Short answers, pulled from the story.
Othniel Charles Marsh examined the first Stegosaurus bones in 1877 and named the species Stegosaurus armatus. The initial discovery included a single dermal plate that led Marsh to believe the animal was an aquatic turtle-like creature. This initial misinterpretation would haunt the scientific understanding of the creature for decades.
Arthur Lakes found the first Stegosaurus fossils in 1877 at Dinosaur Ridge in Morrison, Colorado. Marshall P. Felch later made the most significant discovery of the era by unearthing a nearly complete skeleton at his quarry in Garden Park, Colorado, in 1885. These discoveries were part of the fierce competition known as the Bone Wars between Othniel Charles Marsh and Edward Drinker Cope.
The plates were arranged in alternating rows along the midline of the back rather than in pairs. This staggered double row became the accepted standard by the early 1960s after fossils like the type specimen of Stegosaurus stenops preserved the plates in this specific chiral arrangement. The plates were likely used primarily for display and secondarily for thermoregulation.
No, Stegosaurus did not have a second brain in its hips. The large canal in the hip region of the spinal cord contained a glycogen body that facilitated the supply of glycogen to the animal's nervous system. This space likely functioned as a balance organ or a reservoir of compounds to support the nervous system.
Sophie is the best-preserved Stegosaurus specimen ever found and was discovered by Bob Simon in 2003 at a quarry on the Red Canyon Ranch near Shell, Wyoming. The skeleton was 85% intact and contained 360 bones, providing scientists with unprecedented detail on the animal's anatomy. The specimen went on display in December 2014 at the Natural History Museum in London.
The tail of Stegosaurus was tipped with four dermal spikes known as a thagomizer and was likely a formidable weapon. A study by McWhinney et al. found that 9.8% of Stegosaurus specimens examined had injuries to their tail spikes. The tail was likely much more flexible than that of other dinosaurs, lacking ossified tendons, which allowed the animal to swivel deftly to deal with attacks.