazi.org/id/C6648790-FFD3-2C11-FF3F-0BB8FC8DF9ED
treatment provided by	Carolina
scientific name	Ciconia sp. Brisson, 1760
status

Treatment

MATERIAL: KNM RU 3914, distal end of a right humerus ( fig. 2 View Fig ).

LOCALITY AND AGE: Rusinga Island (Kula Beds), Lake Victoria, western Kenya (see above).

DICUSSION: Although the two living species of Ciconia that fall within the size range of our material, the White Stork ( Ciconia ciconia ) and the Black Stork ( C. nigra ), are strikingly different in their external appearance they are very similar osteologically. Hence, with the exception of some characteristic elements (see above), separation of the two on morphological grounds is often impossible. Harrison (1980), for example, was unable to differentiate a proximal portion of a carpometacarpus from the Miocene of Maboko Island among these two species of Ciconia . Because in its size and structure KNM RU 3914 closely resembles the distal humeri of the recent species and even though its epicondylus dorsalis is somewhat more projected ( fig. 2 View Fig ), we refrain from more specific assignment here based on such limited fossil material.

MEASUREMENTS: KNM RU 3914, maximum distal width— 30 mm; width of shaft proximal to processus supracondylaris dorsalis— 24 mm.

THRESKIORNITHIDAE RICHMOND, 1917

Genus and species indeterminate

MATERIAL: KNM MB 563, cranial end of right coracoid ( fig. 3 View Fig ).

LOCALITY AND AGE: Maboko Island, Lake Victoria, western Kenya.

DISCUSSION: Rich (in Andrews, 1981) tentatively referred this incomplete and damaged coracoid to the charadriiform family Burhinidae (stone-curlews). However, if this element were from a burhinid then it would pertain to a large bird—approaching the dimensions of Esacus , the Great Stone-curlew ( Howard and Moore, 1984). However, KNM MB 563 lacks a welldeveloped processus acrocoracoideus along with the distinct projection on the ventral face of the facies articularis clavicularis that characterises these birds ( fig. 3 View Fig ). Our comparisons of this specimen suggest instead that it should be referred to Threskiornithidae (ibises and spoonbills), and more specifically to the ibises.

The fossil record of Old World ibises from similarly aged deposits is, however, poor. Milne- Edwards (1863) described a Plegadis -sized ibis, Actiornis pagana (see Harrison, 1986 for comments on this genus), from the Upper Oligocene– Lower Miocene of France, and Olson (1985b) described a species, Geronticus apelex , and referred an additional specimen to the extant Threskiornis aethiopicus (Sacred Ibis) . Both these latter taxa have been identified from Early Pliocene sediments in South Africa ( Olson, 1985b). KNM MB 563, however, is very fragmentary and we refrain from referring it to a particular genus. In comparison with extant species, this element is larger than corresponding bones from the Glossy Ibis ( Plegadis falcinellus ) and smaller than those of the Sacred Ibis ( Threskiornis aethiopicus ) and the Bald Ibis ( Geronticus calvus ). KNM MB 563 suggests a threskiornithid of similar size to either the Hadada ( Bostrychia hagedash ) or the Madagascan Ibis ( Lophotibis cristata ).

MEASUREMENTS: KNM MB 563, greatest width of sulcus muscularis supracoracoideus— 9 mm; width of facies articularis clavicularis— 8 mm.