Early 90s children's book about finding dinosaur bones

I'm pretty sure I got it from a scholastic book fair in the early 90s. Set in the early 1900s maybe? A chapter book. My vague memories of the plot: Kids discover dinosaur bones near their homestead. The brother is obsessed with them, he ends up drowning and his sister goes into paleontology instead. I thought it was called Danny's Dinosaur or My Brother's Dinosaur, but those searches aren't turning anything up. I hope someone has heard of this!