We’ve always talked about theropods as the ‘meat-eating’ dinos, but that’s going to change today. Nothronychus was a theropod that lived in the Late Cretaceous in what is now New Mexico. New Mexico was a pretty nice place back then, not to say that it still isn’t nice. Every place has its pros and cons. Anyway, Nothronychus was a theropod, but surprise! It was a herbivore.
Now, before we talk about why this happened, let’s talk some genealogy. So, Nothronychus was a therizinosaur, a group of mostly herbivorous theropods that were closely related to the raptors, oviraptorids, and birds. Therizinosaurs are characterized by a sauropod-like head and long neck, huge arms with long claws, a short tail, and herbivory.
Now that we know what therizinosaurs (and especially Nothronychus) are, we can talk about why they are like that. During the Cretaceous, in which therizinosaurs evolved, there was a huge leap in the diversity of plants. Before the Cretaceous, there were no flowering plants. Most of the world was covered in ferns, cycads, and conifers. In this time, though, flowering plants covered the globe.
Most of the herbivores that were there before the Cretaceous rapidly adapted to the changing conditions or went extinct. With a lot of herbivores dying out, there suddenly was an opening for new herbivores (kinda like a job, but where the employee works for life). The therizinosaurs took advantage of this, especially because there was a lot of competition between the carnivores and eating plants doesn’t waste as much energy.
Nothronychus lived alongside tyrannosaurs like Suskityrannus and the ceratopsian Zuniceratops. Like the tyrannosaurs, raptors, and ceratopsians, the therizinosaurs were all spread across Asia and North America, with both Therizinosaurus and Segnosaurus, the most well-known species, living in East Asia.
Fun fact: Therizinosaurus was the first therizinosaur to be discovered, and it was thought to be a turtle at first!
Anay Ganesh 