The Morphology and Phylogenetic Position of Apsaravis ukhaana from the Late Cretaceous of Mongolia

By J. Clarke, M. Norell. 2002

129 citations recorded by the source corpus.

Abstract The avialan taxon Apsaravis ukhaana from the Late Cretaceous of southern Mongolia is completely described and its phylogenetic position is evaluated. Apsaravis ukhaana is from continental sandstones exposed at the locality of Ukhaa Tolgod, Omnogov Aimag, Mongolia. The holotype specimen consists of the nearly complete, articulated skeleton of a small volant avialan. Apsaravis ukhaana is unambiguously differentiated from other avialans based on the presence of several unique morphologies: a strong tubercle on the proximal humerus, a hypertrophied trochanteric crest on the femur, and extremely well-projected posterior wings of a surface of the distal tibiotarsus that in Aves articulates with the tibial cartilage. Ten other homoplastic characters optimize as autapomorphies of Apsaravis ukhaana in the phylogenetic analysis. They are as follows: ossified mandibular symphysis; dentary strongly forked posteriorly; hooked acromion process on scapula; highly angled dorsal condyle of humerus; humeral condyles weakly defined; distal edge of humerus angling strongly ventrally; humerus flared dorsoventrally at its distal terminus; lateral condyle of tibiotarsus wider than medial one; neither condyle of tibiotarsus tapering toward the midline; and metatarsal II trochlea rounded rather than ginglymoid. Phylogenetic placement of Apsaravis ukhaana as the sister taxon of Hesperornithes + Aves resulted from analysis of 202 characters scored for 17 avialan ingroup taxa. The implications of Apsaravis ukhaana, and the results of the phylogenetic analysis, for the evolution of flight after its origin and character support for enantiornithine monophyly are extensively discussed.

View Paper: https://www.semanticscholar.org/paper/b50f13411c6cc6b7ea31d4b1df3c3dec398d4a2a

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

Citations in the corpus

A beaked basal ornithurine bird (Aves, Ornithurae) from the Lower Cretaceous of China (2006, background): “Z HONGHE Z HOU & F UCHENG Z HANG Accepted: 23 January 2006 doi:10.1111/j.1463-6409.2006.00234.x Most Mesozoic ornithurines are toothed birds (Zhou & Zhang 2001; Clarke & Norell 2002) with only a few exceptions (Zhou & Zhang 2005; Feduccia 2006).”
A Review of Dromaeosaurid Systematics and Paravian Phylogeny (2012, background): “Moreover, the fact that most detailed avialan phylogenetic studies have been conducted outside the context of a species-level coelurosaur dataset (Chiappe and Calvo, 1994; Chiappe, 1995; Norell and Clarke, 2001; Clarke and Norell, 2002; Clarke, 2004; Clarke et al., 2006) complicates a clear understa”
Definitive fossil evidence for the extant avian radiation in the Cretaceous (2005, methodology): “These new data, when included serially in three of the largest cladistic data sets considering Aviala”
Phylogenetic Support for a Specialized Clade of Cretaceous Enantiornithine Birds with Information from a New Species (2009, background): “As in Longipteryx, it appears to be located more on the dorsal surface as opposed to the lateral surface of metatarsal II (e.g. Apsaravis; Clarke and Norell, 2002).”
A revision of enantiornithine (Aves: Ornithothoraces) skull morphology (2011, background): “…teeth and presence of a caudally forked dentary—features otherwise common to modern birds and present in the basal ornithuromorph Apsaravis ukhaana (Clarke & Norell 2002) and in the basal pygostylian Confuciusornis sanctus (Chiappe et al. 1999)—are only known in a single Late Cretaceous taxon…”