The 52nd annual meeting of the Palaeontological Association was held in December 2008 in the University of Glasgow. Although I was unable to attend (someday I will) the following poster presentation caught my eye. Probably not too many people are experts on World War I tunnels, stromatolites, conodonts, dinosaurs, and archosaur trackways but here is where all of these fields finally collide....
Belvedere, M., Mietto, P., Avanzini, M., and M. Rigo. 2008. Dinosaurs stepping on the conodont animals; p. 44 in Programme and Abstracts for the 52nd meeting of the Palaeontological Association. The Palaeontological Association Newsletter 69.
On the roof of a First World War tunnel in the Monte Pasubio (North Eastern Italy), on a supratidal stromatolitic bed of the Dolomia Principale Formation, 11 tracks have been found. Among them occur some clear dinosaurian tridactyl footprints, from small grallatorid-like to medium-large eubrontid, as well as some tetradactyl footprints. This formation contains the principal dinosaur footprints for the Triassic of the southern alps. All previous findings were on fallen blocks which, given the poor paleontological content of the formation, and the lack of precise stratigraphical position, made their biostratigraphical constraints very difficult to determine. In this case, for the first time, the trampled surface crops out in situ, about 500m from the bottom of the formation. Conodont sampling was carried out on the subtidal level just below the trampled surface. Unexpectedly, two conodonts were found: an advanced Epigondolella praeslovakensis and a true Mockina slovakensis, an association exclusive for the Middle Norian (latest Alaunian). Thus being so precisely contrained, the ichnoassociation could be used to date the other isolated blocks of the Dolomites. Moreover this co-occurrence of tetrpod footprints and conodonts can be used to confirm the Middle Norian age of the Eubrontes-Grallator biochron.
Dinosaur skeletons covered with ammonites have been found in marine strata , but as the authors state this is a first for conodonts and footprints. It's too bad that this does not happen more often to tie together marine and non-marine biostratigraphies. By the way, the small tridactyl tracks probably are ornithodiran as no self respecting pseudosuchian would stomp on conodonts ;).
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So, you never know what you are going to walk on when you go for a walk on the beach! Neat discovery.
ReplyDeletePity that conodonts appear to have gone extinct in the Jurassic: the temporal window in which dinosaurs could come in contact with conodonts was narrow in comparison to the total lifespan of both groups.