For many decades, our understanding of Triceratops and its relatives has been solely derived from fossilized skeletal remains. However, a recent endeavor by paleontologists in Japan has successfully reconstructed the internal soft-tissue structures of these horned dinosaurs, uncovering novel features that may elucidate their mechanisms for thermoregulation and respiration.
Triceratops’ nasal cavity. Image credit: K. Sakane.
The Ceratopsia, a group encompassing the well-known Triceratops, represented one of the most varied and successful dinosaur lineages during the Late Cretaceous period.
Their cranial structures stand out as exceptionally elaborate among vertebrates, characterized by a distinct beak, an array of horns and frills, a notably expanded nasal region, and a densely packed dental battery engineered for the efficient processing of coarse plant matter.
Given that these distinctive cranial attributes likely contributed significantly to their ecological dominance on terrestrial environments, scientific inquiry has traditionally concentrated on the functional aspects of these formations – particularly the horns, beak, and frill.
Conversely, the biological significance of their enlarged nasal architecture has remained largely unexplored.
Dr. Seishiro Tada, a paleontologist affiliated with the University of Tokyo Museum, remarks, “My research into the evolutionary trajectory of reptilian cranial features and nasal structures commenced during my Master’s studies.”
He further elaborates, “Triceratops, in particular, possessed an unusually large nasal apparatus, and I found it challenging to conceptualize how its internal organs were accommodated, despite recalling the fundamental patterns observed in extant reptiles.”
“This curiosity spurred my interest in their nasal anatomy, its functional implications, and its evolutionary development.”
In this novel research, Dr. Tada and his collaborators meticulously analyzed several cranial specimens belonging to Triceratops.
“By leveraging CT scan data derived from the cranial remains of a Triceratops, coupled with our understanding of contemporary reptilian nasal morphology, we identified several unique characteristics within its nose, enabling us to formulate the inaugural comprehensive hypothesis regarding the soft-tissue anatomy of these horned dinosaurs,” Dr. Tada stated.
“The internal vascular and neural pathways within the nasal passages of Triceratops were uniquely arranged. In the majority of reptiles, neural and vascular supply to the nostrils originates from the jaw and nasal regions. However, in Triceratops, the skull’s configuration impedes this direct jaw-based route, compelling nerves and blood vessels to utilize the nasal branch.”
“Fundamentally, the tissue structure of Triceratops evolved in this manner to support its substantial nasal cavity. This realization crystallized as I meticulously reassembled 3D-printed segments of a Triceratops skull, much like assembling a complex puzzle.”
The research team also identified a specialized nasal feature within Triceratops known as a respiratory turbinate. This anatomical element is exceptionally rare among other dinosaur groups but is a common characteristic in their avian descendants and in mammals.
These delicate, convoluted nasal surfaces enhance the surface area for interaction between inhaled air and blood, thereby facilitating thermoregulation through heat exchange.
While Triceratops was likely not fully endothermic, the researchers posit that these structures played a crucial role in maintaining stable internal temperature and moisture levels, particularly given the challenge of dissipating heat from such a massive cranial structure.
Dr. Tada commented, “While definitive proof of respiratory turbinates in Triceratops remains elusive, as evidence is lacking in most other dinosaurs, certain avian species exhibit a distinct ridge serving as an attachment point for respiratory turbinates. Notably, horned dinosaurs also present a similar ridge in the corresponding location within their nasal passages.”
“It is this analogous morphology that leads us to conclude the presence of respiratory turbinates, akin to those found in birds.”
“Horned dinosaurs represent the final major clade whose cranial soft tissues have been subjected to this form of scrutiny, thus our investigation has successfully filled the last remaining gap in this dinosaur-centric puzzle.”
“Moving forward, my research aspirations include addressing questions pertaining to the anatomical characteristics and functional roles of other cranial regions, such as their distinctive frills.”
The scholarly publication detailing the team’s findings has been released in the journal Anatomical Record, accessible via the following link.
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Seishiro Tada et al. Nasal soft-tissue anatomy of Triceratops and other horned dinosaurs. Anatomical Record, published online February 7, 2026; doi: 10.1002/ar.70150.
