Sexing dinosaurs mainly small and clear

Women came from Venus, says, and men of Mars - the differences between the sexes within a species can go very far. You may be in dinosaurs are so large that their fossils often be misunderstood as its own species.

In the current issue of the scientific journal "Plos One" researchers are Princeton University now that males and females have a Dinosaurierart are clearly distinguished from each other. These differences in the manifestations of gender equality are also called sexual dimorphism.

This is far more exciting than you would think. Because in contrast to today's animal species, in which visible Sexual dimorphism the rule, is a identification of males and females in a kind fossils not so easy.

We have a very strong, non-human primates for example clearly visible dimorphism. Gorillamannchen are well over twice as big as their female, and also for us human beings, the men usually much more moderate than the women.

Most of our other Dimorphismen but are - from a geological point of view - very ephemeral. It is also by our fossils in 60 million years ago cannot say whether or not the hair growth difference, as we weichteilmaßig were built and whether gender green and the other perhaps was blue.

As for the determination of the sex in fossils only significant characteristics of the Constitution. Our family for example, can be quite clear on the pelvis. But what if you don't know what bony features the sexes within a species differences?

This is precisely the problem with Dinosaurierfossilen. The giant lizards are already in the problematic that different types within a group often only to individual characteristics can be distinguished. In sauropod, the huge Langhalsen, it is also in the Ceratopsia and similar: to which include, for example, the famous Triceratops.

Small is good, as long as it is substantially

Now also clearly succeeded in the remarkable difference between the sexes in Stegosauriern. The palaeontologists Evan Saitta was noticed that it finds in the Stegosaurus mjosi seemed to be two forms in the bony plates, the animals were on the back, could be distinguished: some were pointed, the other rounded. The rounded plates also turned out to be a big, brought it to 45 percent more surface area, such as the researchers in the journal "Plos One" writes.

Saitta had the good fortune to be able to investigate several fossil, died at the same place same time apparently were. Based on different characteristics of the bone he could demonstrate that both variants to adult animals of the same type - the difference of the plates had to be gender-specific.

What form now to what sex is, ultimately, is speculative. Saitta believes that the tips of the females were defensive plates, while the large-scale, highly perfused Rundplatten to males were - keyword Pfau. The plates were able to change color and may seem as sexual signals, for example in the Baelz or have served in the face of the competition.

This, too, is also difficult to prove: If dinosaurs fossils in colors, shapes and eye-catching body decoration as sexual communication, is pure speculation, because of course nothing is received. On the other side they were already a powerful exception in the animal kingdom, would have been if it were not so.