Theropod wishbones

Jeff Poling

The furcula is the "V" shaped bone found in birds formed by the fusion of the clavicles at the breastbone. This bone is the infamous "wishbone," often broken with a wish after a Thanksgiving Day dinner. The furcula was long considered a key synapomorphy of birds, a character lacked by other theropods. Discoveries of the last few decades, including those that came from reexamination of old material, have shown that the furcula is not just a bird characteristic, but a characteristic of many other theropods as well.

The following theropods have been found to have furculae:

• Aves.
• Dromaeosaurids, including a new North American species of Velociraptor.
• Oviraptorids (the furcula of Oviraptor philoceratops is pictured above, and Ingenia has one as well).
• Tyrannosaurids.
• Troodontids
• Coelophysids (Syntarsus and Coelophysis)
• Allosauroids including: the new Dinosaur National Monument allosaurid; Allosaurus fragilis, whose furcula was misidentified for years as gastralia; and a new carcharodontosaurid from Argentina.

The last of the listed theropods, coelophysids and allosauroids, are especially important. All of the other listed theropods share a recent common ancestor, forming the clade maniraptoriformes. However, the presence of furculae in these two groups, which share a common ancestor with maniraptoriformes far down the Dinosauria cladogram and thus are not closely related to them, indicates that furculae, either bony or cartilaginous, may have been common to all theropods.

1. Harris, Jerry D. Re: Just flew back from SVP... Public e-mail to the Dinosaur Mailing List, 5 October 1998.
2. Headden, Jaime A. Re: Just flew back from SVP... Public e-mail to the Dinosaur Mailing List, 5 October 1998.
3. Holtz, Thomas R. Re: Furculae. Private e-mail to the author, 18 November 1996.
4. Holtz, Thomas R. Re: allosaur furcula. Public e-mail to the Dinosaur Mailing List, 3 June 1997.
5. Holtz, Thomas R. Just flew back from SVP... Public e-mail to the Dinosaur Mailing List, 5 October 1998.
6. Olshevsky, George. Re: Furculae. Private e-mail to the author, 17 November 1996.
7. Olshevsky, George. Re: allosaur furcula. Public e-mail to the Dinosaur Mailing List, 4 June 1997.
8. Weishampel, David, Peter Dodson and Halszka Osmolska, ed. 1990. The Dinosauria. Berkeley: University of California Press.