Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

With a crush: A Jurassic brother of the enigmatic tuataras

01.11.2012
Tuataras are often regarded as a classic example of a living fossil. They are the last survivors of an ancient lineage, which is said to have lost the evolutionary struggle with the modern lizards.

A new find from the Late Jurassic (c. 148 Ma ago) of southern Germany demonstrates that the fossil relatives of the tuatara showed a much greater evolutionary plasticity than previously recognized and were at the height of their ecological diversity at a time, when modern lizards were already widespread. This challenges the idea of their evolutionary inferiority and suggests that other reasons might be responsible for their decline.


Figure 1 (Tuatara.jpg): The tuatara, Sphenodon puctatus, which grows to up to 50 cm in length and lives on a few islands off the coast of New Zealand. Photo courtesy Helmut Tischlinger.
Photo: Helmut Tischlinger


Figure 2 (Oenosaurus.jpg): The skull of Oenosaurus in palatal view, with the tooth plates being well visible. Scale bar is 1 cm.
Photo: SNSB

It looks like a “normal” lizard, but belongs to an ancient lineage apart from modern lizards: the Tuatara, which is represented by only two species that live on a few islands off the coast of New Zealand. With a brain and mode of locomotion that is said to be intermediate between amphibians and reptiles, tuataras are among the most enigmatic living animals and are often regarded as living fossils, as a perfect model for an ancient lizard ancestor.

However, their parent lineage, the Rhynchocephalia ("Beak Heads") were wide-spread and diverse during the Mesozoic, the “age of dinosaurs”. To answer the question what led to their decline in the late Mesozoic seemed easy enough: with their obviously primitive appearance, rhynchocephalians were clearly inferior to the true lizards and even more so to the primitve mammals that radiated at that time. Were they really?

A new fossil relative of the tuataras found in the latest Jurassic of southern Germany challenges this idea, in line with other recent finds of rhynchocephalians. In a paper recently published in the scientific journal PLoS One, the German brother of the tuataras was given the name Oenosaurus muehlheimensis, revering the exquisite wine of the Franconian Alb and the village of Mühlheim, close to the place where the fossil was found. Oenosaurus closely resembles the living tuataras, but it has a dentition that is unique amongst tetrapods.

“When the specimen was found and only the palatal view of the skull was visible, we were all wondering what kind of animal it might be”, recalls Dr. Oliver Rauhut of the Bavarian State Collection for Palaeontology and Geology, the lead author of the study: “no one of us had ever seen such teeth in a reptile.” The dentition of Oenosaurus consists of massive tooth plates, the structure of which indicates that they might have been growing continuously, balanced by wear on the surface of the plate. Such teeth are otherwise only found in chimaeran and dipnoan fishes.

“We analysed the tooth plates with the help of computer tomography, and when I showed the pictures to a colleague who is specialized in the microstructure of fish teeth, she first found nothing unusual – until I told her that these were the teeth of a reptile”, says Dr. Adriana López-Arbarello, fish expert of the State Collection and one of the co-authors of the paper. “Then she almost couldn’t believe it”, she adds with a little smile. This discovery represents a previously unknown trophic adaptation in rhynchocephalians, indicating a diet of hard-shelled organisms. Rhynchocephalians otherwise have a very specialized kind of dentition, well adapted to cutting or tearing functions, which has been hypothesized to limit their evolutionary adaptability.

Thus, the dentition of Oenosaurus demonstrates an unexpected evolutionary plasticity in these animals and underlines the fact that rhyncocephalians were actually highly diverse, both morphological and ecological, during the latest Jurassic in Europe, just before the decline of this lineage on this continent. This contradicts the popular view that rhynchocephalians were inferior to lizards and early mammals and that selection pressure by these animals is sufficient to explain the demise of the group in the late Mesozoic; instead, climate change in the course of the fragmentation of the supercontinent of Pangaea might have played a major role.

The remains of Oenosaurus were found by Roland Pöschl in the outcrops of the Mörnsheim Formation in the Schaudiberg quarry in Mühlheim near Mörnsheim, central Bavaria, Germany. The owners of the quarry immediately recognized the scientific value of the fossil and kindly donated it to the Bayerische Staatssammlung für Paläontologie und Geologie in Munich. The Mörnsheim Formation is slightly younger than the well-known Solnhofen Formation, which, among others, has yielded the famous Urvogel, Archaeopteryx. The Mörnsheim Formation is also very fossiliferous, but much more poorly known, since, in contrast to the Solnhofen Formation, there are few commercial quarries in these rocks.

“We have just begun to explore these rocks, and more surprises are sure to come”, affirms Alexander Heyng. The geologist analyses the succession of rocks in the Schaudiberg quarry and also arranged the contact between the quarry owners and the scientists of the Bavarian State Collection. A large part of the Schaudiberg quarry is now open for exploration by visitors (http://www.besuchersteinbruch.de/), who can get actively involved in the fascinating adventure of discovering the Jurassic life and further support scientist in the challenge of deciphering the early history and evolutionary pathways of the modern organisms.

Link to article: http://dx.plos.org/10.1371/journal.pone.0046839

Contact:
Dr. Oliver Rauhut
Dr. Adriana López-Arbarello
Bayerische Staatssammlung für Paläontologie und Geologie
Richard-Wagner-Str. 10
80333 München
o.Rauhut@lrz.uni-muenchen.de
+49 / (0)89/21806645 / 0163 741 7552
a.Lopez-Arbarello@lrz.uni-muenchen.de
+49 / (0)89/21806725

Dr. Eva-Maria Natzer | idw
Further information:
http://dx.plos.org/10.1371/journal.pone.0046839
http://www.palmuc.de/bspg/
http://www.snsb.mwn.de/Joomla/index.php

More articles from Earth Sciences:

nachricht Less radiation in inner Van Allen belt than previously believed
21.03.2017 | DOE/Los Alamos National Laboratory

nachricht Mars volcano, Earth's dinosaurs went extinct about the same time
21.03.2017 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars

22.03.2017 | Physics and Astronomy

New gel-like coating beefs up the performance of lithium-sulfur batteries

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>