[Animals] This was the first giant animal that inhabited the Earth

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A marine reptile the size of a sperm whale lived before the dinosaurs

The first giant to inhabit the earth was not a dinosaur, but a marine reptile the size of a sperm whale. It lived about 246 million years ago and was more than 17 meters long. A group of scientists, after discovering in the Augusta Mountains, in Nevada (United States), a fossil of its enormous skull - two meters long -, parts of the spine, the shoulder and the front fin, has given it its name : Cymbospondylus youngorum. It is the oldest giant ichthyosaur ever found.

The find is shedding new light on the rapid growth of marine reptiles to become giants of the oceans. This colossal animal in turn comes from a reptile that is still unknown today that came out of the water to return to it, millions of years later. Furthermore, he lived only three million more years after that return, a surprisingly short period of time.

So while ichthyosaurs dominated the oceans while dinosaurs did the same on land, this newly discovered specimen was at least three million years ahead of the appearance of the great terrestrial saurians.

"We live in an age of ocean giants: today's blue whales, right whales, sperm whales, and killer whales are not only extremely large marine predators, but each represents the largest examples of their lineages." , The scientific article SQUID AND FISH, THEIR PREFERRED PREY
"In particular, the gigantism of whales appears to be a relatively recent phenomenon, which has only evolved in the last million years, which is only a fraction of its total evolutionary history," note the authors, who wonder if this delay in the increase of gigantism it is valid for the oceanic giants in other times of the past. that reveals the discovery of Cymbospondylus youngorum begins.

Cymbospondylus youngorum Recreation | Stephanie abramowicz
"After all, dozens of reptile and mammal lineages have invaded ocean ecosystems over the past 300 million years, and whale-sized vertebrates have evolved many times over," add the researchers who describe "the first ocean giant." .

What do scientists know about this amazing reptile? For example, that it had an elongated snout and conical teeth suggested that it fed on squid and fish, although due to its size it could have also hunted smaller and juvenile marine reptiles.

The giant predator probably had some stiff competition. Using a sophisticated computational model, the authors recreated the ancient environment and others found that marine food webs were able to support even more colossal carnivorous ichthyosaurs.

The researchers believe that ichthyosaurs of different sizes and survival strategies proliferated at that time, comparable to modern cetaceans, from relatively small dolphins to filter-feeding baleen whales and giant squid-hunting sperm whales.

Study co-author and ecological modeler Eva Maria Griebeler, from the University of Mainz in Germany, notes: “Due to their large size and the resulting energy demands, the densities of the largest ichthyosaurs must have been substantially lower than suggested. by our field census ”.

 

SIMILARITIES WITH WHALES
The discovery of Cymbospondylus youngorum can decisively help the understanding of the evolution of whales, since both share more than one size range, have similar body plans and arose after mass extinctions. "These similarities make them scientifically valuable for comparative study," the scientists emphasize.

In fact, they have already discovered that although both cetaceans and ichthyosaurs evolved towards very large body sizes, their respective trajectories towards gigantism are different. "Ichthyosaurs had an initial boom in size, becoming giants early in their evolutionary history, while whales took much longer to reach the outer limits of the enormous," they point out.

They find connections between large size and two aspects: active predation and tooth loss. For example, giant whales, which are the largest animals that ever lived, are filter feeders.

 

A woman poses next to the skull of C. youngorum | Martin sander
According to the researchers, the ichthyosaurs' initial foray into gigantism was likely due to the rise of ammonites (extinct cephalopod mollusks) and conodonts (extinct marine chordates) that filled the ecological void that followed the mass extinction of the late Permian and which could have been their main source of food.

"Another interesting aspect is that Cymbospondylus youngorum is a testament to the resilience of life in the oceans after the worst mass extinction in the history of the Earth", that of the Permian, highlights Jorge -Vélez-Juarbe, paleontologist and expert in marine mammals from the Los Angeles County Museum of Natural History (NHM).

AN EVEN BIGGER ICTIOSAUR: 26 METERS
But this cyclopean animal is not the largest ichthyosaur known. There were much older. Four years ago, a group of scientists discovered in Gloucestershire (United Kingdom) fossil remains of another animal of epic proportions: a marine reptile that lived 205 million years ago and that measured 26 meters, almost the length of a blue whale. It was even larger than Shonisaurus sikanniensis, a 21-meter-long ichthyosaur discovered in 2004 in Canada.

That finding led experts to question whether, as was previously believed, creatures larger than blue whales could have been plying the Earth's oceans. At the moment they have not been found, but scientists do not rule out that they appear at any time.

Ichthyosaurs were the marine contemporaries of dinosaurs, with body shapes superficially similar to those of dolphins. They reached their greatest diversity about 210 million years ago, in the Upper Triassic, but some lasted until the Upper Cretaceous. They disappeared from the fossil record about 25 million years before the mass extinction that wiped out the non-avian dinosaurs.

 

Link: https://www.sport.es/es/noticias/medio-ambiente/primer-animal-gigante-habito-tierra-13050210