Huge new ichthyosaur, one of the largest animals ever, uncovered high in the Alps

Jan 27, 2020
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By Taylor and Francis

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The habitat and animals that were found together with the giant ichthyosaurs. Credit: Heinz Furrer

Paleontologists have discovered sets of fossils representing three new ichthyosaurs that may have been among the largest animals to have ever lived, reports a new paper in the peer-reviewed Journal of Vertebrate Paleontology.

Unearthed in the Swiss Alps between 1976 and 1990, the discovery includes the largest ichthyosaur tooth ever found. The width of the tooth root is twice as large as any aquatic reptile known, the previous largest belonging to a 15-meter-long ichthyosaur.

Other incomplete skeletal remains include the largest trunk vertebra in Europe that demonstrates another ichthyosaur rivaling the largest marine reptile fossil known today, the 21-meter long Shastasaurus sikkanniensis from British Columbia, Canada.

Dr. Heinz Furrer, who co-authors this study, was among a team who recovered the fossils during geological mapping in the Kössen Formation of the Alps. More than 200 million years before, the rock layers still covered the seafloor. With the folding of the Alps, however, they had ended up at an altitude of 2,800 meters.

Now a retired curator at the University of Zurich's Paleontological Institute and Museum, Dr. Furrer said he was delighted to have uncovered "the world's longest ichthyosaur; with the thickest tooth found to date and the largest trunk vertebra in Europe."

And lead author P. Martin Sandler, of the University of Bonn, hopes "maybe there are more remains of the giant sea creatures hidden beneath the glaciers."

"Bigger is always better," he says. "There are distinct selective advantages to large body size. Life will go there if it can. There were only three animal groups that had masses greater than 10-20 metric tons: long-necked dinosaurs (sauropods); whales; and the giant ichthyosaurs of the Triassic."

These monstrous, 80-ton reptiles patrolled Panthalassa, the world's ocean surrounding the supercontinent Pangaea during the Late Triassic, about 205 million years ago. They also made forays into the shallow seas of the Tethys on the eastern side of Pangaea, as shown by the new finds.

Ichthyosaurs first emerged in the wake of the Permian extinction some 250 million years ago, when some 95 percent of marine species died out. The group reached its greatest diversity in the Middle Triassic and a few species persisted into the Cretaceous. Most were much smaller than S. sikanniensis and the similarly-sized species described in the paper.

Roughly the shape of contemporary whales, ichthyosaurs had elongated bodies and erect tail fins. Fossils are concentrated in North America and Europe, but ichthyosaurs have also been found in South America, Asia, and Australia. Giant species have mostly been unearthed in North America, with scanty finds from the Himalaya and New Caledonia, so the discovery of further behemoths in Switzerland represents an expansion of their known range.

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Heinz Furrer with the largest ichthyosaur vertebra. Credit: Heinz Furrer

Paleontologists have discovered sets of fossils representing three new ichthyosaurs that may have been among the largest animals to have ever lived, reports a new paper in the peer-reviewed Journal of Vertebrate Paleontology.

Unearthed in the Swiss Alps between 1976 and 1990, the discovery includes the largest ichthyosaur tooth ever found. The width of the tooth root is twice as large as any aquatic reptile known, the previous largest belonging to a 15-meter-long ichthyosaur.

Other incomplete skeletal remains include the largest trunk vertebra in Europe that demonstrates another ichthyosaur rivaling the largest marine reptile fossil known today, the 21-meter long Shastasaurus sikkanniensis from British Columbia, Canada.

Dr. Heinz Furrer, who co-authors this study, was among a team who recovered the fossils during geological mapping in the Kössen Formation of the Alps. More than 200 million years before, the rock layers still covered the seafloor. With the folding of the Alps, however, they had ended up at an altitude of 2,800 meters.

Now a retired curator at the University of Zurich's Paleontological Institute and Museum, Dr. Furrer said he was delighted to have uncovered "the world's longest ichthyosaur; with the thickest tooth found to date and the largest trunk vertebra in Europe."

