Triceratops nasal soft-tissue anatomy (free pdf)

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

A new paper:

Free pdf:

Seishiro Tada, Takanobu Tsuihiji, Hiroki Ishikawa, Noriyuki Wakimizu, Soichiro Kawabe & Kodai Sakane (2026)
Nasal soft-tissue anatomy of Triceratops and other horned dinosaurs
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.70150
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70150

Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.70150



Although ceratopsid dinosaurs possess a characteristically hypertrophied narial region, soft-tissue anatomy associated with such a skeletal structure and their biological significance remain poorly understood. The present study provides the first comprehensive hypothesis on the soft-tissue anatomy in the ceratopsid rostrum based on the Extant Phylogenetic Bracket approach. Several cranial specimens of Triceratops including the computed tomography-scan data of an isolated premaxilla as well as those of phylogenetically diverse ceratopsids were examined and compared to the anatomical features of the rostrum in extant reptiles. The resulting hypothesis includes the narial neurovascular pathways and locations of the nasal gland and nasolacrimal duct. Particularly, the narial innervation pattern in ceratopsids is inferred to be unique among reptiles and is suggested to have evolved in response to the enlargement of the naris. In addition, respiratory turbinates are inferred to have been present in ceratopsids for the first time based on an osteological correlate and would likely have served for cephalic thermal regulation as in extant birds and mammals. Acquisition of such a structure might have mitigated a thermal problem associated with the large size of the ceratopsid head.

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[Gregory Paul]

This paper reminds me of an incident from the 90s that occurred partly on this list. Back in the day biologist John Ruben was trying to tell all us clueless paleos that dinosaurs were obviously low metabolic rate reptiles. For reasons obscure he had an in at Science and published a series of papers there saying so. One was on respiratory turbinates, which birds and mammals have big nasal cavities to contain, and reptiles do not. RT are necessary to properly process air among endotherms according to R. Ruben et al. measured the nasal passages of some dinosaurs and found they were too small to contain RT, ergo they were ectotherms. 

There were lots of problems with this hypothesis. One was the small sample of examples living and extinct. Among the latter absence were sauropods. On this list I casually noted that they have nasal cavities large enough to park a Buick in. 

Shortly after that a seething R called me up. Warned me to never do anything like that again. Like I cared.

I did an extensive analysis on the RT issue in Dinosaurs of the Air. Including dimensions of ceratopsid nasal cavities which you can park a Ford 150 in (no need to call R). So now we have the below study. Nice to see that they cite the DoA analysis. 

GSPaul

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[Jaime Headden]

Ruben was in the audience at SVP 2001 as I recall, during Tsuihiji's initial presentation of this research. There, they were talking about osteological features of the narial cavity, and part of the conclusion was that centrosaurines and chasmosaurines each have peculiar features the other lacks relating to a far more complex internal structure of either cartilage or unpreserved bone. The narial prong and medial ridge was raised as a possible attachment for turbinates, but without *exceptional* preservation, it can only be inferred.

There's not a lot of physical features in the nasal cavity that can be anchored to the lateral wall (maxilla/nasal, as shown in the paper), regardless if you pretend birds aren't dinosaurs. A medial flange of cartilage and associated soft tissue would almost certainly indicate higher surface area that would break airflow into and out of the nasopharyngeal passage across its surface, how the turbulence within it can be modeled, and how that effects vascularization of the ENORMOUS narial cavity in these animals. Even if we don't find out what connects to the posterior chasmosaurine premaxillary processes, or why there's a giant foramen through the fused anterior bit, we do know that there was a massive amount of vascular tissue in that bony cavity, and turbinates become one of the more reasonable explanations.

This was also prior to the corkscrew/bendy-straw noses of ankylosaurs were described, or maths on sauropod necks and hadrosaur crests that required a stronger and warmer breath to push air through them, that would necessarily result in a natural higher metabolism to support. I fully expected Ruben to stand up at the Q&A at the end and make an issue of the research, but alas, he did not. It's really hard when there's not a lot you CAN say but repeat the same canards ad nauseam. It seems Ruben left that to his students.

Cheers,

To view this discussion visit https://groups.google.com/d/msgid/DinosaurMailingGroup/1375830770.159372.1770557124067%40mail.yahoo.com.

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Jaime A. Headden

The Bite Stuff: http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth" - P. B. Medawar (1969)

[Gregory Paul]

Back in 1998 in the Modern Geology Morrison volumes I pointed out that to be over a tonne and tall on land, especially the long necks of sauropods, requires high aerobic power and metabolic rates, which I have been calling terramegathermy. Also did so in The Complete Dinosaur. This is in line with Roger Seymour's noting the need for high BPs in tall animals that in turn requires high metabolic rates. GIgantothermy in which aerobic performance and MRs converge in land animals of great size is a myth, yet it still is referred to. No one refers to terramegathermy even though the relationships between high mass, height and metabolism it is tacitly acknowledged by some to exist.

The MG paper was also the first to statistically show that sauropod mouths are big enough to feed a high MR. I kept trying to get it in Nature or Science but reviewers kept killing it -- one dismissed it as yet another futile attempt to use anatomy to restore metabolics when the results actually show mouth width does not correlate with metabolism. Shortly after the MG paper came out Pre Christiansen showed the same thing, now it is universally accepted.  

In DoA I showed that kiwis have very narrow nasal passages. Ruben dismissed this as kiwis being sluggish. Which they are not. I went to the National Zoo where their keeper had a good laugh at that, at night when it is cool they are very active and energetic. She invited to pet a kiwi as she held it, which was way cool. 

GSPaul

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