Answer:
Hadrosaurs were better runners than earlier thought
Step-by-step explanation:
Before this discovery, the fossils for Hadrosaurs were incomplete in different types area of its body. So, they only use prediction to guess the type of bones that might fill the missing piece and formulate their hypothesis regarding Hadrosaurs speed from there.
The findings in north dakota indicates that Hadrosaurs have heavier tails than it originally expected. Among mamals, this would mean that their speed will become slower due to the increase of bodyweight. But, Most reptiles can use their tails to help them accelerate their speed, which is why they can draw a conclsuoion that Hadrosaurs were better runners than earlier thought