A night heron (Ciconiiformes, Ardeidae) and a stork (Ciconiidae) from the Pliocene of Myanmar (Burma)

作者:Stidham, Thomas A.*; Tsubamoto, Takehisa; Zin-Maung-Maung-Thein; Thaung-Htike; Egi, Naoko; Nishioka, Yuichiro; Maung-Maung; Takai, Masanaru
来源:Palaeontologia Electronica, 2016, 19(3): 36A.
DOI:10.26879/636

摘要

Two new avian specimens from the Pliocene part of the Irrawaddy sediments of central Myanmar represent the youngest known fossil records of birds from Myanmar (Burma) that previously was restricted to one specimen of an ibis from the middle Eocene. The age of the Sulegon-1 fossil locality is likely from the later part of the Pliocene based on the presence of the suid Sivachoerus prior, the anthracotheriid Merycopotamus dissimilis, and the Sumatran rhinoceros Dicerorhinus sp. cf. D. sumatrensis. The distal tarsometatarsus is from a night heron (Ardeidae: Nycticoracini) and exhibits derived (and primitive) features consistent with night herons, but not other groups of ardeids, including the absence of a lateral deflection of trochlea III and a trochlear furrow extending to the proximal plantar end of trochlea III. The night heron fossil is not distinguishable from some species of Gorsachius and Nycticorax and may derive from one of the extant species in Southeast Asia. The other specimen (a distal tibiotarsus) represents a taxon of stork (Ciconiidae: cf. Leptoptilini) and displays many characters associated with that group (incuding a large centrally positioned intercondylar tubercle, a rounded intercondylar fossa, and distally notched trochlear rims). This stork is smaller than the 'giant' storks known from the Plio-Pleistocene of Asia and Africa, and may represent a relative of one of the large extant Asian storks. The inferred paleohabitat of the Sulegon locality as a tidal deltaic habitat is consistent with the lifestyle of both the extant night herons and large storks that occur in southeastern Asia today.

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