dear colleague,

i guess it depends on the situation. if you are really sure about the identification, then i'd had no problem to extend the fossil's stratigraphic range. it's in fact quite usual that the full range is unknown. on the other hand it depends on where you got the age information from and whether you consider it reliable. if the age is based on poor biostratigraphic data i'd be careful. but if you have quite precise info from microfossils or whatever - why not!

i hope that helped a bit!

best wishes, thomas

Agree with Neubauer. This is one baffling circular argument we often land at. This problem is discussed at length in D.Ager's interesting book-"The Nature of the Stratigraphic Record". You may browse through the discussion under 'Marxist Stratigraphy and the Golden Spike".

Dear Mr. Gregoriev,

mosasaur material is a little bit tricky sometimes, esp. if you are dealing with isolated teeth (which are the most common remains). Nevertheless, you have to compare fossil vertebrate remains with all the material, known from the group. Depending on the region where your site is situated, a lot of new things can be found, as Thomas mentioned, the biostratigraphic record of Cretaceous vertebrates is poor. Especially the material from Russia (and adjacent countries) ist very often not described very properly and you have to deal with a lot of synonyms sometimes.

Best regards

Johannes

Please note that resedimentation (reworking) may always play a role. In the Netherlands, we have mammal fossils from the Early Pleistocene embedded in Late Pleistocene sands. In these sands also some Eocene shells (that came from Belgium with river Schelde) and even an occasional Mesozoic crinoid from Northern France can be found! Older fossils in younger sediments thus not necessarily stretch the stratigraphic range of a taxon. A younger fossil in older sediments does.

I agree with all the answers given already: possibility of a new taxon, extended stratigraphic or geographic range, imprecise dating or reworking of remains mean that you should not limit comparisons to a single stratigraphic interval but always identify (if possible) based on intrinsic features of the fossils themselves.

Thank you all for your answers and advices!

For me the overall conclusion is that it is better to not giving a generic name for each tooth (roughly) and to rely only on diagnostic characters. Age of the deposits could be revised by stratigraphers on the next week, and all conclusions that were made on the basis of stratigraphy will be invalid...Same thing with resedimentation (as mentioned by Mr. Reumer)

yes, you can do but for this you also have to corerelate the other associated faunal elements, exactly excavated from the site.

As others have suggested, I would be especially careful about signs of redeposition with vertebrate material, especially teeth and heavy bones in marine deposits.  I have observed that Late Cretaceous shark's teeth can be recycled through several generations of transgression and regression. With sharks, one can see freshly deposited teeth have translucent edges and crisp serration,whereas the redeposits lose the fine edges and have rounded cusps. Redeposition changes age relations, of course and can lead to serious age errors.  For example, on the coast of South Carolina, a deposit contains both hadrosaur (dinosaur) teeth and camel bones, mixing Pliocene and Cretaceous fossils.

I agree! But the main question was about the importance of sediments age (precisely defined and not residementationed) in defining of the vertebrate material...