Ciconia minor ( Harrison, 1980 )

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 : 7-8

Ciconia minor ( Harrison, 1980)

MATERIAL: KNM RU 3075, incomplete proximal end of right humerus; KNM RU 3898, distal end of left tarsometatarsus lacking the trochlea for metatarsal II ( fig. 2 ).

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

DISCUSSION: The first of the two fossil specimens that we refer here to Ciconia minor consists of the articulating head of a right humerus broken distal to the sulcus ligamentosus transversus ( fig. 2 ). The caput humeri and tuberculum dorsale of KNM RU 3075 are preserved, however, and present characters that can be used for referral. The caput humeri of this specimen is evenly domed and bears a distinct muscle attachment scar that slants over the cranial side of the tuberculum dorsale as seen typically in extant Ciconia ( fig. 2 ). In caudal view, the caput humeri is markedly projected as in C. minor ( Harrison, 1980) more so than in the other extant species of this genus. This feature, combined with the presence of numerous foramina distal to the caput humeri, is consistent with species the same size or larger than C. minor .

The second specimen referred here (KNM RU 3898) consists of just the distal extremity of a left tarsometatarsus including a small portion of shaft ( fig. 2 ). This specimen is very similar to extant ciconiids we have examined—the dorsal margin of trochlea metatarsal II is prominent and projects distally below the level of trochlea metatarsal III, as in Ciconia ( fig. 2 ). KNM RU 3898 corresponds with extant specimens of C. minor in its preserved size.

MEASUREMENTS: KNM RU 3075, maximum width across caput to tuberculum dorsale— 23 mm; depth of caput humeri— 10 mm. KNM RU 3898: total length to trochlea metatarsal III— 36 mm; total length to trochlea metatarsal IV— 34 mm; width of shaft— 30 mm; maximum width of trochlea metatarsal III— 4 mm.

Figures

Fig. 2. New records of Miocene Kenyan waterbirds. Ciconia minor, incomplete proximal right humerus (KNM RU 3075) in cranial (A) and caudal (B) views; Ciconia sp., distal right humerus (KNH RU 3914) in cranial (C), caudal (D), and proximal (E) views; Ciconia minor, distal left tarsometatarsus (KNM RU 3898) in dorsal (F) and plantar (G) views; Anhinga cf. pannonica, proximal end of right humerus (KNM BN 1968) in cranial (H) and caudal (I) views. Not to scale, see text for measurements.