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upstart writes:

Meraxes gigas' short but burly forelimbs may have helped with mating:

Tyrannosaurus rex's tiny arms have launched a thousand sarcastic memes: I love you this much; can you pass the salt?; row, row, row your ... oh.

But back off, snarky jokesters. A newfound species of big-headed carnivorous dinosaur with tiny forelimbs suggests those arms weren't just an evolutionary punchline. Arm reduction — alongside giant heads — evolved independently in different dinosaur lineages, researchers report July 7 in Current Biology.

Meraxes gigas, named for a dragon in George R. R. Martin's "A Song of Ice and Fire" book series, lived between 100 million and 90 million years ago in what's now Argentina, says Juan Canale, a paleontologist with the country's CONICET research network who is based in Buenos Aires. Despite the resemblance to T. rex, M. gigas wasn't a tyrannosaur; it was a carcharodontosaur — a member of a distantly related, lesser-known group of predatory theropod dinosaurs. M. gigas went extinct nearly 20 million years before T. rex walked on Earth.

[...] But, Canale says, M. gigas' arms were surprisingly muscular, suggesting they were more than just an inconvenient limb. One possibility is that the arms helped lift the animal from a reclining to a standing position. Another is that they aided in mating — perhaps showing a mate some love.

Journal Reference:
Juan I. Canale, Sebastián Apesteguía, Pablo A. Gallina, et al., New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction [open], Curr Bio, 2022. (DOI: 10.1016/j.cub.2022.05.057)

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