Books with title Secret of the Old Sleigh

This mystery story for young readers deals with an issue that is becoming more important in the scientific community: the illegal excavation and sale of dinosaur fossils. In this book, four friends accidentally discover some old bones that have recently been dug up, but are hidden out of sight. Something about these bones and the way they have been hidden seems really strange to the four friends, and they decide that it is up to them to discover the truth about the old bones.

When the Lewis and Clark Squad discover a trunk full of old rifles--and one with a mysterious code written inside--they're off on their next adventure. What does the code mean? And who could have put it there? The Squad wants to know. Between basketball practices and games they follow up on all the clues. And those clues take them back more than fifty years to a robbery, an explosion, and the deeds of a mysterious stranger. There seems to be a link. But the kids aren't sure what it is. Then, a breakthrough. A girl with family connections to the rifle comes to town. If the Lewis and Clark Squad can catch up with her, they might be able to crack the code and sold this mystery. But then again, maybe the answer lies somewhere else....