Imperfect Imitation is (Sometimes) the Best Form of Flattery

21 03 2012

A letter published March 21 in the online edition of the journal Nature indicates that there are evolutionary reasons why some animals that mimic other more aggressive or dangerous species do so rather imperfectly.

The study conducted by a team of Canadian researchers indicated that, at least in hoverfly populations, predators impose less selection if the mimic is smaller.  Thus, small mimic species need to have less fidelity with the species they are mimicking than do larger ones.  The team concludes that the most likely reason for this is that the mimics are less profitable prey species and are not apt to be pursued as strongly as are larger species.  So, less fidelity will do.

The team was also able to show little or no correlation of mimicry to several other theories that had been posited over the years as explanations for the imperfections.  Among these, they were able to show that human ratings of mimetic fidelity are positively correlated with both morphometric measures and avian rankings of the mimicry, indicating that variation in mimetic fidelity is not just an illusion based on human perception.

See here for the complete paper.


Canadian Scientists Discover Yet Another New Horned Dinosaur

31 05 2010

It seems like there have been a lot of new horned dinosaurs discovered lately.  I’ve reported on several (see here and here).  Today comes a report, from, of yet another new horned dinosaur.  Known as Medusaceratops lokii, it lived during the Cretaceous period, approximately 80 million years ago, along the eastern shores of Laramidia (the western part of North America), near what is today the Alberta-Montana border.

The discovery was made by two Canadian scientists, Anthony Russell (a biologist for the University of Calgary), and Michael Ryan (an adjunct professor at Carleton University, as well as the head of vertebrate paleontology at the Cleveland Museum of Natural History).  The new dinosaur is scheduled to be described in the book New Perspectives on Horned Dinosaurs:  The Royal Tyrrell Museum Ceratopsian Symposium, edited by Michael J. Ryan, Brenda J. Chinnery-Allgeier, and David A. Eberth.  The book is being published by Indiana University Press, and is scheduled for release on June 17, 2010.

The new dinosaur was named for the Medusa of Greek myth, because of the snake-like horns that protrude from its massive bone crest.  It’s species name comes from Loki, the Norse god of mischief, because it was such a tricky dinosaur to identify.  According to Ryan, speaking in the interview, it required years of study to finally identify the remains as that of a new species.  This was, in part, because the remains were part of a bone bed, a collection of disarticulated bones grouped together by the force of water or other natural activities.

 According to Ryan, his team at first thought they had found an Albertaceratops, a very similar and closely related genus of ceratopsian.  It did not help, according to Ryan, that he had earlier found one nearby.

Due to copyright concerns, I have not included an image of Medusaceratops lokii.  To see one, follow the link to the article.