In the early 19th century, Jean-Baptiste Lamarck proposed his theory of the transmutation of species, the first fully formed theory of evolution. In 1858, Charles Darwin and Alfred Russel Wallace published a new evolutionary theory that was explained in detail in Darwin’s On the Origin of Species (1859).
Normally, there are 18 pairs of ribs in the horse, but a nineteenth rib on one side or both is not considered all that rare. Eight pairs of ribs are known as true ribs. They join the segments of the sternum or breastbone. The other 10 are known as floating ribs–merely overlapping and being attached to each other.
Most tornadoes form beneath the cumulonimbus clouds of thunderstorms, quite often the large, long-lasting thunderstorms called supercells. Cumulonimbus clouds can be very tall, having bases in the lower troposphere and strong updrafts that carry moisture into middle and upper levels of the troposphere.