In this week's PLoS One, Ewan Wolff and colleagues present evidence that a common parasite of birds, Trichomonas, also infected tyrannosaurid dinosaurs, and may have caused several, including the Field Museum's famous "Sue" to have died of starvation. The authors examined 61 tyrannosaurid specimens and found mandibular lesions in 10 of these that were consistent with similar lesions that are observed in modern-day birds that are infected with these parasites. Today, columbiforms are heavily parasitized by Trichomonas gallinae and these birds are likely the source of infection in raptors when they are consumed as prey (if anyone wants a live demonstration of this, come hang out in my office and watch the red-tails pick off pigeons). Wolff et al. argue that although infection via consumption of Trichomonas-laden prey can certainly not be ruled out, many of the specimens that show the lesions also have evidence of bite wounds on their heads, suggesting that face-to-face transmission may be the bigger culprit. While looking up information on T. gallinae, I also came across an interesting article in the Journal of Parasitology from last year that conducted molecular studies of Trichomonas isolates from doves around the U.S. using the parasites' ITS1, 18S and alpha-tubulin genes. The surprise of that paper was that the isolates from doves generally fell into two distinct clades - one similar to T. gallinae, but others that were genetically similar to the human STD, T. vaginalis! Clearly, more sampling of trichomonads should be done as they may play significant roles in the ecology of avian communities...and, as Wolff et al. suggest, may have even been having large impacts on birds' dino ancestors.
Dechronization is authored by evolutionary biologists interested in the development and application of methods for estimating phylogeny and making phylogeny-based inferences. The goal of the blog is to provide a forum for discussion of the latest research and methods, while also providing anecdotes, tidbits of natural history, and other related information.