Paleontologists from Queen Mary University of London and elsewhere have performed an extensive survey of the literature and fossil collections cataloging a large number of bones of long-necked sauropod dinosaurs like Diplodocus and Brontosaurus from the Upper Jurassic (c. 150 million years old) Morrison Formation of the United States that bear bite traces that can be attributed to carnivorous theropod dinosaurs. Their results suggest preferential feeding by theropods on juvenile sauropod dinosaurs, and likely scavenging of large-sized sauropod carcasses.
Theropod diversity and largest lateral crowns of theropods from the Morrison Formation of North America: (A) crown of Allosaurus; (B) crown of the megalosaurid Torvosaurus tanneri; (C) crown of the allosaurid Allosaurus sp.; (D) crown of the ceratosaurid Ceratosaurus sp.; (E) crown of the piatnitzkysaurid Marshosaurus bicentessimus; (F) crown of the tyrannosauroid Tanycolagreus topwilsoni; (G) crown of the maniraptoriform Ornitholestes hermanni; (H) crown of the troodontid Hesperornithoides miessleri. Image credit: Lei et al., doi: 10.7717/peerj.16327.
Tooth-marked bones provide invaluable insights into the feeding behaviors of long-extinct carnivorous creatures.
While it is commonly thought that the giant tyrannosaurs were the primary culprits behind these tell-tale marks on dinosaur bones, Dr. Roberto Lei from the Università degli Studi di Modena e Reggio Emilia and colleagues took a closer look at other large carnivores’ contributions to this paleontological puzzle.
They performed an extensive survey of the literature and fossil collections, revealing a striking discovery: 68 sauropod bones from the Morrison Formation of the United States bear unmistakable bite traces attributed to theropods.
The findings suggest that while bite traces on large sauropods were less common than in tyrannosaur-dominated environments, they are nonetheless abundant in the Morrison Formation and more so than previously realized.
A particularly intriguing aspect of their discovery is that none of the observed traces showed any evidence of healing, indicating that these bites occurred either in a single, lethal encounter or more likely were post-mortem feeding traces from scavenging.
The paleontologists also looked at the wear on the teeth of Morrison Formation theropods and found that they similarly show wear associated with biting bones more often than previous realized and are closer to the patterns seen in the large tyrannosaurs.
However, attributing bite traces to specific theropod species remains a complex challenge due to the presence of multiple credible candidates and so it is very hard to attribute any single bite on the sauropod bones to the predators around like Allosaurus and Ceratosaurus.
“This new work helps us understand the ecological relationships between dinosaurs in the Jurassic and reveals that the habits of the larger carnivores then were closer to that of the tyrannosaurs than previously thought,” said Dr. David Hone, a paleontologist at Queen Mary University of London.
“It’s another important step in reconstructing the behavior of these ancient animals.”
A paper on the findings was published online today in the journal PeerJ.
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R. Lei et al. 2023. Bite and tooth marks on sauropod dinosaurs from the Morrison Formation. PeerJ 11: e16327; doi: 10.7717/peerj.16327
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