If paleontology serves a purpose, it is to remind us, again and again, that the current breadth of life on Earth is but a meager fraction of its former diversity. We have all, by now, become accustomed to the fleet-footed yales, the lumbering hmungos, the sumo-esque therizinosaurs, but as little as two million years ago there existed a group of herbivores completely unlike any seen today, for the most part.
HISTORYThe eurolophs (order Eurolophia) appeared suddenly in Europe, fully diversified into a number of distinct forms, about 30 million years ago, ruled the continent through the Oligocene, and then disappeared at the end of the Pliocene. Although eurolophs are clearly ornithopods of some kind or other, the eurolophs do not fit in with any other branch of this tree. Their cranial anatomy is advanced, with a long muzzle and three rows of cheek teeth to form a "dental battery" like that of a hadrosaur. However, the jugals (cheek bones) tend to be pronounced, as in the basal ornithopods like Heterodontosaurus, and the ossified tendons that stiffened the tails and spines of every ornithopod since the Jurassic are completely absent.
From Oligocene Europe, Bavarionyx cursor is the earliest relatively complete euroloph yet discovered. This creature is supposed to be an early rhinolophosaur, but shares some features (including its bipedal stance) with the struthiopods. Such a "missing link" may support a European origin for the eurolophs, but the evidence is still fragmentary. This is one of the most controversial fossils found in the world of Spec. Regardless of its validity at the moment, one thing is known for sure, this creature mostly like did give rise to the massive rhinolophosaurs.
The massive rhinolophosaurs of the Oligocene and Miocene were the largest of their breed, strongly convergent with hadrosaurian ungulipede . Indeed, rhinolophosaur material in France was first mistaken for very early ungulipede remains but the first complete rhinolophosaur skeleton, christened Rhinolophosaurus aumalai, was obviously not a hadrosaurian, and so the older finds, under scrutiny, turned out to be of the same stock.While the head of Rhinolophosaurus is indeed rather similar to a hadrosaur, with its battery of chewing teeth and bulbous nose, the rest of the body is not. The legs are short compared to the torso, and the neural spines over the shoulders are enlarged, traits found only in the truly huge hadrosaurs like hmungos and brutons. With such legs and spines, rhinolophs could only have been plodding, graviportal grazers, the earliest known in Eurasia. The tail, which in hadrosaurs counterbalances the body, is, as with all known rhinolophosaurs, devoid of stiffening tendons.
During their time, the rhinolophosaurs were the most successful herbivores in Eurasia, overshadowing the more familiar ceratopsians and hadrosaurs for the duration of the Oligocene epoch. The Haughton impact that began the Miocene took a heavy toll on the eurolophs, drastically reducing rhinolophosaur diversity and outright killing several other euroloph clades (about which very little is known). The rhinolophosaurs came back as strong as ever in the Miocene, producing such forms as the famous Rhinolophosaurus, still the most complete rhinolophosaur material found to date. Rhinolophosaurus and its kin continued quite happily up to the end of the Miocene, but the climatic changes of the Pliocene, coupled with the influx of African ungulapeds from the south had doom for the rhinolophosaurs. While the larger rhinolophosaurus marched into extinction, the smaller eurolophs managed to escape this fate, but their numbers did suffer heavy losses as well.
Struthiopods appeared in the late Oligocene, but only started to resemble modern forms by middle Miocene. These small, fleet-footed herbivores were the only species of eurolophs to survive the Miocene hadrosaur invasion, even reaching their heyday during the Pliocene epoch with a multitude of creatures sprinting across the Eurasian continent. However, this sadly didn't last forever. When the Pleistocene epoch arrived, as well as the addition of colder climates through out the Northern Hemisphere, many magnificent species of struthiopods could not adapt to the changing ecosystem or changing climate.
Eventually, the vast majority of their kind succumbed to the full effects of the Ice Age once the vast grasslands and savannas they had favored were replaced with vast blankets of snow. To make matters worse, the arrival of the highly successful group of small ornithopods known as the Laurasiornithopods (which contains Jackalopes, Vanguards and Duckgongs) had driven out a lot of species of struthiopods which had favored the warmer climates.
Despite this, not all species of struthiopods fell victim to the changing world. Whether by luck or by chance, some remnants managed to hold out in warmer regions of Europe and had eventually migrated back to areas of eastern Europe once the ice age had ended and where the small species of jackalope were absent, even fulfilling similiar roles. Scientists don't have the most crystal clear answer, but with some scattered fossils of creatures matching descriptions the modern day Strek, this is the most wildly accepted theory on how these enigmatic creatures managed to persevere into the modern day world.
Even they aren't as numerous as they once were, with only five species left in the whole Eurasian continent. Struthiopods are bipedal, with long legs and necks, but rather short tails, giving these dinosaurs are low center of gravity and an almost bird-like appearance. The middle toes of the eurolophs' hind legs are greatly enlarged, and when the animals run, only these middle toes touch the ground.
Strek (Struthiopes indigena)
The strek, not to be confused with the species of oviraptors who happen to be referred to as streks which happened to discovered by expeditions to Spec in the early to mid 2000's, is the largest of the struthiopods, and lives in the grassy plains of eastern Europe. Unlike the European ungulipedes who live in the area, struthiopods are still fully oviparous, and are therefore forced to go to great lengths to hide and protect their eggs from nest predation. It has been suggested that this difference is the very reason why the ungulipedes so quickly took over from the eurolophids in the Miocene. Another key feature of the Strek is the lack of crest and horns on the top of its head.