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*Secernosaurus*: Immigrant or Indigenous?
I have been trying to pin down an age for *Secernosaurus*, and I've
been seeing everything from Cenomanian all the way through to
Maastrichtian. Is the dating really that poorly constrained, or what?
But more to the point: what's the current consensus on whether
*Secernosaurus* represents a northern invader or a home-grown local?
Does a consensus even exist? I understand that the material is
fragmentary . . .
I also know it's supposed to be on the primitive side, but I guess
that doesn't automatically exclude it from having a northern-immigrant
heritage, depending on some unknown (to me at least) variables. And,
while an older age is more suggestive of a Gondwanan radiation than a
younger age, I myself:
1) don't know the earliest proposed date for a direct faunal
connection between North and South America (i.e. the "*Alamosaurus*
2) the (as I recall) utter lack of proper hadrosaurids from Africa to
date (or better remains of plesiomorphic hadrosaurs in S. America)
suggests that really solid evidence for a distinct Gondwanan radiation
is presently lacking, so other hypotheses may be appropriate.
Maybe only educated opinions exist for this subject, but those would
still be appreciated.
So: Laramidian immigrant or Gondwanan indigene?