Seltener Fund eines Fischsauriers aus dem Unterjura

I would like to talk today about a very interesting, very important find for us in paleontology, which was already made in 2018, but is now so well prepared and processed that we can make a first assessment about this find. It is a fish sauria, an Ichthyosauria from the time of the Juras, which is about 185 million years old. First of all, a few words about Ichthyosauria, so that we can assess this find correctly. Ichthyosauria is a group of reptiles that already in the Mesozoic, i.e. in the Middle Ages, looked for their way from the mainland to the water very early on. So we are actually dealing with a tetrapod here, with an originally four-legged land animal, which has changed the medium. So it is a group that has migrated from the mainland to the water. And the animals show corresponding adaptations to the permanent life in the water. Some are very obvious, as we can see in this representation. The extremities have transformed into fins. So we have four fins that have formed from arms and legs. We also have other fins on the back of these animals and in the tail area. The change of the life medium, in this case from the air to the water, of course, makes it necessary to develop anatomical adaptations to adapt as best as possible to this habitat. We can derive the continuation from these fins. But there are also other challenges. And one of them is reproduction. This is very obvious when we consider which tetrapods have otherwise gone back into the water. We have to do with several groups, with the ichthyosaurs and the plesiosaurs, who made it independent of the ichthyosaurs. Mosasaurs have also returned to the water. Today's whales are ultimately tetrapods that have returned from the mainland to the water. All these animals show appropriate adaptations and had to find a way to adapt their reproduction to the new medium. We see the difficulty when we look at today's sea turtles. These sea turtles live their entire life in the water and only return to the land to lay their eggs there. The ichthyosaurs, as well as the plesiosaurs, have solved this problem by reducing the egg deposit. They no longer lay eggs, but gave birth to living young. This is also shown in the fossil report, in which we find mammals with embryos in the abdomen. The ichthyosaurs have already taken this needle ear very early in the Mesozoic, went into reproduction in the water and were able to permanently adapt to a life in the water. They were born in the Triassic, in the early Mesozoic, and died around the middle of the Cretaceous, which covers a period of about 150 million years. So it was a very successful group in the Mesozoic. We are very lucky in Westphalia that we can cover all three areas of the Mesozoic with ichthyosaur finds. We have both finds from the Triassic and the Jurassic and the Cretaceous. And what I would like to present today is a find from the Jurassic, which was found near Bielefeld and is about 185 million years old. This is the find on the left side, we see an unprepared piece, on the right side then after the preparation. Manfred Schlösser worked very intensively on this piece. The find is still much more extensive. In 2018, these bones were found by private collectors in a clay pit near Jöllnbeck. They found the material in the loose material, which had already been torn from the band, and they were able to remove about 150 bones from the loose material and then reported it to the museum and handed it over. The big puzzle work started for us, because the geological context was largely destroyed. What we see here is the core of this find, a rock plate with bones, which are partly still in the band, partly also loose, arranged around this partially articulated spine. 150 bones, that's actually quite a lot, if we compare what we usually know about Jurassic ichthyosaurs from Westphalia. These are usually just individual vertebrae, individual rib fragments that appear from time to time. Here we are dealing with a complex of about 150 bones. I would like to show you what this find is about. So here we have this core piece, if we want to call it that, and we first see a core made of brown bones on a gray rock matrix. In between there are invertebrates, i.e. fossils of vertebrate animals, of ammonites and belemnites. So you have to look a little bit to see what bone is and what vertebrate fossil is. If we look at this plate, we first see these disc-shaped vertebrae. These are at least the vertebral centers, which have mostly been preserved here, while the neural arches are unfortunately broken off in most vertebrae. But we have a whole series of these disc-shaped vertebrae, which are very typical of ichthyosaurs. Next to it we have ribs and rib fragments, which occur relatively often, which is not surprising, because the ichthyosaurs consist of many vertebrae and most of the vertebrae also have two ribs, so that the natural relationship is actually already given here. A lot of vertebrae and even more rib fragments. Fortunately, we also find some teeth between this core of ribs and vertebrae. These teeth fell out of the jaw and are now isolated in the sediment. And we are very happy that these teeth are also there, because they are quite pronounced, anatomically pronounced, what kind of ichthyosaur it is here. In addition to these bones and teeth that occur often, we also have individual bones, which are sometimes paired, sometimes really only occur individually. And on this plate we also have three pieces. This is a fragment from the rostral area. The ichthyosaurs have a relatively long snout, which is formed from the upper and lower jaw. We have a fragment of that here. We have a femur, i.e. a very small thigh, which has attached to the vertebrae here. And we have a fragment from the pelvic belt of this animal. In addition, we have other bones. As I said, there are about 150. Partly