Giant marine reptiles at 2,800 meters above sea level
New study shows that fossil finds from the High Alps come from three
giants of the seas

Date:
April 28, 2022
Source:
University of Bonn
Summary:
More than 30 years ago, researchers discovered vertebrae, ribs and
a tooth in the High Alps of eastern Switzerland. The typical shape
indicated that they had to originate from large marine reptiles
known as ichthyosaurs, but there was a lack of corresponding
comparative material.

A new study has now allowed a more precise classification. According
to the findings, they belong to three different ichthyosaurs of
around 15 to around 20 meters in length. The tooth is particularly
unusual: With a root diameter of six centimeters, it is twice as
large as the largest aquatic dinosaur tooth found to date.



FULL STORY ==========================================================================
More than 30 years ago, researchers from the University of Zurich
discovered vertebrae, ribs and a tooth in the High Alps of eastern
Switzerland. The typical shape indicated that they had to originate from
large marine reptiles known as ichthyosaurs, but there was a lack of corresponding comparative material. A new study led by the University
of Bonn now allowed a more precise classification. According to the
findings, they belong to three different ichthyosaurs of around 15 to
around 20 meters in length. The tooth is particularly unusual: With a
root diameter of six centimeters, it is twice as large as the largest
aquatic dinosaur tooth found to date. The results have now been published
in the Journal of Vertebrate Paleontology.


==========================================================================
The first ichthyosaurs swam through the primordial oceans in the
early Triassic period about 250 million years ago. They had an
elongated body and a relatively small head. But shortly before most
of them became extinct some 200 million years ago (only the familiar dolphin-like species survived until 90 million years ago), they evolved
into gigantic forms. With an estimated weight of 80 tons and a length
of more than 20 meters, these prehistoric giants would have rivaled
a sperm whale. However, they left scarcely any fossil remains -- "why
that is remains a great mystery to this day," stresses Prof. Dr. Martin
Sander from the Section Paleontology at the Institute of Geosciences at
the University of Bonn.

Folding of the Alps brought up fossils from the bottom of the sea The
finds now examined come from the Grisons (canton of Graubu"nden). Sander's colleague Dr. Heinz Furrer of the University of Zurich had recovered
them together with students between 1976 and 1990 during geological
mapping in the Ko"ssen Formation. More than 200 million years before,
the rock layers with the fossils still covered the seafloor. With the
folding of the Alps, however, they had ended up at an altitude of 2,800
meters. "Maybe there are more rests of the giant sea creatures hidden
beneath the glaciers," Sander hopes.

The paleontologist first held the fossilized bones in his hands three
decades ago. At that time, he was still a doctoral student at the
University of Zurich.

In the meantime, the material had been somewhat forgotten. "Recently,
though, more remains of giant ichthyosaurs have appeared," the researcher explains. "So it seemed worthwhile to us to analyze the Swiss finds again
in more detail as well." According to the study, the fossils come from
three different animals that lived about 205 million years ago. From
one of the ichthyosaurs, a vertebra is preserved together with ten rib fragments. Their sizes suggest that the reptile was probably 20 meters
in length. In contrast, only a series of vertebrae were excavated from
a second ichthyosaur. Comparison with better preserved skeletal finds
suggests a length of about 15 meters.



========================================================================== "From our point of view, however, the tooth is particularly exciting,"
explains Sander. "Because this is huge by ichthyosaur standards: Its root
was 60 millimeters in diameter -- the largest specimen still in a complete skull to date was 20 millimeters and came from an ichthyosaur that was
nearly 18 meters long." His colleague Heinz Furrer is delighted with
the belated appreciation of the spectacular remains from the Swiss Alps:
"The publication has confirmed that our finds at the time belonged to the world's longest ichthyosaur; with the thickest tooth found to date and
the largest trunk vertebra in Europe!" However, it is unlikely that the animals that populated the primordial oceans 205 million years ago were
much longer than previously thought. "The tooth diameter cannot be used
to directly infer the length of its owner," emphasizes paleontologist
Martin Sander from Bonn. "Still, the find naturally raises questions." Predators larger than a sperm whale are not really possible This is
because research assumes that extreme gigantism and a predatory lifestyle (which requires teeth) are incompatible. There is a reason why the
largest animal of our time is toothless: the blue whale, which can be
up to 30 meters long and weighs 150 tons. Next to it, the teeth-bearing
sperm whale (20 meters and 50 tons) looks like an adolescent. While the
blue whale filters tiny creatures from the water, the sperm whale is a
perfect hunter. This means it requires a larger portion of the calories
it consumes to fuel its muscles.

"Marine predators therefore probably can't get much bigger than a sperm
whale," Sander says.

It is thus possible that the tooth did not come from a particularly
gigantic ichthyosaur -- but from an ichthyosaur with particularly
gigantic teeth.

Participating institutions: The Section Paleontology of the Institute
of Geosciences of the University of Bonn, the Paleontological Institute
and Museum of the University of Zurich, and the Institute of Anatomy of
the University of Bonn were involved in the study.


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


========================================================================== Related Multimedia:
* Fossils_and_life_reconstruction_of_a_giant_ichthyosaur ========================================================================== Journal Reference:
1. P. Martin Sander, Pablo Romero Pe'rez de Villar, Heinz Furrer, Tanja
Wintrich. Giant Late Triassic ichthyosaurs from the Ko"ssen
Formation of the Swiss Alps and their paleobiological
implications. Journal of Vertebrate Paleontology, 2022; DOI:
10.1080/02724634.2021.2046017 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220428085840.htm

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