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The morphology and phylogenetic position of Apsaravis ukhaana from the late Cretaceous of Mongolia

by: Clarke, Julia A

Publication date: 2002

Usage: Attribution-NonCommercial-ShareAlike 4.0 International

Topics: Apsaravis ukhaana, Birds, Fossil, Paleontology, Birds, Evolution, Flight, Enantiornithiformes, Phylogeny, Birds, Fossil -- Mongolia -- Ukhaa Tolgod, Paleontology -- Cretaceous -- Mongolia -- Ukhaa Tolgod, Paleontology -- Mongolia -- Ukhaa Tolgod, Birds -- Evolution, Birds -- Flight, Enantiornithiformes -- Phylogeny

Publisher: New York, NY : American Museum of Natural History

Collection: americanmuseumnaturalhistory; biodiversity

Contributor: American Museum of Natural History Library

Language: English

Rights: http://biodiversitylibrary.org/permissions

Rights-holder: American Museum of Natural History Library

Volume: no. 3387

46 p. : 26 cm

"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"--P. [1]

Title from caption

"December 27, 2002."

Specimen collected from the Camel's Humps sublocality of Ukhaa Tolgod in the Nemegt Basin of southern Mongolia during the 1998 field season of the Mongolian Academy of Sciences-American Museum of Natural History Expeditions to the Gobi Desert

Includes bibliographical references (p. 32-36)

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'--P. [1].