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Description
The lip discussion is a probably endless topic with good arguments on both sides concerning lips or no lips for nonavian theropods/dinosaurs and most likely will not be solved in my comment section here but only by something like soft tissue impressions covering the jaws of a theropod skull. Thus it is not my intention to provoke a lip discussion here but rather to make an artistic contribute. Actually it is not only about lips but excess tissue in general. I think "excess tissue" is supposed to refer to a quantity of soft tissue that goes beyond the minimum that is necessary to cover the skull in a physiologically sensible way. Theropods have been reconstructed with almost no excess tissue during the most recent decades (I am not necessarily talking about "shrink-wrapping") so that you can clearly see the structure of the skull in the living animal, and the pattern of scales also follows the skull shape. I thought it might be a good idea to look at living sauropsidans in order to see if this is realistic. I choose the komodo dragon. Squamates are only very distant relatives of nonavian theropods, but in contrary to the much closer crocodiles and birds which have highly modified skull bones and integument, they have a very standard sauropsidan skull so I think the comparison is not that bad.

At first, I drew a komodo dragon skull by tracking out a photograph (www.skullsunlimited.com/userfi… ) (top). Then I "reconstructed" the soft tissue as if I would reconstruct a theropod in the manner that has been practice of the most recent decades (middle). Then I "reconstructed" the soft tissue by looking at the actual living animal (bottom). The difference is quite huge. The actual komodo dragon carries much more soft tissue on its skull than the "theropod" version, and also the scale pattern does not really follow the bone structure (it is not that bone areas that stick out the most have the largest scales). The mouth line for example does not give anything on the edges of the jaw bones. In the komodo dragon skull you actually also see that the bone surface on the snout is a little more rugose than on the lower jaw, similar to tyrannosaurids but not to the same extent, but you don't see anything of that in the living animal.

I'm not saying one should ignore osteological correlates, not at all. The bone often shows you where areas must have been keratinized and there is no such area on a komodo skull, and a lot of foramina indicate more soft tissue, which is what we find in the komodo skull (see the foramina on the lip area). Many theropods also have plenty of foramina on the jaw edges, tyrannosaurids especially on the chin area which might indicate a lot of excess tissue in the living animal.

I did this drawing just to provoke thought, perhaps it is time to "flesh up" theropod skulls a little bit.

Description
The lip discussion is a probably endless topic with good arguments on both sides concerning lips or no lips for nonavian theropods/dinosaurs and most likely will not be solved in my comment section here but only by something like soft tissue impressions covering the jaws of a theropod skull. Thus it is not my intention to provoke a lip discussion here but rather to make an artistic contribute. Actually it is not only about lips but excess tissue in general. I think "excess tissue" is supposed to refer to a quantity of soft tissue that goes beyond the minimum that is necessary to cover the skull in a physiologically sensible way. Theropods have been reconstructed with almost no excess tissue during the most recent decades (I am not necessarily talking about "shrink-wrapping") so that you can clearly see the structure of the skull in the living animal, and the pattern of scales also follows the skull shape. I thought it might be a good idea to look at living sauropsidans in order to see if this is realistic. I choose the komodo dragon. Squamates are only very distant relatives of nonavian theropods, but in contrary to the much closer crocodiles and birds which have highly modified skull bones and integument, they have a very standard sauropsidan skull so I think the comparison is not that bad.

At first, I drew a komodo dragon skull by tracking out a photograph (www.skullsunlimited.com/userfi… ) (top). Then I "reconstructed" the soft tissue as if I would reconstruct a theropod in the manner that has been practice of the most recent decades (middle). Then I "reconstructed" the soft tissue by looking at the actual living animal (bottom). The difference is quite huge. The actual komodo dragon carries much more soft tissue on its skull than the "theropod" version, and also the scale pattern does not really follow the bone structure (it is not that bone areas that stick out the most have the largest scales). The mouth line for example does not give anything on the edges of the jaw bones. In the komodo dragon skull you actually also see that the bone surface on the snout is a little more rugose than on the lower jaw, similar to tyrannosaurids but not to the same extent, but you don't see anything of that in the living animal.

I'm not saying one should ignore osteological correlates, not at all. The bone often shows you where areas must have been keratinized and there is no such area on a komodo skull, and a lot of foramina indicate more soft tissue, which is what we find in the komodo skull (see the foramina on the lip area). Many theropods also have plenty of foramina on the jaw edges, tyrannosaurids especially on the chin area which might indicate a lot of excess tissue in the living animal.

I did this drawing just to provoke thought, perhaps it is time to "flesh up" theropod skulls a little bit.