[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Paleocene Dinosaurs



>Allison R Tumarkin wrote:
>
>>  The problem with channel deposits is that a
>> stream will transport (1) remains of recently-dead animals AND (2)
>> previously buried (sometimes already fossilized) remains derived from the
>> older deposits which the stream is eroding.  Thus the presence of
>> unassociated, disarticulated dinosaur bits in Paleocene stream deposits
>> does not necessarily mean that dinosaurs survived into the Paleocene, but
>> only shows that the Paleocene stream eroded Mesozoic strata and picked up
>> some dinosaur bones/teeth in the process.
>
>Exactly. Imagine my surprise when I discovered a Mesozoic ammonite
>weathering out of Oligocene sediments in N.W. Nebraska. I would guess
>that during the Oligocene the ammonite was washed down from the higher
>areas of the nearby Black Hills, where ammonite-bearing strata abounds
>and deposited in the floodplain.


I can go one better than that: Miocene trilobites. The limestones at
Riversleigh are Oligo-Miocene in age but are reworked breccias of older
(Cambrian) limestones. On one occassion I found a perfect trilobite
pygidium in the acid residues next to thousands of Miocene bat teeth.
Obviously the trilobite fragment was contained in a clast of Cambrian
limestone within the Miocene stuff, but don't tell the Creationists; they
could misrepresent this case as easily as they cock-up the rest of the
fossil record.

Cheers,

Paul


Dr Paul M.A. Willis
Consulting Vertebrate Palaeontologist
Quinkana Pty Ltd
pwillis@ozemail.com.au