EUENANTIORNITHINE BIRDS FROM THE LATE CRETACEOUS OF EL BRETE (ARGENTINA)

Abstract

Abstract:A taxonomic illustrated review of the Late Cretaceous fossil birds known from the Argentine locality of El Brete (Salta Province, Patagonia, Argentina) is presented here for the first time. Although some of these specimens were first reported in the early 1980s, and then a handful more were presented in literature thoughout the 1990s, this important collection of fossil birds has largely remained undescribed since it was gathered 30 years ago. This is in spite of the fact that the El Brete collection provided the basis of C.A. Walker's insight that enantiornithine birds are anatomically—and phylogenetically—distinct from all other living and extinct avians. A catalogue of the known specimens from this site is also presented, and many elements are illustrated for the first time. We revise the anatomy of taxa from El Brete and provide complete lists of referred specimens, based on casts of the collection held in the Natural History Museum, London, and Walker's original manuscript. Six valid euenantiornithine birds are currently known from the El Brete locality—Enantiornis Walker 1981, Lectavis Chiappe 1993, Soroavisaurus Chiappe 1993, Yungavolucris Chiappe 1993, and Martinavis Walker et al. 2007—alongside a new taxon described and documented in this paper (Elbretornis). This new fossil euenantiornithine is remarkable because its humerus is highly pneumatised, more extensively than any other known Mesozoic fossil bird. The physiological and evolutionary implications of this bird and the other El Brete taxa are discussed.