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Piksi a pterosaur, not a bird from Upper Cretaceous
From: Ben Creisler
A new paper. The pdf is free.
F. L. Agnolin & D. Varricchio (2012)
Systematic reinterpretation of Piksi barbarulna Varricchio, 2002 from
the Two Medicine Formation (Upper Cretaceous) of Western USA (Montana)
as a pterosaur rather than a bird.
Geodiversitas 34 (4): 883-894.
Varricchio (2002) described some forelimb bones from the Late
Cretaceous (Campanian) Two Medicine Formation, Glacier County, Montana
(USA), as the holotype of Piksi barbarulna, a supposed
ornithothoracine bird. However reevaluation of Piksi Varricchio, 2002
instead recognizes this genus as belonging to Pterosauria Kaup, 1834
and not Aves Linnaeus, 1758. Piksi exhibits the following derived
humeral traits of pterosaurs: 1) very large ectepicondyle; 2) large
trochlea; 3) with a deep, wide and poorly deliminated brachial
depression that is proximodistally extended; 4) a wide and deep
olecranal fossa not marked dorsally by a ridge; and 5) lacking a
distal depression of the groove for the m. humerotricipitalis.
Moreover, the putative Early Cretaceous birds Eurolimnornis Jurcsák &
Kessler, 1986 and Palaeocursornis Jurcsák & Kessler, 1986, based on
distal humeri, are also regarded as pterosaurs. The record of Piksi
constitutes an important addition to the Latest Cretaceous