In the upper Jurassic period, about 150 million years ago, Bavaria still looked quite different from today. The Alps did not exist at this time, they were later unfolded, and so Bavaria bounded southwards to the Mediterranean Sea, the Tethys. To the north of the ocean basin, a flat sea stretched far to the continental plate, which also covered the predominant part of Bavaria.
In the north, the Rhenish massif rose, and in the east the Bohemian island. At that time, Central Europe lay much further south than today, and the equator was only a few hundred miles away, so that a tropical climate prevailed. Extensive sponges and coral reefs grew in the southern part of the flat sea in southern Germany, separating the deep sea of the Tethys from a series of shallow sea troughs in the area of today's southern Franconia. In these basins, very fine lime sludge accumulated, in which also the remains of the living beings living in the flat sea and the neighboring islands remained.
This lime sludge became the Solnhofen plate limestone over the millenniums, which are famous far beyond Germany as an extraordinary fossil plant. Several thousand species of fossil creatures have been described so far from the Solnhofen slate limestones and the layers directly above and below them, from single-cell algae over land plants, any species of marine invertebrates (eg squids, sea urchins, crabs, etc.), insects, sharks and bone fish, various reptiles (eg Brückenechsen, turtles, crocodiles, flight dinosaurs, etc.) to the artifact archeology.
Amongst the vertebrate species, especially the bone fish are very species rich, as is expected in an aquatic habitat of course. However, the fauna of the bonefish at the time of the late Jurassic was still significantly different from today's. At present, the fish fauna is dominated by the group of teleosteers, modern bone fish, which, with more than 30,000 known species, represent almost half of the entire vertebrate fauna. On the other hand, the total number of basal bone fishes - pelvic hammers, molluscs, mud fish, and hake - is still 36 species. In the Jura, however, modern bone fish were only one among many groups of bone fish. The gynglimodi, the group to which today's hake belongs, and the Halecomorphi, among which the modern mud fish (Amia calva), were particularly diverse and widespread. In addition, there were also a number of groups of extinct relatives of modern bone fish. One of these groups, which are well represented in the Solnhofen plate limestones, are the Aspidorhynchids, in particular the genus Aspidorhynchus.
Like most basal bone fish, the aspidorhynchids can easily be distinguished from the modern bone fish by their massive bone scales. While this type of bony sclerotic was originally widespread in bone fish, modern bone fish have given up this protection in favor of a much lighter and more flexible scleral of horny scales. Fossil, the modern bone fish can easily be distinguished from other groups. While the vertebral column is clearly visible, it is usually hidden under the dense dandruff in other groups.
The Aspidorhynchids are distinguished by their slender, strongly elongated body and tapering jaw, whence their German name - Schnabelfische - comes from. The back and anterior fins are placed far behind the body and are directly opposite each other. On the whole, the aspidorhynchids are very similar to today's horns (whose English name, needlefishes - needlefishes - is much more striking), which, however, belong to the modern bone fish, the teleosteer. Because of the similarity, it can be assumed that the aspidorhynchids also had a similar way of life as the present hornhits, H. they were swiftly floating predators, which can accelerate rapidly with their streamlined body and the fins far behind. Today's hornbills can also jump high and far out of the water while fleeing.
The fact that this was also possible for the Aspidorhynchids seems not only to be probable, but even a direct indication: A well-preserved specimen of Aspidorhynchus from the Solnhofen plate limestones was found together with a skeleton of a flight dinosaur and the pointed "beak" of the fish had evidently caught himself in the reptile's airport. Although this find also as Attempt of the Aspidorhynchus was interpreted to capture the flight dinosaur, it seems plausible that the beaked fish "shot down" the reptile flying low over the water on a fishing train only accidentally in a jump out of the water. Similar accidents of today's hornhounds, which collide with obstacles in jumps, are often vouched for.
The species Aspidorhynchus acutirostris is one of the first
described species of fish from these rocks due to their abundance in the plate
limestones of the Altmühltal; it was described as early as 1818 by Henri de
Blainville, who at that time regarded the fish as a new species of today's hake
Esox. Only the great Swiss fish explorer Louis Agassiz recognized in 1833 that
it was an extinct fish group and changed the generic name in Aspidorhynchus.
Since the material described by Blainville is no longer preserved, it was necessary
to establish a new specimen as the so-called type of the species, that is to
say, as a reference for the species Aspidorhynchus acutirostris. The specimen
shown here is this so-called neotype. This specimen is not only beautifully
preserved, but was also presented by a hobby collector, Dr. Uwe Eller, has been
excellently prepared so that it shows numerous of the typical features of the
species. This specimen is, therefore, of great scientific value, since it is
determined by it what the investigators understand by Aspidorhynchus
acutirostris.