Contamination and chimerism are perpetuating the legend of the snake-eating cow with twisted horns (Pseudonovibos spiralis). A case study of the pitfalls of ancient DNA

摘要

In 1994, several unusual horns collected from markets in Vietnam and Cambodia were described as a new genus and species of wild bovid, Pseudonovibos spiralis (Peter and Feiler, 1994a,b). The horn sheaths possessed a unique and distinct lyriform twist, as well as annulations throughout their entire length. This animal, named "linh duong" in Vietnam or "kting voar" in Cambodia (but see Brandt et al., 2001), was known only from detached horn sheaths or frontlets (partial frontal bones with bony horn cores) with horn sheaths. This lack of anatomical information was largely responsible for the confusion regarding the taxonomic status of this species, with morphologists debating whether it was a close relative of the tribe Antilopini (gazelles) (Peter and Feiler, 1994a), Caprini sensu lato (goats, sheep, and allies) (Nadler, 1997), or Bovini (oxen, bison, and buffaloes) (Dioli, 1997; Timm and Brandt, 2001). Given both the paucity and variable taxonomic interpretation of the morphological data, hopes were initially high that DNA sequence would resolve the issue of Pseudonovibos' taxonomic status and phylogenetic position. However, three ensuing DNA sequencing studies using different putative P. spiralis specimens gave rise to mutually incompatible hypotheses: