I grandi dinosauri predatori, come il T. rex, hanno sviluppato diverse forme delle orbite per consentire morsi più forti.

Secondo una nuova ricerca, grandi dinosauri predatori come Tirannosauro Rex Sono state sviluppate varie forme di cavità oculari per gestire meglio le forze mordenti più elevate.

Mentre in molti animali, inclusa la maggior parte dei dinosauri, l’orbita dell’occhio è solo un foro circolare nel cranio che contiene il bulbo oculare, questo è abbastanza diverso nei carnivori più grandi.

Un nuovo studio ha rivelato come le insolite orbite ovali o ovali che si trovano nei crani di questi predatori potrebbero essersi evolute per aiutare il cranio ad assorbire lo shock quando si avventa sulla preda. Questa ricerca degli scienziati in Università di Birminghampubblicato oggi (11 agosto 2022) in Biologia della comunicazione.

Ricostruzioni del cranio e della vita in Tyrannosaurus Rex con l’orbita e l’occhio originali (a sinistra) e ricostruzione virtuale utilizzando un’orbita circolare e l’occhio ingrandito (a destra). Credito: Dr. Stefan Lautschlager, Università di Birmingham

Dr. Stefan Luttenschlager, Professore Ordinario di Paleobiologia presso[{” attribute=””>University of Birmingham and author of the new study, analyzed the shape of the eye sockets of ca. 500 different dinosaurs and related species.

“The results show that only some dinosaurs had eye sockets that were elliptical or keyhole-shaped,” said Dr. Stephan Lautenschlager. “However, all of those were large, carnivorous dinosaurs with skull lengths of 1 m or more.”

Computer simulations of hypothetical dinosaur skulls. Colors indicate skull stress. High stresses occur in the skull with a round eye socket (top), lower stresses in a skull with a keyhole-shaped eye socket (bottom). Credit: Dr. Stephan Lautenschlager, University of Birmingham

Dr. Lautenschlager tested what purpose these unusual eye socket shapes could have by using computer simulations and stress analysis.

The results demonstrated that a skull with a circular eye socket was more prone to high stresses during biting. However, if these were replaced with other eye socket shapes stresses were significantly reduced. This allowed top predators, including Tyrannosaurus rex, to evolve high bite forces without compromising skull stability.

The study also showed that most plant-eating species and juvenile individuals retained a circular eye socket. Only large carnivores adopted other morphologies, such as elliptical, keyhole-shaped, or figure-of-eight-shaped eye sockets.

Skulls of different dinosaurs showing variation in eye socket shape (stippled outline). Credit: Dr. Stephan Lautenschlager, University of Birmingham

Dr. Lautenschlager added: “In these species, just the upper part of the eye socket was actually occupied by the eyeball. This also led to a relative reduction of eye size compared with skull size.”

The researchers also investigated what would have happened if eye size had increased at the same rate as skull length. In such a case, the eyes of Tyrannosaurus rex would have been up to 30 cm (12 inches) in diameter and weighed nearly 20 kg (44 pounds). This is instead of an estimated 13 cm (5 inches) and 2 kg (4.4 pounds).

Reference: “Functional and ecomorphological evolution of orbit shape in mesozoic archosaurs is driven by body size and diet” by Stephan Lautenschlager, 11 August 2022, Communications Biology.
DOI: 10.1038/s42003-022-03706-0