Veľkí dinosaurí predátori – ako napríklad T. Rex – Vyvinuté rôzne veľkosti očných jamiek, ktoré umožňujú silnejšie uhryznutie

Podľa nových výskumov veľké dinosaurie predátory, ako napr Tyrannosaurus rex, Vyvinuté rôzne veľkosti očných jamôk, aby sa lepšie vyrovnali s vysokými silami hryzenia.

Zatiaľ čo u mnohých zvierat, vrátane väčšiny dinosaurov, je očná jamka len kruhový otvor v lebke očnej buľvy, u veľkých mäsožravcov je to veľmi odlišné.

Nová štúdia ukazuje, ako sa nezvyčajné eliptické alebo oválne očné jamky nachádzajúce sa v lebkách týchto predátorov mohli vyvinúť, aby pomohli lebkám absorbovať náraz, keď sa vrhli na korisť. Tento výskum vedcov University of BirminghamUverejnené dnes (11. augusta 2022) Komunikačná biológia.

Rekonštrukcia lebky a života Tyrannosaura rexa s pôvodnou očnou jamkou a okom (vľavo) a imaginárna rekonštrukcia so zaoblenou očnou jamkou a zväčšeným okom (vpravo). Poďakovanie: Dr. Stephen Lautenschlager, University of Birmingham

Dr. Stephen Lautenshlager, docent v paleobiológii, Dr.[{“ 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