Before Ada and Napoleon

Remember that scene where Ada and Napoleon ran into the Therizinosaurus harem, well this was the scene before the two tyrannosaurs showed up, with a yet to be discovered large relative of Othneilia, since it's a speculative dinosaur I have no idea what to call it or where it would have been discovered, any ideas? Oh and there's an Ankylosaurus being used as a mount to get to foiliage. The third artwork by my friend Vladimir Nikolov