Thus, the assumption that the modern diversity started to evolve in the late Paleogene, continuing throughout the Miocene and onwards, must also be considered hypothetical given the lack of robust evidence. Still, the "molecular" scenario is entirely possible considering what is known about the evolution and radiation of the Galloanserae, and consistent with the paleogeography of the Americas. The ichnotaxon "Tristraguloolithus cracioides" is based on fossil eggshell fragments from the Late Cretaceous Oldman Formation of southern Alberta, Canada which are similar to chachalaca eggs (Zelenitsky "et al.", 1996), but in the absence of bone material their relationships cannot be determined except that they are apparently not from a dinosaur.