News | Computed Tomography (CT) | July 29, 2016

CT Scans of Dinosaur Skulls Reveal Interior Structure to Researchers

First-ever CT scans of Pawpawsaurus's skull indicate the dino's saving grace from predators may have been an acute sense of smell

CT scan

This is a volume-rendered CT-based reconstruction of the skull of the nodosaur dinosaur PawPawsaurus, from the first-ever CT scans of the PawPawsaurus skull. The bone is rendered semitransparent to show the endocranial cavity in dark blue and the nasal cavities in light blue. Image courtesy of PLosONE/SMU.

CT scan
CT scan

This is a reconstruction of the left inner ear of PawPawsaurus from the first-ever CT scans of the PawPawsaurus skull. Image courtesy of PLosOne/SMU.

Well-known armored dinosaur Ankylosaurus is famous for a hard knobby layer of bone across its back and a football-sized club on its tail for wielding against meat-eating enemies.

It's prehistoric cousin, Pawpawsaurus campbelli, was not so lucky. Pawpawsaurus was an earlier version of armored dinosaurs but not as well equipped to fight off meat-eaters, according to a new study, said vertebrate paleontologist Louis Jacobs, Southern Methodist University, Dallas. Jacobs is co-author of a new analysis of Pawpawsaurus based on the first computed tomography (CT) scans ever taken of the dinosaur's skull.

A Texas native, Pawpawsaurus lived 100 million years ago during the Cretaceous Period, making its home along the shores of an inland sea that split North America from Texas northward to the Arctic Sea.

Like Ankylosaurus, Pawpawsaurus had armored plate across its back and on its eyelids. But unlike Ankylosaurus, Pawpawsaurus didn't have the signature club tail that was capable of knocking the knees out from under a large predator.

Ankylosaurus lived about 35 million years after Pawpawsaurus, around 66 million years ago toward the end of the Cretaceous. During the course of its evolution, ankylosaurids developed the club tail, and bone structure in its skull that improved its sense of smell and allowed it to hear a broader range of sounds. "Stable gaze" also emerged, which helped Ankylosaurus balance while wielding its clubbed tail.

"CT imaging has allowed us to delve into the intricacies of the brains of extinct animals, especially dinosaurs, to unlock secrets of their ways of life," said Jacobs, a professor in the SMU Department of Earth Sciences.

While Pawpawsaurus's sense of smell was inferior to Ankylosaurus, it was still sharper than some primitive dinosaur predators such as Ceratosaurus, said vertebrate paleontologist Ariana Paulina-Carabajal, first author on the study.

"Pawpawsaurus in particular, and the group it belonged to — Nodosauridae — had no flocculus, a structure of the brain involved with motor skills, no club tail, and a reduced nasal cavity and portion of the inner ear when compared with the other family of ankylosaurs," said Paulina-Carabajal, researcher for the Biodiversity and Environment Research Institute (CONICET-INIBIOMA), San Carlos de Bariloche, Argentina. "But its sense of smell was very important, as it probably relied on that to look for food, find mates and avoid or flee predators."

Most dinosaurs don't have bony ridges in their nasal cavities to guide airflow, but Ankylosaurs are unique in that they do.

"We can observe the complete nasal cavity morphology with the CT scans," Paulina-Carabajal said. "The CT scans revealed an enlarged nasal cavity compared to dinosaurs other than ankylosaurians. That may have helped Pawpawsaurus bellow out a lower range of vocalizations, improved its sense of smell, and cooled the inflow of air to regulate the temperature of blood flowing into the brain."

First CT scans shed light on Pawpawsaurus's sensory tools

Pawpawsaurus is more primitive than the younger derived versions of the dinosaur that evolved later, Jacobs said, although both walked on all fours and held their heads low to the ground.

"So we don't know if their sense of smell also evolved and improved even more," Jacobs said. "But we do suspect that scenting the environment was useful for a creature's survival, and the sense of smell is fairly widely distributed among plant eaters and meat eaters alike."

The team's measurements and conclusions are reported in the journal PLOS ONE in the article "Endocranial Morphology of the Primitive Nodosaurid Dinosaur Pawpawsaurus campbelli from the Early Cretaceous of North America." It is published online at http://bit.ly/1TpWiYE.

The skull was identified in 1996 by Yuong-Nam Lee, Seoul National University, Korea, a co-author on the paper, who was then a doctoral student under Jacobs.

The team's discoveries emerged from Computed Tomography (CT) scans of the braincase of Pawpawsaurus campbelli's skull. Pawpawsaurus belongs to one of the least explored clades of dinosaurs when it comes to endocranial anatomy — the spaces in the skull housing the brain.

