Was there a crossable land bridge at the Santa Marta Formation in Antarctica roughly 78 million years ago?

Recently had a short story idea about a group of Antarctopelta siblings crossing a land bridge into Antarctica that’s slowly being flooded. The waters would soon be filled by sharks and a Taniwasaurus. But before attempting such a story, I want to know how accurate of a scenario this could have been. Mostly if this was accurate for the area at the time. Thoughts?