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.

Sunday, March 29, 2015

PARANASAL PNEUMATICITY, MEDIAL VIEW


The paranasal sinus and its diverticula of Tyrannosaurus rex, medial view. This reconstruction is based on casts of AMNH FARB 5027, MOR 555, UCMP 118742, and a cf. Albertosaurus libratus specimen, ROM 1422.

Introduction

Today I resumed an unsuccessful search for a line drawing that I drew of a bird basicranium during my PhD candidate years; instead I came across a file containing illustrations from my Master's degree days. The file contained many line drawings that I did for a 60+ page term paper for my Comparative Anatomy of the Vertebrates course - the assignment was for a 10-page paper; when I beamingly gave my work to the prof, he looked pained and asked "What am I supposed to do with this - read it?!" After working as a prof for a decade, I don't blame him for that reaction at all.

The paper described in loving, subinfinite detail the internal structures - the bony cavities and the soft tissue air sacs that filled them - of the bony paranasal and basisphenoid sinuses of tyrannosaurids. The work culminated in a reconstruction of the air sacs that filled the bony spaces as they would have appeared in Tyrannosaurus rex. One of those illustrations is reproduced here; the labels did not appear in the original work. The names of the structures have not been formalized; I included them here to help place the balloon like structures in the skull with ease.

Overall Goal

The main goal of my term paper was to show the antorbital air sac and its subordinate system of interconnected diverticulae. Therefore, the primary nasal airway (that extends from the external naris to the choana) is not shown; that is why an ostium (connecting hole) is shown at the position of the epiantral recess, as if the airway has been cut away from the system of paranasal air sacs that extend from it laterally. The placement of the ostium is nearly arbitrary; it is one discrete location where the nasal airway directly enters the facial skeleton without the intermediary of the antorbital sinus, which is limited caudal to that opening in the medial wall of the bony maxillary sinus.

This exercise in reconstruction was done purely based on the topography of the bony signatures left by the diverticulae, assuming that the antorbital sinus had a balloon like form, lodged on the lateral and medial sides of the internal antorbital fenestra. That assumption was intended to be a heuristic starting point for the reconstruction.

My secondary goal was to show the impressions left on the air sac system by the bony enclosure, which consists of deep pockets, bulges, constrictions, and bladelike ridges. I imagined that the air sac system, shown whole and freed of the bones, would resemble corrosion casts of bird lungs that are deeply dissected by the buttresses of the lungs and vertebrae into surrealistic pulmonary baskets. This was a short time before endocasts of dinosaur fossils became fashionable in the scientific literature.

Sunday, February 1, 2015

TYRANNOETHICS 4: THE NATURALIS T. REX & THE T. REX LIST OF SHAME, UPDATED

Like smoke, does the price tag hang around after real museums purchase dinosaurs? With apologies to the late Amy Winehouse.