And lead author P. Martin Sandler, of the University of Bonn, hopes "maybe there are more remains of the giant sea creatures hidden beneath the glaciers."

"Bigger is always better," he says. "There are distinct selective advantages to large body size. Life will go there if it can. There were only three animal groups that had masses greater than 10-20 metric tons: long-necked dinosaurs (sauropods); whales; and the giant ichthyosaurs of the Triassic."

These monstrous, 80-ton reptiles patrolled Panthalassa, the world's ocean surrounding the supercontinent Pangaea during the Late Triassic, about 205 million years ago. They also made forays into the shallow seas of the Tethys on the eastern side of Pangaea, as shown by the new finds.

Ichthyosaurs first emerged in the wake of the Permian extinction some 250 million years ago, when some 95 percent of marine species died out. The group reached its greatest diversity in the Middle Triassic and a few species persisted into the Cretaceous. Most were much smaller than S. sikanniensis and the similarly-sized species described in the paper.

Roughly the shape of contemporary whales, ichthyosaurs had elongated bodies and erect tail fins. Fossils are concentrated in North America and Europe, but ichthyosaurs have also been found in South America, Asia, and Australia. Giant species have mostly been unearthed in North America, with scanty finds from the Himalaya and New Caledonia, so the discovery of further behemoths in Switzerland represents an expansion of their known range.
However, so little is known about these giants that there are mere ghosts. Tantalizing evidence from the UK, consisting of an enormous toothless jaw bone, and from New Zealand suggest that some of them were the size of blue whales. An 1878 paper credibly describes an ichthyosaur vertebrae 45 cm in diameter from there, but the fossil never made it to London and may have been lost at sea. Sander notes that "it amounts to a major embarrassment for paleontology that we know so little about these giant ichthyosaurs despite the extraordinary size of their fossils. We hope to rise to this challenge and find new and better fossils soon."These new specimens probably represent the last of the leviathans. "In Nevada, we see the beginnings of true giants, and in the Alps the end," says Sander, who also co-authored a paper last year about an early giant ichthyosaur from Nevada's Fossil Hill. "Only the medium-to-large-sized dolphin- and orca-like forms survived into the Jurassic."While the smaller ichthyosaurs typically had teeth, most of the known gigantic species appear to have been toothless. One hypothesis suggests that rather than grasping their prey, they fed by suction. "The bulk feeders among the giants must have fed on cephalopods. The ones with teeth likely feed on smaller ichthyosaurs and large fish," Sander suggests.

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Martin Sander and Michael Hautmann look over the discovery layers on the southern

The tooth described by the paper is only the second instance of a giant ichthyosaur with teeth—the other being the 15-meter-long Himalayasaurus. These species likely occupied similar ecological roles to modern sperm whales and killer whales. Indeed, the teeth are curved inwards like those of their mammalian successors, indicating a grasping mode of feeding conducive to capturing prey such as giant squid.

"It is hard to say if the tooth is from a large ichthyosaur with giant teeth or from a giant ichthyosaur with average-sized teeth," Sander wryly acknowledges. Because the tooth described in the paper was broken off at the crown, the authors were not able to confidently assign it to a particular taxon. Still, a peculiarity of dental anatomy allowed the researchers to identify it as belonging to an ichthyosaur.

"Ichthyosaurs have a feature in their teeth that is nearly unique among reptiles: the infolding of the dentin in the roots of their teeth," explains Sander. "The only other group to show this are monitor lizards."

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The root of the tooth found has a diameter of 60 Millimeters. This makes it the...

The two sets of skeletal remains, which consist of a vertebrae and ten rib fragments, and seven asssociated vertebrae, have been assigned to the family Shastasauridae, which contains the giants Shastasaurus, Shonisaurus, and Himalayasaurus. Comparison of the vertebrae from one set suggests that they may have been the same size or slightly smaller than those of S. sikkanniensis. These measurements are slightly skewed by the fact that the fossils have been tectonically deformed—that is, they have literally been squashed by the movements of the tectonic plates whose collision led to their movement from a former sea floor to the top of a mountain.

