Halloween Highlights: Crushing Jaws!

Happy Halloween to those goblins and ghouls amongst you! Before you go trick-or-treating tonight, let’s wrap up our month-long series on creepy critters and things that go bump in the night with one final critter and its modern-day cousin.

The unassuming reptile pictured above is the tuatara. The tuatara are found only in New Zealand, and are often called “living fossils” because of their physiological similarities to their ancient ancestors.

In research published today in PLOS ONE, researchers led by Dr. Oliver Rauhut discovered the fossil remains of an ancient relative of the tuatara, Oenosaurus muelheimensis. The species is named in honor of the Franconian Alb, the wine-growing region in Germany where the fossil was discovered, and the German village of Mühlheim.

Pictured to above is the Oenosaurus’ lower jaw, which in life featured a set of ever-growing tooth plates and multitudinous “pencil-like” teeth. Researchers posit that the arrangement and morphology of the lower jaw suggests that it moved in a crushing motion.

We recently invited Dr. Oliver Rauhut, the corresponding author of the paper, to share the group’s thoughts on their new findings. He writes:

The incentive for our research was the find of a new specimen of a rhynchocephalian from the Late Jurassic of Germany, which we name Oenosaurus muelheimensis. Rhynchocephalians are an ancient group of reptiles, today only represented by the Tuatara that lives on small islands off the coast of New Zealand and is regarded as a classic example of a living fossil. The new fossil has an extremely unusual dentition, and at first we were all at a loss as to what kind of animal this was, with ideas ranging from a chimeran fish to a rhynchosaur -[a] pig-like reptile that lived in the Triassic (which, incidently, is also reflected in the name…). After identifying the animal as a rhynchocephalian, we had a closer look at the dentition, which is unique amongst tetrapods in presenting large, continuously growing tooth plates. Such an extreme adaptation in a Jurassic rhynchocephalien contradicts the traditional idea that these animals were conservative and evolutionary inferior to lizards. Thus, we challenge the current opinion that the decline of rhynchocephalians during the later Mesozoic was mainly caused by selection pressure by radiating lizards and early mammals; instead climate change in the wake of continental break-up at that time might have been responsible.

This concludes our month-long celebration of some the spooktacular science you can find on PLOS ONE. If you are interested in learning about other creepy critters that we have covered in past years, please visit these links.

Have a safe and happy Halloween!

 

Citations:

Rauhut OWM, Heyng AM, López-Arbarello A, Hecker A (2012) A New Rhynchocephalian from the Late Jurassic of Germany with a Dentition That Is Unique amongst Tetrapods. PLoS ONE 7(10): e46839. doi:10.1371/journal.pone.0046839

http://en.wikipedia.org/wiki/Tuatara

The first image is provided courtesy of Helmut Tischlinger and can be found accompanying the institution’s press release.

The second image is Figure 2F in the manusript.

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