In terms of iconic dinosaurs, the gargantuan sauropods are certainly up there. Along with the mostly meat eating-theropods, and herbivorous and often armoured ornithischians, they form one of the three major groups, or clades, of dinosaurs, and were the biggest animals to ever walk this Earth.
The end of the Jurassic period, some 145 million years ago, was a pretty important time for sauropods. Their diversity was already in decline through some of the latter part of the Jurassic, but it seems that they were hit pretty badly at the Jurassic/Cretaceous (J/K) boundary, in an extinction event that may have been quite severe among land and marine-dwelling animals.
Often the early evolution and radiation of the first dinosaurs is an overlooked part of their tale, in favour of the more dramatic but arguably no less important tales of their later radiations and extinctions. It is actually a fairly poorly understood part of their evolution too, with the timing, and actual mechanism that drove them to become the most successful land group ever still a bit of a mystery.
We are, however, learning more and more about this important phase of their history, in a time known as the Late Triassic some 231-201 million years ago. A new fossil site from this time in Poland – probably not one of the places you’d associate with important fossils – is helping to fill in the blanks. Usually, dinosaur-bearing sites from around this time are known from the southwestern United States and southern South America, so a European locality can potentially tell us quite a bit!