A furcula in the Coelophysid theropodSyntarsus

Comparative development of the crocodylian interclavicle and avian furcula, with comments on the homology of dermal elements in the pectoral apparatus

“…Recently, Nesbitt et al (2009) reviewed the phylogenetic distribution of the furcula. As they and others (e.g., Bryant and Russell, '93;Chure, and Madesen, '96;Makovicky and Currie, '98;Tykoski et al, 2002) have clearly demonstrated, the furcula is a synapomorphy of theropods and predates the origin of flight. Among outgroups to theropods the situation is less clear.…”

The theropod furcula

“…Since Heilmann's monograph, the furcula has been recognized in several different theropod groups (Barsbold, 1983;Bryant and Russell, 1993;Makovicky and Currie, 1998;Norell and Makovicky, 1999;Tykoski et al, 2002;Yates and Vasconcelos, 2005). However, doubts concerning the homology of the theropod ''furcula'' and the avian ''wishbone'' have persisted because of consistent misinterpretations of the available data.…”

“…Recent identification of furculae in many theropod clades (Barsbold, 1983;Bryant and Russell, 1993;Makovicky and Currie, 1998;Norell and Makovicky, 1999;Tykoski et al, 2002;Yates and Vasconcelos, 2005) has sparked interest in the distribution of the element among theropod dinosaurs. Bryant and Russell (1993) reviewed the distribution of clavicles (and furculae) in dinosaurs and found that it was unclear whether the avian furcula is homologous to the clavicles of other reptiles, or if it was a neomorphic bone shared by some theropod dinosaur clades and birds.…”

Are Current Critiques of the Theropod Origin of Birds Science? Rebuttal to Feduccia (2002)

“…Now, applying his "character by character" approach in this commentary, Feduccia mentions that the furcula of Longisquama in an effort to support the hypothesis that Longisquama is closely related to birds, in direct contradiction to his earlier published conclusions. Simultaneously, he ignores the discoveries since 1998 of furculae or paired clavicles in six to nine major lineages of theropod dinosaurs, including dromaeosaurs, oviraptors, tyrannosaurs, allosaurs, and coelophysids (Tykoski et al 2002). Of course, the only scientifi c way to resolve alternative hypotheses of character evolution and character confl icts are by applying a repeatable, explicit, analytical method to reconstruct evolutionary history of characters and organisms.…”

“…Actually, my enthusiasm is not based on ideological zeal, but on the incomparable scientifi c success of the theropod hypothesis (Prum 2002). Since it was fi rst proposed cladistically by Gauthier (1986), the theropod origin of birds has been supported by numerous discoveries, including many new theropods closely related to birds (Novas and Puerta 1997;Sereno 1999;Xu et al 1999Xu et al , 2000Xu et al , 2001Xu et al , 2003Czerkas et al 2002;Norell et al 2002), many new basal avian fossils that further blur the distinction between birds and other theropods (Forster et al 1998;Zhou and Zhang 2002), many theropod furculae (Tykoski et al 2002), over a dozen feathered theropods (Prum and Brush 2002), the digit frameshift hypothesis (Wagner and Gauthier 1999), and molecular developmental support for the frame-shift (Dahn and Fallon 2000)(see below), the reduction of the temporal paradox by two thirds (Xu et al 1999(Xu et al , 2000(Xu et al , 2001(Xu et al , 2003Czerkas et al 2002;Norell et al 2002), bird-like nesting behavior in theropods (reviewed in Prum 2002), and most recently by four winged dromaeosaurs (Xu et al 2003). Given that the theropod origin of birds is entirely consistent with and supported by all of the new evidence discovered in the last decade, and that many testable predictions generated by the hypothesis have been independently supported, it is an overwhelmingly successful scientifi c theory.…”