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New Mesozoic bird papers in AMNH Novitates
From: Ben Creisler email@example.com
New issues of American Museum of Natural History Novitates
are available online. Two concern Mesozoic birds:
CLARKE, J.A. and M. A. NORELL, 2002. The Morphology and
Phylogenetic Position of Apsaravis ukhaana from the Late
Cretaceous of Mongolia.
American Museum Novitates: No. 3387, pp. 1-44.
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.
KUROCHKIN, E.N., G.J. DYKE, and A. A. KARHU, 2002.
A New Presbyornithid Bird (Aves, Anseriformes) from the
Late Cretaceous of Southern Mongolia.
American Museum Novitates: No. 3386, pp. 1-12.
We describe a new large representative of the important
fossil anseriform taxon Presbyornithidae from the latest
Cretaceous (Maastrichtian) Nemegt Formation of southern
Mongolia. This new taxon, Teviornis gobiensis.n. gen. et
n. sp., is known from the associated manual portion of a
right wing and the distal end of a right humerus, but is
clearly diagnosable with respect to all other known
representatives of the fossil Presbyornithidae. It is
placed within the clades Anseriformes and
Presbyornithidae, respectively, on the basis of a number
of derived characters of the carpometacarpus and digits.
Importantly, description of Teviornis confirms the
presence of members of the neornithine clade Anseriformes
(?waterfowl?) in the Late Cretaceous, as has been
suggested previously on the basis of much less diagnostic
fossil material as well as from clade divergence estimates
founded on molecular sequence data. The extinct
Presbyornithidae thus has a worldwide distribution and
ranged in age from at least the Maastrichtian through to
the uppermost Eocene.