#biozone

What have fossils ever done for us?

Palaeontology has provided the inspiration for many great works. But just what is it that palaeontologists actually do with fossils once they’ve got them out of the ground? Of course, you can clean them up and show them off in a museum, and this is the side of palaeontology that the vast majority of the public sees. Nothing is quite as eye-catching as a dinosaur, and the beauty of ammonites is undeniable. This is the realm of curating, though and although it’s the dream job of many palaeontologists, there are only so many museums in the world. Instead, many palaeontologists work on micro-fossils.

As the name suggests, micro-fossils are fossils which are especially small. Whilst they can be spectacular to look at, their main use is for biostratigraphy. Biostratigraphy is the use of fossils to divide rock sequences into time zones. This is done using what are known as index fossils: fossils that are abundant, wide-ranging, and went extinct relatively fast.

Graptolites, an enigmatic group unique to the Palaeozoic, are a fantastic example of this. These organisms can be found in almost all deep-water deposits in the Ordovician and Silurian. Many individual species last for little more than a million years, with some having ranges as short as 300,000 years. Though an incredibly long time from a human perspective, in geological timescales it’s simply the blink of an eye.

But why do we want to know how old rocks are, and how do we know that? Knowing the age of rocks is important for multiple reasons; for example, oil deposits in some areas of the world occur within shales of certain ages. While radiometric dating is an incredibly useful technique for both igneous and metamorphic rocks, it is not a technique that can be reliably used with sedimentary rocks. As such, other methods need to be found. Microfossils can be extracted from boreholes with very little risk of damage and, by determining the biozone of the species, can be used to determine rock age. Microfossils like these can be extracted from rocks sampled through boreholes and matched with microfossils from other areas; matching index fossils would mean the rocks have the same age!

Biozone ranges are determined by radioactively dating overlying and underlying igneous deposits. This gives a maximum and minimum age for the deposit, though the boundaries are difficult to define beyond this. By finding a good biozone defining species entirely within the deposit, it can be correlated across the world with deposits that have not had the good fortune to be bounded by volcanic layers. Once you have a matching age, you can do all sorts of other comparisons, such as figuring out where shorelines were or where units might have generated resources.

Dale

Encrinus liliiformis – a crinoid from the Triassic that made a career for itself

Animals – not plants

Despite their common name ‘sea lilies’, crinoids are animals but not plants, although they look like a flower (Fig. 1). They are related to the sea urchins, sea cucumbers and starfish, groups that are unified as echinoderms (see, for example, Broadhead and Waters, 1980). Crinoids consist of a “root”, a stem built of many disc-shaped elements (columnals) and a crown.

Fig. 1. A…

Cuidados para la exposición solar @merdelettieres @biozonebsas

Es cierto que tomar el sol es algo saludable y necesario para que el cuerpo realice algunas de sus funciones vitales, pero en los tiempos que corren es importante que sigamos una serie de precauciones para que nuestra piel no sufra. La Dra. Adriana Szapinka, medica especialista en Belleza y Antienvejecimiento y  Directora de BioZone, Centro de Estética (MN63.378), nos brinda los siguientes…