California auction house IM Chait has revealed the truly remarkable lots which will appear in its forthcoming May 16 Spring Natural History Auction.
Sales will include a 20-foot-long dinosaur, outstanding Gem Ammonite fossils and a fine selection of meteorites, including Martian and lunar specimens.
A large gold nugget and Museum-quality fossils, including a Saber-tooth cat skull and a complete Tyrannosaurus, will also appear, along with various pieces of Apollo 11 and Apollo 13 space memorabilia.
Among these is a spectacular complete Hadrosaurid skeleton, Maiasaura peeblesorum, one of the most complete specimens ever to be offered in public.
The Maiasaur - or "good mother lizard" - was one of the numerous "duck-billed" dinosaurs that roamed the plains of Asia, Europe and North America in massive herds during the Upper Cretaceous period, some 99-65m years ago.
From the herbivorous Hadrosaurid family, they were so-named for the shape of their flattened, duck-like "beaks", ideal for stripping the prehistoric foliage from leaves and twigs.
Like all hadrosaurs, Maiasaura was herbivorous with a huge battery of chisel-like teeth which grinded plants to a digestible pulp.
Meanwhile, their strong forearms are thought to have been used for pulling down branches, and for walking or running on all fours to escape local predators such as T-Rex.
The Hadrosaurids' huge herbivorous dinosaur lineage includes the famous "dinosaur mummy," Leonardo and Hadrosaurus foulkii, the very first dinosaur found in the United States in 1858.
The species was first discovered and classified in the 1970s. In 1977, Marion Brandvold and her son David Trexler uncovered an enormous bone-bed nesting ground in Montana, US.
Robert Makela and Jack R Horner (the latter a paleontological consultant for 1993's Steven Spielberg-directed blockbuster film, Jurassic Park) gave Maiasaura its name in 1979.
This example, named "Cory", measures an incredible 15-plus feet long, with a superb woody patina to its bones.
Cory bears the flattened beak distinctive of its family, and particularly good skull and overall 80% of the bone is original throughout the skeleton.
This rare and unusually complete specimen has been prepared to the highest of standards, with no holes and attachments, and will sell estimated at $500,000-700,000.