When and how did Pluto die?

I once read from a college textbook on astronomy published in the 1880's that the Solar System was composed of 4 small rocky planets, surrounded by 4 large gas giant planets.  With our current understanding of planetary formation, these 8 fit a similar pattern -- those closest to the Sun formed small and hot, those further formed large and cold. Pluto, though, is small and cold. The other abberance is that Pluto's and Uranus's orbits cross. Pluto's orbit is about 248 years, Uranus's 84, but for about 20 years, Uranus is actually further away from the Sun than Pluto!  (The last cycle, by the way, ended in 1999 -- Pluto is now again further out than Uranus.) Pluto's orbit is also, unlike all other planets, not within the ecliptical plane. These orbital oddities suggests to astronomers that in times past, Pluto was actually moon of Uranus.

These two factors of size and orbit are what have disqualified Pluto as a planet.  Perhaps when it was discovered back in the 1930's, the desire to add it to the family of planets was strong, being the first one discovered in nearly 100 years.  We know better now.