Naturalis T. rex
Although the SVP ethics does condone the purchase of fossils into the public trust, it is still most dispiriting for me to know colleagues who are engaged in that activity. Nothing dampens my morale more that to hear them blithely discuss the “going market rate” for, say, a T. rex or a Triceratops. How should museums treat that "market", I wonder?
The same people tell me that I represent the “hard line” on the sale of dinosaur fossils. Although we both lament the sale of fossils to private individuals, we in academe find ourselves on opposite sides of the principle of protecting fossils for Science and education.
My fossil purchasing colleagues rationalize their actions by saying that it is better than a given dinosaur fossil landing in private hands; in the end, they say, the fossil is where it belongs despite how it got there. That's just the way it is. The alternative is the oblivion of private ownership where data is lost to science indefinitely, so purchases made by legitimate museums is the lesser of two evils.
Not so fast.
It is with ambivalence I receive the news about the recent purchase of an adult T. rex by the Naturalis Museum (Netherlands) for $5 million euros: I’m glad the specimen is headed for a real museum, but the price tag sticks like a thorn through the eye. Should I be concerned? The concern my fossil-buying colleagues have is that T. rex fossils are “overpriced” and drive up the “market value” of dinosaur fossils in general. Good grief.
The information on the exchange for the specimen is pretty slim, and one source (CIHAN, 2014), provides the backbone of the story:
a) The specimen was found on private land in Montana in May 2013.
b) The specimen includes skull and skeleton of an adult, which is approximately 12 meters long. It is missing the feet, left leg, and arms; it was found in sandstone and the bones are not distorted.
c) Preparation of the specimen, and mounting on a metal armature for display is being done by the Black Hills Institute of Geological Research (BHIGR) Inc.
d) The Naturalis Museum collected the specimen, almost certainly with assistance from BHIGR Inc.
e) “As its excavator Naturalis had the first right for purchase” (emphasis added).
d) The Naturalis had to pay $5 million euros, or $6.1 million USD for the specimen, presumably to the landowner.
e) A crowd funding campaign brought in $230,000.00 euros, and the rest “came from companies, individuals, funds, the municipality of Leiden and Naturalis”. A large part of the funds were raised through kickstarter.
f) The specimen will go on display in mid 2016.
g) The Naturalis Museum says it will publish a bunch of research on the specimen.
Should I be concerned? Regardless of the negotiations between landowner and museum, Naturalis has sent the message to everyone with a dinosaur skeleton on their land that museums will pay just about anything for the fossil and will go to extraordinary lengths to raise the money to buy it. With behavior like that I’m not convinced that legitimate natural history museums aren’t less of a problem as the private hoarders; together they keep the “market” alive and kicking because they’ll pay top dollar. For some perspective, a million dollars could easily fund a decade of a large museum's field program.
My fossil-buying friends would say that it isn’t their fault – the precedent was set by the auction of Sue to the Field Museum for about $8 million USD. Ergo, we’re stuck. From my point of view, it is our responsibility as scientists to treat the price tag of Sue as an anomalously high outlier that no one (in academe at least) has since taken seriously, and no Science respecting museum will ever pay that much again.
Wouldn’t Science be better served if the scientist holding the check book just said “no” to an marked up price tag?! Instead, a museum could, say, offer landowners a percentage of the admission tickets and the merchandizing that stems from the fossil. Certainly there must be alternatives to just paying out astronomical amounts of money that gives the extortion-level “going rate” for dinosaurs, and the “market” itself, no end in sight.
So what happens when a museum doesn’t cave in and a sale flops?  Then the fossils are gone and Science keeps the high road, which of course has a steep cost in terms of the indefinite loss of the specimen. Over time, people with fossils for sale will find that dinosaurs aren't the winning lottery tickets they had thought them to be (assuming that private hoarders wise up to this as well). There is the remote hope that at some point in the future the dinosaur will change hands, or the private hoarder will change heart, and the fossil will be positioned for donation to a museum.
The alternative is for museums to follow the Naturalis example and pay the exorbitant cost and give a clear message to all that the value of the "market" stands head and shoulders above the value of Science.
T. rex list of shame, expanded and updated.
I have added six additional T. rex specimens (in red text) to the T. rex List of Shame that are documented in Larson (2008); that list was up to date as of August 2006. For the present time, I have not included specimens that are housed in what are essentially nonaccredited private collections and privately owned, but nonprofit museums. In their relatively high public profile such places occupy a gray area (perhaps dark gray) between outright private collections on the one hand, and legitimate (i.e., accredited) and long established museums on the other.
Regardless, the 14 specimens in this list represent a substantial and devastating loss to science in that it includes a growth series, from juvenile to adult. Were these specimens in real museums, the sample size of each primary growth stage (juvenile, subadult, young adult, senescent adult) would be increased significantly and we’d have a better sense of the range of variation in each stage.

Unfortunately, I expect this list to increase in number as the years progress unless the culture tips away from commerce and toward Science and education.
 
1. Barnum: partial skull and postcranial skeleton; found in 1996; collected from Wyoming; sold at auction for over $90,000.00 USD to investors from South Dakota in May 2004.
2. Ollie: incomplete skull and skeleton; found in 1998; collected from Montana; owned by Great Plains Paleontology (Madison, WI).
3. Rex-C: partial skull and skeleton; found in 1999; collected from South Dakota.
4. Monty: partial skull and skeleton; found in 2000; collected from Wyoming; owned by Babiarz Institute of Paleontological Studies, Mesa (AZ).
5. Otto: partial postcranial skeleton; found in 2001; collected from Montana; owned by Great Plains Paleontology (Madison, WI).
6. Wayne: partial postcranial skeleton; found in 2004; collected from North Dakota; privately owned.
7. Cupcake: subadult skull and jaws; almost certainly collected from Montana; owned by The Amazing Traveling Dinosaur Show, British Columbia; on display in Victoria, BC in December, 2014.
8. King Kong: adult skull and skeleton; collected from Montana; privately owned by an individual person; a project of The Amazing Traveling Dinosaur Show; was on public display at the Mineralientage Munchen, at Munich Trade Fair Center Oct 24-25 2014.
9. Tinker: subadult skull and skeleton; collected in South Dakota in 1998; privately owned; presently on display in an art gallery in Dubai; for sale for $10 million; found associated with the adult specimen Regina.
10. Regina: adult; found associated with Tinker; the pair is for sale between $12 and $14 million.
11 & 12. Russell: composite skeleton of two adults; offered for sale at the Bonham’s auction in November, 2013; on display at a 2013 Gem and Mineral show (Denver or Tucson).
13. Dueling tyrannosaur: subadult skull and skeleton; offered for sale at the Bonham’s auction in November, 2013; associated with a ceratopsian; owned by CK Productions.
References cited
CIHAN. Dec. 30, 2014. Feature: Night watch, tulips and T. rex in the Netherlands.
Larson, N. 2008. One hundred years of Tyrannosaurus rex: the skeletons; pp. 1-55 in
P. Larson, and K. Carpenter (eds.) Tyrannosaurus rex, the Tyrant King. Indiana University Press, Bloomington.

