Creating Static Meshes or Animations for ARK requires a 3D modeling/animation program that is capable of importing and exporting .fbx files, as well as the ARK Development Kit(ADK).
An .fbx file that contains Animations must have a skeleton with at least one bone called "root" as the parent of any other bones in the skeleton. These type of files are called Skeletal Meshes if they have a mesh parented to their bones, or a Skeleton if there is no mesh parented to the bones.
An .fbx file that does not contain Animations is called a Static Mesh, and requires no bones, if it is not going to be attached to a Skeletal Mesh in ADK. If the Static Mesh is going to be attached to a Skeletal Mesh in ADK, the Static Mesh must be parented to one bone called "root".
The 3D program's .fbx export settings will vary depending on if it is a Static Mesh or an Animation.
It is also possible to export existing Static Meshes or Animations from ADK. These Static Meshes or Animations are exported as an .fbx file by right clicking on them in the content browser, and selecting "Export". Exporting from ADK does not require any settings, and will contain any included animations from the .fbx file. Importing an .fbx file into a 3D program also does not require any settings and the file will contain any included animations or skeletons(bones).