Crazy Arms
When I was boy, one of the greatest mysteries about dinosaurs for me was "who owned the biggest arms of all time?". This question revolved around not one, but two theropod dinosaurs from Late Cretaceous Mongolia: Deinocheirus and Therizinosaurus. For decades, both were known from nothing but a pair of menacing arms, each measuring about eight feet long. Each seemed to belong to jumbo-sized killer theropod, dwarfing and capable of ripping a T. rex to pieces.
Then, in 2001, the Discovery Channel program When Dinosaurs Roamed America aired, and I (along with countless other paleofans, I'm sure) was introduced to a therizinosaur for the first time in the form of Nothronychus. It was a herbivore North American predecessor to its family's namesake that, in the words of narrator John Goodman, "[looked] like a half-plucked turkey and [walked] like a potbellied bear". While it mostly used its arms pull down high branches, Nothronychus at one point used them to smack down an attacking dromaeosaur. Though we have few Therizinosaurus fossils outside of its arms, the image of these dinosaurs as the archosaur version of ground sloths has been cemented by the discovery of other therizinosaurs (particularly the much earlier Beipiaosaurus and Alxasaurus), as well as the portrayal of these animals in subsequent paleo docudramas like Chasing by Dinosaurs: The Giant Claw (featuring Therizinosaurus meeting Nigel Marven) and Planet Dinosaur (featuring Nothronychus again).
And what about Deinocheirus? This contemporary of Therizinosaurus turned out to be stranger still: Paleontologists had long suspected that it was an overgrown ornithomimosaur, based on the similar arms and claws (which were too blunt to be instruments of death). Based on two headless specimens in storage at a Mongolian museum and a skull smuggled into Europe, Deinocheirus a bulky, hump-backed herbivore with a head more like a hadrosaur than an ornithomimosaur. Like Therizinosaurus, it too was a colossal plant-eating theropod that was probably covered in feathers.
While both probably confronted Tarbosaurus, a close cousin to T. rex known from the same bone bed as each, I do wonder if they ever competed for same leaves and branches with one another, indirectly as a species or directly (and perhaps violently) as individuals.
When I was boy, one of the greatest mysteries about dinosaurs for me was "who owned the biggest arms of all time?". This question revolved around not one, but two theropod dinosaurs from Late Cretaceous Mongolia: Deinocheirus and Therizinosaurus. For decades, both were known from nothing but a pair of menacing arms, each measuring about eight feet long. Each seemed to belong to jumbo-sized killer theropod, dwarfing and capable of ripping a T. rex to pieces.
Then, in 2001, the Discovery Channel program When Dinosaurs Roamed America aired, and I (along with countless other paleofans, I'm sure) was introduced to a therizinosaur for the first time in the form of Nothronychus. It was a herbivore North American predecessor to its family's namesake that, in the words of narrator John Goodman, "[looked] like a half-plucked turkey and [walked] like a potbellied bear". While it mostly used its arms pull down high branches, Nothronychus at one point used them to smack down an attacking dromaeosaur. Though we have few Therizinosaurus fossils outside of its arms, the image of these dinosaurs as the archosaur version of ground sloths has been cemented by the discovery of other therizinosaurs (particularly the much earlier Beipiaosaurus and Alxasaurus), as well as the portrayal of these animals in subsequent paleo docudramas like Chasing by Dinosaurs: The Giant Claw (featuring Therizinosaurus meeting Nigel Marven) and Planet Dinosaur (featuring Nothronychus again).
And what about Deinocheirus? This contemporary of Therizinosaurus turned out to be stranger still: Paleontologists had long suspected that it was an overgrown ornithomimosaur, based on the similar arms and claws (which were too blunt to be instruments of death). Based on two headless specimens in storage at a Mongolian museum and a skull smuggled into Europe, Deinocheirus a bulky, hump-backed herbivore with a head more like a hadrosaur than an ornithomimosaur. Like Therizinosaurus, it too was a colossal plant-eating theropod that was probably covered in feathers.
While both probably confronted Tarbosaurus, a close cousin to T. rex known from the same bone bed as each, I do wonder if they ever competed for same leaves and branches with one another, indirectly as a species or directly (and perhaps violently) as individuals.
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