Monday, January 26, 2015

THE MOR DIARIES, ENTRY #6


At the end of two weeks of drawing nonstop are 85 line drawings that don't come even close to a complete documentation of the skeleton! Why on earth am I smiling?! Photograph by John Scannella.
 Part A: Progress Report
My trip to the MOR is now over and done with; in the end, I completed 85 line drawings in two weeks and the revisions bumped the ms up to 1,273 pages. Each day was so labor intensive that I was left mentally and physically exhausted to the extreme that I hadn’t the energy or motivation to post updates.
After the first a full week of making illustrations, it was clear to me that I had to narrow my focus on the articulated skull and exclude the disarticulated bones in the cabinets. Despite appearances, the articulated skull is in several sections that can be taken apart and reassembled. I want this trip to be the last (or second last) time that happens in order to minimize handling and stress upon the large, but delicate fossil. My plan was to fully illustrate the skull in its articulated and disarticulated conditions before I left.
As history turned out, I was able to illustrate nearly the entire skull and jaws, with the exception of much of the braincase and parts of the lower jaws. One of the main benefits of this trip was getting a handle on my weekly progress, which is approximately 43 line drawings a week. This will help me plan my next visit, during which I plan to complete the skull and jaws, and get a good start on the postcranium.
I approach each drawing in three steps, where (1) I draw the outline of the bone, or the outline of a set of articulated bones with a heavy line weight, (2) I then draw outlines of all of the damage, plaster, glue, and epoxy with a thin line weight, and finally (3) I draw in the topography of the bone with a light or medium weight line. In a collections room with diffuse light, I wear a small headlamp to illuminate the specimen. To stave off boredom, especially during the midafternoon, I usually have a maximum of three drawings in progress. In most cases I find that drawing the actual anatomical details gets accomplished very quickly, in contrast to drawing in all of the damage. Since there was such a high volume of illustrations to make for this project, I saved time by holding off the final task of varying the line weights for home except for highly damaged bones such as (in this case) the premaxilla.
Part B: Rationale & Justification for a Big Monograph
In this section I will answer the most frequent questions I get regarding this monograph, with the goal to flesh out my aims for embarking on this sizeable work, as well as that on Jane.
Q: Where do you plan on publishing such a large work?
A: There are several online journals (e.g., ZooKeys, Zootaxa) that do publish large works online, which is enabled by the digital format. There are traditional print journals (e.g., Palaeontology, Journal of Paleontology, Journal of Vertebrate Paleontology) that publish large memoirs in addition to their regular issues. And there are publishers that that will print specialized works in book form (e.g., Springer). I therefore have several venues to consider once the final manuscript is produced.
Q: Why not just break up your monograph into several smaller articles? That way you can boost your publication record.
A: To my mind, a monograph is a single coherent reference work that saves fellow researchers the inconvenience of tracking down separate articles, and personal experience has shown me that a single work (or set of works between two covers) is simply easier to work with. I think the mode of publication ought to benefit the audience more than the author. Put another way, a monograph is a work that the reader can count on as delivering a maximum amount of information content in a single location. That’s the whole point.
Q: Why such a huge monograph on one species? Aren’t you just repeating previous works, like Brochu (2003)?
Why not a huge monograph on one species? Let’s take an honest look at the current landscape of publications on new dinosaur taxa: most articles in the premier journals are 30 pages long or less, and each bone is usually covered in a paragraph or two. How is that acceptable when we know that bones aren’t that simple and there is a huge volume of literature behind most groups of dinosaurs that needs adequate comparison with new fossils. I think we’re in an unfortunate historical moment where less information is seen as better than more; I suspect that this has more to do with publication costs of printed media than anything else.
With regard to the specific project at hand I am describing a growth series, which significantly bumps up the page length. This also helps make the argument for a large work, not against it; a monograph provides the opportunity to capture the variation of a taxon in detail. Again, my basic argument is the same: maximizing information content is better than minimization. Why leave people guessing?
The question of repetition strikes me as a little bizarre, since the taxon I’m working on isn’t an adult T. rex; the question implies that there’s so little difference between T. rex and its immediate relatives that there’s no reason to treat any of them in detail. But that would be to argue from ignorance of the tyrannosaurid literature, the history of the group, and variation in the clade; we really don’t know that much about tyrannosaurid osteology and variation, and we must take every opportunity we have to enrich our knowledge if we are to have any hope of understanding their biology and their place in Cretaceous ecosystems
I agree that Brochu (2003) is worthy of some discussion here. That is an exemplary work, and I have used it as a template for the Two Med tyrannosaurine monograph and for the Jane monograph. But it has to be kept in mind that more taxa and more information has been published since that time and we’re currently in a phase (perhaps perpetual) of catching up with new knowledge. For example, I’ve drafted below a table contrasting the information content of the maxilla in Brochu (2003) from that in the Two Med tyrannosaurine monograph by comparing the number of subheadings that correspond to primary osteological features. A quick glance shows a huge difference of information content, showing that my effort isn’t redundant by any measure, but rather it is complementary. The difference is primarily one of resolution. Also Brochu (2003) takes care of the maxilla in about three printed pages, whereas in my case, the maxilla is covered in 74 (double spaced) pages.
Brochu (2003)
Two Med tyrannosaurine monograph
General form
General form
Ventral margin of lateral alveolar process
Ventral margin of lateral alveolar process
Alveoli
Alveoli
Teeth, number and shape
Teeth, number and shape
Circumfenestral foramina
Circumfenestral foramina
Alveolar foramina
Alveolar foramina
Maxillary nerve channel
Maxillary nerve channel
Subnarial foramen
Subnarial foramen
Jugal ramus
Jugal ramus
Subcutaneous surface
Subcutaneous surface
Antorbital fossa
Antorbital fossa
Maxillary fenestra, size and shape
Maxillary fenestra, size and shape
Interfenestral strut
Interfenestral strut
Promaxillary recess
Promaxillary recess
Promaxillary fenestra, position and shape
Promaxillary fenestra, position and shape
Vestibular bulla
Vestibular bulla
Caudal antromaxillary fenestra
Caudal antromaxillary fenestra
Antorbital fenestra
Antorbital fenestra
Palatal process
Palatal process
Bony choana
Bony choana
Maxillary antrum
Maxillary antrum
Maxillary antrum, medial wall
Maxillary antrum, medial wall
Sutural contacts
Sutural contacts
-
Condition

