The Earth Story

Carbon Dating Dinos: It just doesn’t work

I have a bit of a pet peeve; it's films perpetuating the misconception that you can carbon date dinosaurs. I recently watched Transformers: Age of Extinction (not exactly renowned for its science, but still) and was disappointed when the lead scientist excitedly claims they have dated the dinosaur “remains” to 70ma using carbon dating.

My brother who was sat watching with me made a very good point: if dinosaurs contain carbon why can’t you carbon date them?

Fossil bees!

This pair of images shows, on top, a modern-day leafcutter bee from the species Megachile rotundata and a very cool fossil find from the LaBrea Tar Pits. The bees come from a pair of full nests exhumed from a part of the tar pits; the same location has produced bones from animals 23,000 to 40,000 years old, and carbon-14 dating of the material in the nests gives the same age, so these bees are about that old. Many interesting specimens are preserved in the nests and have been found by scientists exhuming material from the tar pits, including the leafy walls of the nests themselves, adults, and pupae like this one.

The bees are from species that are widespread in the United States, but the presence of these bees at this site actually helps constrain how their distributions have changed during the big climate shifts that happened since the nests were made. The bees today have expanded ranges at higher elevations than is suggested by these fossil finds, indicating that as the climate of the area warmed, the bees moved uphill to follow similar temperature levels.

-JBB

Image credit:

Image credit: PLOS One (Open access journal): http://www.plosone.org/article/info%3Adoi/10.1371/journal.pone.0094724

The painting and the bomb

This image shows the painting Contraste de Formes (Contrast of forms) by French artist Fernand Léger. The original painting was composed in 1913 as part of a series of paintings showing these sorts of abstract shapes.

This particular painting was purchased by American art patron Peggy Guggenheim and placed in the collections of that museum. However, in the 1970’s, scholar Douglas Cooper suggested that the painting owned by the Guggenheim was a forgery.

Afterwards, scholars were unable to agree on the authenticity of the work and so it was not displayed. Research done by the Italian Institute for Nuclear Physics has actually answered that question.

In the 1950s and early 1960s, the United States and the Soviet Union detonated large numbers of nuclear weapons in the atmosphere. Nuclear detonations give off enormous amounts of high-energy radiation and, as a result, produce isotopes that aren’t commonly found in the atmosphere, including radioactive isotopes.

One of those isotopes is Carbon-14. A small amount of Carbon-14 is made naturally in the atmosphere due to interactions between solar radiation and Nitrogen-14, but in the 1950’s nuclear tests added a much larger pulse of Carbon-14 to the atmosphere. Any organic material made after this date carries the signal of this bomb-generate Carbon-14; everything from your own body to the fabric used in paintings.

The Italian scientists took a small corner of this fabric and tested its isotopic composition. Carbon-14 has a half life of over 5000 years, so the pulse of C-14 from the bomb tests would still show up today, only 50 years after the tests. When they tested this painting, supposedly made in 1913, they found the bomb-test carbon present.

The painting owned by the Guggenheim is a forgery, made sometime after airborne nuclear tests began. In fact, they estimated the painting was probably made close to 1959, as that is the best match to the isotopic composition of the fabric. Another fascinating use of techniques deployed everyday in the earth sciences.

-JBB

Image credit: Wikipaintings http://www.wikipaintings.org/en/fernand-leger/contrast-of-forms-1913

The painting and the bomb This image shows the painting Contraste de Formes (Contrast of forms) by French artist Fernand Léger. The original painting was composed in 1913 as part of a series of paintings showing these sorts of abstract shapes. This particular painting was purchased by American art patron Peggy Guggenheim and placed in the collections of that museum. However, in the 1970’s, scholar Douglas Cooper suggested that the painting owned by the Guggenheim was a forgery. Afterwards, scholars were unable to agree on the authenticity of the work and so it was not displayed. Research done by the Italian Institute for Nuclear Physics has actually answered that question. In the 1950s and early 1960s, the United States and the Soviet Union detonated large numbers of nuclear weapons in the atmosphere. Nuclear detonations give off enormous amounts of high-energy radiation and, as a result, produce isotopes that aren’t commonly found in the atmosphere, including radioactive isotopes. One of those isotopes is Carbon-14. A small amount of Carbon-14 is made naturally in the atmosphere due to interactions between solar radiation and Nitrogen-14, but in the 1950’s nuclear tests added a much larger pulse of Carbon-14 to the atmosphere. Any organic material made after this date carries the signal of this bomb-generate Carbon-14; everything from your own body to the fabric used in paintings. The Italian scientists took a small corner of this fabric and tested its isotopic composition. Carbon-14 has a half life of over 5000 years, so the pulse of C-14 from the bomb tests would still show up today, only 50 years after the tests. When they tested this painting, supposedly made in 1913, they found the bomb-test carbon present. The painting owned by the Guggenheim is a forgery, made sometime after airborne nuclear tests began. In fact, they estimated the painting was probably made close to 1959, as that is the best match to the isotopic composition of the fabric. Another fascinating use of techniques deployed everyday in the earth sciences. -JBB Image credit: Wikipaintings http://www.wikipaintings.org/en/fernand-leger/contrast-of-forms-1913