Known as the Kössen Formation, the rocks from which these fossils derive were once at the bottom of a shallow coastal area—a very wide lagoon or shallow basin.

This adds to the uncertainty surrounding the habits of these animals, whose size indicates their suitability to deeper reaches of the ocean. "We think that the big ichthyosaurs followed schools of fish into the lagoon. The fossils may also derive from strays that died there," suggests Furrer.

"You have to be kind of a mountain goat to access the relevant beds," Sander laughs. "They have the vexing property of not occurring below about 8,000 feet, way above the treeline."

"At 95 million years ago, the northeastern part of Gondwana, the African plate (which the Kössen Formation was part of), started to push against the European plate, ending with the formation of the very complex piles of different rock units (called 'nappes') in the Alpine orogeny at about 30-40 million years ago," relates Furrer. So it is that these intrepid researchers found themselves picking through the frozen rocks of the Alps and hauling pieces of ancient marine monsters nearly down to sea level once again for entry into the scientific record.

See: https://phys.org/news/2022-04-huge-ichthyosaur-largest-animals-uncovered.html

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An artist rendering of what it is believed Jurassic marine Ichthyosaur with teeth would have looked like.
(Image: Getty)


See: https://www.newscientist.com/article/mg25634180-900-largest-ever-animal-may-have-been-triassic-ichthyosaur-super-predator/?utm_source=nsnew&utm_medium=email&utm_campaign=nsnew_291222&utm_term=Newsletter NSNEW_Weekly

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animalia-life.com

Ichthyosaurs were the most marine-adapted type of all the reptiles. When they first make their appearance in the fossil record in the Triassic, they are already recognizable as ichthyosaurs adapted to an aquatic existence. For this reason, their ancestry has remained a mystery since their discovery in the eighteenth century. Ichthyosaurs ranged in size from less than a meter to over thirteen meters in length.

Early ichthyosaurs had already modified their forelimbs and hindlimbs into winglike structures. The limbs in ichthyosaurs had hyperphalangeal conditions, whereby there was an increase in the usual number of phalanges in each finger. Some ichthyosaurs expanded the width of the wing by adding extra rows of fingers, a condition known as hyperdactyly. The tails had reevolved a fin that either extended from the middorsal surface to the midventral surface or formed a semilunate tail. In these ichthyosaurs, the body plan already was porpoiselike, with a barrel-shaped thorax and tapering tail. Along these lines, icthyosaurs reevolved a dorsal fin.

The skull, with its beaklike rostrum, had a narrow snout with large orbits, with sclerotic plates for maintaining the shape of the eyes. The nostrils had migrated backward to lie in front of the orbits and the temporal region was reduced. The skull behind the large eyes was much reduced. The ichthyosaurs retained one large temporal fenestra (bone opening) that housed the pseudotemporalis muscle. The other main jaw adductor, the pterygoideus, originated on the palate.

Based upon the temporal fenestral pattern, these forms were classified as either their own class of reptiles or were considered to be a member of the Euryapsida. Evidence from the skull and reproductive strategy point to another ancestry. The ichthyosaur skull shows the loss of the lower temporal opening of the diapsid skull condition. In addition, ichthyosaurs were live bearers of their young, with a placenta-like structure. The only reptilian group with the loss of the lower temporal fenestra and loss of the eggshell is the diapsid Lepidosauria. All other reptilian groups use the eggshell for the main source of calcium for the skeletal development of the embryo, and thus the eggshell cannot be eliminated in their reproductive cycle.


Ichthyosaurs are typed according to their mode of locomotion or by the morphology and shape of the pectoral flippers. The Neoceratodus type, or lungfish type, is so called because their straight tails resembled the tails of lungfish. These types had equally sized pectoral and pelvic flippers. It is considered that these forms had a flexible body with some degree of tail undulation possible for locomotion. The winglike forelimbs, with their hyperphalangy condition, gave them a hydrodynamic shape, and may have been their main propulsion system, acting as wings.

