Monday, March 30, 2015

PARANASAL PNEUMATICITY, LATERAL VIEW

The paranasal sinuses of Tyrannosaurus rex in lateral view; same empirical sources as for the medial view. Outline of skull after Osborn (1912); the jugal sinuses are almost certainly after Molnar (1991).  The duct that connects the ventral lacrimal sinus with the orbitonasal diverticulum is blocked from view by the ventral lacrimal sinus. In a similar fashion, the air sac of the maxillary antrum is blocked from view by the lateral diverticulum of the antorbital sinus.
Paranasal Sinuses, Lateral View

Above is the complementary illustration to the medial view of the paranasal air sacs. The general mediolateral position of the component air sacs is shown, as well as their presumed continuity, and the creases produced by ridges in surrounding bones and by abrupt constrictions at pneumatic foramina. Below is a pairwise comparison of the lateral and medial views for ease of identifying gross differences between sides. The presence of the lacrimonasomaxillary suture in the lateral view only is intentional, to show the position of the sinuses relative to the nasal bone; whereas in the medial view the intent is to emphasize position and form over detailed structural context.

In terms of quality of illustration, these are amateurish and clearly precede the time before I began collaborating (in 1993) with my friend and illustrator, Dino Pulera. For example, there is no definite light source, which should be from the upper left. As such, the contours of the sinuses are washed out and flattened; the images lack the depth that such structures would have actually had. A different medium, such as pencil, carbon dust, wash, or digital paint would have been more effective in capturing form, depth, detail, and a continuous surface. Stipple has the illusion of being content rich, where in reality the white space is an information deficit and the black dots are incapable of rendering at a high resolution; it is actually worse than the highly pixellated photographs seen in newpapers because the artist lacks any control over the stipple shape. Also, the black fenestrae and teeth outcompete the actual subject of the illustration and rob it of its focus. Finally, the skull outlines should have been a light and continuous gray to emphasize the highlights on the air sacs.

The antorbital sinus system of Tyrannosaurus rex compared in lateral and medial views.


References cited

Molnar, R.E. 1991. The cranial morphology of Tyrannosaurus rex. Palaeontographica Abteilung A 217: 137176.

Osborn, H. F. 1912. Crania of Tyrannosaurus and Allosaurus. Memoirs of the American Museum of Natural History 1: 330.

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