The Scales and Patterns of Saurolophus

Skin Patches from Saurolophus angustirostris (A,B,&D) and Edmontosaurus annectens (C)

Saurolophus was a type of Hadrosaur (Duck-Billed Dinosaur) from the Late Cretaceous of both Canada and Mongolia and is one of the few dinosaurs known to have spanned multiple continents. Saurolophus is a well known and well documented Hadrosaur, almost all of it's anatomy is known, including skin impressions that show small scales in fine detail. These scales have been known for many years, but now a new study posted a few days ago shows that these scales might hold true some interesting little details about the animal's patterns in life.

The study was started by Dr.Phil R. Bell, a scientist at University of Alberta that wanted to try something nobodies ever done before; Compare the skin impressions of two species of dinosaur and try to see if he could tell them apart through the patterns in the skin, and not by using bones. This was monumental, as nobody had ever done this before, and it's given  us some great new insights to Dinosaur appearances.

He decided to work on the two valid species of Saurolophus; S. angustirostris (from Mongolia) and S. osborni (from Alberta), and mapped the location of skin on certain areas of the body to try to find differences in texture. Normally, differences in the texture of modern reptile scales typically indicates differences in color pattern, thus we would expect the same for dinosaurs. After mapping the locations of the different types of scales on a representation of the animal, he found a pattern.


Lighter area shows where skin impressions were taken from
S. osborni (top) and S. angustirostris (bottom)

The tail of S. osborni showed areas of different-sized scales that were in a mottled pattern, somewhat like that of a mosaic. S. angustirostris on the other hand showed areas above the tail with finer scales going up and down that in life probably represented stripes. Different areas of the body showed even more surprised, he found some evidence of counter shading on S. angustirostris, and both species seem to have had bird-like scutes on their feet that might have protected their legs while walking through thick vegetation like ferns.* Some areas even show signs of wrinkling skin and the top of the tail of S. angustirostris showed a long line of ridges down it's back, something that S. osborni lacked, but is known in some other species of Hadrosaur.

*My bad. Turns out that I made a boo-boo there. They don't have bird-like scales on their feet, instead, and perhaps more interestingly, they're covered in reticulae, which are found on the underside of bird feet. I thank   Matt Martyniuk for pointing that out on an awesome blog post that he made concerning the scales on dinosaur feet. Be sure to check it out on DinoGoss. :) 

By using these models and examining differences between scales in different body areas, he was able to make the most accurate reconstruction of Saurolophus yet:

Differences between the skin of S. osborni (A) & S. angustirostris (B)

While we don't know the exact coloration of these two, we now know that patterns, and likely colors, varied wildly between species of dinosaur. This study has also opened up new possibilities for the future, being the first of it's kind to actually show the differences between two species on the outside of the animal. Similar studies might eventually show us a good representations of the Edmontosaurus named Dakota, or the recently discovered Brachylophosaurus called Leonardo, both of which are mummies that have their skin and internal organs preserved.

Even more exciting is that, in the future, we might be able to distinguish differences between male and female, and even differences with age for all kinds of dinosaurs. But until then, I expect the next Saurolophus I see in a book to either have stripes or mottled pattern on it. Same goes or any documentaries or movies. X)

For anyone who's interested in reading the full article on PLoS:

http://www.ploscollections.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0031295;jsessionid=102E790ADA13BC05B6DB3E4C850393F5

Until next time, stay sharp as a Raptor's Talon!