Life on Europe
Carcharodontosaur image; Credit: © Matthew Deary/Ultimate Dinsoaurs
When you think of archipelagos, the norm is Philippines, Azores, or perhaps the beautiful Cook Islands. Revise your ideas and drift back in time to an oceanic collection of Europea! During the Late Cretaceous, there was certainly global warming and sea level change before the well-accepted impact event of the K-Pg boundary. In that ancient world, European vertebrates had colonised the islands from continents to the north and south and now intensive research has thrown it all together to create a view of some of the fauna and flora of the time
Zoltan Csiki-Sava, Eric Buffetaut, Attila Ősi, Xabier Pereda-Suberbiola and Stephen L.Brusatte from The Universities of Bucharest, Edinburgh and Universidad del País Vasco and several other institutions publish a very learned review in the journal ZooKeys. Their efforts are much appreciated by us, as they shed light on so much ancestry and even current biodiversity. While North America had its famed dinosaur fauna, recent studies have shown us many forms, from fish to mammals, evolving under very different conditions, but with no sign of large extinctions until the asteroid landed!
From Russia to Spain, thousands of species have been reviewed and placed in their approximate ecosystems. With their previous supercontinent of Pangaea breaking up, organisms must have adapted to the Mediterranean Tethys area and new small
slivers of land that were inundated by new seas as global warming took place with a vengeance. Archosaurs (crocodile relatives and pterosaurs and dinosaurs) are familiar from France and England in Grey Chalk deposits. The latest discoveries in the Charentes region (an island at the time) include very diverse marine vertebrates that show up changes from continental ecosystems to pure marine groups of animals. The French Massif Central was not so massive at this time. While freshwater fish disappear, terrestrial tetrapods outnumber their marine relatives. Snakes and scincomorph (skink-like) reptiles are joined by many dinosaurs, especially the Theropods. Some have the feathers beloved of Chinese dinosaurs, while others are velociraptor-like dromaeosaurs and the giant Carcharodontosaurs (also known from nearby North Africa.) These monsters are similar to North American Tyrannosaurus but not quite as large as their Spinosaurus.
The mammals are represented by the earliest European mammals such as the stem marsupial Arcantiodeelphys, but it is the dinosaurs that dominate, with no sign of any early demise. Since another recent discovery from Asturias, Spanish records now include many island and marine species such as titanosaurs that resemble Argentinosaurus. European fossils associated with the later Santonian stage (83-86 milllon years ago) show a revival of land area and its associated species. More theropods and iguanodonts appear both in Central Europe and in western France, though not elsewhere. Fossil feathers (bird or reptile) from Slovenia and lots of hadrosaurs from Italy next-door, show the biodiversity increasing. Small dinosaurs are typical, possibly associated with their island speciations.
Later in the late-late Cretaceous, more species appear as does more land area from the sea. Theropods appear in Sweden and many pterosaurs have been found in SE Russia (Rybushka) Three families of mammals are hardly dominant at any Cretaceous stage in Europe, but with the arrival of the extra-terrestrial influence in the form of an asteroid, most groups became extinct. The multituberculate mammals survived better than their relatives in America, where more modern mammals (eutherians) survived better. The latest non-avian dinosaurs became extinct and several bird groups went with them just as in North America. Huge ground birds (Gastornithines) replaced unrelated large ground birds in Europe, presumably in similar
recovery niches as top herbivores.
The only successful crossings of the K-Pg boundary were by the Amphibia. All major groups such as salamanders and discoglossids (the midwife
toads )survived, along with aquatic turtles. Ecologically, Europe and North America differ little in the selection of survivors. Both show survival in slow-worm relatives and iguanids while the amphisbaenids only appear after the Palaeocene (after the K-Pg boundary.) The wonderful terrestrial squamates, dinosaurs and mammals became extinct with some obvious exceptions. The comparison between the 2 continents is intriguing, however. The authors note that secretive groups survived, such as omnivorous mammals and aquatic turtles while they became extinct in America, but the pattern overall is similar. I must apologise for the length of this summary, as you can find all the clever stuff in the paper above. I hope the history of Europe now makes more sense, as far as some animal groups are concerned! The next time you visit an archipelago, imagine a new continent may arise in the distant future, with another unique collection of endemics, dwarfed or enlarged by many factors involved in the transition!
To make up for the long lists here, this is a chummy group of large mammals you may love, from more recent evolutions, 8mya!