Thousands of years ago, the Gorn could've suffered a cultural split much like the Vulcans/Romulans. One group set out to find a new home and ended up in our galaxy. Beginning anew.
And the Gorn velociraptor from Enterprise seemed much quicker than his TOS counterpart.
Easy as pie.
No not very quick as Archer was crawling away as fast he was approaching. Still slow and plodding and no tail. The biggest change via CGI was the eyes.