Paleobiogeografia dei Vertebrati e del Molluschi continentali dell’area alpina sud-orientale

Abstract

BIOGEOGRAPHIA — vol. XI/I — 1987 Biageografla delle Alpi Sud-Orientali Paleobiogeografia dei Vertebrati e dei Molluschi continentali dell’area alpina sud—orientale(qq‘) DANIELA ESUqqq — TASSOS KOTSAKISqq“q“q qqqq Dz'pczrtz'77zeI2to dz‘ Sczenze dellzz Terra, U7zz'11ersz'tc2 «La Sczpz'e7zzcz», Roma. qqqqq Ceiztro di Studio per la Geologia de[l’Iz‘aZz'tz Centmle, C.N.R. c/0 Dz'pm*tz'I7ze7zt0 dz‘ Scienze della Term, Um'1Jersz'tz2 «La Sapz'e7zzzz», Roma. SUMMARY The study of fossil vertebrates and continental molluscs of South»Eastern Alpine region allows to point out the following palaeobiogeographical observations. 1) During Carboniferous emerged areas of Friuli are colonized by plants of European origin. Amphi- bian foot-prints testify the same meaning too. 2) Permian data are not sufficient to do some palaeobiogeographic hypothesis. 3) During Triassic the coastal reptiles community which populate this area are spread along the Te- thian Northern coast. This datum is confirmed also by the finding of a pterosaur. Perhaps an island near the European coast of Tethys was populated by a little endemic thecodont. ) Data about Jurassic are lacking. 5) During Cretaceous lldinosaurians» foot-prints show the possibility of communications between Istria and a not better identified mainland, almost during two moments. Nevertheless the aigialo- saurids and dolichosaurids, semi-aquatic lizards, seem to testify the presence of a Tethyan archipe- lago which was including Dinarids (Istria inclusive). 6) The continental Paleocene molluscs (Lower and ?Middle Paleocene) of Trieste Karst point out insularity conditions with very strong endernisrns. Fossil Charophyta confirm this hypothesis. 7) During Middle Eocene the Friuli emerged area seems to be colonized by continental molluscs of Western European origin. 8) The Oligocene few continental fossil molluscs of Friuli testify connections with Central Europe. 9) During Upper Miocene connections between Friuli and Central—Eastern Europe are postulated by the study of continental molluscs and by the finding of the single mammal remain of this period. 10) Continental Pliocene fossils of this area are unknown. 11) About Pleistocene more data are available. Few Villafranchian remains indicate the presence of wide distribution European species. At the beginning of Middle Pleistocene some eastern species appear, they spread later on all along the Italian Peninsula. During Mindel some Central Asian species appear for a short time (Oc/Jotomz purillzz, Micro/us gregalis). During the whole Middle Pleistocene the genus Di2zaromyr persist in the Southeastern alpine region; at present this genus survives only in the Dinaric areas. During Riss some boreal elements, as Mztratzzr OEEOIZOIIZZIJ, arrives in the area. Other arctic elements (Gt/10 gzllo) arrive during W/'iirrn, Rarzgzfer tzzramzlz/r real ches the borders of the investigated area, while Alopex lzzgapur and Dicrartolzyx tarqzzzztus don’t invade the area. 12) At the beginning of Holocene the fauna is similar to the present, there is also some elements that later will disappear (Castor fiber, Crztetzzlzzr /7zz'gratarz'ur). INTRODUZIONE I resti fossili di vertebrati e di molluschi continentali sono distribuiti in maniera discontinua nell’area alpina sud-orientale. Per il Paleozoico si conc- (‘*) Si dedica questo lavoro alla Memoria di Maria Luisa Zucchi Stolfa. 57