Horizontal ramus (excluding antorbital fossa)

Horizontal ramus (including antorbital fossa)

Interdental septa

Sulci of the alveolar row of foramina

Subnarial region

Joint surface for the premaxilla

Premaxillary buttress

Narial fossa

Circumfossa ridge

Teeth, position

Dorsal jugal process

Ventral jugal process

Caudal alveolar foramen

Joint surface for the jugal

Nasomaxillary suture

Ascending ramus, lateral view

Maxillolacrimal suture

Ascending ramus, medial view

Antorbital fossa, subordinate fossae and foramina

Maxillary fenestra, position

Maxillary position, form of edges

Maxilla, medial surface

Interdental plates, form

Interdental plates, position and texture

Medial alveolar process

Dental pits

Joint surface for the palatine

Palatal process, form

Palatal process, medial wall

Palatal process, dorsal surface

Maxillary sinus system

Maxillary antrum, caudal region

Maxillary antrum, epiantral recess

Intermaxillary process

Intermaxillary joint surface

Intermaxillary process, foramina

Medial surface above maxillary sinus system

It also has to be kept in mind how much our knowledge of tyrannosaurid osteology has come since 2003. Since then, different authors will describe features not mentioned by others, which has expanded the amount of anatomy to write up. The number of phylogenetic characters published for the clade is now well into the hundreds, which is additional incentive to expand the osteological descriptions and to describe how each feature varies. Therefore, a monograph that aims to capture all of that information will have a huge payoff for other researchers in that the full range and hierarchy of variaton is captured, including phylogenetic, ontogenetic, and individual.
References cited
Brochu, C. A. 2003. Osteology of Tyrannosaurus rex: insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull. Society of Vertebrate Paleontology Memoir 7: 1-138.