Identifying Canid Skulls

[RichW9090]

The following data taken from Nowak's classic paper shows the difficulty of relying on size to identify fossils.

Summary upper carnassial tooth length of canids: LP4

Canis dirus: 28.7 - 35.5

Canis lupus 22.2 - 30.5

Canis latrans 17.6 - 22.8

Canis familiaris 14.4 - 22.7

Canis armbrusteri 26.6 - 29.5

Canis edwardi 24.0

Canis lepophagus 19.0 - 20.7

In some cases (the fossils) the sample is small. In others, (lupus and latrans) it is more than 100 skulls.

Coyotes overlap with wolves, and wolves overlap with Dire Wolves, but in each case, a significant portion of the individuals can be allocated to the correct taxon by size alone. Domestic dogs are a mess, as they overlap with both coyotes and wolves. When you throw in the remaining fossil canids, size ends up being pretty useless as the sole determiner of identity. Usually some knowledge of the geologic context can help eliminate some of the fossil taxa.

This is an old data set, and I'll run a similar analysis of Tedford and Wang's data and post that later.

Edited August 13, 2013 by RichW9090

[Corri]

Hello

Very interesting...

I'd love to find out more about Canis lepophagus.

I found a study that, unfortunately, I have only limited access to.

To quote: "Braincase height was the only variable identified that could provide complete morphologic seperation between C. lepophagus and C. latrans."

Now, that variable and it's exact measurements I cannot find.

Here is a link to the study http://contentcat.fhsu.edu/cdm/singleitem/collection/thesis/id/503/rec/1

[RichW9090]

Here is Tedford, Wang and Taylor added to the mix:

Summary upper carnassial tooth length of canids: LP4

Taxon Nowak 1979 Tedford, Wang Tayor 2009

Canis dirus 28.7 - 35.5 29.2 - 33.8 (RLB); 27.5 - 31.4 (Irvingtonian)

Canis lupus 22.2 - 30.5 24.0 - 28.0 (C. lupus occidentalis western Canada)

Canis latrans 17.6 - 22.8 18.1 - 21.3 (C. latrans , Nevada)

Canis familiaris 14.4 - 22.7 ------

Canis armbrusteri 26.6 - 29.5 25.2 - 29.0

Canis edwardi 24.0 18.8 - 23.8

Canis lepophagus 19.0 - 20.7 16.6 - 20.6

Different samples, slightly different results. Some of the difference may be in how the teeth were measured. Nowak doesn't illustrate how the measurements were taken; TWT do. Also, TWT used generally smaller samples, particularly of the living canids, trying to get actual population samples.

[RichW9090]

So, let's play with this a bit, eh? Suppose I came into this forum with a skull I wanted you all to identify. It's clearly a canid. So one of you grabs TWT and looks up the information, and writes it down, just like I did. That person might say : There is no overlap between coyotes, wolves and dire wolves. Measure the length of the crnassial and I'll be able to tell you what it is. The data is clear, we'd be 100% sure."

Suppose the tooth measured 32.0 mm. Pretty clearly C. dirus, eh? And if it measured 18.0 mm, pretty clearly coyote. But what if it measured 28.5 mm? How would you identify it? You couldn't. But maybe if you had a larger data base, you'd be able to, right? So look at Nowak: 28.5 is smaller than the smallest direwolf, but not by much - just 0.2 mm, which is almost certainly within the range of error of your ability to measure it. So is it a direwolf or a gray wolf? Or suppose it mesured 22.5 mm? It could be either coyote or wolk - thier ranges overlap.

Size alone, as I've argued before, is seldom a good criterion. It can be helpful, but it isn't absolute.

Rich

[RichW9090]

The coyote lineage is one of the best documented, Corri, starting with Canis ferox, then Canis lepophagus then Canis latrans.