Shape, Sex, and Size

Very basic research on canid skeletal variation is a big part of our project. For example, how do dog and wolf skeletal remains differ from those of other canids like grey wolves or coyotes? How do dog skeletons vary by sex? How can one determine the size of a dog, including its height and weight, from its skeletal remains?



Our project includes the use of new techniques (in zoo archaeology at least) for analyzing shape, including geometric morphometrics, but we also utilize a suite of traditional morphometric approaches. Dogs are generally smaller than wolves–they have smaller teeth, smaller heads, and overall smaller bodies. Their heads are even slightly smaller relative to the rest of their bodies when compared with wolves. There are of course other differences between dogs and wolves, and it was long though that the shape of dogs’ skulls was essentially like that of juvenile wolves. More recently, this has been shown to be incorrect, and that dog skulls differ significantly from those of wolves in previously unrecognized ways. For example, when compared to wolves, dogs’ snouts are in essence rotated upward relatively to their brain cases (the back half of the skull), and such differences only show up when shape is analyzed with the new techniques. These analyses, conducted previously by Dr. Abby Drake, raise a suite of other questions, including how else dog and wolf skeletal elements differ from one-another, and how such difference might be identified in the remains of some of world’s earliest domesticated wolves (the first dogs).



Relationship between body mass in dogs and wolves and cranium length. Wolves have longer heads in comparison to dogs of similar body weights. Figure from Losey et al. 2014, International Journal of Osteoarchaeology.


Differentiating male and female dogs using their skeletal remains is very challenging. While there are some exceptions–male dogs have penis bones–the skeletons of male and female dogs are very similarly shaped. Some studies have proposed that simple measurements of the cranium, for example, can be used to tell male and female dogs skulls apart. However, these studies are based on a small number of individuals from single modern breeds of dogs. What happens when such analyses are applied to a variety of dogs? Are the differences solely based on the sizes of the bones being examined? Male dogs tend to be slightly larger than female dogs, at least within single breeds. Male and female human skulls differ (on average) from each other in a variety of ways, including in several non-metric characteristics. Do dog skulls also have such sex patterning? How do any such differences compare to those observed in wolves?




In one of our recent papers (see Publications), we demonstrated that the size of both the cranium and mandible can be used to roughly estimate the body mass of both dogs and wolves. However, bones of the limbs should be more reliable indicators of body mass than the skull, as the limbs carry the weight of the animal. Key to developing a reliable means for estimating body mass in dogs will be analysis of bones from dog skeletons where the weight of the animal is known. This can prove challenging, as most museum collections typically have only the skulls of dogs (and other animals), and when limb elements are kept, they are often from animals where the weight was not recorded. We need YOUR HELP in this regard, so please see HELP US tab at the top of this page.

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