有啊,化石都给你找出来了:
图中的剪影分别是O. johnstoni, S. major和G. camelopardalis,对应短颈鹿,中颈鹿,长颈鹿。
参考
Fossil evidence and stages of elongation of the Giraffa camelopardalis neck
Melinda Danowitz, Aleksandr Vasilyev, Victoria Kortlandt, Nikos Solounias
R. Soc. open sci. 2015 2 150393; DOI: 10.1098/rsos.150393. Published 7 October 2015