Re: Ichthyosaur exinction

[Danvarner@aol.com]

  jedimr_thomas@hotmail.com (Thomas de Wilde) asks:

<< Can somebody tell me where the youngest Platypterygius were found, and 
where
the mosasaurs arose. If it's the same locality this might be it >>

       As I recall, in the Black Hills area of South Dakota and Wyoming the 
last Platypterygius specimens are found in the Cenomanian Mowry Shale. The 
first sizeable mosasaur remains are found in the Coniacian Sage Breaks Member 
of 
the Carlile Shale, although smaller forms are found in the Turonian Turner 
Sandy member. The last ichthyosaurs in the region were seperated from the 
earliest 
mosasaurs by the Belle Fourche Shale and the Greenhorn Limestone formations. 
I don't have the actual dates, but it was a few million years, I think. This 
maybe out of date, however. I am. DV