Re: Paleogene Titanosaurs in South America? Paleogene ammonoids in the Persian Gulf? Not quite, but analogous...

["franklin e. bliss" <frank@blissnet.com>]

You can find reworked seeds and leaves in clasts (chunks) of older  
sediments.  I find mud pebbles with occasional leaves in them mixed  
into the pure channel sands in the Hell Creek.  The mud chunk was  
ripped up and moved down river, rounded as it traveled.  They were  
probably (no doubt) contemporaneous though. Therefore the question of  
whether the plant frag was a fossil at the time it was ripped up is  
the real issue.  It is possible to find Hell Creek clasts in Holocene  
sediments too which of course could hold true for any older sediment  
exposed, fragmented and reworked.   There is almost always a  
compositional difference between the clast and the sediment it is  
encased in otherwise it would be hard to identify as a clast.  Of  
course you also find individual fossil frags being reworked like wood  
chunks, pollen etc.  Leaves are pretty delicate for that though unless  
they are encased in something else.

Frank (Rooster) Bliss
MS Biostratigraphy
Weston, Wyoming
www.wyomingdinosaurs.com


On Apr 11, 2008, at 4:19 PM, David Marjanovic wrote:

> > And the fossils really aren't reworked? What are they, seeds?
>
> So I can answer my own questions: the fossils are leaves, which are  
> probably impossible to rework.
>
> The paper also mentions pollen of Podocarpaceae from the Miocene  
> of... Alaska. Geographically, this is a major surprise, too...
>
> Seed plant phylogeny seems to be a headache. All molecular  
> phylogenies I've seen find a monophyletic Gymnospermae, which is  
> quite surprising from a morphological point of view.