The use of eye-size and snout shape I consider to be unreliable. I initially considered linking to photos, such as the AROD titlepage for Furina ornata, to demonstrate this. Instead, I figured use of the term “definitive”, meaning definite and clear (not the same as “diagnostic”) would highlight the difference. It seemed your post was only directed at mine and clearly ignored this weaker prior post... “Why?” I asked myself. As a result I began my response petulantly. In the cold, hard light this is not acceptable. I genuinely apologise Scott.
It would seem apparent that we are tackling separate issues. I was attempting to provide characteristics visible in the photo provided to validate a clear cut-out decision between F. ornata and P. textilis – nothing more! interpretation of my post.
It seems that you are providing diagnostic features to distinguishing between the two genera. You also incorporated the ontogenetic changes in young browns. For me, this is not relevant and Again I wondered why. Add to the fact you made no mention of ontogenetic changes and Furina. In the photo prvided the ventral surface was not visible so I deliberately omitted referring to, despite it being the best diagnostic tool. My descriptions of the extent of the head patches are my own. They are based on my collective experiences over time of personal observations of specimens and viewing photos in books and on the net. I have seen very few Furina in person.
Being sexually dimorphic does mean that males and female can’t “look alike”. Snakes may be sexual dimorphic because different genders attain different total length, differ in adult body robustness or rate of tail taper, whether or not spurs are present etc. Such differences do not preclude an overall similarity in appearance i.e. look alike.
I hope that clarifies the situation mate,