This 2015 video is about giraffe evolution.
From Science journal:
Odd creature was ancient ancestor of today’s giraffes
By Sid Perkins
24 November 2015 7:15 pm
A distant relative of today’s giraffes was a bit of an odd creature: It was about the size of a bull moose, but it had a long neck that could stretch both up to eat tree leaves and down to eat grass. That’s the conclusion of the first comprehensive analysis of a complete set of fossilized neck bones from the animal, known as Samotherium major. Samotherium, which lived in the open woodlands of Eurasia about 7 million years ago, had a neck about 1 meter long—about half the length of that of today’s giraffes. (And like the vast majority of mammals, from tiny mice to towering giraffes, it had seven neck vertebrae.)
Some scientists have long presumed today’s giraffe (Giraffa camelopardalis), which includes a handful of subspecies scattered throughout sub-Saharan Africa, evolved from an animal that looked like its close cousin the okapi (Okapia johnstoni), which lives in the tropical forests of central Africa. The team’s analyses of bones from all three animals bolster that notion—and not just because the neck bones are of a length between the giraffe’s and the okapi’s. For example, ridges and other features that are prominent on the okapi’s neck bones and missing entirely on the giraffe’s are typically present but smaller on Samotherium’s, the researchers report online today in Royal Society Open Science.
See also here.
Mysterious skin disease make giraffes vulnerable to lions: here.