Jurassic ichthyosaurs saw the development of a tunalike semilunate tail fin. These types, known as Inia type, named after the Amazon dolphin, were considered to be faster and more maneuverable swimmers than the Neoceratodus type. The hind limbs are reduced in these forms, and it is considered by some that the forelimbs were used as wings and the tail was used as a steering device. Others consider that the semilunate tail was used in a form of swimming used by tunas, known as carangiform swimming, using rapid movements of the tail.

The vertebral column here extended into the lower lobe of the tail. A cartilage ray extended into the leading edge of the upper lobe of the tail, as seen in beautifully preserved tail found in the upper Jurassic deposits around Solnhofen, Germany. These forms also had a well-developed dorsal fin to aid in the prevention of rolling during swimming. It is thought that these ichthyosaurs had a more rigid body and thus had less drag on the body during swimming. Another ichthyosaur form, the Leptopterygius type, had well-developed hind limb flippers and pelvic girdle, and slightly reduced pectoral flippers.

Undulation of the tail was considered the main propulsion system of these ichthyosaurs. Finally, in the Mixosaurus type, undulation of the body seems to have been the mode of locomotion. In this body form, a series of elongated neural spines supported the tail fin.

There seem to be two opposing views of ichthyosaur swimming speed and prey capture. Some authors believe that ichthyosaurs were high-speed swimmers, while others feel that ichthyosaurs were slower moving but highly maneuverable, and perhaps capable of short, high-speed swimming bursts. Much is known about the diet of ichthyosaurs through the preservation of stomach contents. Many ichthyosaur species relied heavily on squid and, to a lesser degree, fish. There are reports of pterosaur remains preserved in the guts of ichthyosaurs as well.

Surprisingly, much is also known concerning the reproductive habits of ichthyosaurs. Because of their wing limbs and their round-girthed bodies, it is unlikely that ichthyosaurs came out of the water. How then did they give birth? The answer to this question lay in some of the most spectacular fossils of ichthyosaurs housed in the Stuttgart Museum in Germany. Female ichthyosaurs were preserved in the act of giving birth, whether from problems arising in the birthing process or possibly from poisonous dinoflagellate blooms that killed the ichthyosaurs during the birthing process. In some of these fossils the preserved offspring can be seen lying in a placenta-like structure expelled from the female’s body. Other baby ichthyosaurs are often seen in the abdominal area of the ichthyosaur, and were previously thought to be the result of cannibalism. However, it is more likely that these were developing fetuses.

Ichthyosaur Facts
Classification:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Craniata
Class: Reptilia
Subclass: Lepidosauria
Order: Ichthyopterygia
Family: Ophthalmosauria
Genus and species: Ophthalmosaurus icenicus
Geographical location: Oceans of the Mesozoic Era
Habitat: Marine
Gestational period: Unknown
Life span: Unknown
Special anatomy: Limbs transformed to flippers (wings) that employ hyperphalangy to elongate flipper; reevolve dorsal fin and tail fluke in some; smooth skin without scales; rostrum elongate with conical labyrinthodont teeth; live-bearing

See: https://animalia-life.club/ichthyosaur.html

I cannot begin to grasp the size and the complexity of these identified ichthyosaurs. However, the massive size of a predator is directly proportional to the availability and size of their prey. The oceans, especially Panthalassa, the world's ocean surrounding the supercontinent Pangaea during the Late Triassic, about 205 million years ago, and the Tethys Sea, must have been chocked full of edible species. Predators who depend on prey as food, and their fates are linked strongly to key prey species, may be particularly vulnerable to changes in climate that affect the subnivean habitats of their prey. All carnivores are predators and herbivores—and sometimes omnivores or other carnivores—are their prey.
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