The Pawpawsaurus skull was discovered 24 years ago by 19-year-old Cameron Campbell in the PawPaw Formation of Tarrant County near Dallas. Conventional analysis of the skull was carried out years ago to identify it as a never-before-seen nodosaurid ankylosaur. However, these are the first CT scans of Pawpawsaurus's skull because it's only been in recent years that fossils have been widely explored with X-rays.

In humans, a medical CT will scan the body to "see inside" with X-rays and capture a 3-D picture of the bones, blood vessels and soft tissue. In fossils, a much stronger dose of radiation than can be tolerated by humans is applied to fossils to capture 3-D images of the interior structure.

From the scans, paleontologists can then digitally reconstruct the brain and inner ear using special software.

"Once we have the 3-D model, we can describe and measure all its different regions," Paulina-Carabajal said. "We can then compare that to existing reptile brains and their senses of hearing and smell. Hearing, for example, can be determined from the size of the lagena, the region of the inner ear that perceives sounds."

The size of the lagena in Pawpawsaurus suggests a sense of hearing similar to that of living crocodiles, she said.

Olfactory acuity, the sense of smell, is calculated from the size ratio of the olfactory bulb of the brain and the cerebral hemisphere.

"In Pawpawsaurus, the olfactory ratio is somewhat lower than it is in Ankyloxaurus, although both have high ratios when compared with most carnivorous dinosarus," Paulina-Carabajal said. "They are exceeded only by carcharodontosaurids and tyrannosaurids. The olfactory ratios of ankylosaurs in general are more or less similar to those calculated by other authors for the living crocodile."

Related Content

Siemens Healthineers Demonstrates Artificial Intelligence, Healthcare Digitalization at HIMSS19
News | Artificial Intelligence | February 13, 2019
February 13, 2019 — At the 2019 Healthcare Information and Management Systems Society (HIMSS) global conference and e
Canon Adds Radiation Therapy Package to Aquilion Prime, Lightning CT Systems
News | Computed Tomography (CT) | February 11, 2019
In the patient-centric world of radiation oncology, it is critical that computed tomography (CT) simulation is...
Korean National Training Center Installs Carestream OnSight 3D Extremity System
News | Computed Tomography (CT) | February 07, 2019
Jincheon National Training Center in Jincheon, South Korea, installed a Carestream OnSight 3D Extremity System at its...
Canon Medical Debuts Alphenix 4-D CT at RSNA 2018
Technology | Angiography | February 06, 2019
Canon Medical Systems USA Inc. recently introduced a new angiography configuration featuring its Alphenix Sky + C-arm...
MaxQ AI's Accipio Software Integrated to GE's Smart Subscription Platform
News | Computed Tomography (CT) | January 29, 2019
MaxQ AI and GE Healthcare announced that MaxQ's Accipio artificial intelligence (AI) platform will now be a part of GE...
Siemens Healthineers Debuts AI-Rad Companion Chest CT
News | Artificial Intelligence | January 25, 2019
Siemens Healthineers presented its first intelligent software assistant for radiology, the AI-Rad Companion Chest CT,...
3-D Reconstruction of Ichthyosaurus Skull

A 3-D reconstruction of the ichthyosaurus skull from a computed tomography (CT) scan. Image courtesy of Nigel Larkin, taken at Royal Veterinary College, London.

News | Computed Tomography (CT) | January 09, 2019
A nearly meter-long skull of a giant fossil marine ichthyosaur found in a farmer's field more than 60 years ago has...
SCCT Releases New Guideline for CT Use During TAVR
News | Computed Tomography (CT) | January 08, 2019
The Society of Cardiovascular Computed Tomography (SCCT) has released a new expert consensus document for computed...
Artificial Intelligence Pinpoints Nine Different Abnormalities in Head Scans

A brain scan (left) showing an intraparenchymal hemorrhage in left frontal region and a scan (right) of a subarachnoid hemorrhage in the left parietal region. Both conditions were accurately detected by the Qure.ai tool. Image courtesy of Nature Medicine.

News | Artificial Intelligence | January 07, 2019
The rise in the use of computed tomography (CT) scans in U.S. emergency rooms has been a well-documented trend1 in...
CT Technique Expands Possibilities of Imaging Ancient Remains
News | Computed Tomography (CT) | December 27, 2018
Researchers in Sweden using computed tomography (CT) have successfully imaged the soft tissue of an ancient Egyptian...