"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

November 22, 2010

November 22 - Trichomonas gallinae

There's certainly no doubt that dinosaurs had parasites. The problem is, soft-bodied things like tapeworms and nematodes, let alone smaller things like trypanosomes or malaria parasites just don't fossilize well, so actually being able to say which species of parasites the "terrible lizards" might have been infected with is close to impossible. Recently, though, jaw bones from Tyrannosaurus rex specimens were re-examined and lesions in them were attributed to a parasite that continues to plague modern-day birds, Trichomonas gallinae. These single-celled parasites, closely related to the human STD, Trichomonas vaginalis, produce "cheesy" lesions in the mouth, pharynx and crop of birds such as pigeons, chickens, and your soon-to-be Thanksgiving turkey, causing a disease that is sometimes called "canker". These birds acquire the infection through consumption of contaminated water, but avian predators, such as falcons, can also be infected from eating parasitized prey. The authors of the paper that makes this link between lesions and T. gallinae hypothesize that even the Field Museum's famous "Sue" may have died of starvation as a result of this parasite damaging its mouth so badly. The image is an artist's vision of what the parasitized dino may have looked like. (Click on the thumbnail to get a better look and see the "cheesy" lesions in its mouth and check out this site for pictures of the parasite in pigeons.)


  1. I have always wondered if anyone has ever gone through any of the frozen mammoths that have been found intact for nematodes. I believe there are a couple of species of stomach bots described from mammoths. Those bots, like the mammoths, are also extinct.

  2. Mike, I remember wondering the exact same thing about 2 years during a conversation with a fellow parasitologist! We were wondering "Hey, those mammoths are frozen, we've managed to retrieve parasites from frozen carcasses, why not those mammoths?"

    Is there a reference for those stomach bots? They sound interesting.

  3. Grunin, K.Y. 1973. The first finding of the stomach bot-fly larvae of the mammoth: Cobboldia (Mamontia, subgen. n.) russanovi, sp. nov. (Diptera, Gasterophilidae). Entomol. Obozr. 52: 228-33. [English translation, 1973, Entomol. Rev. 52(1): 165-69.]

  4. Thanks Mike. There's a trove of very good parasitological work from Russia, but unfortunately most of it are unaccessible to anyone who doesn't know how to read Russian, so these days those texts tend to become lost and forgotten...

  5. So having Russian as native may come out really useful =)

    Seriously, the body of parasites-related information in Russian is way too big to be translated. That's a shame; it just misses out.

  6. The parasite Trichomonas gallinae is also a very interesting parasite. The most interesting part about this parasite is that there is evidence that it once infected Tyrannosaurus rex species and is still present today in birds. It’s also interesting how the symptoms found in the avians is very similar to what was found on T. rex fossils!