The theropod furcula

Abstract

The furcula is a structure formed by the midline fusion of the clavicles. This is the element which is unique to theropods and is important for understanding the link between birds and other theropods. New specimens from basal theropods suggest that the furcula appeared very early in theropod history. We review furcula development, function, and morphology, as well as the anatomical terminology applied to it. Furcular morphology is highly variable in crown-group avians but is rather conserved among nonavian theropods. Here we review, or describe for the first time, the furculae in many nonavian theropods. Furculae occur in nearly all major clades of theropods, as shown by new theropod specimens from the Early Cretaceous of China and a close inspection of previously collected specimens. Informative phylogenetic characters pertaining to the furcula occur throughout Theropoda, though care should be take to consider taphonomic effects when describing furcular morphology.

Osteology of Khaan mckennai (Oviraptorosauria: Theropoda)

“…The furcula is not unlike that of typical maniraptoran furculae (Nesbitt et al, 2009). It has an interclavicular angle (,90u) that corresponds closely with Oviraptor philoceratops and Heyuannia huangi (Nesbitt et al, 2009) and overall possesses a dorsoventrally flattened morphology (fig.…”

The Early Evolution of Archosaurs: Relationships and the Origin of Major Clades

“…The clavicles of some nonsauropod sauropodomorphs (e.g., Massospondylus) may contact each other at the midline, but do not fuse (Yates and Vasconcelos, 2005). A furcula (5 fused clavicles) is present in nearly all theropods known from complete skeletons including Coelophysis bauri (AMNH FR 30647; Rinehart et al, 2007;Nesbitt et al, 2009d) and Allosaurus fragilis (UUVP 6102; Chure and Madsen, 1996). This character has been employed by various datasets exploring theropod relationships (e.g., Norell et al, 2001;Clarke, 2004).…”

New Specimens ofAnchiornis huxleyi(Theropoda: Paraves) from the Late Jurassic of Northeastern China

“…13), as in Microraptor, Archaeopteryx, and Xiaotingia (Hwang et al, 2002;Xu et al, 2011;Rauhut, 2014). As in Microraptor and Archaeopteryx, the ventral margin of the furcula is rounded, in contrast to Mei and Oviraptor in which a prominent hypocleidium is developed (Hwang et al, 2002;Xu and Norell, 2004;Nesbitt et al, 2009;Rauhut, 2014). A U-shaped furcula is also exposed in BMNHC PH804, with a smooth and rounded ventral margin.…”