they are associated, as we have seen in this core piece. Many of them are also completely isolated, which are now free as bones without a matrix. Here we have another piece, where we first thought it would be five vertebral bodies, which lie next to each other here. After the preparation, it turned out that there are four vertebrae and a basioccipital, i.e. the area of ​​the skull where the vertebral column is located. And that's great for us. This is a bone that is quite pronounced, as far as the determination of this Ichthyosauria is concerned. That's it. Yes, and here is another part plate, on which we mainly see these long-stretched bellimites, which do not belong to the Ichthyosauria. But we also see the disc-shaped vertebral centers again. And we see three special bones. On the one hand again a femur. And on top of that, in this case, I have the humerus of this animal, which is much larger than the femur. So we can already see here how the weighting of the front and back fin is. The front fin is significantly larger. Also included in this piece, and that is also an exciting thing, a valuable find, is the Atlas-axis complex. These are the first two cervical vertebrae, which are very often mixed with the Ichthyosauria. So here we have this combination of the first and second cervical vertebrae. Yes, what do we have from this Ichthyosauria? As I said, there are about 150 bones, including the teeth. And if we look at where these bones are located in the living animal, we can see that actually the entire body is represented by these 150 bones. The skeleton is not complete, but we actually get information from all body regions about the anatomy of this animal. So we have represented the skull area, we have teeth, we have the spine, both from the torso and from the tail area. We have parts of the extremities, both front and rear extremities. The pelvic girdle is definitely also represented. So in short, it goes across the Ichthyosaurian body. Unfortunately, it is not as aesthetic as many Ichthyosauria that we know. Here, for example, we know one from England or from southern Germany. We know these fully articulated Ichthyosauria, where the entire skeleton, from the tip of the nose to the back of the tail, is articulated. This is not the case with this find from Jöllenbeck. Nevertheless, we have a find that is so comprehensive that it can actually represent the entire animal. What do these bones tell us now? What do the teeth tell us? They indicate, pretty sure, that this is a representative Ichthyosauria. Leptonectis is an Ichthyosauria that actually looks like a typical Ichthyosauria in the Jurassic period. A long, stretched body, adapted to swim, pointed teeth, a long mouth. So an animal that is made for catching and eating fish. Leptonectis, this genus is known from the Upper Trias, and it goes into the lower Jurassic period. It crosses the Trias-Jura border, which is quite important for paleontology, because it is characterized by a mass extinction in earth history. So a very serious section actually. Leptonectis seems to be a passer-by. So a genus that actually survived this mass extinction. It also reaches far into the Lower Jura. And we know it, especially geographically, from the classic finds of Germany and South Germany, also from Belgium and Switzerland, recently also from Spain, and with the find from Jollenbeck now also from East Westphalia. And that is very important, because with this find we expand our knowledge about the geographical spread of this genus significantly to the northeast. This find is also exciting in terms of stratigraphy, because it is the youngest proof of Leptonectis at all. Although not by much distance to the most recent find, but we have another fairly young proof of this genus, so that our knowledge about Leptonectis is expanded. Stratigraphically, this find from Jollenbeck actually falls into a gap. I just said there are classic finds for Ichthyosauria in England and South Germany. Holzmaden is the keyword there, where estimated 3,000 Ichthyosauria skeletons have been excavated. They are represented worldwide in the natural history museums where they are exhibited and collected. However, the finds from Holzmaden are younger than what we found in Jollenbeck, and the finds from England are older. Our find from Jollenbeck strategically falls into Plinsbachium, blessed with finds of marine reptiles, including the Ichthyosauria. And so we can strategically close a gap with the find from Jollenbeck, and this find is one of a small number of important finds from Westphalia that fall into Plinsbachium. We also have paddle lizards like Westphalia saurus and Armini saurus that have already been found here and have closed parts of this gap. And there are also very rarely individual Ichthyosauria in Westphalia that help us to fill this bridge, this white spot in the stratigraphy with knowledge. In summary, we can say to this find near Jollenbeck that it is a very complete Ichthyosauria, even if the first impression is different, because we only have this mass of bones in front of us, but they come from the whole body. Systematically it seems to be a Leptonectis, which is exciting, because we can thus obtain the most recent stratigraphic proof of this species and it is also the northeasternmost find of this species, so that we also geographically experience an expansion. And with that, in the end, this Leptonectis falls into the gap that the fossil report in Plinsbachium has and we have another representative of marine reptiles here, which is incredibly valuable in paleontology. With this I would like to thank you, especially Father and Son Müller, who made the find and so carefully secured material and reported it to the Nature Conservatory and handed it over. I would also like to thank the Stork company, which supported the search very much and of course for the attention. Thank you very much.