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Another dinosaur was found in South America this last week, and it was such a bizarre find that I just had to talk about it.
Vespersaurus paranaensis is a new theropod dinosaur named for a set of recently-described bones from modern-day Brazil. Living around 70 million years ago, it belonged to a bizarre clade of predators called the Noasaurines, known for their unique anatomical features that stretch the idea of what we expect carnivorous dinosaurs to look like. Some had oversized teeth that didn't fit into the jaw, others had fingers that outmeasured their entire arm. V. paranaesis was no exception.
The collection was surprisingly full for a species of such a small size, containing several vertebrae, ribs, and skull fragments. The most surprising thing about it, though, was its feet. While most other theropods balanced on three toes of mostly equal length, the middle toe of this dinosaur was grossly longer than the other two (three, including the dewclaw). We can find similar foot structures in ancestral horses, implying the alien idea of a functionally one-clawed dinosaur.
Again, the best answer to why it stopped balancing on its outer toes can be found in horses. Many modern-hooved animals such as horses and donkeys evolved this feature to conserve energy while traveling. Longer feet mean a more powerful lever that can propel them forward for much farther distances than shorter feet can with the same amount of energy, and it is far less biologically expensive to extend one toe than the entire foot. Perhaps Vespersaurus was moving along the same path, using its strange foot to make long journeys across the Late Cretaceous deserts and prairies. This paints a picture of thriving ecosystems that would have developed into very special, otherworldly places if the asteroid had never hit.
Just a side note- the official description doesn't mention feathers at all, but given how wide-spread they were through the dinosaur family tree, I figured it wouldn't be too big of a stretch to place them here.
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