9. The marine environment fills up

Some 228-217 million years ago – the late Carnian era

The bottom of the sea became increasingly less deep until the sea became filled with sediment. The sea beat a temporary retreat and some new lands emerged. At this time the climate varied from wet to arid and the sediment included a great many plant and animal remains. These were the environments in which the first dinosaurs appeared.

The general subsidence of the region declined and this, together with variations in the sea level, led to the emergence of numerous islands. The ecology of the sea changed with the appearance of new communities of marine animal species, such as coral and sponges, very little different from those living in the oceans of today. The underwater slopes became less steep and the arrival of ever more sediment would inevitably fill up the sea. This era was marked by some particular climatic events. In the newly emerged areas, wet periods allowed a huge variety of plant life to develop. Among the dolomite fossils of this era is amber, a fossil resin containing the world’s earliest known mites and ticks. Subsequently there was a return to an arid climate, coinciding with a formation of a flatter coastline, making possible new deposits of gypsum created by the massive evaporation of the sea water. When the wet climate returned, the reason for which is not yet clear, a reorganisation of the ecological niches took place, among whose consequences was the spread of the dinosaurs. These environments played host to numerous species of herbivorous and carnivorous dinosaurs, among the most ancient in the world, and when these reptiles walked or swam in the shallow water, they left their footprints in the mud.

Text by Dolomiti Project

Some rocks and fossils from this era