Latouchella

About Natural History

Archive for the month “September, 2013”

Shells and Bones?

Could anyone imagine that a world in which no skeletal parts would exist could replace the world as we know it?
Well it already has existed, in fact this was the world during the whole of the Precambrian.

Do we not take all the skeletal parts for granted? Most of the time, the animals that surround us, that we notice the most, are composed of one sort of skeleton or another. Cats, dogs, snails, chickens… all have a kind of skeleton. But how often to we think about why do we even have hard mineralized bones? How are bones and shells made? Why do not all animals have it?

During the last couple of decades research on the topic of bio-mineralizations, or how do organisms create hard parts, has taken off. The major axes of interest are the mechanics and the genetic signal and control of the elaboration of skeletal parts in animals, the functional history of these genes etc.

Before the Cambrian, many animals existed as attests the famous Ediacara fauna, and it is believed that many more must have existed but we have no fossils to trace. The main reason for this is that these creatures did not possess skeletal elements, therefore making the fossilisation process extremely unlikely. The other consequence is that it is very difficult to assess the biodiversity of the Precambrian. And one very interesting problem arises: the Cambrian explosion cannot be seen as a real explosion of life, a moment of rapid diversification of life.
Indeed, for a long period of time – and today still, the Cambrian era was considered as the time when biodiversity increased considerably in a very short time lapse, simultaneously with the first appearance of skeletal parts. For this, it is only logical to believe that the genes must have existed previously to the “explosion” itself. Questions rise as to the true nature of the beginning of the Cambrian; it seems to be more of an extinction crisis: the organisms that weren’t able to keep up with the new technological advancement of the skeletal parts, and the first known predation advancements that also occurred during the Cambrian.

© SWEDISH MUSEUM OF NATURAL HISTORY. PHOTOS: STEFAN BENGTSON.

Early tube-dwelling Cambrian animals. © SWEDISH MUSEUM OF NATURAL HISTORY. PHOTOS: STEFAN BENGTSON.

Many things we do take for granted but do not stop to think about why and how they exist, and yet so many questions and mysteries lie in their study.

Counting life

What do most people know about the field of Systematics? When I tell someone in Greece that Systematics is an important and very interesting field of biology, they mostly ask me “the systematic study of what?”. How does it help and what does it do? I am only going to focus on the basis of this science and on how it is linked with museum collections.

We are used to hearing biodiversity questions and how species preservation is crucial in the current ecological disasters. But what is biodiversity and how can it be counted? How is it possible to know if it is increasing or decreasing? How does one know if the changes observed in a small-scale are significant or if similar changes have occurred in the past?
Systematics is the science that defines species and inevitably counts them. The criteria are brought by some rules (Nomenclature), recommendations and the art of defining species (Taxonomy).

While talking to a friend of mine who is a collection manager in the Natural History Museum of Paris, I thought of this: say that it’s not possible to travel the world collecting specimens and seeing specimens in museums – rather realistic in the current economy context. It then becomes crucial to be able to use museum collections that others have put together so carefully. It is all the more important in order to be able to understand the history of each species that we study, its range of morphology, its name attribution etc.

Furthermore, in order to count today’s biodiversity, species need to be defined and this is the first reason why museum collections are important: previous studies or their absence help but also prevent one from making a mistake (naming a species that already exists).

Is it not a shame that most people are not aware of what collections are and what purpose they serve? It is not just for the glory of having the largest collections, they are valuable for many scientists. Sometimes it also happens that new species are discovered while searching old collections as it happened for Xenoceratops foremostensis.

So let’s pay more credit to all precious collections worldwide, unfortunately a lot of them are in poor shape because of the lack of financial support as far as their maintenance is concerned.

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