Wednesday, July 1, 2009

More On Chewy Hadrosaurs

First, thanks to those who commented and emailed regarding my post on the controversial hadrosaur chewing mechanics paper (see "Nom nom nom"). Vince Williams, lead author of the paper in question, was among those who contacted me about it, and he pointed out an error that stems from (yet again) science reporting that isn't all there.

Above: Underside of the skull of Leonardo, the Brachylophosaurus mummy. By Ed T., from Flikr. Licensed.

My last post reiterated a statement from this MSNBC article, that gut contents of the famous hadrosaur mummy "Leonardo" seem to contradict Williams et al.'s findings, because the plant matter was

a) chopped or sheared, not chewed, and
b) mainly coniferous, indicating that hadrosaurs were browsers rather than grazers.

Well, I checked up on the source that MSNBC used for this information (Leonardo is, despite documentaries on the History Channel, not fully studied and published on yet). That lead me to another MSNBC article on Leo, which appears to state the opposite! From the older, cited article:
  • "An analysis of the gut contents from an exceptionally well-preserved juvenile dinosaur fossil suggests that the hadrosaur's last meal included plenty of well-chewed leaves digested into tiny bits."
  • "An analysis of pollen found in the specimen's gut region revealed a variety of plants, including ferns, conifers and flowering plants. Although the pollen could have been ingested when the dinosaur drank water, the tiny leaf bits, under 5 millimeters (a quarter-inch) in length, indicate that Leonardo was a big browser of plants, Chin said."
So, the gut contents in question actually would seem to support, at least in part, Williams' findings. Even stranger given the apparent lack of cranial kinesis reported last December. Obviously further study is needed on this...


  1. The presence of "well chewed" gut contents only indicates that oral processing was occurring, but oral processing doesn't require pleurokinesis to occur.

  2. True, but it also is a bit different from the previous article which reported sheared food, as opposed to chewed. I am curious to know what the threshold would be for one or the other. How big does a particle of gut content have to be to qualify as sheared or "well-chewed", and what does average particle size tell you about what kind of oral processing was going on?

  3. The plant fragment size for Leo is comparable to the fingernail of an adult human's little finger. Interestingly, the size of fragments in the gut contents of the ankylosaur Minmi is even smaller. The MSNBC description of the Leo work doesn't sound like our stuff at all; it sounds more like the Senckenberg mummy (maybe something got edited wrong-way around?). One of the outstanding characteristics of the Leo stuff (unfortunately) is that it's homogeneous dark carbonaceous bits. Bark and twigs, if present, were not apparent.

  4. Oh, and there is one peer-reviewed Leo pub: Tweet, J.S., K. Chin, D.R. Braman, and N.L. Murphy. 2008. Probable gut contents found within a specimen of Brachylophosaurus canadensis (Dinosauria:Hadrosauridae), from the Upper Cretaceous Judith River Formation of Montana. Palaios 23(9):624-635. abstract here