Football-Shaped Head Won Dinosaur Mates

The sex lives of dinosaurs are starting to come to light, and it looks like at least one species loved the look of football-shaped heads.

With Super Bowl 50 less than a month away comes news that at least one dinosaur was turned on by football-shaped heads.

The "football," colored watermelon red in recreations, was actually a bony appendage called a frill that was attached to the head of the dinosaur Protoceratops andrewsi. The determination that the appendage was used in sexual displays and to assert social dominance marks the first time that scientists have directly linked the function of anatomy to mating choice in dinosaurs.

The findings are published in the journal Palaeontologia Electronica.

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"Paleontologists have long suspected that many of the strange features we see in dinosaurs were linked to sexual display and social dominance, but this is very hard to show," co-author David Hone said in a press release.

"The growth pattern we see in Protoceratops matches that seen for signaling structures in numerous different living species and forms a coherent pattern from very young animals right through to large adults," added Hone, who is a lecturer in zoology at Queen Mary University of London.

For the study, Hone and his colleagues analyzed the remains of 37 Protoceratops individuals from fossils found in the Djadochta Formation of the Gobi desert and from previous published research. Protoceratops was a dinosaur with small horns that was similar in size to a sheep.

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The scientists assessed the change in length and width of the dinosaur frill over four life stages: hatchling babies, young animals, near-adults, and adults. Not only did the frill change in size but it also changed in shape, becoming proportionally wider as the dinosaur became older.

This growth pattern, according to the researchers, strongly suggests that the bony head appendage was used to attract suitable mates and for displays among males for territory and social positioning.

Co-author Rob Knell said, "Biologists are increasingly realizing that sexual selection is a massively important force in shaping biodiversity both now and in the past."

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Knell added, "Not only does sexual selection account for most of the stranger, prettier and more impressive features that we see in the animal kingdom, it also seems to play a part in determining how new species arise, and there is increasing evidence that it also has effects on extinction rates and on the ways by which animals are able to adapt to changing environments."

Image: Reconstruction of Protoceratops andrewsi engaging in speculative display postures. Credit: Rebecca Gelernter/QMUL