Fossil growth reveals insights into the climate
Researchers examined bones of the puzzling Panthasaurus maleriensis

Date:
September 8, 2020
Source:
University of Bonn
Summary:
Panthasaurus maleriensis is an ancestor of today's amphibians
and has been considered the most puzzling representative of the
Metoposauridae.

Paleontologists examined the fossil's bone tissue and compared
it with other representatives of the family also dating from the
Triassic. They discovered phases of slower and faster growth in
the bone, which apparently depended on the climate.



FULL STORY ========================================================================== Panthasaurus maleriensis lived about 225 million years ago in what is now India. It is an ancestor of today's amphibians and has been considered
the most puzzling representative of the Metoposauridae. Paleontologists
from the universities of Bonn (Germany) and Opole (Poland) examined
the fossil's bone tissue and compared it with other representatives
of the family also dating from the Triassic. They discovered phases of
slower and faster growth in the bone, which apparently depended on the
climate. The results have now been published in the journal PeerJ.


========================================================================== Temnospondyli belong to the ancestors of today's amphibians. This
group of animals became extinct about 120 million years ago in the
Early Cretaceous. The Temnospondyli also include the Metoposauridae,
a fossil group that lived exclusively in the Late Triassic about 225
million years ago. Remains of these ancestors are present on almost
every continent. In Europe, they are found mainly in Poland, Portugal
and also in southern Germany.

Panthasaurus maleriensis, the most puzzling representative of the Metoposauridae to date, lived in what is now India, near the town of
Boyapally.

"Until now, there were hardly any investigation opportunities because the fossils were very difficult to access," explains Elzbieta Teschner from
the University of Opole, who is working on her doctorate in paleontology
in the research group of Prof. Dr. Martin Sander at the University
of Bonn.

Researchers from the Universities of Bonn and Opole, together with
colleagues from the Indian Statistical Institute in Kolkata (India),
have now examined the tissue of fossil bones of a metoposaur from the
Southern Hemisphere for the first time. The amphibian, which resembled
a crocodile, could grow up to three meters in length.

Valuable insight into the bone interior "The investigated taxon is
called Panthasaurus maleriensis and was found in the Maleri Formation
in Central India," notes Teschner with regard to the name. So far, the
fossil has only been examined morphologically on the basis of its external shape. "Histology as the study of tissues, on the other hand, provides
us with a valuable insight into the bone interior," says Dr. Dorota
Konietzko- Meier from the Institute for Geosciences at the University of
Bonn. The histological findings can be used to draw conclusions about age, habitat and even climate during the animal's lifetime.

The histological examinations revealed that the young animals had very
rapid bone growth and that this growth decreased with age. The Indian
site where the bones were found provides evidence of both young and
adult animals, in contrast to Krasiejo'w (south-western Poland), where
only young animals were found.

Geological and geochemical data show that the Late Triassic consisted
of alternating dry and rainy periods, as in the present monsoon climate
of India.

"This sequence is also reflected in the material examined," says Teschner.

"There are phases of rapid growth, known as zones, and a slowdown,
known as annulus." Normally, one can still observe stagnation lines in
the bones, which develop during unfavorable phases of life, for example
during very hot or very cold seasons.

In Panthasaurus maleriensis, however, growth never comes to a complete cessation. In comparison: the Polish Metoposaurus krasiejowensis
shows the same alternation of zones and annuli in one life cycle and no stagnation lines, whereas the Moroccan representative of the metoposaurs Dutuitosaurus ouazzoui shows stagnation lines -- that is, a complete
stop in growth -- in each life cycle.

The different growth phases in the bones allow for a comparison of
climatic conditions. This means that the climate in the Late Triassic
would have been milder in Central India than in Morocco, but not as
mild as in the area that today belongs to Poland. Sander: "Fossil bones therefore offer a window into the prehistoric past."

========================================================================== Story Source: Materials provided by University_of_Bonn. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Elżbieta M. Teschner, Sanjukta Chakravorti, Dhurjati
P. Sengupta,
Dorota Konietzko-Meier. Climatic influence on the growth pattern
of Panthasaurus maleriensis from the Late Triassic of India deduced
from paleohistology. PeerJ, 2020; 8: e9868 DOI: 10.7717/peerj.9868 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200908131058.htm

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