How did chetahs get their unique spinal cord

Of course not.
The Cheetah devolved from the Cat Kind that was on the Ark.How did all the animals fit on Noah’s Ark?
How did all the animals fit on Noah's Ark? - creation.com

Smilodon is an extinct cat that probably lived in the post flood world.Recent DNA sequencing data confirm that such distinctions are not fundamental in nature and that all cats share a common genetic ancestry. More recently described hybridizations between great cats and small cats, along with various other studies described in the present article, further support the hypothesis that all cats belong to a single clearly delineated basic type. The Nimravidae (paleosabers), the Machairodontinae (neosabers inclding Smilodon) and the genus Panthera each underwent a prominent radiation during the tertiary period. All three taxa represent cat-like placental carnivores, and they may all have arisen from the same basic type.
http://creation.com/images/pdfs/tj/j25_2/j25_2_118-124.pdf

Since dinosaurs are land vertebrates they probably were on the Ark, but have since become extinct. This would explain the worldwide legends of "dragons".The largest dinosaur eggs were the size of a football so by taking young ones even Brontosaurus would have had no trouble getting on board.