General, Research, Technology

Is it possible to determine the sex of a dinosaur by its bones?

Occasionally paleontologists who studyfossilized remains of ancient animals and plants, discover new species of dinosaurs. By studying their bones, scientists can determine with great accuracy how they looked and what they ate. But, studying the structure of bones, they practically cannot name the exact sex of the discovered individual, because they simply don’t know how the males differed from the females - the genitals are not preserved to this day. Previously, the sex of some dinosaurs was determined by bone size, but a new study by an international group of paleontologists proves that this method of identifying males and females produces incorrect results.

Paleontologist Kenneth Carpenter believes that the sex of dinosaurs can be determined by their bones, but is that so?

Content

  • 1 What is sex dimorphism?
  • 2 Gender differences in dinosaurs
  • 3 Modern dinosaurs
  • 4 Difficulties in the study of dinosaurs

What is dimorphism of the sexes?

The differences between females and males of the same species are usually called sexual dimorphisms. A striking example of this phenomenon can be consideredthe presence of lush mane in male lions and the absence of "luxurious hair" in lionesses. You can also look at peacocks - males have a very bright plumage, while females do not have such beauty.

Lions have luxurious hair on their heads - this is how they differ from females

Sometimes it happens the other way around when the distinctive sexual characteristics are more pronounced in females. So-called reverse sexual dimorphism can be seen in the smallest birds in the world -hummingbird. Walking through the expanses of North and South America or watching a documentary while sitting on the couch, you will notice that some individuals are much larger than others. So, females possess large bodies, and the size of males can be as little as 5 centimeters.

Based on the above, we can assume that on the left is a female hummingbird

Gender differences in dinosaurs

In 1992, paleontologist Kenneth Carpenter (KennethCarpenter) announced that it found signs of reverse sexual dimorphism in tyrannosaurs, which are considered perhaps the most famous dinosaurs in the world. In his scientific work Variation in Tyrannosaurus rex / Dinosaur Systematics: Approaches and Perspectives, he concluded that female tyrannosaurs were larger than males. He put forward his assumption after he examined the remains of 25 individuals of ancient predators.

Something like that depicted females and males of tyrannosaurs in the film by Steven Spielberg "Jurassic Park"

The public quickly mastered this information - statementthat females of tyrannosaurs were larger than males can still be found on sites with “interesting facts”. However, recently a group of scientists from the UK, USA and Canada, almost destroyed this myth. As part of their scientific work, they decided to find out whether signs of gender difference can persist on fossil remains.

Modern dinosaurs

As objects of study, the resultswhich were published in the scientific journal PreeJ, they took 106 gavial skulls provided by various museums around the world. Gaviales are called a special type of crocodile with long, pointed noses. Their distant ancestors existed millions of years ago, during the time of the dinosaurs, so it is not surprising that the present gavials have many similarities with ancient predators.

The gavials are believed to be on the brinkextinction. But in 2019 it became known that they began to breed actively - in South Asia hundreds of cubs of these crocodiles were found. Read more about this event in our material.

Like dinosaurs, gavials are largereptiles that lay eggs. They have sexual dimorphism - on the nose of males there is a noticeable "bump", consisting of soft tissues and supported by small bones in the nostrils. Studying hundreds of fossilized remains, scientists could hardly determine the sex of reptiles, even with such an obvious clue as bone structures on the nose. If the distinguishing features of reptiles have been destroyed over time, it is simply impossible to distinguish males of ancient predators from females.

In the photo - male gavial with a "bump" on the nose

Difficulties learning dinosaurs

Based on this, scientists came to the conclusion thatto determine the sex of dinosaurs by their bones is impossible. Firstly, the males and females of the ancient giants did not have distinctive features such as growths on the nose - at least nothing similar was found in tyrannosaurs. Secondly, the assumption of different body sizes in tyrannosaurs of opposite sexes was made on the basis of data obtained by studying the bones of 25 individuals. And this, according to scientists, is too small a sample to make such loud statements as “female tyrannosaurs were larger than males”.

Unfortunately, many dinosaurs are found only in a single copy.

Perhaps a method for determining the sex of dinosaurs bybones will be invented when paleontologists manage to discover the remains of at least a couple of hundred individuals. But even in this case, it will be applicable only to some types of dinosaurs, and not to all. For example, in the future, scientists may find bone processes on the remains of male tyrannosaurs, the presence of which will distinguish them from females. But whether such times come, it is not known - over time, the bones of dinosaurs can be destroyed by moving tectonic plates underground, or under the influence of other factors.

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And at the moment we can only be contentthe discovery of new species of dinosaurs, individuals of which are usually found in a single copy. Take, for example, the dinosaur Vayuraptor nongbualamphuensis, excavated in Thailand, whose body length was 4.5 meters, and the legs were similar to chicken. I recommend reading the material about this unusual predator right now - the article also explains why dinosaurs almost did not occur in Russia.