Therizinosaur Study Adds “Bite” to the Purpose of Beaks in the Dinosauria
New Research Sheds Light on the Role of Beaks in Some Members of the Dinosauria
Many different types of dinosaur had beaks, the role of the beak, was thought to simply act as an efficient device for, in most cases, getting plant material into the jaws but a new study using computerised tomography suggests that these keratinous structures may have served a more subtle function. The beak may have helped stabilise those light dinosaur skulls and helped to reduce stresses on the skull bones during feeding.
In new research published in the academic journal “The Proceedings of the National Academy of Sciences”, a team of international researchers including palaeontologists from Bristol University in collaboration with American palaeontologist Lawrence M, Witmer studied the fossilised skull of a four metre long, theropod dinosaur called Erlikosaurus andrewsi. This dinosaur belongs to a bizarre group called the therizinosaurs (Scythe Lizards). Although, descended from meat-eating dinosaurs, the therizinosaurs seem to have adapted to a herbivorous diet. All the therizinosaurs described to date are thought to have possessed beaks.
An Illustration of a Typical Therizinosaur (T. cheloniformis)
Picture credit: Everything Dinosaur
E. andrewsi is known from an almost complete fossilised skull found in Mongolia (Bayenshiree Svita) and other fragmentary fossil remains. Like all the known therizinosaurs, it had huge claws on its three-fingered hands. Scientists still debate what these claws were used for, they were probably efficient hooks that could grab branches to help with feeding, although some palaeontologists have abandoned the idea of this type of dinosaur being a herbivore and suggested that the claws could have been used to tear termite nests open.
The Erlikosaurus fossil material dates from the Cenomanian/Turonian faunal stages of the Cretaceous. The skull is almost preserved in three-dimensions with very little distortion, the fossil is the best example of a therizinosaur skull found to date. Using sophisticated three-dimensional CT scans, a digital representation of the original specimen was created and from this a complete skull with jaw muscle groups and other muscles located. The research team were then able to model how the beak and the jaws functioned and they examined the stresses and bite forces exerted.
The team’s findings demonstrate that this dinosaur’s beak played an important role in stabilising skeletal structure during feeding, making the skull less susceptible to bending and deformation. Beaks, as seen in extant Aves were traditionally thought of being an adaptation that came about as powered flight evolved. The beak evolving as teeth and heavier jaws were lost.
Commenting on this research, lead author of the study, Dr Stephan Lautenschlager (Bristol University) stated:
“It has classically been assumed that beaks evolved to replace teeth and thus save weight, as a requirement for the evolution of flight. Our results, however, indicate that keratin beaks were in fact beneficial to enhance the stability of the skull during biting and feeding.”
Picture credit: Proceedings National Academy of Sciences/University of Bristol
Kinetic Modelling of Dinosaur Skulls
“Using Finite Element Analysis, a computer modelling technique routinely used in engineering, we were able to deduce very accurately how bite and muscle forces affected the skull of Erlikosaurus during the feeding process. This further allowed us to identify the importance of soft-tissue structures, such as the keratinous beak, which are normally not preserved in fossils.”
This is not the first time that techniques and methods used in other fields of study have been used in palaeontology. Many new insights into fossil material have been made using techniques that have been developed originally for use in physics, medicine, chemistry as well as engineering.
American palaeontologist, Professor Lawrence Witmer (Ohio University Heritage College of Osteopathic Medicine) stated:
“Beaks evolved several times during the transitions from dinosaurs to modern birds, usually accompanied by the partial or complete loss of teeth and our study now shows that keratin-covered beaks represent a functional innovation during dinosaur evolution.”
Picture credit: Everything Dinosaur
For therizinosaur dinosaur replicas and models of feathered dinosaurs and other prehistoric animals: CollectA Age of Dinosaurs Popular Models.